This paper studied the competitive adsorption of nitrate and oxalic acid on TiO2. It found that while nitrate had a higher Langmuir adsorption coefficient, oxalic acid adsorbed about 10 times more due to its ability to bind in two ways. In competitive adsorption, oxalic acid preferentially adsorbed, inhibiting nitrate uptake by up to 93% at higher oxalic acid concentrations. This inhibition could reduce the effectiveness of photocatalytic nitrate remediation, suggesting surface modification may be needed to enhance nitrate adsorption for faster reaction rates.
Using Tunisian Phosphate Rock and Her Converted Hydroxyapatite for Lead Remov...IJERA Editor
Natural and synthesis apatites represent a cost effective soil amendment, which can be used for in situ reduction of lead bioavailability and mobility. In our previous work, we selected Tunisian Phosphate Rock (TPR) and Hydroxyapatite (CaHAp) as promising minerals for the removal of lead from aqueous solutions. X-ray powder diffraction patterns (DRX), Infra Red (IR), Thermogravimetric analysis (TGA) and Scanning Electron Microscopy (SEM) were used to characterize TPR and CaHAp. CaHAp was prepared from TPR and employed for the removal of Pb2+ ions at different concentrations from aqueous solution to determine the adsorption properties of CaHAp and compare them with those of a TPR. The kinetic data obtained indicated that the adsorption performances of the adsorbents depended both on their specific surface area and crystallinity. Complexation of lead ion on the adsorbent surface favoured the dissolution of hydroxyapatites characterized by a Ca/Pb molar ratio of 1.69. The maximum adsorption capacity of CaHAp for Pb2+ ions at 25 °C was 1.806 mmol /g relative to 1.035 mmol /g for TPR at the same temperature. The higher capacity of CaHAp was explained in terms of its porosity and crystallinity. The Pb2+ ions sorption results could be modelled by the Langmuir and Freundlich isotherms. The simulations of adsorption isotherms of Pb2+ on CaHAp allow us to conclude that there is a good correlation between the experimental data and the Langmuir model. On TPR, we show a good correlation between the experimental data and the Langmuir and Freundlich model.
Equilibrium and kinetic study on chromium (vi) removal from simulatedGJESM Publication
Gooseberry seed (Phyllanthus acidus) was used as an adsorbent to determine its feasibility for the removal of Cr(VI). Various parameters such as pH, temperature, contact time, initial metal concentration and adsorbent dosage were investigated to determine the biosorption performance. Equilibrium was attained within 60 minutes and maximum removal of 96% was achieved under the optimum conditions at pH 2. The adsorption phenomenon demonstrated here was monolayer represented by Langmuir isotherm with R2 value of 0.992 and the Langmuir constants k and q0 was found to be 0.0061 (L/mg) and 19.23 (mg/g). The adsorption system obeyed Pseudo second order kinetics with R2 value of 0.999. The results of the present study indicated that gooseberry seed powder can be employed as adsorbent for the effective removal of hexavalent chromium economically.
Computer Science
Active and Programmable Networks
Active safety systems
Ad Hoc & Sensor Network
Ad hoc networks for pervasive communications
Adaptive, autonomic and context-aware computing
Advance Computing technology and their application
Advanced Computing Architectures and New Programming Models
Advanced control and measurement
Aeronautical Engineering,
Agent-based middleware
Alert applications
Automotive, marine and aero-space control and all other control applications
Autonomic and self-managing middleware
Autonomous vehicle
Biochemistry
Bioinformatics
BioTechnology(Chemistry, Mathematics, Statistics, Geology)
Broadband and intelligent networks
Broadband wireless technologies
CAD/CAM/CAT/CIM
Call admission and flow/congestion control
Capacity planning and dimensioning
Changing Access to Patient Information
Channel capacity modelling and analysis
Civil Engineering,
Cloud Computing and Applications
Collaborative applications
Communication application
Communication architectures for pervasive computing
Communication systems
Computational intelligence
Computer and microprocessor-based control
Computer Architecture and Embedded Systems
Computer Business
Computer Sciences and Applications
Computer Vision
Computer-based information systems in health care
Computing Ethics
Computing Practices & Applications
Congestion and/or Flow Control
Content Distribution
Context-awareness and middleware
Creativity in Internet management and retailing
Cross-layer design and Physical layer based issue
Cryptography
Data Base Management
Data fusion
Data Mining
Data retrieval
Data Storage Management
Decision analysis methods
Decision making
Digital Economy and Digital Divide
Digital signal processing theory
Distributed Sensor Networks
Drives automation
Drug Design,
Drug Development
DSP implementation
E-Business
E-Commerce
E-Government
Electronic transceiver device for Retail Marketing Industries
Electronics Engineering,
Embeded Computer System
Emerging advances in business and its applications
Emerging signal processing areas
Enabling technologies for pervasive systems
Energy-efficient and green pervasive computing
Environmental Engineering,
Estimation and identification techniques
Evaluation techniques for middleware solutions
Event-based, publish/subscribe, and message-oriented middleware
Evolutionary computing and intelligent systems
Expert approaches
Facilities planning and management
Flexible manufacturing systems
Formal methods and tools for designing
Fuzzy algorithms
Fuzzy logics
GPS and location-based app
Using Tunisian Phosphate Rock and Her Converted Hydroxyapatite for Lead Remov...IJERA Editor
Natural and synthesis apatites represent a cost effective soil amendment, which can be used for in situ reduction of lead bioavailability and mobility. In our previous work, we selected Tunisian Phosphate Rock (TPR) and Hydroxyapatite (CaHAp) as promising minerals for the removal of lead from aqueous solutions. X-ray powder diffraction patterns (DRX), Infra Red (IR), Thermogravimetric analysis (TGA) and Scanning Electron Microscopy (SEM) were used to characterize TPR and CaHAp. CaHAp was prepared from TPR and employed for the removal of Pb2+ ions at different concentrations from aqueous solution to determine the adsorption properties of CaHAp and compare them with those of a TPR. The kinetic data obtained indicated that the adsorption performances of the adsorbents depended both on their specific surface area and crystallinity. Complexation of lead ion on the adsorbent surface favoured the dissolution of hydroxyapatites characterized by a Ca/Pb molar ratio of 1.69. The maximum adsorption capacity of CaHAp for Pb2+ ions at 25 °C was 1.806 mmol /g relative to 1.035 mmol /g for TPR at the same temperature. The higher capacity of CaHAp was explained in terms of its porosity and crystallinity. The Pb2+ ions sorption results could be modelled by the Langmuir and Freundlich isotherms. The simulations of adsorption isotherms of Pb2+ on CaHAp allow us to conclude that there is a good correlation between the experimental data and the Langmuir model. On TPR, we show a good correlation between the experimental data and the Langmuir and Freundlich model.
Equilibrium and kinetic study on chromium (vi) removal from simulatedGJESM Publication
Gooseberry seed (Phyllanthus acidus) was used as an adsorbent to determine its feasibility for the removal of Cr(VI). Various parameters such as pH, temperature, contact time, initial metal concentration and adsorbent dosage were investigated to determine the biosorption performance. Equilibrium was attained within 60 minutes and maximum removal of 96% was achieved under the optimum conditions at pH 2. The adsorption phenomenon demonstrated here was monolayer represented by Langmuir isotherm with R2 value of 0.992 and the Langmuir constants k and q0 was found to be 0.0061 (L/mg) and 19.23 (mg/g). The adsorption system obeyed Pseudo second order kinetics with R2 value of 0.999. The results of the present study indicated that gooseberry seed powder can be employed as adsorbent for the effective removal of hexavalent chromium economically.
Computer Science
Active and Programmable Networks
Active safety systems
Ad Hoc & Sensor Network
Ad hoc networks for pervasive communications
Adaptive, autonomic and context-aware computing
Advance Computing technology and their application
Advanced Computing Architectures and New Programming Models
Advanced control and measurement
Aeronautical Engineering,
Agent-based middleware
Alert applications
Automotive, marine and aero-space control and all other control applications
Autonomic and self-managing middleware
Autonomous vehicle
Biochemistry
Bioinformatics
BioTechnology(Chemistry, Mathematics, Statistics, Geology)
Broadband and intelligent networks
Broadband wireless technologies
CAD/CAM/CAT/CIM
Call admission and flow/congestion control
Capacity planning and dimensioning
Changing Access to Patient Information
Channel capacity modelling and analysis
Civil Engineering,
Cloud Computing and Applications
Collaborative applications
Communication application
Communication architectures for pervasive computing
Communication systems
Computational intelligence
Computer and microprocessor-based control
Computer Architecture and Embedded Systems
Computer Business
Computer Sciences and Applications
Computer Vision
Computer-based information systems in health care
Computing Ethics
Computing Practices & Applications
Congestion and/or Flow Control
Content Distribution
Context-awareness and middleware
Creativity in Internet management and retailing
Cross-layer design and Physical layer based issue
Cryptography
Data Base Management
Data fusion
Data Mining
Data retrieval
Data Storage Management
Decision analysis methods
Decision making
Digital Economy and Digital Divide
Digital signal processing theory
Distributed Sensor Networks
Drives automation
Drug Design,
Drug Development
DSP implementation
E-Business
E-Commerce
E-Government
Electronic transceiver device for Retail Marketing Industries
Electronics Engineering,
Embeded Computer System
Emerging advances in business and its applications
Emerging signal processing areas
Enabling technologies for pervasive systems
Energy-efficient and green pervasive computing
Environmental Engineering,
Estimation and identification techniques
Evaluation techniques for middleware solutions
Event-based, publish/subscribe, and message-oriented middleware
Evolutionary computing and intelligent systems
Expert approaches
Facilities planning and management
Flexible manufacturing systems
Formal methods and tools for designing
Fuzzy algorithms
Fuzzy logics
GPS and location-based app
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Second order and Third order NLO studies of L- alanine crystals grown in aque...Editor IJCATR
Nonlinear optics is a fascinating field, which plays a vital role in the emerging field of photonics and optoelectronics. A
nonlinear optical crystal of L-alanine grown in aqueous solution of hydrofluoric acid is done by slow evaporation method. L-alanine is
an NLO material and it has a Second Harmonic Generation (SHG) efficiency of about 0.3 times that of KDP. To alter the various
properties of L-alanine, single crystals of L-alanine have been grown in the aqueous solution of hydrofluoric acid. In this work, Lalanine
was admixtured with hydrofluoric acid (LAHF) in the molar ratio of 1:1. The grown crystals were colorless and transparent
and they were subjected to various studies for characterization.The third-order nonlinearities of LAHF crystal have been investigated
by Z-scan method. The values of nonlinear refractive index (n2), the nonlinear absorption coefficient (β) and third-order nonlinear
susceptibility (χ(3)) are estimated for the sample
Monitoring of the Sulfur and Nano Silver in Water by Method of Laser Spectros...IJERA Editor
We developed new automatic method that combines the method of forced lumines-cence and stimulated Brillouin scattering (SBS). We used the method for the pathogens monitoring in water supply system earlier. We have researched spectral peaks of gases and show that method allows determining H2S content with 0.01% accuracy and determining the content constituents of nano silver in water.
Removal of Heavy Metals from Aqueous Solutions by Modified Activated Carbon f...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
The present work was carried out to evaluate the removal of p-nitrophenol by adsorption onto olive cake based activated carbon having a BET surface area of 672 m²/g. The batch adsorption experimental results indicated that the equilibrium time for nitrophenol adsorption by olive cake-based activated carbon was 120min. The adsorption data was modeled by equilibrium and kinetic models. The pseudo- first and second order as well as the Elovichkinetic models were applied to fit the experimental data and the intraparticle diffusion model was assessed for describing the mechanism of adsorption. The data were found to be best fitted to the pseudo-second order model with a correlation coefficient (R2=0.986). The intraparticle diffusion mechanism also showed a good fit to the experimental data, showing two distinct linear parts assuming that more than one step could be involved in the adsorption of nitrophenol by the activated carbon. The equilibrium study was performed using three models including Langmuir, Freundlich and Temkin. The results revealed that the Temkin equilibrium model is the best model fitting the experimental data (R2=0.944). The results of the present study proved the efficiency of using olive cake based activated carbon as a novel adsorbent for the removal of nitrophenol from aqueous solution.
Nalbuphine hydrochloride (5a,6a)-17-(Cyclobutylmethyl)-4,5- epoxymorphinan-3,6,14-triol hydrochloride, is narcotic analgesic drug which is a morphine- like drug with agonist activity at the k- opioid receptor and antagonist activity at the μ-opioid receptor. Nalbuphine is recommended for use in moderate to serve pain and its indications include pain after myocardial infraction.
Study of the Influence of Nickel Content and Reaction Temperature on Glycerol...IJRESJOURNAL
ABSTRACT: La2O3-SiO2-supported nickel catalysts were evaluated in glycerol steam reforming. The samples (30wt% La and 5, 10 and 15wt% of Ni on 70wt% commercial SiO2), prepared by the simultaneous impregnation method, were characterized by EDX, nitrogen physisorption, XRD, in-situ XRD, XANES and TPR. The analyses revealed NiO species weakly interact with the support and the different metallic surface areas of the catalysts. Catalytic tests were performed in a fixed bed reactor at 600oC and 15Ni catalyst, which showed the best performance, was also evaluated at 500oC and 700oC. According to the results, the Ni content on the catalyst surface interferes in the distribution of gaseous products H2, CO, CO2 and CH4. The increase in the Ni content increases the carbon formation during reaction. The reaction temperature affected the catalytic performance and the best results were obtained with the 15Ni catalyst at 600oC, which was also tested for 20 hours for the analysis of its stability.
Characterization of mining tailings containing sulfides and carbonates applyi...Judson Arantes
Acid mine drainage (AMD) is the process resulting from the oxidation of sulfides exposed to the action of oxygen and water. The characterization of the minerals likely the formation and neutralization of AMD is important for the follow and evaluation of environmental impact. The analysis of X-ray diffraction (XRD) together with the Rietveld method is presented as a promising alternative to favor the identification and quantification of mineral phases. The results of the static test ANC achieved by accounting for carbonates consumed during the test, were correlated with the results obtained by the characterization techniques of X-ray diffraction (XRD) combined with the Rietveld method. The highest concentration of carbonate buffering found in AM2E, which may explain the static test results to be neutralizing for the sample. The major phases identified for both samples were aluminosilicates and quartz, with greater than 70% by weight levels.
Removal of cadmium from aqueous solution using cobalt silicate precipitation ...IJSIT Editor
Cobalt silicate precipitation tube (CoSPT), prepared through ‘silica garden’ route was found to be a
potential adsorbent for removal of cadmium from aqueous medium. Detail adsorption study of Cd(II) on
CoSPT was investigated. Batch adsorption studies were carried out as a function of contact time, adsorbent
dose, adsorbate concentration (50-300 mg L-1), temperature (298-323K). Cd(II) loading on CoSPT was
dependent on initial Cd(II) concentration. Experimental adsorption data were modeled using Freundlich and
Langmuir isotherm equations. pH variation study revealed that the adsorption increased with increase in pH
of the solution. Cd(II) loading capacity of CoSPT was estimated at 319 mg g-1, which ranks high amongst
efficient Cd(II) adsorbents. Adsorption data were analyzed using two kinetic models, Lagergren first order
and pseudo second order. It was observed that pseudo second order rate equation represented the best
correlation.
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Second order and Third order NLO studies of L- alanine crystals grown in aque...Editor IJCATR
Nonlinear optics is a fascinating field, which plays a vital role in the emerging field of photonics and optoelectronics. A
nonlinear optical crystal of L-alanine grown in aqueous solution of hydrofluoric acid is done by slow evaporation method. L-alanine is
an NLO material and it has a Second Harmonic Generation (SHG) efficiency of about 0.3 times that of KDP. To alter the various
properties of L-alanine, single crystals of L-alanine have been grown in the aqueous solution of hydrofluoric acid. In this work, Lalanine
was admixtured with hydrofluoric acid (LAHF) in the molar ratio of 1:1. The grown crystals were colorless and transparent
and they were subjected to various studies for characterization.The third-order nonlinearities of LAHF crystal have been investigated
by Z-scan method. The values of nonlinear refractive index (n2), the nonlinear absorption coefficient (β) and third-order nonlinear
susceptibility (χ(3)) are estimated for the sample
Monitoring of the Sulfur and Nano Silver in Water by Method of Laser Spectros...IJERA Editor
We developed new automatic method that combines the method of forced lumines-cence and stimulated Brillouin scattering (SBS). We used the method for the pathogens monitoring in water supply system earlier. We have researched spectral peaks of gases and show that method allows determining H2S content with 0.01% accuracy and determining the content constituents of nano silver in water.
Removal of Heavy Metals from Aqueous Solutions by Modified Activated Carbon f...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
The present work was carried out to evaluate the removal of p-nitrophenol by adsorption onto olive cake based activated carbon having a BET surface area of 672 m²/g. The batch adsorption experimental results indicated that the equilibrium time for nitrophenol adsorption by olive cake-based activated carbon was 120min. The adsorption data was modeled by equilibrium and kinetic models. The pseudo- first and second order as well as the Elovichkinetic models were applied to fit the experimental data and the intraparticle diffusion model was assessed for describing the mechanism of adsorption. The data were found to be best fitted to the pseudo-second order model with a correlation coefficient (R2=0.986). The intraparticle diffusion mechanism also showed a good fit to the experimental data, showing two distinct linear parts assuming that more than one step could be involved in the adsorption of nitrophenol by the activated carbon. The equilibrium study was performed using three models including Langmuir, Freundlich and Temkin. The results revealed that the Temkin equilibrium model is the best model fitting the experimental data (R2=0.944). The results of the present study proved the efficiency of using olive cake based activated carbon as a novel adsorbent for the removal of nitrophenol from aqueous solution.
Nalbuphine hydrochloride (5a,6a)-17-(Cyclobutylmethyl)-4,5- epoxymorphinan-3,6,14-triol hydrochloride, is narcotic analgesic drug which is a morphine- like drug with agonist activity at the k- opioid receptor and antagonist activity at the μ-opioid receptor. Nalbuphine is recommended for use in moderate to serve pain and its indications include pain after myocardial infraction.
Study of the Influence of Nickel Content and Reaction Temperature on Glycerol...IJRESJOURNAL
ABSTRACT: La2O3-SiO2-supported nickel catalysts were evaluated in glycerol steam reforming. The samples (30wt% La and 5, 10 and 15wt% of Ni on 70wt% commercial SiO2), prepared by the simultaneous impregnation method, were characterized by EDX, nitrogen physisorption, XRD, in-situ XRD, XANES and TPR. The analyses revealed NiO species weakly interact with the support and the different metallic surface areas of the catalysts. Catalytic tests were performed in a fixed bed reactor at 600oC and 15Ni catalyst, which showed the best performance, was also evaluated at 500oC and 700oC. According to the results, the Ni content on the catalyst surface interferes in the distribution of gaseous products H2, CO, CO2 and CH4. The increase in the Ni content increases the carbon formation during reaction. The reaction temperature affected the catalytic performance and the best results were obtained with the 15Ni catalyst at 600oC, which was also tested for 20 hours for the analysis of its stability.
Characterization of mining tailings containing sulfides and carbonates applyi...Judson Arantes
Acid mine drainage (AMD) is the process resulting from the oxidation of sulfides exposed to the action of oxygen and water. The characterization of the minerals likely the formation and neutralization of AMD is important for the follow and evaluation of environmental impact. The analysis of X-ray diffraction (XRD) together with the Rietveld method is presented as a promising alternative to favor the identification and quantification of mineral phases. The results of the static test ANC achieved by accounting for carbonates consumed during the test, were correlated with the results obtained by the characterization techniques of X-ray diffraction (XRD) combined with the Rietveld method. The highest concentration of carbonate buffering found in AM2E, which may explain the static test results to be neutralizing for the sample. The major phases identified for both samples were aluminosilicates and quartz, with greater than 70% by weight levels.
Removal of cadmium from aqueous solution using cobalt silicate precipitation ...IJSIT Editor
Cobalt silicate precipitation tube (CoSPT), prepared through ‘silica garden’ route was found to be a
potential adsorbent for removal of cadmium from aqueous medium. Detail adsorption study of Cd(II) on
CoSPT was investigated. Batch adsorption studies were carried out as a function of contact time, adsorbent
dose, adsorbate concentration (50-300 mg L-1), temperature (298-323K). Cd(II) loading on CoSPT was
dependent on initial Cd(II) concentration. Experimental adsorption data were modeled using Freundlich and
Langmuir isotherm equations. pH variation study revealed that the adsorption increased with increase in pH
of the solution. Cd(II) loading capacity of CoSPT was estimated at 319 mg g-1, which ranks high amongst
efficient Cd(II) adsorbents. Adsorption data were analyzed using two kinetic models, Lagergren first order
and pseudo second order. It was observed that pseudo second order rate equation represented the best
correlation.
Talk on "Technological Challenges Posed By Web 2.0" given at the Fellows Conference 2007.
See http://www.ukoln.ac.uk/web-focus/events/conferences/fellows-conference-2007/
Morgan O'Driscoll 'Off The Wall May Online Art AuctionMorgan O'Driscoll
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Chemical Examination Of Sandbox (Hura Crepitans) Seed: Proximate, Elemental A...IOSRJAC
A study in terms of proximate, elemental and fatty acid contents of (Hura crepitans) seed was investigated using standard analytical techniques. The results of proximate composition in % were as follows: moisture 12.82 ± 0.01, crude protein 24.76 ±0.04, crude fibre 10.15 ± 0.03, fat 10.68 ± 0.01, ash 3.16 ± 0.02 and carbohydrate 34.75 ± 0.05. The elemental composition of the seed showed Na, K, Ca and Mg in mg/100g to be 6.00 ± 0.01, 123.00 ± 0.02, 10.40 ± 0.03, 112.00 ± 0.01 respectively while other elements determined in mg/kg were Fe and Zn with 7.10 ±0.04 and 2.60± 0.01. The (%) free fatty acid compositions of the seed oil were as follows: lauric (1.310 ±0.015), palmitic (0.389 ±0.012), palmitoleic (1.211 ±0.013), stearic (2.436 ± 0.004), oleic (6.138 ±0.003), linoleic (8.625 ±0.001) and linolenic (2.469 ± 0.102). The results revealed linoleic and oleic acids to be the most common in terms of abundance while palmitic acid was the least. The seed of Hura crepitans could be described as a good food because it contained significant amount of essential nutrients required by man.
Because of strong Vander Waal force, carbon nanotubes tend to aggregate into bundle that
limits its applications in various fields. Homogenous dispersion of carbon nanotubes is an important issue. This
paper reports the effect of chemical functionalization of multiwalled carbon nanotubes (MWCNTs) by
introducing polar groups such as carboxyl groups in order to get better dispersibility in aqueous medium.
Functionalization of MWCNTs was done by acid (HCl, HNO3, Aquaregia)and non-acid (NH4OH/H2O2)
treatment.All treatments followed with variation of ultra-sonication time.The dispersion of MWCNTs was
monitored by UV-VIS absorption spectroscopy. Functionalization removes the impurities present in pristine
MWCNTs and adds different functional group on the surface of MWCNTs which helps further dispersion. The
chemical change after functionalization of MWCNTwas investigated by FT-IR and Raman spectroscopy. Among
four chemical reagents, HNO3acid treated MWCNTs show higher dispersion than other three. The dispersion
increases with increasing the sonication time.
Equilibrium and Kinetics Adsorption of Cadmium and Lead Ions from Aqueous Sol...theijes
Sourcing cheap adsorbents for the treatment of waste water is imperative for local environments. The adsorption of cadmium (Cd) and lead (Pb) from aqueous solution onto bamboo activated carbon prepared by chemical activation with ZnCl2 was investigated. The unwashed chemical activated bamboo carbon (UCABC) achieved up to 87.81% and 96.45% removal of Cd and Pb at pH-5 and 11, respectively. Removal equilibrium was attained within 1hr and 2.5hrs for Cd and Pb, respectively. The Cd and Pb adsorption increased with adsorbent dosage decrease while removal rate (%) increased with Cd and Pb concentration. Adsorption isotherm of Cd and Pb onto UCABC was determined and correlated with four isotherm models (Langmuir, Freundlich, Temkin and Hills). The equilibrium data fitted into Freundlich Cd (R2 = 0.9873, SSE = 0.045), Pb (R2 =0.9903, SSE = 0.051); Temkin Cd (R2 =0.9730, SSE = 0.052), Pb (R2 = 0.9079, SSE = 0.056); Hills Cd (R2 = 0.9961, SSE = 0.048), Pb (R2.= 0.9183, SSE = 0.053) and Langmuir Cd (R2 = 0.9653, SSE = 0.302), Pb (R2 = 0.9899, SSE = 0.136) isotherms. The Freundlich fitting showed isotherm adsorption capacity constants Kf = 7.843 and 5.098 (mg/g) for Cd and Pb, respectively. Furthermore, their adsorption kinetics correlated with the Pseudo-first order, Pseudo-second order and Intra-particle diffusion models and could be best described by the Pseudo-second order equation, suggesting chemisorptions as the limiting process. This study demonstrated that the UCABC can remove Cd2+ and Pb+ ions from aqueous solution to avert expensive commercial adsorbents
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
SYNTHESIS AND CHARACTERIZATION OF KAOLINITE COATED WITH CU-OXIDE AND ITS EFFE...Premier Publishers
In this paper, a novel copper oxide coated kaolinite was prepared as an adsorbent of Hg(II) ions from aqueous media. The materials used for this study were synthesized, characterised and the product tested for mercury ion removal using standard laboratory procedures. Reactivity and removal kinetic models derived from Freundlich isotherm were used to investigate contact time and pH effects on the coefficient of protonation and rate of mass transfer of Hg(II) ions to the reactive sites, Proton coefficient of 0.89 indicated a decrease in proton consumption function when compared with uncoated kaolinite. At the 12th h reaction time, a maximum adsorption capacity of 85% was achieved. Mass transfer rates of 0.9359h-1 and 0.0748h-1 for the first and second reaction phases indicated a reduction when compared with uncoated kaolinite. These changes may be ascribed to masking of reaction sites and exposed surface area of the Cu-Oxide coated kaolinite.
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by...CrimsonpublishersEAES
Isotherm Modeling and Thermodynamic Study of the Adsorption of Toxic Metal by the Apricot Stone by Moussa Abbas*, Tounsia Aksil and Mohamed Trari in Environmental Analysis & Ecology Studies
Adsorption Characteristics and Behaviors of Natural Red Clay for Removal of B...ijtsrd
The present study deals with the analysis and adsorption of Basic Yellow 28 BY28 onto low-cost natural red clay NRC . Adsorbent characterized by XRD, SEM, TG DTA, BET and BJH. The effect of the contact time, the temperature, the initial concentration, the pH and the adsorbent mass and on adsorption process were investigated using by batch adsorption technique and then the adsorption isotherm, kinetics, thermodynamics and equilibrium studies were performed. The pH effect on the removal of BY28 efficiency was not important. It was found that the isotherm model best suited to the equilibrium data obtained from the adsorption of BY28 on NRC was the pseudo-second order. It was found that the kinetic model best suited to the data obtained from the adsorption of BY28 on NRC was the Langmuir model. The maximum monolayer adsorption capacity was 370 mg. g-1. In the thermodynamic studies, it can be said that the adsorption of BY28 onto NRC takes place spontaneously, physically and endothermic ally. Finally, the use of NRC shows a greater potential for the removal of cationic dyes, as no costly equipment is required. Omer Lacin | Ali Haghighatnia | Fatih Demir | Fatih Sevim "Adsorption Characteristics and Behaviors of Natural Red Clay for Removal of BY28 from Aqueous Solutions" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-2 , February 2019, URL: https://www.ijtsrd.com/papers/ijtsrd21544.pdf
Paper URL: https://www.ijtsrd.com/engineering/engineering-chemistry/21544/adsorption-characteristics-and-behaviors-of-natural-red-clay-for-removal-of-by28-from-aqueous-solutions/omer-lacin
The adsorption potential of two samples of clays namely Kaolinite (KAO) and Metakaolinite
(MKB) for the adsorption of Cu2+ ions from aqueous solution was investigated. The effects of pH, contact time,
adsorbent dosage and initial concentration of Cu2+ ions solution were studied on the adsorption feasibility onto
KAO and MKB. The maximum adsorption capacities of Cu2+ ions onto KAO and MKB were found to be 14.3
and 21.3 mg.g−1
respectively .The Dubinin-Kaganer-Radushkevich model’s revealed that, the Cu2+ ions
adsorption onto KAO and MKB was governed by physical adsorption and the equilibrium study obeyed the
Freundlich isotherm model. The kinetic investigation of Cu2+ ions adsorption onto KAO and MKB fitted well the
pseudo-first-order kinetic model.
1. Proceedings of the World Congress on New Technologies (NewTech 2015)
Barcelona, Spain – July 15-17, 2015
Paper No. 162
Insights into Competitive Adsorption Between Nitrate and
Oxalic Acid Over Tio2 and Consequences for Photocatalytic
Remediation
Haruna Adamu
Surface Chemistry and Catalysis Research Group, Department of Chemistry, Meston Building, University
of Aberdeen, AB24 3UE, UK.
r01ha12@abdn.ac.uk
James A. Anderson
Surface Chemistry and Catalysis Research Group, Department of Chemistry, Meston Building, University
of Aberdeen, AB24 3UE, UK.
Materials and Chemical Engineering Group, School of Engineering, University of Aberdeen,
AB24 3UE, UK
j.anderson@abdn.ac.uk
Abstract ‒The adsorptive behaviour of nitrate and oxalic acid on TiO2 in single and bi-component systems was
studied. It was found that the Langmuir adsorption coefficient for nitrate is 4 times higher than that of the oxalic
acid. However, the amount of oxalic acid adsorbed by TiO2 was about 10 times greater than the amount of nitrate
adsorbed. In the bi-component system, oxalic acid was preferentially adsorbed on the TiO2 surface. Thus, in the
presence of oxalic acid, adsorption of nitrate was inhibited and despite its higher Langmuir adsorption coefficient, at
oxalic acid concentrations of 4 and 8 mM uptake was negligible. Consequently, the impact of inhibition on the
adsorption of nitrate by oxalic acid could be responsible for low rate of photocatalytic remediation of nitrate in
aqueous suspension of TiO2. Therefore, enhancing adsorption of nitrate on TiO2 through surface modification could
be a key parameter for accelerating the photocatalytic reaction.
Keywords: TiO2, adsorption, inhibition, nitrate, oxalic acid.
1. Introduction
Nitrate ions are the abundant components of industrial, agricultural and municipal wastewater
streams and discharges from these source points result in excess concentrations in water supplies. High
concentration of nitrate ions in drinking water source has been considered to be deleterious to human
health as it can be transformed into carcinogenic compound and therefore, its removal from drinking
water is essential. For this reason, heterogeneous photocatalytic remediation of nitrate on TiO2 has been
developed and emerged to be a promising advanced green remediation technology for denitrification of
drinking water sources (Anderson, Fernandez-Garcia 2009). The technology exploits the oxidation and
reduction potentials of the photogenerated holes and electrons that are simultaneously created in the solid
following exposure to radiation of energy greater than the band gap. If suitable scavengers are available to
trap the electrons and holes, the rate of recombination is reduced and consequently, redox reactions and
proportianaly enhanced. In the case of photocatalytic remediation of nitrates, upon photo-excitation of
TiO2, the photogenerated electrons and positively holes can reduce and oxidise adsorbed nitrate and
organic hole scavenger on the surface of TiO2, respectively. To this effect and achieve effective
photochemical conversions of these substances simultaneously, preadsorption of nitrate and organic
species on the TiO2 surface is a prerequisite step in the entire process, since interfacial charge carrier
trapping needs to be very fast. More importantly, nitrate should be adsorbed more efficiently than an
2. 2
organic hole scavenger, since the interfacial transfer of electron occurs slower than the hole transfer
(Hoffmann et al. 1995). However, it has been reported that organic hole scavenger was preferentially
adsorbed on the surface of TiO2 whereas the adsorption of nitrate was to a lesser extent or even inhibited
(Li, Wasgestian 1998). With this observation, detail studies in the literature that elucidate how the two
solutes behave under competitive conditions have not been well explored. Therefore, from the
heterogeneous photocatalysis purview, it is of great interest to investigate the co-adsorption of nitrate and
organic hole scavenger on TiO2 surface, which can allow an understanding of the effect of organic hole
scavenger on nitrate adsorption. The derived co-adsorption parameters may be a key in trying to develop
improved photocatalysts for better performance in the photocatalytic remediation of nitrate that could be
attained by enhancing nitrate adsorption capacity.
In the present paper, co-adsorption of nitrate and oxalic acid in aqueous suspension of TiO2 is
reported. This binary system was considered since this pair is often employed in the photocatalytic
removal of nitrate, but few studies report on the strength or extent of adsorption of the two components
when combined in a competitive environment.
2. Separate And Co-Adsorption Adsorption Test Of Nitrate And Oxalic Acid
The adsorption tests for single-component systems were conducted at constant temperature of 25 ±
0.1 °C and without pH adjustment using different initial concentrations of nitrate and oxalic acid. 0.25 g
of P25-TiO2 was thoroughly mixed in a series of capped 100 ml Pyrex bottles contained 25 ml of nitrate
or oxalic acid solutions with concentrations in the range 10 ‒ 100 mg/L (1.61 x 10-4
‒ 1.61 x 10-3
mol/dm3
) and 0.001, 0.002, 0.004, 0.008 and 0.010 mol/dm3
, respectively, in a thermostat water
bath/shaker for 24 h. After the 24 h shaking, the suspensions were centrifuged, filtered with syringe filter
0.45 μm (Millipore) and then then analysed for equilibrium concentrations of nitrate and oxalic acid were
determined at 340 and 262 nm, respectively, using UV-visible spectrophotometer (Lambda 25,
PerkinElmer). For nitrate, nitrate kit (spectroquant) was used for its residual concentration determination,
whereas oxalic acid was based on its characteristic functionality.
To determine the maximum adsorption uptake for both nitrate and oxalic acid, the amount of nitrate
and oxalic acid adsorbed per unit mass of TiO2 (mol/g) was calculated using the expression (1)
qe = (Ci ‒ Ce) V/m (1)
where qe is the amount adsorbed at equilibrium (mol/g), Ci is the initial concentration (mol/dm3
), Ce
is the solution equilibrium concentration (mol/dm3
), V is the volume of the aqueous phase (dm3
), and m is
the mass of TiO2 used.
In the co-adsorption experiment, a similar procedure was used. Solutions of oxalic acid (0.001, 0.002,
0.004 and 0.008 mol/dm3
) and fixed nitrate concentration of 100 mg/L (0.00161 mol/dm3
) were mixed
with 0.25 g TiO2. The equilibrium concentrations in the samples were determined in the same way as
employed for the individual components.
2. 1. Error Analysis
The regression Chi-square (χ2
) test was employed as a criterion for fitting quality. The statistical
analysis is based on the sum of the square of the differences between the experimental adsorption data
and model calculated data, of which each squared difference was divided by the corresponding data
obtained by calculating from models (Ho 2004). The chi-square can be presented by the following
equation:
χ2
= ∑ [
(𝑞𝑒𝑒 ‒ 𝑞𝑒𝑐)2
𝑞𝑒𝑐
] (2)
3. 3
where qee is the equilibrium capacity of the adsorbent obtained from experiment (mol/g), and qec is
the calculated equilibrium uptake according to the model (mol/g). A low value of χ2
indicates that
experimental data provides a good quality fit to the value from the model. Therefore, data were analysed
to confirm the best-fit isotherms for the adsorption systems of both nitrate and oxalic acid.
3. Results and Discussion
3. 1. Individual Adsorption Isotherms Of Nitrate And Oxalic Acid
The equilibrium relationship between adsorbent and adsorbate is commonly established by
adsorption isotherms and thus, is of great importance to heterogeneous photocatalysis. Equilibrium
adsorption studies provide the uptake capacity of the adsorbent and delineate the surface properties and
affinity of the adsorbent for an adsorbate via certain constants. With respect to this, Langmuir and
Freundlich models, as the most frequently used isotherms, were employed to explore adsorption
behaviour of TiO2 towards nitrate and oxalic acid in single and bi-component systems. The commonly
linearised Freundlich and Langmuir equations used are expressed in equation 3 and 4, respectively.
log qe = log KF + 1/nlog Ce (3)
where qe is the adsorption capacity (mol/g); Ce is the equilibrium concentration (mol/dm3
),
respectively; KF and 1/n are the adsorption capacity and intensity of adsorption, respectively. The values
of KF and 1/n were determined from the intercept and slope respectively, of the logarithmic plot, whereas
the expression below is the linearised Langmuir equation used-
Ce/qe = (1/KLqm) + (1/qm)Ce (4)
where qe is the amount of nitrate adsorbed at equilibrium (mol/g); Ce is the equilibrium concentration
of nitrate and oxalic acid (mol/dm3
); KL (dm3
/mol or M-1
) and qm (mol/g) are the Langmuir constant and
predicted maximum adsorption capacity. The constants qm and KL were determined from the intercept and
slope of the linear plot of the experimental data of Ce/qe vs. Ce.
Fig. 1a and b indicate that the uptake processes were continuous until saturation attained, suggesting
conceivable monolayer coverage of both nitrate and oxalic acid onto the surface of the TiO2. The
equilibrium uptake, qe, were 8.38 x 10-5
and 8.20 x 10-4
mol/g for nitrate and oxalic acid, respectively,
confirming that the amount of oxalic acid adsorbed was about 10 times higher than the amount of nitrate
adsorbed by TiO2. Similarly, the isotherms given by the Langmuir equation for the two adsorbates are
shown in Fig. 1c. Table 1 show the calculated values of Freundlich and Langmuir isotherm parameters for
single-component adsorption experiments, which reveal that the adsorption data of both oxalic acid and
nitrate were best fitted to the Langmuir model with a correlation coefficient, r2
> 0.99. In addition, the
smaller values of the χ2
further reveal the agreement between the measured and Langmuir model-
predicted uptake for both adsorbates, which characterise the quality of fit of the Langmuir isotherm model
describing the data. However, it is obvious from the linearised Langmuir plot that nitrate has a strong
affinity for TiO2 as implied by the initial rise at low concentrations of adsorbate (Vimonses et al. 2009a,
Vimonses et al. 2009b). Additionally, the extracted value of Langmuir adsorption coefficient, KL, for
nitrate is 4 times greater than that of oxalic acid (Table 1), suggesting that the strength of adsorption of
nitrate was significantly greater than oxalic acid. Despite this, the amount of oxalic acid was adsorbed on
the TiO2 surface was much greater. This observation could be attributed to the formation of oxalate
complexes at the surface of TiO2, since C2O4
2-
is a good bidentate ligand (Robert et al. 2000, Thomas,
Syres 2012, Mendive et al. 2009). The explanation could also be due to the ability of oxalic acid to bind
via two adsorption routes, which are either by two carbonyl groups or one carbonyl and one hydroxyl
groups (Fahmi et al. 1995, Mendive et al. 2007). This reflects that, at highest coverage, one oxalic acid
4. 4
conceivably covered 2 TiO2 units, indicating it ability to reach more adsorption sites of TiO2 than nitrate
with monodentate characteristics.
Table. 1. Adsorption parameters for nitrate and oxalic acid on TiO2.
0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009
0.0003
0.0004
0.0005
0.0006
0.0007
0.0008
0.0009
Experimental
Langmuir model
qe/molg-1
Ce/mol dm-3
(a)
0.0002 0.0004 0.0006 0.0008 0.0010 0.0012 0.0014 0.0016
0.000045
0.000050
0.000055
0.000060
0.000065
0.000070
0.000075
0.000080
0.000085
Experimental
Langmuir model
qe/molg-1
Ce/mol dm-3
(b)
0.000 0.002 0.004 0.006 0.008 0.010
2
4
6
8
10
12
14
16
18
Oxalic acid
Nitrate
Linear fit
Linear fit
Ce/qe/gL-1
Ce/mol dm-3
(c)
Fig. 1. (a) Oxalic acid and (b) nitrate adsorption isotherms (c) Langmuir plot for oxalic acid and nitrate.
3. 2. Co-Adsorption Isotherms Of Nitrate And Oxalic Acid
In heterogeneous photocatalytic remediation of nitrate using oxalic acid as hole scavenger, the nitrate
(electron acceptor) and oxalic acid (electron donor) are presence together in the reaction. Accordingly,
these two pollutants require adsorption sites on TiO2 surface and would be doubtful if their respective
ions are adsorbed in equal quantities and thus, competition is a relevant criterion to be investigated and
quantified. To test the adsorption behaviour of nitrate in presence of oxalic acid or vice visa, the extended
Langmuir isotherm for competitive adsorption developed by Jain and Snoeyink (1973) was applied.
5. 5
Hence, the amount of oxalic acid adsorbed on TiO2 surface upon competition with nitrate was
calculated from equation (5), which can be expressed as-
qe,oxalic = (qm,oxalic ̶ qm,nitrate) KL,oxalic Ce,oxalic / (1 + KL,oxalic Ce,oxalic) + (qm,nitrate KL,oxalic Ce,oxalic) / 1 + KL,oxalic
Ce,oxalic + KL, nitrate Ce,nitrate (5)
Similarly, the amount of nitrate adsorbed on TiO2 in competition with oxalic acid was calculated
from equation (6) written as-
qe,nitrate = (qm, nitrate KL, nitrate Ce, nitrate) / 1 + KL, oxalic Ce, oxalic + KL, nitrate Ce, nitrate (6)
where qe, oxalic and qe, nitrate are the amounts of oxalic acid and nitrate adsorbed per unit mass of TiO2 at
equilibrium concentrations of Ce,oxalic and Ce, nitrate, respectively. Qm, oxalic and qm, nitrate are maximum amount
of adsorption with complete monolayer coverage on TiO2 with oxalic acid and nitrate, respectively, which
are determined from single-component systems with their corresponding Langmuir constants.
Fig. 2 shows the adsorption behaviour of each in presence of both adsorbates. Compared to nitrate
single-solute adsorption onto TiO2 surface, competitive adsorption infers a significant decrease in uptake.
Despite the low Langmuir coefficient for oxalic acid, it was preferentially adsorbed onto TiO2 surface and
adsorption of nitrate was strongly inhibited. The inhibition by oxalic acid in preventing nitrate adsorption
increased from 12 to 93 % at 1.0 and 8.0 mM oxalic acid concentration, respectively. This implies that
nitrate can only successfully compete with oxalic acid at low concentrations equal or lower than 1.0 mM,
because even at 2.0 mM the inhibition effect reached 60 % (Fig. 2). However, at low concentration of
oxalic acid, the amount of oxalic acid that could be adsorbed maybe insufficient to trap the
photogenerated holes and as a result, effective nitrates reduction is limited. On the other hand, at high
concentrations, because of the preferential adsorption of oxalic acid, nitrate adsorption is greatly inhibited
and therefore, nitrate reduction cannot be efficiently performed due to reduced rate of acceptance of
electrons. The dependence of nitrate reduction upon oxalic acid concentration is shown in equation 7,
which indicates 2.5: 1 molar ratio of oxalic acid to nitrate. However, to avoid the likelihood of the
photocatalytic reduction process ceasing due to rapid consumption of oxalic acid, the concentration needs
to be double of the stoichiometric amount. Therefore, the concentration regions at which oxalic acid can
produce desired reduction of nitrate is at minimum of 4.0 mM and 8.0 mM maximally against 1.61 mM of
nitrate, concentration regions where oxalic acid prevented the adsorption of nitrate by 87 and 93 %
inhibition, respectively (Fig. 2). Hence, the reported lower degradation rate of nitrate in aqueous
suspension of TiO2 (Anderson 2012) may be related to the low amount of nitrate adsorbed on the
photocatalyst surface cause by preferential adsorption of oxalic acid. Consequently, to enhance the
adsorption of nitrate in the photocatalytic reduction process without compromising the required oxalic
acid concentration, surface modification of TiO2 with a high surface area adsorbent such as an activated
carbon might help in increasing adsorption capacity.
5H2C2O4(aq) + 2NO3
-
+ 2H+
N2 + 10CO2(g) + 6H2O (7)
4. Conclusion
The adsorption of nitrate and oxalic acid in aqueous suspension of TiO2 was investigated both in
single-solute and bi-solute systems. For single-solute adsorption, the results obtained fitted the Langmuir
adsorption isotherm model, which suggests higher uptake of oxalic acid than nitrate despite its lower
Langmuir adsorption coefficient. In the case of bi-component adsorption, it was found that nitrate
adsorption onto TiO2 was strongly inhibited in the presence of oxalic acid at stoichiometric amounts and
above. This distinct inhibition effect imposed on nitrate may be attributed to the dissimilar ability of
adsorption competition with oxalic acid on the surface of the photocatalysts. This better understanding of
the adsorption behaviour of nitrate and oxalic acid in bi-component system is likely to be employed in
6. 6
surface modification of TiO2 with high surface area materials, which may result in improvement in the
uptake of nitrate without a compromise on the stoichiometric concentration of oxalic acid for enhanced
photocatalytic remediation of nitrate.
0.0000 0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 0.0007 0.0008
0.00000
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
0.00007
0.00008
0.00009
Nitrate
Oxalic acid
Oxalic acid Ce/ mol dm-3
qe/molg-1
(a)
0.0000
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007
qe/molg-1
0.0007 0.0008 0.0009 0.0010 0.0011 0.0012 0.0013 0.0014 0.0015 0.0016
0.00000
0.00001
0.00002
0.00003
0.00004
0.00005
0.00006
0.00007
0.00008
0.00009
Nitrate
Oxalic acid
Nitrate Ce/ mol dm-3
qe/molg-1
0.0000
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007
qe/molg-1
(b)
Fig. 2. (a) Co-adsorption isotherm of nitrate and oxalic acid as a function of equilibrium concentration of oxalic
acid, (b) as a function of equilibrium concentration of nitrate.
Acknowledgements
We express our gratitude to Petroleum Technology Development Fund (PTDF, Nigeria) for the
award of PhD scholarship (HA), as well as Abubakar Tafawa Balewa University, Bauchi-Nigeria for the
granted fellowship.
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