1. The document summarizes a study that evaluated the effect of mixed corrosion inhibitors in a cooling water system. Carbon steel specimens were immersed in mixtures of sodium phosphate and sodium glocunate at different concentrations and temperatures.
2. The corrosion inhibitors efficiency was calculated to be 98.1% using inhibited versus uninhibited water. The corrosion rate decreased with higher inhibitor concentration and temperature, with the lowest rate of 0.014gmd at 80 ppm and 100°C for 5 days.
3. Corrosion occurs electrochemically when an electric current flows from one part of a metal to another through water. Various factors like dissolved solids, pH, alkalinity, and hardness affect corrosion
This document provides an overview of cooling water problems and solutions. It discusses common issues like scaling, corrosion, and biological growth that result from poor water quality. The document then covers critical water parameters like conductivity, pH, alkalinity, hardness, and saturation index. It explains different types of scale and methods to control scale, such as water softening, pH adjustment, controlling concentration cycles, and chemical treatment. The focus is on maintaining water quality to prevent problems and reduce maintenance costs for cooling systems.
This document discusses cooling water chemistry and chemical treatment. It outlines the sources and typical chemistry of cooling water makeup. Key factors that must be controlled include calcium carbonate, chlorides, pH, and suspended solids. Major cooling water problems are corrosion, scaling, biofouling, and fouling. Chemicals added to control these include zinc phosphate for corrosion inhibition, scale inhibitors, oxidizing and non-oxidizing biocides, and dispersants. Maintaining proper cooling water chemistry limits is important for the effective functioning and protection of cooling systems.
This document discusses cooling water treatment at a fertilizer plant in India. It provides details on the plant's cooling towers and water chemistry parameters. Cooling water treatment is needed to prevent corrosion, scaling, and microbial fouling of the system. Common issues like corrosion, scaling, and biofouling are discussed along with the mechanisms of corrosion inhibition, scale inhibition, and microbial control through chemical treatment.
The document discusses a water treatment seminar that covers properties of water, pH, chiller and cooling tower operation, and common problems in cooling tower water like scale, corrosion, fouling, and microbiological fouling. It explains how water treatment chemicals can prevent scale through crystal distortion and dispersancy, and inhibit corrosion through the formation of protective films on metal surfaces. Proper bleed-off is also important to control mineral concentrations and prevent scale formation.
Chemical oxygen demand (COD) is a measure of the oxygen-consuming capacity of inorganic and organic matter in water. COD determines the amount of oxygen required to oxidize organic compounds and inorganic matter in water. There are two main methods to measure COD - the open reflux method and closed reflux method. The open reflux method involves refluxing the sample and dichromate solution for 2 hours, then titrating the remaining dichromate with ferrous ammonium sulfate to determine COD concentration in mg/L. A high COD means more oxidizable organic material is present in water, which can reduce dissolved oxygen and harm aquatic life. COD is useful for assessing waste strength and effects on receiving environments
IRJET-Review of Marine Environmental Corrosion and Application of an Anti-Cor...IRJET Journal
This document discusses corrosion of ship hulls and methods to prevent corrosion through protective coatings. It provides background on corrosion processes and types, including uniform corrosion and localized corrosion like pitting and crevice corrosion. Different zones of a ship are discussed in relation to corrosion risk and appropriate paint types. Various international standards for marine paints are also outlined. The conclusion emphasizes the importance of using a primer coat and high-quality filler and paint, as well as the potential for sampling inspection plans to improve coating quality and monitoring on ship hulls.
The document summarizes an experimental study of gas hydrate formation and deposition in oil and condensate systems using a visual rocking cell. Key findings include:
- Hydrate deposition was observed in all systems tested, with higher deposition on surfaces exposed to condensate or gas compared to oil-wetted surfaces.
- Porous hydrate deposits formed under conditions with a large temperature gradient and high subcooling, which then suffered sloughing due to fluid shear.
- Hydrate formation in a system with mineral oil, 30% water cut, and an anti-agglomerant resulted in a transportable hydrate slurry.
1991_Sensitivity to Iron Impurity Content of Corrosion Rate of Mg-15Al_Cotton...James D. Cotton
The corrosion rates of extrusions produced from rapidly-solidified Mg-15wt%AI alloy powder containing varying levels of iron (Fe) impurity (0.003-0.020wt%) were studied. Trace amounts of Fe were found to have a strong exponential effect on the corrosion rate, consistent with previous studies. However, the sensitivity to Fe content was markedly lower for the rapidly-solidified alloys compared to conventionally-cast alloys. This effect is explained by the microstructural refinement produced by rapid solidification, which decreases the scale of microstructure and distributes corrosion more evenly. Both pitting and filiform corrosion were observed and characterized using various microscopy techniques.
This document provides an overview of cooling water problems and solutions. It discusses common issues like scaling, corrosion, and biological growth that result from poor water quality. The document then covers critical water parameters like conductivity, pH, alkalinity, hardness, and saturation index. It explains different types of scale and methods to control scale, such as water softening, pH adjustment, controlling concentration cycles, and chemical treatment. The focus is on maintaining water quality to prevent problems and reduce maintenance costs for cooling systems.
This document discusses cooling water chemistry and chemical treatment. It outlines the sources and typical chemistry of cooling water makeup. Key factors that must be controlled include calcium carbonate, chlorides, pH, and suspended solids. Major cooling water problems are corrosion, scaling, biofouling, and fouling. Chemicals added to control these include zinc phosphate for corrosion inhibition, scale inhibitors, oxidizing and non-oxidizing biocides, and dispersants. Maintaining proper cooling water chemistry limits is important for the effective functioning and protection of cooling systems.
This document discusses cooling water treatment at a fertilizer plant in India. It provides details on the plant's cooling towers and water chemistry parameters. Cooling water treatment is needed to prevent corrosion, scaling, and microbial fouling of the system. Common issues like corrosion, scaling, and biofouling are discussed along with the mechanisms of corrosion inhibition, scale inhibition, and microbial control through chemical treatment.
The document discusses a water treatment seminar that covers properties of water, pH, chiller and cooling tower operation, and common problems in cooling tower water like scale, corrosion, fouling, and microbiological fouling. It explains how water treatment chemicals can prevent scale through crystal distortion and dispersancy, and inhibit corrosion through the formation of protective films on metal surfaces. Proper bleed-off is also important to control mineral concentrations and prevent scale formation.
Chemical oxygen demand (COD) is a measure of the oxygen-consuming capacity of inorganic and organic matter in water. COD determines the amount of oxygen required to oxidize organic compounds and inorganic matter in water. There are two main methods to measure COD - the open reflux method and closed reflux method. The open reflux method involves refluxing the sample and dichromate solution for 2 hours, then titrating the remaining dichromate with ferrous ammonium sulfate to determine COD concentration in mg/L. A high COD means more oxidizable organic material is present in water, which can reduce dissolved oxygen and harm aquatic life. COD is useful for assessing waste strength and effects on receiving environments
IRJET-Review of Marine Environmental Corrosion and Application of an Anti-Cor...IRJET Journal
This document discusses corrosion of ship hulls and methods to prevent corrosion through protective coatings. It provides background on corrosion processes and types, including uniform corrosion and localized corrosion like pitting and crevice corrosion. Different zones of a ship are discussed in relation to corrosion risk and appropriate paint types. Various international standards for marine paints are also outlined. The conclusion emphasizes the importance of using a primer coat and high-quality filler and paint, as well as the potential for sampling inspection plans to improve coating quality and monitoring on ship hulls.
The document summarizes an experimental study of gas hydrate formation and deposition in oil and condensate systems using a visual rocking cell. Key findings include:
- Hydrate deposition was observed in all systems tested, with higher deposition on surfaces exposed to condensate or gas compared to oil-wetted surfaces.
- Porous hydrate deposits formed under conditions with a large temperature gradient and high subcooling, which then suffered sloughing due to fluid shear.
- Hydrate formation in a system with mineral oil, 30% water cut, and an anti-agglomerant resulted in a transportable hydrate slurry.
1991_Sensitivity to Iron Impurity Content of Corrosion Rate of Mg-15Al_Cotton...James D. Cotton
The corrosion rates of extrusions produced from rapidly-solidified Mg-15wt%AI alloy powder containing varying levels of iron (Fe) impurity (0.003-0.020wt%) were studied. Trace amounts of Fe were found to have a strong exponential effect on the corrosion rate, consistent with previous studies. However, the sensitivity to Fe content was markedly lower for the rapidly-solidified alloys compared to conventionally-cast alloys. This effect is explained by the microstructural refinement produced by rapid solidification, which decreases the scale of microstructure and distributes corrosion more evenly. Both pitting and filiform corrosion were observed and characterized using various microscopy techniques.
This document discusses corrosion in cooling water systems. It outlines the corrosion process and the elements required for corrosion to occur. The rate and type of corrosion are determined by factors at the cathode and anode. Various types of corrosion in cooling water systems are described, including general etch, concentration cell corrosion, cracking, and mechanical damage. Finally, general methods for corrosion inhibition are presented, such as using corrosion resistant materials, coatings, cathodic protection, water chemistry adjustments, and corrosion inhibitors.
Selection of an appropriate corrosion inhibitor, inhibitor combination or package is an exceptionally cost
effective and materials saving measure in various industries.
The document discusses key terms and concepts related to water pollution, including chemical oxygen demand (COD), biochemical oxygen demand (BOD), and dissolved oxygen (DO). COD measures all organic and inorganic compounds that can be oxidized, while BOD specifically measures biologically degradable organic matter. BOD tests how much oxygen is consumed by microbes to break down organic waste over 5 days. COD values are always higher than BOD since COD includes non-biodegradable materials. Turbidity is a measure of cloudiness caused by suspended particles, while total suspended solids is a direct measurement of particulate matter in water.
Power plant chemistry corrosion theory and its preventionumar farooq
The document provides information about corrosion theory and prevention in power plants. It defines corrosion and discusses corrosion mechanisms such as the corrosion cell and various corrosion reactions. It also covers different types of corrosion like general corrosion, pitting, galvanic corrosion and stress corrosion cracking. Additionally, it lists factors that affect corrosion rates like dissolved gases, solids, temperature and acidity. Finally, it discusses methods of corrosion control like using corrosion inhibitors and promoting protective scales to change the corrosive environment. The document is a technical report on corrosion prepared by Umar Farooq, a chemist at SEC in Saudi Arabia.
This document discusses corrosion issues related to transporting ethanol in pipelines. It examines the properties of ethanol, including that it contains small amounts of acetic acid which is corrosive when combined with moisture. The document outlines the corrosion mechanisms of acetic acid and how it can cause general or localized pitting corrosion of pipeline materials at certain pH levels. It recommends selecting pipeline materials like carbon steel that can be effectively protected with corrosion inhibitors. Proper material selection and inhibition programs are necessary to prevent corrosion when transporting ethanol in pipelines.
Nuclear power plants are a type of power plant that use the process of nuclear fission in order to generate electricity. They do this by using nuclear reactors in combination with the Rankine cycle, where the heat generated by the reactor converts water into steam, which spins a turbine and a generator. You can check this link for more professional presentation design, template and slides;
https://bit.ly/2NStcZ9
This document discusses key concepts related to waste water treatment including biochemical oxygen demand (BOD), chemical oxygen demand (COD), and dissolved oxygen (DO). BOD measures the amount of oxygen required by microorganisms to break down organic matter in water. COD determines the oxygen required to oxidize organic compounds. DO refers to oxygen dissolved in water that aquatic life requires. The document outlines typical values and measurement methods for BOD, COD and DO in waste and natural waters. It also describes the nature of waste water pollutants and an overview of waste water treatment processes.
'Corrosion' may seem to be a simple word. But the underlying mechanism and its significance in Major industries are just reviewed in the presentation named "FAC- Flow Accelerated Corrosion"
The document discusses prognostic and deterministic analysis of thinning rates due to flow accelerated corrosion. It outlines developing a mechanistic model to predict thinning rates in nuclear power plant pipelines. The model considers factors like flow velocity, temperature, pH and water chemistry. Mathematical equations are presented for calculating the mass transfer coefficient and solubility driving force. CFD simulations are performed and results are validated against experimental data. Finally, the model is used to determine a 5.5 year time interval for maintenance scheduling to prevent pipe wall thickness from falling below the failure threshold.
This document provides an introduction to water treatment. It discusses the water cycle and distribution of water on Earth. Only 1% of water is usable, with surface water often contaminated and groundwater usually suitable for direct use if not contaminated. Water treatment methods aim to remove impurities and are classified as physical, chemical, or biological. Common treatment includes coagulation, sedimentation, filtration, and disinfection. Standards for drinking water quality are also presented.
This document discusses water treatment for cooling towers. It aims to control corrosion, scale, and algae/bacterial growth in order to extend equipment life and efficiency. Common dissolved solids like calcium, magnesium, and minerals are naturally present in water and can cause issues if not controlled. Cycles of concentration concentrate solids and must be managed through bleed-off. Scale forms when minerals exceed solubility and can be prevented through scale inhibitors and dispersants. Corrosion results from oxygen interacting with metals and is controlled by preventing this interaction.
BOD measures the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material in water, while COD measures the amount of oxygen required to chemically oxidize organic compounds. COD is generally higher than BOD because it measures oxidation of all organic compounds, whereas BOD only measures biologically degradable compounds. Both are used to assess water quality, but COD provides a faster and more accurate measurement than BOD. The ratio of COD to BOD can also indicate the toxicity of wastewater.
This document summarizes a study on the effects of shear stress and oxygen levels on the toxicity of contaminated sediment and overlying water. Gust chambers were used to subject sediment cores to different shear stresses and oxygen concentrations. Testing found that oxygen had a greater effect than shear stress on the release of metals like copper from sediments. Under oxygenated conditions, more metal sulfides dissolved, releasing metals into the water. While toxicity was low under experimental conditions, substantial metal release occurred even at low shear stresses. The presence of oxygen significantly increased metal release from sediments.
Corrosive microenvironments at lead solder surfaces arising from galvanic cor...dondeyas
1) When stagnant water contacts copper pipe and lead solder, a corrosion cell is formed that can accelerate the corrosion of lead if the galvanic current exceeds 2 μA/cm2.
2) High galvanic currents from waters with relatively high chloride levels can prevent the passivation of solder surfaces and contribute to lead contamination.
3) If the chloride concentration increases relative to sulfate in the water, galvanic currents and associated lead contamination are greatly reduced as solder surfaces become readily passivated.
This document reviews materials for corrosion prevention in the oil industry. It discusses how corrosion impacts oil production, transportation, and processing. Common causes of corrosion include mineral acids formed from salts in crude oil. Recent research has focused on developing new corrosion-resistant materials, chemicals to remove water and neutralize acids, and surface-active substances. Various amines, nitrogen compounds, and commercial inhibitors like HERCULES-30617 and DEOL-4241 are used to inhibit corrosion in different operations. The review aims to analyze existing approaches and develop new materials for applications in corrosion prevention.
01 Judd Sundine - Mine Water Solutions in Extreme Environments 2015Judd Sundine
This document summarizes an article on using electrocoagulation (EC) to remove heavy metals and other contaminants from mine wastewater in an innovative, economical, and efficient way. EC uses electric current passed through metal blades in water to destabilize particles, allowing contaminants to be removed through precipitation and filtration. EC has been shown to remove over 99% of some heavy metals and is more cost effective than traditional chemical coagulation methods. The produced sludge meets standards for non-hazardous waste disposal.
Dissolved Oxygen Demand (DO) AND Chemical Oxygen Demand (COD) PDFchetansingh999
Dissolved oxygen (DO) refers to the level of oxygen present in water or other liquids. It is important for assessing water quality and supporting aquatic life. Chemical oxygen demand (COD) measures the amount of oxygen required to chemically break down pollutants in water. DO enters water through diffusion from air and as a byproduct of photosynthesis. It can be measured using electrochemical, optical, or colorimetric methods. COD is determined by using potassium dichromate as an oxidizing agent under acidic conditions, then measuring the amount of chromium formed.
1. Corrosion is the reaction of a metallic material with its environment that causes measurable changes to the material and can result in failure. Rusting of iron is a common example of corrosion.
2. Corrosion occurs through either dry corrosion involving direct attack of gases on metals, or wet corrosion involving direct attack of aqueous media through electrochemical reactions.
3. Factors that influence the rate of corrosion include material properties, solution pH, temperature, velocity of corrosive media, and presence of impurities.
Biochemical Oxygen Demand and its Industrial SignificanceAdnan Murad Bhayo
BOD is the amount of dissolved oxygen needed by aerobic biological organism in a body of water to breakdown organic material present in a given water sample at certain temperature over a specific time period .
Most of Bacteria in the aquatic columns are aerobic. Escherichia coli, Bacillus subtilis, Vibrio cholera.
Atmosphere contains 21% oxygen (210000 mg/dm3)
Higher the temperature of water higher will be the rate of respiration. So, concentration of oxygen decreases.
Many Animal species can grow and reproduce normally when dissolved oxygen level is ~ 5.0 mg/L.
HYPOXIA: When dissolve oxygen content below 3.0 mg/L. Many Species move elsewhere and immobile species may die
ANOXIA: When dissolve oxygen content below 0.5 mg/L. All aerobic species will die
Fertilizer contains Nitrate contributes to high BOD
Phosphate present in Soap and detergent that enhances the growth of algal blooms. As a result depletion of oxygen occur.
In a body of water with large amount of decaying organic material , the dissolved oxygen level may drop by 90 %, this would represent High BOD
In a body of water with small amount of decaying organic material , the dissolved oxygen level may drop by 10 %, this would represent Low BOD
ANALYSIS OF BOD OF WATER
Use glass bottles having 60 mL or greater capacity. Take samples of water.
Turn on the constant temperature chamber to allow the
controlled temperature to stabilize at 20°C ±1°C.
Record the DO level (ppm) of one immediately.
Place water sample in an incubator in complete darkness at 20 C for 5 days. Exclude all light to prevent possibility of photosynthetic production of DO
If don't have an incubator, wrap the water sample bottle in aluminum foil or black electrical tape and store in a dark place at room temperature (20o C or 68 °F).
DILUTION OF SAMPLE
Most relatively unpolluted streams have a BOD5 that ranges from 1 to 8 mg/L
Dilution is necessary when the amount of DO consumed by microorganisms is greater than the amount of DO available in the air-saturated.
If the BOD5 value of a sample is less than 7 mg/L, sample dilution is not needed.
The DO concentration after 5 days must be at least 1 mg/L and at least 2 mg/L lower in concentration than the initial DO
(American Public Health Association and others, 1995).
BOD of the dilution water is less than 0.2 mg/L.
Discard dilution water if there is any sign of biological growth.
pH of the dilution water needs to be maintained in a range suitable for bacterial growth
Bacterial growth is very good between 6.5 to 7.5
Sulfuric acid or sodium hydroxide may need to be added to the dilution water to lower or raise the pH, respectively.
CALCULATION:
The general equation for the determination of a BOD5 value is:
BOD = D1-D2/P
Where
D1 = initial DO of the sample,
D2 = final DO of the sample after 5 days, and
P = decimal volumetric fraction of sample used.
If 100 mL of sample a
1. The document describes an experiment to determine the hardness of water samples through titration with EDTA using indicators. Total hardness, calcium hardness, and magnesium hardness were calculated based on the titration volumes.
2. Hardness is caused by calcium and magnesium ions in water and is a measure of its ability to form precipitates with soap. It can be temporary, from bicarbonates, or permanent, from chlorides and sulfates.
3. The results found a total hardness of 400 mg/L as CaCO3, calcium hardness of 140 mg/L as CaCO3, and magnesium hardness of 260 mg/L as CaCO3 for the water sample tested.
This document discusses cooling water problems like scaling, corrosion, and biological growth. It provides an overview of common cooling water treatment methods to control these issues, including water softening, pH adjustment, controlling cycles of concentration, and using chemical treatments like polymers, phosphonates, and chelants. The key parameters for cooling water quality are discussed, such as conductivity, total dissolved solids, hardness, pH, alkalinity, and saturation index. Common types of scaling like calcium carbonate and calcium sulfate are also summarized.
Benefit from improved water quality management. Maintaining good water quality ensures clean heat exchangers, corrosion free piping and equipment's life and maximize a plant's productivity.
This document discusses corrosion in cooling water systems. It outlines the corrosion process and the elements required for corrosion to occur. The rate and type of corrosion are determined by factors at the cathode and anode. Various types of corrosion in cooling water systems are described, including general etch, concentration cell corrosion, cracking, and mechanical damage. Finally, general methods for corrosion inhibition are presented, such as using corrosion resistant materials, coatings, cathodic protection, water chemistry adjustments, and corrosion inhibitors.
Selection of an appropriate corrosion inhibitor, inhibitor combination or package is an exceptionally cost
effective and materials saving measure in various industries.
The document discusses key terms and concepts related to water pollution, including chemical oxygen demand (COD), biochemical oxygen demand (BOD), and dissolved oxygen (DO). COD measures all organic and inorganic compounds that can be oxidized, while BOD specifically measures biologically degradable organic matter. BOD tests how much oxygen is consumed by microbes to break down organic waste over 5 days. COD values are always higher than BOD since COD includes non-biodegradable materials. Turbidity is a measure of cloudiness caused by suspended particles, while total suspended solids is a direct measurement of particulate matter in water.
Power plant chemistry corrosion theory and its preventionumar farooq
The document provides information about corrosion theory and prevention in power plants. It defines corrosion and discusses corrosion mechanisms such as the corrosion cell and various corrosion reactions. It also covers different types of corrosion like general corrosion, pitting, galvanic corrosion and stress corrosion cracking. Additionally, it lists factors that affect corrosion rates like dissolved gases, solids, temperature and acidity. Finally, it discusses methods of corrosion control like using corrosion inhibitors and promoting protective scales to change the corrosive environment. The document is a technical report on corrosion prepared by Umar Farooq, a chemist at SEC in Saudi Arabia.
This document discusses corrosion issues related to transporting ethanol in pipelines. It examines the properties of ethanol, including that it contains small amounts of acetic acid which is corrosive when combined with moisture. The document outlines the corrosion mechanisms of acetic acid and how it can cause general or localized pitting corrosion of pipeline materials at certain pH levels. It recommends selecting pipeline materials like carbon steel that can be effectively protected with corrosion inhibitors. Proper material selection and inhibition programs are necessary to prevent corrosion when transporting ethanol in pipelines.
Nuclear power plants are a type of power plant that use the process of nuclear fission in order to generate electricity. They do this by using nuclear reactors in combination with the Rankine cycle, where the heat generated by the reactor converts water into steam, which spins a turbine and a generator. You can check this link for more professional presentation design, template and slides;
https://bit.ly/2NStcZ9
This document discusses key concepts related to waste water treatment including biochemical oxygen demand (BOD), chemical oxygen demand (COD), and dissolved oxygen (DO). BOD measures the amount of oxygen required by microorganisms to break down organic matter in water. COD determines the oxygen required to oxidize organic compounds. DO refers to oxygen dissolved in water that aquatic life requires. The document outlines typical values and measurement methods for BOD, COD and DO in waste and natural waters. It also describes the nature of waste water pollutants and an overview of waste water treatment processes.
'Corrosion' may seem to be a simple word. But the underlying mechanism and its significance in Major industries are just reviewed in the presentation named "FAC- Flow Accelerated Corrosion"
The document discusses prognostic and deterministic analysis of thinning rates due to flow accelerated corrosion. It outlines developing a mechanistic model to predict thinning rates in nuclear power plant pipelines. The model considers factors like flow velocity, temperature, pH and water chemistry. Mathematical equations are presented for calculating the mass transfer coefficient and solubility driving force. CFD simulations are performed and results are validated against experimental data. Finally, the model is used to determine a 5.5 year time interval for maintenance scheduling to prevent pipe wall thickness from falling below the failure threshold.
This document provides an introduction to water treatment. It discusses the water cycle and distribution of water on Earth. Only 1% of water is usable, with surface water often contaminated and groundwater usually suitable for direct use if not contaminated. Water treatment methods aim to remove impurities and are classified as physical, chemical, or biological. Common treatment includes coagulation, sedimentation, filtration, and disinfection. Standards for drinking water quality are also presented.
This document discusses water treatment for cooling towers. It aims to control corrosion, scale, and algae/bacterial growth in order to extend equipment life and efficiency. Common dissolved solids like calcium, magnesium, and minerals are naturally present in water and can cause issues if not controlled. Cycles of concentration concentrate solids and must be managed through bleed-off. Scale forms when minerals exceed solubility and can be prevented through scale inhibitors and dispersants. Corrosion results from oxygen interacting with metals and is controlled by preventing this interaction.
BOD measures the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material in water, while COD measures the amount of oxygen required to chemically oxidize organic compounds. COD is generally higher than BOD because it measures oxidation of all organic compounds, whereas BOD only measures biologically degradable compounds. Both are used to assess water quality, but COD provides a faster and more accurate measurement than BOD. The ratio of COD to BOD can also indicate the toxicity of wastewater.
This document summarizes a study on the effects of shear stress and oxygen levels on the toxicity of contaminated sediment and overlying water. Gust chambers were used to subject sediment cores to different shear stresses and oxygen concentrations. Testing found that oxygen had a greater effect than shear stress on the release of metals like copper from sediments. Under oxygenated conditions, more metal sulfides dissolved, releasing metals into the water. While toxicity was low under experimental conditions, substantial metal release occurred even at low shear stresses. The presence of oxygen significantly increased metal release from sediments.
Corrosive microenvironments at lead solder surfaces arising from galvanic cor...dondeyas
1) When stagnant water contacts copper pipe and lead solder, a corrosion cell is formed that can accelerate the corrosion of lead if the galvanic current exceeds 2 μA/cm2.
2) High galvanic currents from waters with relatively high chloride levels can prevent the passivation of solder surfaces and contribute to lead contamination.
3) If the chloride concentration increases relative to sulfate in the water, galvanic currents and associated lead contamination are greatly reduced as solder surfaces become readily passivated.
This document reviews materials for corrosion prevention in the oil industry. It discusses how corrosion impacts oil production, transportation, and processing. Common causes of corrosion include mineral acids formed from salts in crude oil. Recent research has focused on developing new corrosion-resistant materials, chemicals to remove water and neutralize acids, and surface-active substances. Various amines, nitrogen compounds, and commercial inhibitors like HERCULES-30617 and DEOL-4241 are used to inhibit corrosion in different operations. The review aims to analyze existing approaches and develop new materials for applications in corrosion prevention.
01 Judd Sundine - Mine Water Solutions in Extreme Environments 2015Judd Sundine
This document summarizes an article on using electrocoagulation (EC) to remove heavy metals and other contaminants from mine wastewater in an innovative, economical, and efficient way. EC uses electric current passed through metal blades in water to destabilize particles, allowing contaminants to be removed through precipitation and filtration. EC has been shown to remove over 99% of some heavy metals and is more cost effective than traditional chemical coagulation methods. The produced sludge meets standards for non-hazardous waste disposal.
Dissolved Oxygen Demand (DO) AND Chemical Oxygen Demand (COD) PDFchetansingh999
Dissolved oxygen (DO) refers to the level of oxygen present in water or other liquids. It is important for assessing water quality and supporting aquatic life. Chemical oxygen demand (COD) measures the amount of oxygen required to chemically break down pollutants in water. DO enters water through diffusion from air and as a byproduct of photosynthesis. It can be measured using electrochemical, optical, or colorimetric methods. COD is determined by using potassium dichromate as an oxidizing agent under acidic conditions, then measuring the amount of chromium formed.
1. Corrosion is the reaction of a metallic material with its environment that causes measurable changes to the material and can result in failure. Rusting of iron is a common example of corrosion.
2. Corrosion occurs through either dry corrosion involving direct attack of gases on metals, or wet corrosion involving direct attack of aqueous media through electrochemical reactions.
3. Factors that influence the rate of corrosion include material properties, solution pH, temperature, velocity of corrosive media, and presence of impurities.
Biochemical Oxygen Demand and its Industrial SignificanceAdnan Murad Bhayo
BOD is the amount of dissolved oxygen needed by aerobic biological organism in a body of water to breakdown organic material present in a given water sample at certain temperature over a specific time period .
Most of Bacteria in the aquatic columns are aerobic. Escherichia coli, Bacillus subtilis, Vibrio cholera.
Atmosphere contains 21% oxygen (210000 mg/dm3)
Higher the temperature of water higher will be the rate of respiration. So, concentration of oxygen decreases.
Many Animal species can grow and reproduce normally when dissolved oxygen level is ~ 5.0 mg/L.
HYPOXIA: When dissolve oxygen content below 3.0 mg/L. Many Species move elsewhere and immobile species may die
ANOXIA: When dissolve oxygen content below 0.5 mg/L. All aerobic species will die
Fertilizer contains Nitrate contributes to high BOD
Phosphate present in Soap and detergent that enhances the growth of algal blooms. As a result depletion of oxygen occur.
In a body of water with large amount of decaying organic material , the dissolved oxygen level may drop by 90 %, this would represent High BOD
In a body of water with small amount of decaying organic material , the dissolved oxygen level may drop by 10 %, this would represent Low BOD
ANALYSIS OF BOD OF WATER
Use glass bottles having 60 mL or greater capacity. Take samples of water.
Turn on the constant temperature chamber to allow the
controlled temperature to stabilize at 20°C ±1°C.
Record the DO level (ppm) of one immediately.
Place water sample in an incubator in complete darkness at 20 C for 5 days. Exclude all light to prevent possibility of photosynthetic production of DO
If don't have an incubator, wrap the water sample bottle in aluminum foil or black electrical tape and store in a dark place at room temperature (20o C or 68 °F).
DILUTION OF SAMPLE
Most relatively unpolluted streams have a BOD5 that ranges from 1 to 8 mg/L
Dilution is necessary when the amount of DO consumed by microorganisms is greater than the amount of DO available in the air-saturated.
If the BOD5 value of a sample is less than 7 mg/L, sample dilution is not needed.
The DO concentration after 5 days must be at least 1 mg/L and at least 2 mg/L lower in concentration than the initial DO
(American Public Health Association and others, 1995).
BOD of the dilution water is less than 0.2 mg/L.
Discard dilution water if there is any sign of biological growth.
pH of the dilution water needs to be maintained in a range suitable for bacterial growth
Bacterial growth is very good between 6.5 to 7.5
Sulfuric acid or sodium hydroxide may need to be added to the dilution water to lower or raise the pH, respectively.
CALCULATION:
The general equation for the determination of a BOD5 value is:
BOD = D1-D2/P
Where
D1 = initial DO of the sample,
D2 = final DO of the sample after 5 days, and
P = decimal volumetric fraction of sample used.
If 100 mL of sample a
1. The document describes an experiment to determine the hardness of water samples through titration with EDTA using indicators. Total hardness, calcium hardness, and magnesium hardness were calculated based on the titration volumes.
2. Hardness is caused by calcium and magnesium ions in water and is a measure of its ability to form precipitates with soap. It can be temporary, from bicarbonates, or permanent, from chlorides and sulfates.
3. The results found a total hardness of 400 mg/L as CaCO3, calcium hardness of 140 mg/L as CaCO3, and magnesium hardness of 260 mg/L as CaCO3 for the water sample tested.
This document discusses cooling water problems like scaling, corrosion, and biological growth. It provides an overview of common cooling water treatment methods to control these issues, including water softening, pH adjustment, controlling cycles of concentration, and using chemical treatments like polymers, phosphonates, and chelants. The key parameters for cooling water quality are discussed, such as conductivity, total dissolved solids, hardness, pH, alkalinity, and saturation index. Common types of scaling like calcium carbonate and calcium sulfate are also summarized.
Benefit from improved water quality management. Maintaining good water quality ensures clean heat exchangers, corrosion free piping and equipment's life and maximize a plant's productivity.
This document provides information about feed water treatment methods used in power plants. It discusses the necessity of feed water treatment due to impurities in raw water and the effects of those impurities like scale formation, corrosion, priming and foaming. It then summarizes various treatment methods including zeolite treatment, demineralization, and reverse osmosis. It provides details on how each process works to purify water and remove dissolved solids and minerals. The document is a student presentation covering key aspects of feed water treatment technologies.
This document discusses cooling water problems such as corrosion, scale, fouling, and microbiological contamination. It explains the causes and factors that influence these problems, as well as methods to control and prevent each problem. Key topics covered include the corrosion process, scale formation mechanisms, types of fouling, factors influencing microbial growth, and chemical treatment options for control and prevention.
The document discusses cooling water systems and issues related to corrosion, scaling, and biofouling. It describes three types of cooling water systems - once through, closed re-circulating, and open re-circulating. Major cooling water problems include corrosion, scaling, biofouling, and fouling. Scaling can be caused by high concentrations of calcium carbonate, magnesium, and other substances above the control limits. Chemical treatments use zinc phosphate as a corrosion inhibitor and scale inhibitors along with dispersants to control scaling and suspended solids.
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Evaluation of corrosion inhibitor by weight loss
1. Al-Khwarizmi
Engineering
Journal
Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 76- 87 (2011)
Effect of Mixed Corrosion Inhibitors in Cooling Water System
Dina Raheem
Department of Engineering of Medical instrument/ College of Electronic and Electrical technique
Email: dinarrhh78@yahoo.com
(Received 7 February 2011; Accepted 28 September 2011)
Abstract
The effect of mixed corrosion inhibitors in cooling system was evaluated by using carbon steel specimens and
weight loss analysis. The carbon steel specimens immersed in mixture of sodium phosphate (Na2 HPO4) used as
corrosion inhibitor and sodium glocunate (C6 H11 NaO7) as a scale dispersant at different concentrations (20,40, 60, 80
ppm) and at different temperature (25,50,75 and 100)ºC for (1-5) days. The corrosion inhibitors efficiency was
calculated by using uninhibited and inhibited water to give 98.1%. The result of these investigations indicate that the
corrosion rate decreases with the increase the corrosion inhibitors concentration at 80 ppm and at 100ºC for 5 days, (i.e,
corrosion rate= 0.014gmd).
Keywords: corrosion in cooling tower, carbon steel corrosion, corrosion inhibitor of cooling tower.
1. Introduction
The term “corrosion” (in a cooling water
system) is defined as the electrochemical
deterioration of a metal that is in contact with
cooling water. Corrosion occurs when an electric
current flows from one part of the metal (anode)
through the water (electrolyte) to another part of
the metal (cathode). Corrosion takes place at the
anode only. The cathode is the driving force of
the corrosion action, as shown in the equation;
Metal → Metal ions + electrons
→ + + …(1)
This process degrades the metal, reduces its
strength, thickness, and in some extreme cases,
creates pits and then holes in the material. At
some point in the corrosion process , the metal
can no longer do its job as a system component.
Corrosion, in general, and pitting corrosion, in
particular, must be guarded against in order to
ensure the long term integrity of the cooling
system.[1]
In the corrosion of iron the reaction may proceed
by a single step oxidation Fe into ferric ion :
Fe → Fe+3
+ 3e-
…(2)
In practice, a two-step process occurs in
which iron is first oxidized to ferrous ion
depending on the anode potential,
Fe → Fe+2
+ 2e-
…(3)
And then is oxidized into ferric ion
Fe2+
→ Fe+3
+ e-
…(4)
The reactions above take place at the anode
and must be balanced by other reduction
processes that occur at the cathode. For example:
O2 (gas) + 4H-
+ 4e- → 2H2O …(5)
O2 (gas) + H2O + 4e- →4OH-
…(6)
The formation of OH- at the cathode causes
the pH here to be higher than in the bulk
solution. Eventually, ion migration of OH-
occurs, towards the anode, which promotes the
formation of ferric hydroxide
Fe+3
+ 3OH-
→ Fe(OH)3 …(7)
Fe(OH)3 appears in the form of reddish brown
colloid. This ferric hydroxide may react further
in the presence of ferrous ions to produce Fe3O4
[2].
2. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
77
The primary objectives of cooling water
treatment are to maintain the operating
efficiency of the cooling water system and to
protect the equipment that contacts the cooling
water. These objectives are accomplished by
controlling or minimizing deposition, corrosion,
and microbiological growth on the cooling water
equipment.
The deposits that occur in cooling water
systems are usually divided into two categories:
scale and fouling. The presence of either type of
deposit in the heat exchangers or in the film fill
can interfere with heat transfer, thereby reducing
the efficiency of operation. Deposits can also
promote under-deposit corrosion.
Scale is formed from minerals, formerly
dissolved in water, that were deposited from the
water onto heat transfer surfaces or in-flow
water lines. As water is evaporated in a cooling
tower, the concentration of dissolved solids
becomes greater until the solubility of a
particular scale-causing mineral salt is exceeded.
When this situation occurs in an untreated
cooling water system, the scale will form on any
surface in contact with the water, especially on
heat transfer surfaces. The most common scaling
minerals are calcium carbonate(CaCo3), calcium
phosphate(CaPo4), calcium sulfate(CaSo4), and
silica, usually in that order. Formation of
magnesium silicate scale is also possible under
certain conditions. Most other salts, including
silica, are more soluble in hot water than in cold
water; however, most calcium and magnesium
salts, including calcium phosphate and calcium
carbonate, are more soluble in cold water than in
hot water. This is called “reverse solubility.” The
water temperature will increase as recirculating
water passes through the cooling system. As a
result, calcium and magnesium scales may form
anywhere in the system, but most likely on
heated surfaces such as heat exchangers or
surface condensers. Silica will form in areas
having the lowest water temperature, such as in
the cooling tower fill.
The principle factors responsible for scale
formation are:
1. As alkalinity increases, calcium carbonate- the
most common scale constituent in cooling
systems - decreases in solubility and deposits.
2. The mechanism for scale formation is the in-
situ crystallization of sparingly soluble salts
as the result of elevated temperatures and/or
low flow velocity. Most salts become more
soluble as temperature increases, however,
some salts, such as calcium carbonate,
become less soluble as temperature increases.
Therefore they often cause deposits at higher
temperatures.
3. High TDS water will have greater potential
for scale formation. [4]
The water is used in cooling systems as a heat
transfer medium and frequently also as the final
point to reject heat into the atmosphere by
evaporating inside cooling towers. Depending on
the quality of available fresh water supply,
waterside problems develop in cooling water
systems from: Scaling, Corrosion ,Dirt and dust
accumulation and Biological growth .
Any of these problems or more usually a
combination of them result in costly
unscheduled downtime, reduced capacity,
increased water usage, high operation and
maintenance costs, expensive parts
replacements, and acid cleaning operations
which reduce the life of the cooling system.
Selection of water treatment program for a
specific system depends on:
1. System design, including system capacity,
cooling tower type, basin depth, materials of
construction, flow rates, heat transfer rates,
temperature drop and associated accessories
2. Water, including makeup water composition /
quality, availability of pre-treatment and
assumed cycle of concentration
3. Contaminants, including process leaks and
airborne debris
4. Wastewater discharge restrictions
5. Surrounding environment and air quality
The critical parameters for cooling water are:
conductivity, total dissolved solids (TDS),
hardness, pH, alkalinity and saturation index.
Conductivity is a measure of the ability of
water to conduct electrical current and it
indicates the amount of the dissolved solids
(TDS) in water. Pure distilled water will have a
very low conductivity (low minerals) and sea
water will have a high conductivity (high
minerals). Dissolved solids present no problem
with respect to the cooling capacity of water,
since the evaporation rate of seawater, which has
30,000ppm total dissolved solids, is only 1% less
than that of distilled water. The problem with
dissolved solids is that many of the chemical
compounds and elements in the water will
combine to form highly insoluble mineral
deposits on the heat transfer surfaces generally
referred to as “scale”. The scale stubbornly
3. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
78
sticks to the surfaces, gradually builds up and
begins to interfere with pipe drainage, heat
transfer and water pressure.
pH: is a measure of how acidic/basic water
is. The range goes from 0 - 14, with 7 being
neutral. pHs of less than 7 indicate acidity,
whereas a pH of greater than 7 indicates a base.
pH is reported in "logarithmic units," like the
Richter scale, which measures earthquakes.
In general, when pH points to acidic
environment, the chances for corrosion increase
and when pH points to alkaline environment, the
chances for scale formation increase.
Alkalinity: The pH values above 7 signify
alkalinity. At pH values less than 8.3, most of
the alkalinity in the water is in the bicarbonate
form, and scale formation is normally not a
problem. However, when the pH rises above 8.3,
the alkalinity converts from the bicarbonate to
the carbonate and the scale will start to form.
Hardness: The amount of dissolved calcium
and magnesium in water determines its
"hardness." The total hardness is then broken
down into two categories:
a. The carbonate or temporary hardness
b.The non-carbonate or permanent hardness
Hardness particularly the temporary hardness is
the most common and is responsible for the
deposition of calcium carbonate scale in pipes
and equipment. Technically any bivalent metal
ion such as iron, manganese or tin would
constitute hardness, but calcium and magnesium
are the two most prevalent forms.
Saturation Index: The saturation index of a
water or Langlier Saturation Index (LSI) is a
measure of the stability of the water with respect
to scale formation. When LSI readings are
positive they tend to be scale forming, and when
they are negative they tend to be corrosive.
Normally readings within 1.0 unit from zero are
considereds Table [5, 6].
In cooling water systems, two basic techniques
are used to provide corrosion protection to the
metals that the water contacts: use of chemical
corrosion inhibitors, and raising the pH of the
cooling water.
Most military cooling water systems contain
components fabricated primarily of copper alloy
and mild steel. Galvanized steel is present in
galvanized cooling towers and stainless steel
may be present in piping. As the cooling water
pH is increased (ideally to within the range of
8.0 to 9.5.
Corrosion inhibitors are chemicals, which
inhibit or reduce the corrosion rate of the steel or
metallic surfaces. Corrosion is an
electrochemical phenomenon, which occurs due
to anodic and/or cathodic. Reactions. Generally,
the anodic reaction is the metal ion oxidation,
and the cathodic reaction is the hydrogen ion
reduction. Therefore, the corrosion analysis and
the corrosion inhibitors used to control the
anodic reactions are classified as anodic
corrosion inhibitor and the cathodic reactions are
called as cathodic inhibitors. Anodic Inhibitors
form a protective film coating on the anodic
metal (where the metal is lost) and thus directly
control corrosion by preventing the reaction that
results in corrosion. Any unprotected areas will
corrode at a much faster rate than the protected
areas, a factor that could result in pitting or
localized attack of the unprotected areas.
Cathodic Inhibitors form a protective film
coating of the cathodic metal (where metal is not
lost) and thus indirectly prevent corrosion by
interfering with the current flow required for the
electrochemical reaction to proceed between the
cathodic and anodic metals. The corrosion
reaction rate is governed by the size and type of
the cathode relative to the anode. Even when
cathodic areas are not completely covered by the
protective film, corrosion will occur, but usually
more slowly and uniformly than when using
anodic inhibitors alone. The occurrence of
localized corrosion or pitting attack is greatly
reduced. [6]
The criteria for the selection of corrosion
inhibitors are shown in Table (1). The principal
strategy for a cooling system corrosion
protection program is to ensure protection of the
metal in the heat exchanger (metal that is the
thinnest metal in the system). The secondary
goal is to provide protection from corrosion of
the mild steel piping. When galvanized steel
cooling towers are part of the cooling system,
specialized corrosion inhibitors are the best
control method. Galvanized steel is corroded at
pH levels above 9.0 and below 6.0.
Effective corrosion control requires
maintaining appropriate pH levels, plus adding
maintenance dosages of chemical corrosion
inhibitors. Chemical corrosion inhibitors form a
protective film or barrier on the cooling system
metal surfaces that have been cleaned prior to
adding an initial high dosage of inhibitor. The
initial high dosage of inhibitor passivates
(protects) the metal. The appropriate dosage of
corrosion inhibitor must be maintained
4. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
79
continuously in the cooling water to ensure
continuing protection. The examples of various
passivation and maintenance dosage levels of
corrosion inhibitors are shown in Table (2) [7, 8]
In order to prevent corrosion on galvanized steel
cooling towers and associated pipes, formation
of a non-porous surface layer of zinc carbonate
is one of the effective methods. The formation of
zinc carbonate layer is called passivation, which
is accomplished by controlling pH during initial
operation of the cooling tower. Control of the
cooling water pH in the range of 7 to 8 for 45 to
60 days usually allows passivation of galvanized
surfaces to occur. In addition to pH control,
operation and moderate hardness levels of 100 to
300ppm as CaCO and alkalinity levels of 100 to
300ppm as CaCO will promote passivation. The
chemical cleaning and passivation formulation
apply when the water system pH is 7.5 to 8.5
and adjust pH as required. Formulation
limitations may require adding separate
components to keep things in solution. Other
formulations may be used:
*Orthophosphate or hexametaphosphate as
(PO4): 60 ppm
* Polyacrylate (active): 20 ppm
* Tolyltrizol (active): 10 ppm
* Soduim gluconate: 50 ppm
* Pluronic L-61 (active)(non ionic surfactant
with antifoam: 400 ppm
* Phosphate scale inhibitor: 50 ppm . [9]
Table 1,
Criteria for Corrosion Inhibitor Selection.
Corrosion Inhibitor
Metal
Steel Copper Aluminum
pH Range (ideal)
Cathodic Inhibitor
Polyphosphate Excellent Attacks Attacks 6.5-8.5
Zinc salts Excellent None None 6.5-8.5
Polysilicate Excellent Excellent Excellent 7.5-10.0
Molybdate Good Fair Fair 7.5-10.0
Anodic Inhibitor
Orthophosphate Good Attacks Attacks 6.5-8.5
Orthosilicate Good Good Good 7.5-10.0
.
Table 2,
Guide lines for Passivation Film Formation and Subsequent Maintenance.
Corrosion inhibitor
Dosage (ppm)
Initial Maintenance
Film formation
Time (days)
Cathodic inhibitor
Polyphosphate 40-60 as po4 10-20 as po4 5-6
Zinc salts 10-20 as zn 3-5 as zn 5-6
Polysilicate 40-60 as SiO2 10-20 as SiO2 10-12
Molybdate 40-60 as Mo 5-20 as Mo 10-12
Anodic inhibitor
Orthoophosohate 40-60 as po4 15-20 as po4 5-6
Orthosilicate 40-60 as SiO2 10-15 as SiO2 10-12
Copper Corrosion inhibitor
Tolyltrizole 10-20 as TTA 1-2 as TTA 5-6
5. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
80
In general, other types of corrosion inhibitors
are: Mixed inhibitor: is composes of two or three
types of inhibitor and majority of the proprietary
corrosion inhibitor formula falls into this
category.
Adsorption inhibitor: Protective absorbed film
is formed over the entire metal surface if
adsorption inhibitor is used. The film helps to
protect electrochemical reactions between metal
and aqueous ions. Some of the organic
compounds are suitable to act as adsorption
inhibitors [10].
2. Experimental Procedure
A lab rotary test was used in this investigation,
the hot plate and stirrer (Jenway 1000) were used
and a 500 ml of beaker capacity was filled with
mixture of corrosion inhibitors and specimen
immersed for (1-5) days. The carbon steel
specimen materials used in this investigation has
the chemical composition which done in the Al
doura refinery by spectrometer Ultima 2000 as
shown in Table (3):
The surface of rectangular carbon steel alloy
specimens which has the dimensions (10 x 3 x
0.2cm), (9 x 2 x 0.25 cm) were abraded by using
emery paper of different grade numbers (220, 320,
400, 600), after abrasion the surfaces were
cleaned with running tap water , followed by
acetone rinse for 5 minutes and were dried in
discator. Different concentration of corrosion
inhibitor were prepared, (20, 40, 60 and 80 ppm)
mixture of Na2 HPO4 and C6 H11 NaO7 .
After specimen׳s preparations, weighing the
specimen and record W1, the specimen was
clamped and immersed in a mixture of corrosion
inhibitors at 20 ppm concentration , (i.e. The
ratio= =
10
10
) using hot plate stirrer at
medium velocity and at temperature 25°c, after
1day the immersion specimen, was removed and
cleaned by washing it with running tap water and
brushing it with bristle brush . Then the specimens
were immersed in benzene for 5 minutes to ensure
removal of corrosion products from metal surface.
The specimens were immersed in ethanol were
dried in discator, then weights represented as W2.
the procedure by using (40, 60 and 80 ppm)
concentration and immersion for 2, 3 and 5 days
at (50,75 and 100°C) temperature as shown in
Fig.(1) and Fig.(2)
Table 3,
The chemical Composition for Carbon Steel
Fe Si Mn Cr Ni Mo Cu Co Al C S HB Total Elements %
74.2 2.2 9.0 2.2 2.7 3.5 1.1 2.5 1.3 1.2 0.1 300 100
Fig.1. Carbon Steel Specimen Immersed In Mixture
of Sodium Phosphate And Sodium Gluconate.
Fig. 2. Carbon Steel Specimen Immersed in Mixture
of Corrosion Inhibitor on Hot Plate and Stirrer at
Meduim Velocity .
7
6. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
81
The efficiency of mixture corrosion inhibitors
and scales dispersant (sodium phosphate and
sodium glocunate) were calculated ,by using make
up water(raw water) without corrosion inhibitor
then calculated the corrosion rate for (1,2,3 and 5)
days with corrosion inhibitor as shown in Fig. (3),
and analyze make up water and an inhibited water
chemically.
Fig . 3. Carbon Steel Specimen Immersed in
Makeup Water.
3. Results and Discussion
3.1. Sodium phosphate effect
The effect of corrosion inhibitor of sodium
phosphate indicates that the film of iron phosphate
(Fe2 (PO4 )2 ) produced to protect the surface of
the specimen to passivate them and prevent the
corrosion .as shown in the eq.
2Na2HPO4 + 3Fe +2H2O → Fe3 (Po4) 2 + 4NaOH
+ H2 …(8)
The results indicate that when the specimen
immersed in the mixture of corrosion inhibitor for
5 days at a concentration of 30-40 ppm, this gave
low value of corrosion rate than the immersion for
1 day. The relation was linear, this mean that the
corrosion rate decrease with increasing the
concentration and the time , as shown in Table (4)
and Fig. (4).
Table 4,
Corrosion Rate of Carbon Steel in Mixture of Sodium Phosphate And Sodium Gluconate at Different
Concentration and 25 °C Temperature .
Test no. Time /day
Conc. in
ppm
Weight/w1
in gram
Weight/w2
in gram
∆w
Surface
area (cm)
*C.R. in
gmd
1 1 20 47.1500 47.1516 0.0016 0.00652 0.24
2 1 40 47.1500 47.1514 0.0014 0.00652 0.21
3 1 60 47.1400 47.1412 0.0012 0.00652 0.18
4 1 80 47.1400 47.1411 0.0011 0.00652 0.16
5 2 20 47.1500 47.152 0.002 0.00652 0.15
6 2 40 47.1500 47.1519 0.0019 0.00652 0.14
7 2 60 47.2999 47.301 0.0011 0.00415 0.13
8 2 80 47.2999 47.3008 0.0009 0.00415 0.10
9 3 20 47.1500 47.1519 0.0019 0.00652 0.097
10 3 40 47.1400 47.1418 0.0018 0.00652 0.092
11 3 60 47.1400 47.1411 0.0011 0.00415 0.088
12 3 80 47.2999 47.3007 0.0008 0.00415 0.064
13 5 20 47.1423 47.1439 0.0016 0.00652 0.049
14 5 40 47.1400 47.1411 0.0011 0.00652 0.033
15 5 60 47.3300 47.3305 0.0005 0.00415 0.024
16 5 80 47.3300 47.3303 0.0003 0.00415 0.018
2
7. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
82
Fig. 4. Effect of Concentration of Mixture Inhibitor on Corrosion Rate.
3.2. Sodium glocunate effect
The effect of sodium glocunate as scale
dispersant indicates that the total dissolved solids
(T.D.S.) will be decreased from 3000 ppm and to
300 ppm then minimize the electrochemical
reaction under the deposit and tubes failed. Their
effect as sequestering agent forming water
solution complexes with calcium in alkaline
media and with iron in near neutral solutions is
shown in the equation:
2C6H11NaO7 + CaCo3 +H2O → Ca(C6H11O7)2 +
NaHCo3 + NaOH ...(9)
The concentration at 30-40 ppm of sodium
glocunate indicates that the corrosion rate
decreases for 5 days of immersion as shown in
Table (4) and Fig.(4) .
3.3. Time effect
The corrosion rate decreases with increasing
time at constant concentration according to the
equation of corrosion rate. Time and longer
protective layer of mixture will prevent and
decrease the corrosion rate as shown in Fig.(5).
=
∆ ( )
( )× ( )
[11] .
Fig. 5. Effect of Time on Corrosion Rate with Different Conc. of Mixture Inhibitor.
0
0.05
0.1
0.15
0.2
0.25
0.3
20 40 60 80
C.R.ingmd
Concentration in PPM
1 Day
2 Days
3 Days
5 Days
0
0.05
0.1
0.15
0.2
0.25
0.3
1 2 3 4 5
C.R.ingmd
Time in Days
20 ppm
40 ppm
60 ppm
80 ppm
8. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
83
3.4. Temperature effect
The corrosion rate increased at temp. (25,50
and 75) °C for 1and 2 days because temp.
increasing caused low passivity of corrosion
inhibitors at 100 °C, the temp. effect will be less
on the corrosion rate at 3 and 5 days because of
the passivation film that will reduce heat transfer
on the metal surface as shown in Table(5) and
fig.(6).
Table 5,
Corrosion Rate of Carbon Steel in Mixture of Sodium Phosphate and Sodium Gluconate at 80 ppm
Concentration and at Different Temperature.
Test no. Time /day Temp. in
°C
Weight/w1
in gram
Weight/w2
in gram
∆w Surface
area (cm)
*C.R. in
gmd
1 1 25 47.1500 47.1511 0.0011 0.00652 0.16
2 1 50 47.1498 47.1415 0.0017 0.00652 0.27
3 1 75 47.1432 47.1445 0.0022 0.00652 0.34
4 1 100 47.1400 47.1414 0.0014 0.00652 0.23
5 2 25 47.2999 47.3008 0.0009 0.00415 0.10
6 2 50 47.2998 47.3014 0.0016 0.00415 0.20
7 2 75 47.1500 47.1539 0.0039 0.00652 0.30
8 2 100 47.1500 47.1515 0.0015 0.00652 0.20
9 3 25 47.2999 47.3007 0.0008 0.00415 0.064
10 3 50 47.1400 47.1417 0.0017 0.00652 0.09
11 3 75 47.1400 47.1429 0.0029 0.00652 0.15
12 3 100 47.3300 47.3312 0.0012 0.00415 0.12
13 5 25 47.3300 47.3303 0.0003 0.00415 0.018
14 5 50 47.1500 47.1506 0.0006 0.00652 0.02
15 5 75 47.1400 47.1409 0.0009 0.00652 0.028
16 5 100 47.2999 47.3002 0.000029 0.00415 0.014
Fig. 6. Effect of Temp. on Corrosion Rate at Different Times and at 80 ppm of Mixture Corrosion Inhibitors
Concentration.
2
9. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
84
3.5. Mixture efficiency
The efficiency of mixture of sodium
phosphate and sodium glocunate were (83.3, 87.5,
93.8 and 98.1%) at 80 ppm concentration, and at
1,2,3,5 days respectively, the corrosion rate of
makeup water (raw water) were calculated for 1,
2, 3 and 5 days to compare the efficiency of the
mixture by applying the equation of the
efficiency, where the efficiency increases with
time as shown in the Table (6) and Table (7).
=
–
× 100%
[12]
When carbon steel is immersed in raw water, the
anodic reaction is:
Fe → Fe2+
+ 2e−
…(10)
The cathodic reaction is:
O2 + 2H2O + 4e−
→ 4OH−
…(11)
Table 6,
The Corrosion Rate of Makeup Water.
Time/day W1( gram) W2(gram) ∆w Surface area cm2
C. R. ( gmd)
1 47.1423 47.1486 0.0063 0.00652 0.96
2 47.1414 47.1558 0.0144 0.00652 1.1
3 47.3200 47.3402 0.0202 0.00415 1.5
5 47.1435 47.2184 0.0749 0.00652 2.3
Table 7,
Efficiency of Mixture of Sodium Phosphate and Sodium Glocunate at 80 ppm.
Then after 5 days the uniform corrosion will
occur while the protective layer of Fe3 (PO4 ) 2
formed on the surface of carbon steel specimen as
shown in Fig.(7) and Fig.(8) respectively, The
chemical analysis of cooling water (inhibited
water) were obtained from Al-doura refinery
explain the values of alkalinity and pH increased
because of mixture effect as shown in Table (8).
Table 8,
Chemical analysis for make up(raw water) and cooling tower water.
Water Parameter Make up water Cooling water
Alkalinity as ppm 144 374
Total Hardness as ppm 250 544
T.D.S as ppm 397 1370
pH 7.4 8.27
Conductivity in mmhoms 663 1712
Sodium phosphate as ppm - 80
Sodium gluconate as ppm - 80
Time (day) C.R.(uninhibited water) C.R.(inhibited water) Efficiency%
1 0.96 0.16 83.3
2 1.1 0.15 87.5
3 1.5 0.092 93.8
5 2.3 0.042 98.1
10. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
85
Fig. 7.Uniform Corrosion on Carbon Steel
Specimen.
Fig. 8.Protective Layer on Carbon Steel
Specimen.
4. Conclusion
From experimental results using corrosion
inhibitor mixture (sodium phosphate as corrosion
inhibitor and sodium glocunate as scale
dispersant)in cooling tower at 20,40,60 and 80
ppm concentration ,one concludes that at 80 ppm
concentration of mixture and at temp. above 75 °C
and for 5 days is more efficiently in cooling tower
treatment to format passive film and decrease the
corrosion rate.
5. Recommendation
Some recommendations are suggested to
improve the future work Because of
microbiological growth in cooling tower such as
algae, fugi and bacteria, then:
1- The treatment with biocides by adding to
sample of cooling water :
a. Oxidizing Biocides such as( Chlorine,
Bromine, Chlorine Dioxide, Ozone, Silver
Peroxide, etc)
b. Non-oxidizing Biocides :Organic chemical
compounds .
c. Biodispersants : Surfactant.
2- Study the effect of the microbiological growth
in cooling tower and measure the corrosion
rate of carbon steel with effect of
microbiological growth.
3- Calculate the corrosion rate of carbon steel
immersed in corrosion inhibitor ,scale
dispersant and biodispersant mixing .
6. References
[1] P.R. Roberge, Handbook of Corrosion
Engineering, McGraw- Hill, 1999.
[2] R. Wiston, Uhlig’s, Corrosion Handbook,
2nd Edition, page 173, John Wiley and
Sons Inc., 2000.
[3] Mario Machado , "Cooling tower
Technologies and Management – Water
Minimization", Australian industry
group,2010
[4] John kubis, "power station zero discharge
,cooling tower", NACE international
,No.08396,2010.
[5] RL Martin, B.A. Alink, T.G. Braga and
A.J. McMahon, R.
"Weare,Environmentally accepTable
water soluble corrosion inhibitors",
Corrosion 95, Paper No.36, NACE, 1995.
[6] A. Bhatia, "cooling water problems and
solution",web
siteinfo@cedengineering.com , 2010.
[7] Dr. E.Moses Road," Inorganic phosphates
based corrosion inhibitors for industrial
cooling water system, Ion Exchange India
Ltd. 2010.
[8] Irvin Cotton,”Analyst Spring 2003 –
Cooling System – Chemical treatment “ .
[9] DONALD L. BASHAM, P.E, "Industrial
water treatment operation and
maintenance", by united facilities criteria
(UFC), http://dod.wbdg.org/. 25 may
2005.
11. Dina Raheem Al-Khwarizmi Engineering Journal, Vol. 7, No. 4, PP 86- 97(2011)
86
[10] C.C.Nathan “Corrosion
inhibitors” National Association and
Corrosion Engineer, Vol.21,PP.120, No.3,
June, (1983).
[11] Annual book of ASTM standard
"Corrosivity of water in the absence of
heat transfer (weight loss
method)",Designation :D
2688,Feb.15,1983.
[12]C.C.NATHAN, "Studies on the inhibition
by amines of the corrosion of iron by
solutions of high acidity ", National
Association of Corrosion Engineer ,vol.9
,p.199 ,1948.