Personal Research Database

Full Text: 2007\J Haz Mat141, 637.pdf

Abstract: Coir pith is a by-product from padding used in mattress factories. It contains a high amount of lignin. Therefore, this study investigated the use of coir pith in the removal of hexavalent chromium from electroplating wastewater by varying the parameters, such as the system pH, contact time, adsorbent dosage, and temperature. The maximum removal (99.99%) was obtained at 2%(w/v) dosage, particle size <75 µm, at initial Cr(VI) 1,647 mgl^-1, system pH 2, and an equilibrium time of 18 hours. The adsorption isotherm of coir pith fitted reasonably well with the Langmuir model. The maximum Cr(VI) adsorption capacity of coir pith at 15C, 30C, 45C and 60C was 138.04, 197.23, 262.89 and 317.65 mg Cr(VI) g^-1 coir pith, respectively. Thermodynamic parameters indicated an endothermic process and the adsorption process was favored at high temperature. Desorption studies of Cr(VI) on coir pith and X-ray absorption near edge structure (XANES) suggested that most of the chromium bound on the coir pith was in Cr(III) form due to the fact that the toxic Cr(VI) adsorbed on the coir pith by electrostatic attraction was easily reduced to less toxic Cr(III). Fourier transform infrared (FTIR) spectrometry analysis indicated that the carbonyl (C=O) groups and mechanism of chromium adsorption. The reduced Cr(III) on the coir pith surface may be bound with C=O groups and O-CH₃ groups through coordinate covalent bonding in which a lone pair of electrons in the oxygen atoms of the methoxy and carbonyl groups can be donated to form a shared bond with Cr(III).

Keywords : Chromium, Coir Pith, Adsorption, Langmuir Isotherm, Lignin

? Golder, A.K., Samanta, A.N. and Ray, S. (2007), Removal of Cr³⁺ by electrocoagulation with multiple electrodes: bipolar and monopolar configurations. Journal of Hazardous Materials, 141 (3), 653-661.

Full Text: 2007\J Haz Mat141, 653.pdf

Abstract: Removal of Cr³⁺ from aqueous solutions by electrocoagulation (EC) with multiple electrodes was studied with both bipolar and monopolar configurations. The influence of chloride ions, pH, initial Cr³⁺ concentration and cell current on removal performance was investigated in a batch stirred cell. It was noted that, the enhancement of solubility of Cr(OH)₃ and co-precipitated [Cr, Fe](OH)₃ in presence of chloride ions results in reduction of removal efficiency. Removal of Cr³⁺ improved at higher pH due to combined effect of precipitation, co-precipitation as solid solution like species, adsorption, cathodic reduction and sweep coagulation. The maximum Cr³⁺ removal per unit charge loading was found to be increasing with increase in initial Cr³⁺ concentration. The cell current efficiency was less than that predicted from Faraday’s law of electrolysis for both configurations. The operating cost was estimated from the power cost and cost of electrode material. The former was 40% and the later was 43% higher for bipolar configuration compared to monopolar configuration for achieving final chromium discharge limit of 2.0 mg/l.

Keywords: Electrocoagulation, Bipolar, Monopolar, Electrode Configuration, Current Efficiency

? Kiran, B., Kaushik, A. and Kaushik, C.P. (2007), Biosorption of Cr(VI) by native isolate of Lyngbya putealis (HH-15) in the presence of salts. Journal of Hazardous Materials, 141 (3), 662-667.

Full Text: 2007\J Haz Mat141, 662.pdf

Abstract: Industrial wastewaters containing heavy metals along with high concentration of soluble salts pose a major environmental problem that needs to be remedied. The present study reports on biosorption of Cr(VI) by native isolate of Lyngbya putealis HH-15 in batch system under varying range of pH (2.0 to 10.0), initial metal ion concentration (10 to 100 mg/l) and salt concentration (0 to 0.2%). Maximum metal removal (94.8%) took place at pH 3.0 with initial Cr concentration of 50 mg/l, which got reduced (90.1%) in the presence of 0.2% salts. Adsorption equilibrium and kinetic behavior of Cr(VI) in solution was also examined. Both Langmuir and Freundlich models fitted well to explain the adsorption data (R² = 0.90, 0.87, respectively) at 0.2 % salt concentration. Pseudo-second order kinetic model also fitted well to both the systems viz. Cr(VI) and Cr(VI) + salt.

Keywords: Adsorption, Adsorption Isotherms, Algae, Behavior, Biomass, Biosorption, Capacity, Chromium(VI), Concentration, Cr(VI), Environmental, Environmental Problem, Equilibrium, Freundlich, Heavy Metals, Heavy-Metal Biosorption, Hexavalent Chromium, Ion, Ions, Kinetic, Kinetic Model, Langmuir, Lead, Lyngbya Putealis, Metal, Metal Removal, Metals, Model, Models, pH, Range, Removal, Sorption, Wastewaters

? Batzias, F.A. and Sidiras, D.K. (2007), Simulation of dye adsorption by beech sawdust as affected by pH. Journal of Hazardous Materials, 141 (3), 668-679.

Full Text: 2007\J Haz Mat141, 668.pdf

Abstract: The effect of pH on the batch kinetics of methylene blue adsorption on beech sawdust was simulated, in order to evaluate sawdust potential use as low cost adsorbent for wastewater dye removal. The zero point of charge pHpzc of the sawdust, in order to explain the effect of pH in terms of pHpzc, was measured by the mass titration and the automatic titration methods. The adsorption capacity, estimated according to Freundlich’s model, indicate that increase of the pH enhances the adsorption behaviour of the examined material. The lower adsorption of methylene blue at acidic pH is due to the presence of excess H⁺ ions that compete with the dye cation for adsorption sites. As the pH of the system increases, the number of positively charged sites decreases while the number of the negatively charged sites increases. The negatively charged sites favour the adsorption of dye cation due to electrostatic attraction. The increase in initial pH from 8.0 to 11.5 increases the amount of dye adsorbed.

Keywords: Basic Dyes, Methylene Blue, Adsorption, pH, Sawdust, Wood

? Han, R.P., Wang, Y.F., Yu, W.H., Zou, W.H., Shi, J. and Liu, H.M. (2007), Biosorption of methylene blue from aqueous solution by rice husk in a fixed–bed column. Journal of Hazardous Materials, 141 (3), 713-718.

Full Text: 2007\J Haz Mat141, 713.pdf

Abstract: In this study, the ability of rice husk to adsorb Methylene Blue (MB) from aqueous solution was investigated in a fixed-bed column. The effects of important parameters, such as the value of initial pH, existed salt, the flow rate, the influent concentration of MB and bed depth, were studied. The Thomas model was applied to adsorption of MB at d ifferent flow rate, influent concentration and bed depth to predict the breakthrough curves and to determine the characteristic parameters of the column useful for process design using non-linear regression. The bed-depth/service time analysis (BDST) model was also applied at different bed depth to predict the breakthrough curves. The two models were found suitable for describing the biosorption process of the dynamic behavior of the rice husk column. All the results suggested that rice husk as adsorbent to removal MB from solution be efficient, and the rate of biosorption process be rapid. When the flow rate was 8.2 ml min-1 and the influent concentration of MB was 50 mg l^-1, the equilib rium adsorption biomass reached 4.41 mg g^-1 according to Thomas model.

Keysords: Rice Husk, Methylene Blue, Biosorption, Thomas Model, BDST Model

? El-Kamash, A.M., El-Gammal, B. and El-Sayed, A.A. (2007), Preparation and evaluation of cerium(IV) tungstate powder as inorganic exchanger in sorption of cobalt and europium ions from aqueous solutions. Journal of Hazardous Materials, 141 (3), 719-728.

Full Text: 2007\J Haz Mat141, 719.pdf

Abstract: Cerium(IV) tungstate powder was chemically synthesized and exploited as adsorbent material for the decontamination study of cobalt and europium ions from radioactive waste solutions under simulated conditions using batch technique. The influences of pH, particle size and temperature have been reported. The uptake of europium was found to be slightly greater than that of cobalt and the apparent sorption capacity increases with increase in temperature. Thermodynamic parameters such as changes in Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) were calculated. The numerical value of ΔG° decreases with an increase in temperature, indicating that the sorption reaction of each ion was spontaneous and more favorable at higher temperature. The positive values of ΔH° correspond to the endothermic nature of sorption processes and suggested that chemisorption was the predominant mechanism. A comparison of kinetic models applied to the sorption rate data of each ion was evaluated for the pseudo first-order, the pseudo second-order, intraparticle diffusion and homogeneous particle diffusion kinetic models. The results showed that both the pseudo second-order and the homogeneous particle diffusion models were found to best correlate the experimental rate data. The numerical values of the rate constants and particle diffusion coefficients were determined from the graphical representation of the proposed models. Activation energy (E_a) and entropy (ΔS^‡) of activation were also computed from the linearized form of Arrhenius equation.

Keywords: Activation, Activation Energy, Adsorbent, Adsorption-Kinetics, Antimonate, Aqueous Solutions, Batch, Beads, Cadmium, Capacity, Cerium(IV) Tungstate, Cesium, Changes, Chemisorption, Cobalt, Comparison, Data, Decontamination, Diffusion, Diffusion Coefficients, Endothermic, Energy, Enthalpy, Entropy, Europium, Evaluation, Experimental, First Order, Gibbs Free Energy, Intraparticle Diffusion, Kinetic, Kinetic Models, Kinetics, Mar, Mechanism, Modeling, Models, Nuclear-Waste Solutions, Particle Diffusion, Particle Size, pH, Pseudo First Order, Pseudo First-Order, Pseudo Second Order, Pseudo Second-Order, Pseudo-First-Order, Pseudo-Second-Order, Rate Constants, Removal, Representation, Rights, Second Order, Second-Order, Separation, Size, Solutions, Sorption, Sorption Capacity, Temperature, Thermodynamic, Thermodynamic Parameters, Thermodynamics, Uptake, Value, Waste, Zeolite

? Hu, T.J., Zeng, G.M., Huang, D.L., Yu, H.Y., Jiang, X.Y., Dai, F. and Huang, G.H. (2007), Use of potassium dihydrogen phosphate and sawdust as adsorbents of ammoniacal nitrogen in aerobic composting process. Journal of Hazardous Materials, 141 (3), 736-744.

Full Text: 2007\J Haz Mat141, 736.pdf

Abstract: Three kinds of adsorbents —Potassium Dihydrogen Phosphate, Sawdust and mixture of Potassium Dihydrogen Phosphate and Sawdust were added respectively into composting to investigate their adsorption effect on ammonia. The experimental results showed that all the adsorbents could restrain ammonia volatilizing, with the sorption of Potassium Dihydrogen Phosphate adsorbents being the best of all, the sorption of mixture adsorbent with Potassium Dihydrogen Phosphate and sawdust being the second and the sorption of sawdust adsorbent being the last. Therefore, the total nitrogen loss ratios respectively reduced from 38% to 13%, 15% and 21% after adding these three kinds of adsorbents into composting. However, Potassium Dihydrogen Phosphate produced negative influence on composting properties as its supplemented amount exceeded a quantity basis equivalent to 18% of total nitrogen in the composting, for examp le: pH value had been lessened, microorganism activity reduced, which finally resulted in the reduction of biodegradation ratio of organic matter. But it did not result in these problems when using the mixture of Potassium Dihydrogen Phosphate and sawdust as adsorbent, in which the amount of Potassium Dihydrogen Phosphate was under a quantity basis equivalent to 6% of total nitrogen in the composting. Moreover, the mixture adsorbent produced better adsorption effect on ammonia, and raised biodegradation ratio of organic matter from 26% to 33%.

Keywords: Aerobic Composting, Ammonia, Adsorbents, Composting Property

? Özer, A. (2007), Removal of Pb(II) ions from aqueous solutions by sulphuric acid-treated wheat bran. Journal of Hazardous Materials, 141 (3), 753-761.

Full Text: 2007\J Haz Mat141, 753.pdf

Abstract: Sulphuric acid-treated wheat bran (STWB) was used as an adsorbent to remove Pb(II) ions from aqueous solution. It was observed that the adsorption yield of Pb(II) ions was found to be pH dependent. The equilibrium time for the process was determined as 2 hours. STWB gave the highest adsorption yield at around pH 6.0. At this pH, adsorption percentage for an initial Pb(II) ions concentration of 100 mg/L was found to be 82.8 at 25 ºC for contact time of 2 hours. The equilibrium data obtained at different temperatures fitted to the non-linear form of Langmuir, Freundlich and Redlich-Peterson and linear form of Langmuir and Freundlich models. Isotherm constants were calculated and compared for the models used. The maximum adsorption capacity (q_max) which was obtained linear form of Langmuir model increased from 55.56 to 79.37 mg/g with increasing temperature from 25 °C to 60 °C. Similar trend was observed for other isotherm constants related to the adsorption capacity. Linear form of Langmuir isotherm data was evaluated to determine the thermodynamic parameters for the process. Thermodynamic parameters show that adsorption process of Pb(II) ions is an endothermic and more effective process at high temperatures. The pseudo nth order kinetic model was successfully applied to the kinetic data and the order (n) of adsorption reaction was calculated at the range from 1.711 to 1.929. The values of kad were found to be 5.82×10^-4 and 21.81×10^-4 (1/min)(mg/g)^1-n at 25 and 60 °C, respectively. Activation energy was determined as 29.65 kJ/mol for the process. This suggest that the adsorption Pb(II) ions by STWB is chemically controlled.

Keywords: Wheat Bran, Sulphuric Acid, Adsorption, Pb(II) Ions

? Aktaş, Ö. and Çeçen, F. (2007), Adsorption, desorption and bioregeneration in the treatment of 2-chlorophenol with activated carbon. Journal of Hazardous Materials, 141 (3), 769-777.

Full Text: 2007\J Haz Mat141, 769.pdf

Abstract: This study aims to clarify the effect of activated carbon type on the extent of adsorbability, desorbability, and bioregenerability in the treatment of 2-chlorophenol. Four different activated carbon types; thermally activated and chemically activated powdered carbons (PAC), and their granular countertypes (GAC) with similar physical characteristics were used. Thermally activated carbons adsorbed 2-chlorophenol much better than chemically activated ones. However, adsorption was more reversible in the case of chemically activated ones. The use of powdered and granular activated carbon countertypes resulted in comparable adsorption and desorption characteristics. For each activated carbon type, 2-chlorophenol exhibited higher adsorbability and lower desorbability than phenol. Biodegradation of 2-chlorophenol took place very slowly when it was used as the sole carbon source in acclimated and non-acclimated activated sludges. Bioregeneration occurred only via desorption due to an initial concentration gradient and no further desorption took place due to low biodegradability. Bioregeneration of activated carbon loaded with 2-chlorophenol was not a suitable option when 2-chlorophenol was the only carbon source. It is suggested to remove 2-chlorophenol via adsorption onto activated carbon rather than applying biological treatment. Also in such cases, the use of thermally activated carbons with higher adsorption and lower desorption capacities is recommended rather than chemically activated carbons.

Keywords: Activated Carbon, Activation Method, Bioregeneration, 2-Chlorophenol, Irreversible Adsorption

? Tor, A. (2007), Removal of fluoride from water using anion-exchange membrane under Donnan dialysis condition. Journal of Hazardous Materials, 141 (3), 814-818.

Full Text: 2007\J Haz Mat141, 814.pdf

Abstract: The transport of fluoride through Neosepta-ACM anion-exchange membrane has been studied as a function of feed phase and receiver phase concentration and co-existence anions under Donnan dialysis condition. It was observed that the transport of fluoride was maximum at pH 6 of feed phase and at pH 1 of receiver phase. Moreover, transport of fluoride increased with increase of feed and receiver phase concentration and decreased in the presence of other co-existence anions in the feed phase. The transport of fluoride was also correlated with the flux data and explained according to structure of membrane.

Keywords: Removal of Fluoride, Donnan Dialysis, Anion-Exchange Membrane, Transport

Notes: highly cited

? Hameed, B.H., Din, A.T.M. and Ahmad, A.L. (2007), Adsorption of Methylene blue onto bamboo-based activated carbon: Kinetics and equilibrium studies. Journal of Hazardous Materials, 141 (3), 819-825.

Full Text: 2007\J Haz Mat141, 819.pdf

Abstract: Bamboo, an abundant and inexpensive natural resource in Malaysia was used to prepare activated carbon by physiochemical activation with potassium hydroxide (KOH) and carbon dioxide (CO₂) as the activating agents at 850C for 2 h. The adsorption equilibrium and kinetics of methylene blue dye on such carbon were then examined at 30C. Adsorption isotherm of the methylene blue (MB) on the activated carbon was determined and correlated with common isotherm equations. The equilibrium data for methylene blue adsorption well fitted to the Langmuir equation, with maximum monolayer adsorption capacity of 454.2 mg/g. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equation were selected to follow the adsorption processes. The adsorption of methylene blue could be best described by the pseudo-second-order equation. The kinetic parameters of this best-fit model were calculated and discussed.

Keywords: Acid, Activated Carbon, Activation, Adsorbents, Adsorption, Adsorption Capacity, Adsorption Equilibrium, Agents, Aqueous-Solution, Bamboo, Capacity, Carbon, Carbon Dioxide, CO₂, Dye, Equilibrium, Isotherm, Kinetic, Kinetic Models, Kinetic Parameters, Kinetics, Langmuir, Langmuir Equation, Malaysia, Methylene Blue, Model, Models, Monolayer, Natural, Parameters, Porosity, Potassium, Pseudo-Second-Order, Removal, Sorption, Stones, Surface-Area, Waste

? Das, B., Hazarika, P., Saikia, G., Kalita, H., Goswami, D.C., Das, H.B., Dube, S.N. and Dutta, R.K. (2007), Removal of iron from groundwater by ash: A systematic study of a traditional method. Journal of Hazardous Materials, 141 (3), 834-841.

Full Text: 2007\J Haz Mat141, 831.pdf

Abstract: A traditional method for removal of iron from ground water by using ash has been systematically investigated. Ashes from five different sources, viz., banana rind, banana pseudostem, banana leaf, rice husk and bamboo has been studied. The principle applied is enhanced precipitation of iron at high pH caused by ash. The study included laboratory analysis of some relevant chemical parameters of the ashes and the efficiency of the ashes in removing iron from prefabricated water with respect to quantity of ash and corresponding increase in pH of water. The ash of banana pseudostem has been found to be most suitable for removal of iron. A low-cost and easily made iron removal system for household use has been designed and tested. The ash of banana pseudostem has been found to remove iron to below 0.3 ppm without increasing the pH above the acceptable limit. The optimum values of the different parameters for removal of iron are 200-300 mg l^-1 ash, 1.0 lh^-1 flow rate and 1 h of contact time with ash for groundwater having [Fe] of about 2.20 ppm. The amount of ash can be increased for groundwater having higher [Fe] and can be decreased gradually during continuous use of the system. Acceptability of the method has been examined based on chemical analysis of the treated water. Increase in the essential minerals such as Ca, K has been in the water after treatment. The designed iron removing system is expected to be suitable for household use.

Keywords: Groundwater, Iron Removal, Ash, Banana Pseudostem, Traditional Method

? Hsueh, C.C. and Chen, B.Y. (2007), Comparative study on reaction selectivity of azo dye decolorization by Pseudomonas luteola. Journal of Hazardous Materials, 141 (3), 842-849.

Full Text: 2007\J Haz Mat141, 842.pdf

Abstract: This study is to inspect how the variation of molecular structures and functional groups present in our model azo dyes (i.e., Congo red, Eriochrome black T (EBT), methyl orange, and methyl red) affects biodecolorization capability of Pseudomonas luteola. The most viable decolorization was found at pH 7-9 and the optimal cellular age for the most effective decolorization was 7 days after static incubation in dye-free cultures. In decolorization, the maximal absorption wavelength in UV-VIS spectra for the different dye-containing cultures shifted from visible light range towards the ultraviolet visible range. Methyl red was not decolorized in contrast to methyl orange, Congo red, and Eriochrome Black T. The sulfonic group para to azo bond (-N=N-) in methyl orange was a strong electron-withdrawing group through resonance to cause an enhancement of color removal to be easily biodecolorized. As a charged carboxyl group on methyl red is at ortho position (i.e., in the proximity) to azo bond, this led to a complete inhibition to decolorization. However, decolorization of Congo red and EBT in the absence of charged group (e.g., hydroxy or amino group) near azo bond was not completely repressed like methyl red. Thus, the presence of electron-withdrawing groups as the substituents on azo dyes enhanced decolorization capability for biodegradability. In addition, Monod kinetic model provided better predictions to all dye decolorization at initial short periods of time due to negligible intermediate formed at initial short time duration, but significant intermediate accumulation took place at longer period of time. In contrast, the decolorization performances of methyl orange at 400 ppm and EBT at 230 ppm were significantly less than those predicted from the Monod kinetic model likely due to accumulated intermediates exceeding the threshold levels for feedback inhibition.

Keywords: Bacterial Decolorization, Pseudomonas Luteola, Azo Dye, Chemical Structure, Monod Kinetics

Notes: highly cited

? Mohan, D. and Pittman, Jr., C.U. (2007), Arsenic removal from water/wastewater using adsorbents: A critical review. Journal of Hazardous Materials, 142 (1-2), 1-53.

Full Text: 2007\J Haz Mat142, 1.pdf

Abstract: Arsenic’s history in science, medicine and technology has been overshadowed by its notoriety as a poison in homicides. Arsenic is viewed as being synonymous with toxicity. Dangerous arsenic concentrations in natural waters is now a worldwide problem and often referred to as a 20th–21st century calamity. High arsenic concentrations have been reported recently from the USA, China, Chile, Bangladesh, Taiwan, Mexico, Argentina, Poland, Canada, Hungary, Japan and India. Among 21 countries in different parts of the world affected by groundwater arsenic contamination, the largest population at risk is in Bangladesh followed by West Bengal in India. Existing overviews of arsenic removal include technologies that have traditionally been used (oxidation, precipitation/coagulation/membrane separation) with far less attention paid to adsorption. No previous review is available where readers can get an overview of the sorption capacities of both available and developed sorbents used for arsenic remediation together with the traditional remediation methods. We have incorporated most of the valuable available literature on arsenic remediation by adsorption (600 references). Existing purification methods for drinking water; wastewater; industrial effluents, and technological solutions for arsenic have been listed. Arsenic sorption by commercially available carbons and other low-cost adsorbents are surveyed and critically reviewed and their sorption efficiencies are compared. Arsenic adsorption behavior in presence of other impurities has been discussed. Some commercially available adsorbents are also surveyed. An extensive table summarizes the sorption capacities of various adsorbents. Some low-cost adsorbents are superior including treated slags, carbons developed from agricultural waste (char carbons and coconut husk carbons), biosorbents (immobilized biomass, orange juice residue), goethite and some commercial adsorbents, which include resins, gels, silica, treated silica tested for arsenic removal come out to be superior. Immobilized biomass adsorbents offered outstanding performances. Desorption of arsenic followed by regeneration of sorbents has been discussed. Strong acids and bases seem to be the best desorbing agents to produce arsenic concentrates. Arsenic concentrate treatment and disposal obtained is briefly addressed. This issue is very important but much less discussed.

Keywords: Adsorption, Arsenic, Adsorbents, Solid Waste Utilization, Activated Carbons, Low-Cost Adsorbents, Arsenic Remediation, Arsenic Removal, Arsenic Adsorption

? Aravindhan, R., Rao, J.R. and Nair, B.U. (2007), Removal of basic yellow dye from aqueous solution by sorption on green alga Caulerpa scalpelliformis. Journal of Hazardous Materials,