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Evt 621 Research Methodology Slide Evt 621 Research Methodology Slide Presentation Transcript

  • Removal of Zinc (II) Ion from Synthetic Wastewater Solution by using Activated Carbon Prepared from Corn Cob By: Mohd Aminurrasyid bin Mohd Amin (2005679824) B. Sc. (Hons.) Environmental Technology Under supervision of: Mr. Mohd Nizam bin Yusof
  • Introduction Removal of Zinc (II) Ion from Synthetic Wastewater Solution by using Activated Carbon Prepared from Corn Cob
  • Introduction: Industrial Wastewater
    • Disposal of industrial wastewater is one of the major environmental issues
      • the pollutants inside are usually so toxic
      • wastewater has to be treated before it can be reused or disposed in water bodies
    • Industrial processes generate wastewater containing heavy metal contaminants
      • Most of heavy metals are hard to be degraded into non-toxic forms
        • Their concentrations must be reduced to acceptable levels before being discharged into the environment
        • Otherwise, it could pose threats to public health and/or affect the aesthetic quality of potable water
      • Metals of most immediate concern are chromium, zinc, iron, mercury and lead (WHO, 1984)
  • Introduction: Heavy Metals
    • Heavy metals in wastewater come from industries and municipal sewage
    • One of the main causes of water and soil pollution
    • The presence of heavy metals in wastewater strongly reduces microbial activity, thus adversely affecting biological wastewater treatment processes
    • Heavy metal contamination that does get into the environment could cause permanent negative ecological effects (Micera et al., 1988)
  • Introduction: Zinc
    • Zinc is the 23 rd most abundant element in the Earth's crust (Wikipedia, 2007b)
    • Most zinc ore found naturally in the environment is found as the salt, zinc sulfide
    • Zinc salts are widely used in industry
      • Zinc sulfide and zinc oxide are used to make white paints, ceramics, and several other products
      • Zinc oxide is also used in producing rubber
      • Zinc acetate, zinc chloride, and zinc sulfate, are used in preserving wood and manufacturing and dyeing fabrics (Irwin, R.J., 1997)
  • Introduction: Zinc (cont’)
    • Natural zinc level in surface water < 0.01 mg/l
    • Natural zinc level in groundwater < 0.05 mg/l
      • May be varied due to natural processes and human activities which cause the release of zinc to water bodies
    • Waste streams from zinc and other metal manufacturing and zinc chemical industries, domestic waste water, and run-off from soil can discharge zinc into waterways
    • The level of dissolved zinc in water may increase as the acidity of water increases (Irwin, R.J., 1997)
  • Problem Statement
    • Discharge of zinc into natural streams and rivers from the industries cause severe environmental problems
    • Elevated zinc concentration in water is particularly toxic to many species of algae, crustaceans, and salmonids, and have especially strong impacts on macroinvertebrates such as molluscs, crustaceans, odonates, and ephemeropterans (Irwin, R.J., 1997)
  • Problem Statement (cont’)
    • In mammals , excess zinc can cause copper deficiencies , affect iron metabolism , and interact with the chemical dynamics of lead and drugs (Irwin, 1997)
    • In human , excessive absorption of zinc in can suppress Cu 2+ and Fe 2+ absorption (Wikipedia, 2007) , nausea , vomiting , fever , headache , tiredness , and abdominal pain (Irwin, 1997)
    • The free zinc ion in solution is highly toxic to plants , invertebrates , and even vertebrate fish (Wikipedia, 2007)
  • Problem Statement (cont’)
    • According to EQA 1974, Environmental Quality (Sewage & Industrial Effluents) Regulations 1979, [Regulations 8 (1), 8 (2), 8 (3)], 3 rd Schedule: Parameter limits of effluent of Standard A and B (Appendix A), Zinc concentration for both Standard A and Standard B effluent should not exceed 2.0 mg/l .
  • Significance of Study
    • To find other type of activated carbon as an alternative for the removal of Zinc from industrial wastewater
      • Current methods for removal of zinc from wastewater:
        • Precipitation
        • Coagulation/Flocculation
        • Sedimentation
        • Filtration
        • Membrane process
        • Electrochemical process
        • Ion exchange
        • Biological process
        • Chemical reaction
          • (Rachakornkij et al., 2003)
  • Significance of Study (cont’)
      • Most common methods to remove or reduce the zinc and other heavy metals concentrations in the environment are found to be somewhat impractical and costly
      • Adsorption by activated carbon:
        • Has excellent adsorption capability
        • Very efficient in removing heavy metals from waste streams
        • Widely used
        • High cost – unsuitable for developing countries
        • Demand for low-cost activated carbon
          • (Rachakornkij et al., 2003)
      • Activated carbon produced from agricultural waste
        • Low-cost
        • May reduce solid waste disposal problem
        • May minimize the cost of activated carbon production
  • Objectives of Study
    • To examine the ability of activated carbon prepared from corn cob in the removal of Zn (II) ion in aqueous solution
    • To determine:
        • optimum contact time between adsorbent and solution
        • optimum adsorbent dosage
        • effect of interfering anions ( SO 4 2- and Cl 2- )
    • for the removal of Zn (II) ion by using activated carbon prepared from corn cob
  • Literature Review Removal of Zinc (II) Ion from Synthetic Wastewater Solution by using Activated Carbon Prepared from Corn Cob
  • Literature Review: Utilization of Corn Cobs as Activated Carbon
    • Many studies reported on the utilization of agricultural waste as activated carbon, especially corn cob
    • Most of the research on utilization of corn cob as activated carbon is focused on the process of carbonization and activation by impregnation with chemical activator such as zinc chloride (Tsai et al., 1998), potassium carbonate (Tsai et al., 2001), and potassium hydroxide (Cao et al., 2006; Tsai et al., 2001) with different approaches
    • Even though corn cob is considered as a potential low-cost adsorbent, only a few studies have been done on the application of this corn cob activated carbon in removing heavy metals including zinc
  • Literature Review: Tsai et al. (1998)
    • Preparation of activated carbon by chemical activation with ZnCl 2
      • Powdered corn cobs (1.44 mm) was impregnated with ZnCl 2
        • Impregnation ratio: 20-200 wt%
        • T: 85°C
        • Done in a boiler-reflux condenser for 2 h
      • Activation
        • T: 400-800°C
        • Heating rate: 10°C/min
        • N 2 flow rate: 300 cm 3 /min at STP
      • Post-activation:
        • Boiled with 3 N HCl for 30 min
        • Washed several times with warmed distilled water
          • to remove chlorine ions and other residues
        • Dried at 105°C overnight
  • Literature Review: Tsai et al. (1998) (cont’)
    • Findings:
      • Percentage of micropore decrease at higher impregnation ratios
      • Optimal condition for producing high surface area carbons with ZnCl 2 activation
        • Activation temperature of 500°C
        • Impregnation ratio of 175 wt%
        • Soaking time of 0.5 h
  • Literature Review: Tsai et al. (2001)
    • Potassium salts (KOH and K 2 CO 3 ) was used in stead of ZnCl 2 as activator
        • since it has the least impact on the environment than other activators such as ZnCl 2 and H 3 PO 4
      • Powdered corn cobs (1.0 – 2.0 mm) was impregnated with potassium solution (KOH or K 2 CO 3 ) of known concentration, at 80°C in a boiler-reflux condenser for 2 h
      • Activated with pyrolysis temperature ramp rate of 10°C/min in a N 2 flow (200 cm 3 /min at STP), then switched to CO 2 flow (200 cm 3 /min at STP) after reaching 800°C
      • Post-activation:
        • Washed with 3 N hot HCl solution
        • Vacuum filtered
        • Washed several times with 80°C distilled water
          • to remove chlorine ions and other residues
        • Dried at 120°C overnight
  • Literature Review: Tsai et al. (2001) (cont’)
    • Findings:
      • Large surface areas > 1600 m2/g of were obtained
      • KOH and K 2 CO 3 were effective activating agents for chemical activation
      • The optimal condition
        • Ramping rate of 10°C/min
        • Subsequent gasification (physical activation) at a soaking period of 800°C
  • Literature Review: Cao et al. (2006)
    • Process effects on activated carbon with large specific surface area from corn cob
      • Powdered corn cobs (250 µm) was carbonized
        • Done in a column-typed stainless steel tube of 200 ml for 4 h
        • T-ramp rate: 30°C/min
        • T: 450°C
        • Protective gas: N 2 (flow rate: 90ml/min)
      • Treated with 3 different activator (KOH solid, KOH solution and KOH-soap mixture) for 30 min
      • Activated for 1.2 h at 850°C after drying
      • Neutralized with distilled water
      • Filtered and dried at 120°C
  • Literature Review: Cao et al. (2006) (cont’)
    • Findings:
      • The SSA of activated carbon from corn cobs reached 2700 m 2 /g with narrow pore size distribution (78% micro-pores) under optimal conditions
      • Addition of soap as surfactant shortens the soaking time
      • SSAs of activated carbon obtained from carbonized material with activator was found to be relatively higher than the one from raw material with activator
        • Indicate that a great deal of activator could not get into the inner of raw material and could not react with the carbon effectively
  • Literature Review: Abia and Igwe (Jun 2005)
    • K inetics of sorption and intraparticulate diffusivities of Zn, Cd and Pb using maize (corn) cob
      • Activated carbon was prepared in a simpler chemical activation method process
        • Powdered maize cobs (850 – 1000 µm) was soaked with dilute HNO 3 solution (2% v/v) overnight
        • Rinsed with deionized water
        • Air dried
      • Effect of contact time was studied, and the intraparticulate diffusivity and the fractional attainment of equilibrium were calculated
  • Literature Review: Abia and Igwe (Jun 2005)
    • Findings:
      • Amount of the metal ions adsorbed increasing with time
      • Highest sorption rates:
        • Zn 2+ : 71%
        • Cd 2+ : 32%
        • Pb 2+ : 30%
      • Zn 2+ reached equilibrium first, followed by Pb 2+ and Cd 2+
      • The sorption of these ions on maize cob is particle diffusion controlled
        • Coefficients for particle diffusion:
        • Zn 2+ : 0.070 min -1
        • Pb 2+ : 0.053 min -1
        • Cd 2+ : 0.081 min -1
  • Materials and Methods Removal of Zinc (II) Ion from Synthetic Wastewater Solution by using Activated Carbon Prepared from Corn Cob
  • Materials and Methods
    • Materials
      • Sample:
        • Corn cobs obtained from local market in Shah Alam, Selangor
      • Chemicals:
        • Zinc stock solution (1000 ppm)
        • Zinc sulphate (ZnSO 4 )
        • Zinc chloride (ZnCl 2 )
        • Distilled water
        • Deionized water
        • Potassium hydroxide (KOH)
  • Materials and Methods (cont’)
    • Materials (cont’)
      • Equipment:
        • Grinder
        • Sieve 300 µm & 250 µm (mesh No. 50 & 60)
        • Oven
        • Muffle furnace
        • Dessicator
        • Shaker
        • Atomic Absorption Spectrophotometer (AAS)
  • Materials and Methods (con’t)
    • Method
      • Preparation of Activated Carbon
        • Involve 2 steps:
          • Pulverization (Pre-treatment)
          • Carbonization & Activation
        • Derived from Abia and Igwe (2005), Igwe et al.(2005), Tsai et al. (1997 & 2001) and Cao et al. (2006).
      • Adsorption Studies
        • Effect of contact time
        • Effect of adsorbent dosage
        • Effect of interfering anions ( SO 4 2- and Cl 2- )
  • Pulverization of Sample Carbonization & Activation of Sample Effect of Adsorbent Dosage Effect of Contact Time Effect of Interfering Anions Adsorption Studies Preparation of Activated Carbon
  • Preparation of Activated Carbon Step 1: Pulverization (Pre-treatment) Corn cobs (separated from its pitch/chaff) Rinsed with distilled water Air dried Cut into small pieces Grinded into powder Sieved (300 µm) Sieved (250 µm) Heated (105°C, 12 h) in oven Cooled / stored in dessicator
    • - To get a uniform particle size
    • The powdered corn cob retained on
    • the 250 µm mesh is used
    - Obtained from local market - To remove impurities - To remove moisture content - To ease grinding process - Reduce the particle size - To make sure the sample is really dry - Keep pre-treated sample dry until use
  • 100 g powdered corn cobs Heated to 450°C (T-ramp rate 30°C/min, 4 h) Cooled to room temperature Treated with KOH solution for 30 min Air dried Activated in furnace (850°C, 1.2 hr) Washed with warm distilled water until neutralization Filtered Dried at 120°C Cooled / Stored in dessicator until use - From pre-treated sample - Carbonize the raw material - Cool down the sample - Open up the pores - Dry the sample prior to activation - Activate the sample - Neutralize the sample - Separate / recover the sample - Remove moisture content - Keep sample dry until use Step 2: Carbonization & Activation
  • Adsorption Studies
    • Based on 3 parameters:
      • Effect of contact time
      • Effect of adsorbent dosage
      • Effect of interfering anions ( SO 4 2- and Cl 2- )
    • Determination of:
      • Optimum contact time
      • Optimum adsorbent dosage
      • Effect of interfering anions
  • Put in 250 ml conical flask (Flask 1A) Take 100 ml Add 2 g adsorbent Add 2 g adsorbent Add 2 g adsorbent Add 2 g adsorbent Add 2 g adsorbent Add 2 g adsorbent Add 2 g adsorbent Leave for 10 min Filter Determine final conc. Leave for 20 min Leave for 30 min Leave for 45 min Leave for 60 min Leave for 90 min Leave for 120 min Filter Determine final conc. Filter Determine final conc. Filter Determine final conc. Filter Determine final conc. Filter Determine final conc. Filter Determine final conc. Plot Graph Take 100 ml Take 100 ml Take 100 ml Take 100 ml Take 100 ml Take 100 ml Put in 250 ml conical flask (Flask 1B) Put in 250 ml conical flask (Flask 1E) Put in 250 ml conical flask (Flask 1C) Put in 250 ml conical flask (Flask 1D) Put in 250 ml conical flask (Flask 1F) Put in 250 ml conical flask (Flask 1G) Zinc Synthetic Wastewater Solution (1000 ppm) Determine initial concentration Determine equilibrium contact time Experiment #1: Different contact time at constant adsorbent dosage
  • Put in 250 ml conical flask (Flask 2A) Take 100 ml Add 2 g adsorbent Add 8 g adsorbent Add 4 g adsorbent Add 6 g adsorbent Add 10 g adsorbent Filter Determine final conc. Leave for adsorption process, according to the equilibrium contact time obtained from experiment #1 Filter Determine final conc. Filter Determine final conc. Filter Determine final conc. Filter Determine final conc. Plot Graph Take 100 ml Take 100 ml Take 100 ml Take 100 ml Put in 250 ml conical flask (Flask 2D) Put in 250 ml conical flask (Flask 2B) Put in 250 ml conical flask (Flask 2C) Put in 250 ml conical flask (Flask 2E) Zinc Synthetic Wastewater Solution (1000 ppm) Determine initial concentration Determine optimum adsorbent dosage Experiment #2: Different adsorbent dosage at constant contact time
  • Leave for adsorption process, according to the equilibrium contact time obtained from experiment #1 Filter Determine final conc. Filter Determine final conc. Determine percent removal of Zinc (II) ion Put in 250 ml conical flask (Flask 3B) Put in 250 ml conical flask (Flask 3A) Zinc Sulfate Solution (1000 ppm) Determine initial concentration Experiment #3: Effect of interfering anion ( SO 4 2- and Cl 2- ) Zinc Chloride Solution (1000 ppm) Determine initial concentration Add adsorbent according to the optimum adsorbent dosage obtained from experiment #2 Compare result with result in experiment #2
  • Interpretation of Results
    • Experiment 1: Effect of Contact Time
      • Percentage of zinc removal (%) = ( C 1 – C 2 ) × 100
      • C 1
        • where,
          • C 1 is the initial concentration (mg/l)
          • C 2 is the final concentration (mg/l)
      • Graph of percentage of zinc removal versus time is plotted
      • The optimum contact time was obtained when there is almost no more adsorption occurred
  • Interpretation of Results (cont’)
    • Experiment 1: Effect of Contact Time (cont’)
      • Amount of zinc adsorbed = ( C 1 – C 2 ) × V
        • where,
          • C 1 is the initial concentration (mg/l)
          • C 2 is the final concentration (mg/l)
          • V is the volume of synthetic wastewater (l)
      • The maximum uptake capacity of the adsorbent, expressed in mg of heavy metal adsorbed per g of adsorbent, is calculated based on adsorption at optimum contact time
  • Interpretation of Results (cont’)
    • Experiment 1: Effect of Contact Time (cont’)
      • The maximum zinc uptake capacity of the activated carbon (mg/g) is calculated by using the following formula:
        • Zinc uptake capacity of A.C. = ( A × V ) / D
          • where,
            • A is the amount of zinc adsorbed
            • V is the volume of synthetic wastewater (l)
            • D is the adsorbent dosage (g)
  • Interpretation of Results (cont’)
    • Experiment 2: Effect of Adsorbent Dosage
      • Percentage of zinc removal (%) = ( C 1 – C 2 ) × 100
      • C 1
        • where,
          • C 1 is the initial concentration (mg/l)
          • C 2 is the final concentration (mg/l)
      • Graph of percentage of zinc removal versus adsorbent dosage is plotted
      • The optimum adsorbent dosage was obtained when there is almost no more adsorption occurred
  • Interpretation of Results (cont’)
    • Experiment 3: Effect of Interfering anion
      • Percentage of zinc removal (%) = ( C 1 – C 2 ) × 100
      • C 1
        • where,
          • C 1 is the initial concentration (mg/l)
          • C 2 is the final concentration (mg/l)
      • Percentage removal of both ZnSO 4 and ZnCl 2 are compared with the result obtained in experiment 2.
  • References Removal of Zinc (II) Ion from Synthetic Wastewater Solution by using Activated Carbon Prepared from Corn Cob
  • References
    • Abia, A.A. & J.C. Igwe (2005). “Sorption kinetics and intraparticulate diffusivities of Cd, Pb and Zn ions on maize cob”. African Journal of Biotechnology , Vol. 4 (6): 509-512, June 2005.
    • Cao, Q, Ke-Chang Xie, Yong-Kang Lv & Wei-Ren Bao (2005). “Process Effects on Activated Carbon with Large Specific Surface Area from Corn Cob”. Bioresource Technology, 97 (2006): 110-115.
    • Igwe, J.C., Ogunewe, D.N. & Abia, A.A. (2005). “Competitive adsorption of Zn (II), Cd (II) and Pb (II) ions from aqueous and non-aqueous solution by maize cob and husk”. African Journal of Biotechnology , Vol. 4 (6): 509-512, October 2005.
    • Irwin, R.J. (1997). Environmental Contaminants Encyclopedia: Zinc Entry . Water Resources Divisions, Water Operations Branch, National Park Service, Colorado. July 1, 1997, pp. 88.
    • Micera, G. & A. Dessi (1988). “Chromium Adsorption by Plant Roots and Formation of Long-Lived Cr (V) Species: An Ecological Hazard?” Journal of Inorganic and Biochemistry , 34 (1988): 157-166.
  • References
    • Rachakornkij, M., S. Ruangchuay & P. Satidwattanaporn (2003). “Utilization of Bagasse and Bagasse Fly Ash as Adsorbent for Removal of Lead from Aqueous Solution”. National Research Center for Environmental and Hazardous Waste Management (NRC-EHWM) Chulalongkorn University, Bangkok, Thailand . Proceedings of INREF-AGITS Conference 2003, Chiang Mai University, Chiang Mai, Thailand, October 10-12, 2003.
    • Tsai, W.T., C.Y. Chang & S.L. Lee (1998). “A Low Cost Adsorbent from Agricultural Waste Corn Cob by Zinc Chloride Activation”. Bioresource Technology , 64 (1998): 211-217.
    • Tsai, W.T., C.Y. Chang, S.Y. Wang, C.F. Chang, S.F. Chien & H.F. Sun (2001). “Preparation of Activated Carbons from Corn Cob Catalyzed by Potassium Salts and Subsequent Gasification with CO 2 ”. Bioresource Technology , 78 (2001): 203-208.
    • World Health Organization (1984). Geneva, Guidelines for drinking Water Quality.
    • Wikipedia (2007b). “Zinc”. Wikipedia, the free encyclopedia . Wikimedia Foundation, Inc. Retrieved March 7, 2007 from http://en.wikipedia.org/wiki/Zinc
  • Plan of Studies Removal of Zinc (II) Ion from Synthetic Wastewater Solution by using Activated Carbon Prepared from Corn Cob
  • Plan of Studies
  • Questions & Answers Thank You