Personal Research Database

Full Text: W\Wat Air Soi Pol138, 199.pdf

Abstract: While sorbate/sorbent, sorbate/water, and sorbent/water (S/W) ratios in a batch system are known to affect the adsorption of sorbate, the effect of different S/W ratios on the adsorption of inorganic sorbates has seldom been addressed. This study investigates the adsorption phenomena of Cu²⁺ in different sorbate/sorbent/water ratios in a batch system. Batch experiments are performed to examine the adsorption, and the linear (K-D), Langmuir (K-L), and Freundlich (K-F) adsorption coefficients of Cu²⁺ in lateritic soil. These experiments are conducted using solutions with initial concentrations of 0.5 to 50 mg Cu²⁺ L^-1 equilibrated with an appropriate amount of soil to give S/W ratios of 0.1 to 2 g mL^-1. Although the variations in the sorbed amount and adsorption coefficients apparently originate from a change in the sorbate/sorbent/water ratio, only the equilibrium concentration significantly affects adsorption. On the other hand, the linear and Langmuir isotherm cannot adequately describe the adsorption data. In this study, the Freundlich equation gave an excellent fit to the adsorption data with a goodness-of-fit (R²) > 0.984. However, adsorption isotherms should be regarded as only a curve-fitting model or a mathematical tool and cannot be employed to interpret any particular adsorption mechanism. Meanwhile, the solids effect reveals that K-F and maximum adsorption (b) of the Langmuir equation increase when S/W ratio decreases. The sorbate in the stagnant phase must be considered as part of the equilibrium concentration in the solid phase to avoid underestimating the sorbed amount at a lower S/W ratio and/or a higher sorbate concentration level.

Keywords: Adsorption, Adsorption Coefficients, Sorbent/Water Ratio, Stagnant Phase, Organic-Chemical Sorption, Sediment Concentration, Partition-Coefficient, Water Systems, Cadmium, Montmorillonite, Batch, pH

Kannan, N. and Meenakshisundaram, M. (2002), Adsorption of Congo Red on various activated carbons. A comparative study. Water Air and Soil Pollution, 138 (1-4), 289-305.

Full Text: W\Wat Air Soi Pol138, 289.pdf

Abstract: Studies on the removal of Congo Red (CR) by adsorption on various activated carbons [commercial activated carbon (CAC) and indigenously prepared activated carbons(IPACs) from raw materials like bamboo dust, coconut shell, groundnut shell, rice husk, and straw] have been carried out with an aim to obtain information on treating effluents from dye/textile industries. The effect of various experimental parameters has been investigated by following batch adsorption technique at 30±1C. The percentage removal of dye increased with the decrease in initial concentration, initial pH of the dye solution and particle size of IPACs and increase in contact time and dose of adsorbent. Adsorption data were modelled with the Freundlich and Langmuir adsorption isotherms and first order kinetic equations such as Natarajan and Khalaf, Lagergren, Bhattacharya and Venkbachar equations and intra-particle diffusion model and the models were found to be applicable. The kinetics of adsorption is observed to be first order with intra-particle diffusion as one of the rate determining steps. Removal of dye using IPACs is found to be favourable and hence, IPACs could be considered as alternatives to CAC for the treatment of textile effluents, especially for the removal of dye(s).

Keywords: Adsorption, Comparison, Congo Red, First Order Kinetic Equations, Freundlich and Langmuir Isotherms, Indigenously Prepared Activated Carbons (IPACs), Intra-Particle Diffusion Process, Removal of Dye/Colour, Low-Cost Adsorbents, Aqueous-Solution, Equilibrium, Dyestuffs, Removal

Cheng, S.F. and Hseu, Z.Y. (2002), In-situ immobilization of cadmium and lead by different amendments in two contaminated soils. Water Air and Soil Pollution, 140 (1-4), 73-84.

Full Text: W\Wat Air Soi Pol140, 73.pdf

Abstract: Different soil amendments, including 1% zeolite, 1% bentonite, 5% Penghu soil (PHS), 5% Penghu soil + 1% manganese oxide (PHS + MO), 1% MO, and 1.5% silicate slag (SS), were used to immobilize Cd and Pb in two contaminated soils evaluated by single and sequential extractions and by uptake of Chinese cabbage (Brassica Chinensis L.). Results indicated that the PHS and MO significantly (p < 0.05) reduced the 0.1 M HCl extractable Cd and Pb in the two contaminated soils. All amendment treatments did not change the organic and residual amounts of Cd and Pb in soils A and B, but the PHS and PHS + MO treatments significantly reduced the exchangeable amounts of Cd and Pb in the two soils as measured by sequential extraction. The combination of PHS and MO amendments was associated with a high pH value and negative soil surface charge showed the best immobilizing efficiency of Cd and Pb in this study. All soil amendments investigated did not increase the dry matter weight of the plant, and most of them decreased the uptake of Cd and Pb, especially for the PHS and MO. The PHS and MO treatments reduced the extractability of Cd and Pb in two soils and their uptake by the plant, but only the Pb content in Chinese cabbage from the amended soils was less than the background levels of heavy metals in leaf vegetables of Taiwan.

Keywords: Adsorption, Amendment, Availability, Cadmium, Contamination, Copper, Heavy Metal, Heavy Metals, Hydrous Ferric-Oxide, In Situ Immobilization, Lead, Metals, Remediation, Sequential Extraction, Sorption, Speciation, Zeolite, Zinc

Seuntjens, P. (2002), Field-scale cadmium transport in a heterogeneous layered soil. Water Air and Soil Pollution, 140 (1-4), 401-423.

Full Text: W\Wat Air Soi Pol140, 401.pdf

Abstract: Heavy metals such as Cd and Zn that have been deposited on soils in the surroundings of non-ferrous industries, are often observed in soil water and groundwater in concentrations above groundwater clean-up values. The present study addresses the field-scale migration of Cd in a heterogeneous 1 m deep layered sandy soil profile. Numerical calculations of field-scale Cd leaching are performed using probability density functions of chemical and physical transport variables in a stream-tube convective-dispersive model approach. The performance of the stochastic model is evaluated by comparing measured and predicted Cd profiles for two types of sorption isotherms. The first isotherm is linear, containing a field-based Cd soil-water distribution coefficient. The second is a nonlinear adsorption isotherm obtained from laboratory batch experiments, which is adapted to field conditions of pH, organic matter content and pore water composition. Numerical calculations made using the nonlinear isotherm better predicted the measured Cd depth profiles than did the linear isotherms. The stochastic simulations further showed that chemical heterogeneity (i.e., due to variations in sorption constant) largely affects the position and the shape of the Cd plume, resulting in an early Cd breakthrough at the bottom of the soil profile and a long-term leaching in concentrations above groundwater clean-up values due to tailing of the breakthrough curve. When calculations were made to investigate the effect of amendment of the topsoil layers, the results indicated that the average time to reach groundwater clean-up values is significantly reduced from approximately 230 to 80 yr.

Keywords: Cadmium, Monte-Carlo, Solute Transport, Spatial Varability, Stream-Tube, Models, Uncertainty Adsorbing Solute Transport, Heavy-Metal Displacement, Sandy Soil, Sorption, Calcium.

Ho, Y.S., Porter, J.F. and McKay, G. (2002), Equilibrium isotherm studies for the sorption of divalent metal ions onto peat: Copper, nickel and lead single component systems. Water Air and Soil Pollution, 141 (1-4), 1-33.

Full Text: W\Wat Air Soi Pol141, 1.pdf

Abstract: The sorption of three divalent metal ions - copper, nickel and lead - from aqueous solution onto peat in single component systems has been studied and the equilibrium isotherms determined. The experimental data have been analysed using the Langmuir, Freundlich, Redlich-Peterson, Tóth, Temkin, Dubinin-Radushkevich and Sips isotherm models. In order to determine the best fit isotherm for each system, six error analysis methods were used to evaluate the data: the coefficient of determination, the sum of the errors squared, a hybrid error function, Marquardt’s percent standard deviation, the average relative error and the sum of absolute errors. The error values demonstrated that the Sips equation provided the best model for the three sets of experimental data overall.

Keywords: Copper, Isotherm, Lead, Nickel, Peat, Sorption, Dilute Aqueous-Solutions, Heavy-Metals, Adsorption-Isotherms, Organic Pollutants, Activated Carbon, Removal, Biosorption, Thermodynamics, Exchange, Equation

Elifantz, H. and Tel-Or, E. (2002), Heavy metal biosorption by plant biomass of the Macrophyte Ludwigia stolonifera. Water Air and Soil Pollution, 141 (1-4), 207-218.

Full Text: W\Wat Air Soi Pol141, 207.pdf

Abstract: Ludwigia stolonifera biomass of roots, floating roots and leaves were tested for their performance as heavy metal biofilters. Cadmium (Cd) and nickel (Ni) (50 ppm) solutions were filtered through 0.5–1.5 g packed columns with each biomaterial, to determine their metal removal efficiency. Root column was more efficient in removing Ni (as low as 6 ppb in the effluent) than of Cd (as low as to 22 ppb in the effluent). This tendency was also observed upon treatment of a mixed solution of both metals. Floating roots column reduced Cd content to the same level as the root column, but its metal binding capacity was higher; 93 mg Cd g^-1 DW in floating roots in comparison to 43 mg Cd g^-1 DW in the roots biofilter. Leaf biomass column demonstrated the best metal binding capacity; 128 mg Cd g^-1 DW, and Cd concentration in the effluent was 17 ppb. Pectin content was 5, 8 and 10% W/W in roots, leaves and floating roots biofilters, respectively. It seems that ion exchange is the major mechanism by which the metal is biosorbed. Evidence for the exchange of the bound heavy metal ions against the discharge of light metal ions such as calcium (Ca), magnesium (Mg), potassium (K) and sodium (Na) was provided.

Keywords: Biofilter, Biosorption, Cadmium, Ludwigia stolonifera, Metal Binding Capacity, Nickel, Pectin

Thirunavukkarasu, O.S., Viraraghavan, T. and Subramanian, K.S. (2003), Arsenic removal from drinking water using iron oxide-coated sand. Water Air and Soil Pollution, 142 (1-4), 95-111.

Full Text: W\Wat Air Soi Pol142, 95.pdf

Abstract: This article describes experiments in which iron oxide-coated sand (IOCS) was used to study the removal of both As(V) and As(III) to a level less than 5 g L^-1 in drinking water. Iron oxide-coated sand 2 (IOCS-2) prepared through high temperature coating process was used in batch and column studies to assess the effectiveness and suitability. The isotherm study results showed that the observed data fitted well with the Langmuir model, and the adsorption maximum for IOCS-2 at pH 7.6 was estimated to be 42.6 and 4 1.1 g As g^-1 I OCS-2 for As(V) and As(III), respectively. In the fixed bed column tests to study arsenic removal from the tap water, good performance of IOCS-2 was observed in respect of bed volumes achieved and arsenic removal capacity. Five cycles of column tests were conducted to evaluate the performance of IOCS-2, and arsenic was successfully recovered from the media through regeneration and backwash operations. High bed volumes (860 to 1403) up to a breakthrough concentration of 5 g L^-1 were achieved in the column studies with tap water, and the bed volumes achieved in the studies with natural water (containing arsenic) were 1520. The results of both the batch and column studies showed that iron oxide-coated sand filtration could be effectively used to achieve less than 5 g L^-1 As in drinking water.

Keywords: Adsorption, Arsenic Removal, Batch Studies, Column Tests, Drinking Water, Iron Oxide, Speciation, Ground-Water, Adsorption, Coagulation, Hydroxide, Ferrihydrite, Filtration, North

Ulmanu, M., Marañón, E., Fernández, Y., Castrillón, L., Anger, I. and Dumitriu, D. (2003), Removal of copper and cadmium ions from diluted aqueous solutions by low cost and waste material adsorbents. Water Air and Soil Pollution, 142 (1-4), 357-373.

Full Text: W\Wat Air Soi Pol142, 357.pdf

Abstract: The sorption of copper and cadmium ions using activated carbon, kaolin, bentonite, diatomite and waste materials such as compost, cellulose pulp waste and anaerobic sludge as sorbents is reported. Equilibrium isotherms were obtained for the adsorption of these metals in single and binary solutions. Bentonite presented the highest adsorption capacities for both copper and cadmium. A competitive uptake was observed when both metals are present; copper being preferentially adsorbed by all materials with the exception of anaerobic sludge. Equilibrium data were fitted to Langmuir and Freundlich models, with satisfactory results for most of the adsorbent-metal systems studied. Of all the adsorbents studied, bentonite and compost presented the highest removal efficiencies, reaching 99% for copper when cadmium is also present, for initial solution concentrations of up to 100 mg L^-1. Anaerobic sludge has a greater preference for cadmium, even in the presence of copper, with removal efficiencies of 98% for similar concentrations to those mentioned above.

Keywords: Activated Carbon, Adsorbents, Adsorption, Bentonite, Cadmium, Cellulose, Copper, Heavy-Metal Binding, Isotherms, Kinetics, Peat, Removal, Sawdust, Sorption, Thermodynamics, Waste Materials, Water, Zinc

? Ghosh, U.C., Dasgupta, M., Debnath, S. and Bhat, S.C. (2003), Studies on management of chromium(VI) - Contaminated industrial waste effluent using hydrous titanium oxide (HTO). Water Air and Soil Pollution, 143 (1-4), 245-256.

Full Text: 2003\Wat Air Soi Pol143, 245.pdf

Abstract: The anion exchange behaviour of hydrous titanium oxide (HTO) has been exploited for the management of industrial waste effluents contaminated with chromium(VI). The adsorption of chromium(VI) by HTO (74.0-140.0 micron) in the pH range 0.5-8.0 has been studied. It is found that the adsorption of chromium(VI) by HTO is at a maximum in the pH range 1.5-2.0. The interference of diverse foreign ions such as nitrate, chloride, sulfate, phosphate, calcium, magnesium, nickel, iron(III), barium etc. on the adsorption of chromium(VI) by HTO at optimum pH has been investigated by a batch-operation technique. Break-through capacity, adsorption and elution of chromium(VI) using HTO have been studied. It is found that HTO could be reused as an adsorbent for chromium(VI). Finally, chromium(VI) was recovered as insoluble chromate compound from waste effluent of Hindustan Motor Limited (HML) of Hooghly, West Bengal, India.

Keywords: Adsorbent, Chromium(VI), Hydrous Titanium Oxide (HTO), Ion-Exchange, Recovery, Waste Effluent

Solé, M., Casas, J.M. and Lao, C. (2003), Removal of Zn from aqueous solutions by low-rank coal. Water Air and Soil Pollution, 144 (1), 57-65.

Full Text: W\Wat Air Soi Pol144, 57.pdf

Abstract: The ability of an immature coal (leonardite) to remove zinc from aqueous solutions was studied as a function of pH, contact time and concentration of metal solutions. Effective removal of Zn²⁺ was demonstrated at pH values of 5–6. Kinetic study showed that the adsorption of Zn²⁺ occurs in two phases: a rapid phase followed by a quasi-equilibrium state attained within the first two hours. The adsorption isotherm was measured at 25 °C, using adsorptive solutions at the optimum pH value to determine the adsorption capacity.

Keywords: Adsorption, Leonardite, Removal, Wastewater Treatment, Zn²⁺

Lazaridis, N.K. (2003), Sorption removal of anions and cations in single batch systems by uncalcined and calcined Mg-Al-CO₃ hydrotalcite. Water Air and Soil Pollution, 146 (1-4), 127-139.

Full Text: W\Wat Air Soi Pol146, 127.pdf

Abstract: In this study, the sorption removal of two anions (phosphates, thiocyanates) and three cations (cadmium, lead, nickel), in single batch systems, was investigated from aqueous solutions. The process involves the sorption of the ions by hydrotalcite, which is a double-layered mixed-metal hydroxide and belongs to the family of anionic clays. The sorbent used was Mg-Al-CO₃ hydrotalcite in two forms: uncalcined and calcined at 500 degreesC. The calcined material showed the higher sorption capacity, for all the ions, than the uncalcined. The approximate sorption capacity of calcined material was: phosphates 250 mg g^-1, thiocyanates 80 mg g^-1, nickel/lead 100 mg g^-1 and cadmium 70 mg g^-1. The kinetic results of the anions were fitted satisfactory with the Lagergren equation. Since the sorption capacity is relatively high, hydrotalcite can be considered as a potential material for sorption of both anions and cations in wastewater treatment systems.

Keywords: Cadmium, Hydrotalcite, Lead, Nickel, Phosphates, Sorption, Thiocyanates, Phosphate Removal, Waste-Water, Metal-Ions, Adsorption, Cadmium, Equilibrium, Decomposition, Biosorption, Effluents, Sorbents

? Chantawong, V., Harvey, N.W. and Bashkin, V.N. (2003), Comparison of heavy metal adsorptions by Thai Kaolin and Ballclay. Water Air and Soil Pollution, 148 (1-4), 111-125.

Full Text: 2003\Wat Air Soi Pol148, 111.pdf

Abstract: The adsorption characteristics of heavy metals: cadmium(II), chromium(III), copper(II), nickel(II), lead(II), and zinc(II) ions by kaolin (kaolinite) and ballclay (illite) from Thailand were studied. This research was focussed on the pH, adsorption isotherms of single-metal solutions at 30–60 °C by batch experiments, and on ion selectivityin mixed and binary combination solutions. It was found that, except Ni, metal adsorption increased with increased pH of the solutions and their adsorption followed both Langmuir and Freundlich isotherms. Adsorption of metals in the mixture solutions by kaolin was: Cr > Zn > Cu  Cd  Ni > Pb, and for ballclay was: Cr > Zn > Cu > Cd  Pb > Ni. The adsorption of metals was endothermic, with the exception of Cd, Pb and Zn for kaolin, Cu and Zn for ballclay. Kaolin and ballclay exhibited relatively hard Lewis base adsorption site. The presence of other metals may reduce or promote the adsorption of heavy metals. The presence of Cr³⁺ induced the greatest reduction of metal adsorptiononto kaolin, as did the presence of Cu²⁺ for ballclay.

Keywords: Adsorption Isotherm, Cadmium, Chromium, Copper, Counter-Ion, Lead, Nickel, Zinc

Gebremedhin-Haile, T., Olguin, M.T. and Solache-Ríos, M. (2003), Removal of mercury ions from mixed aqueous metal solutions by natural and modified zeolitic minerals. Water Air and Soil Pollution, 148 (1-4), 179-200.

Full Text: W\Wat Air Soi Pol148, 179.pdf

Abstract: Research works on the removal of mercury from water by zeolitic mineral show that small quantities of this element are sorbed. In this work the mercury sorption from aqueous solutions in the presence and absence of Cu(II), Ni(II) and Zn(II) onto a Mexican zeolitic mineral unmodified and modified with cysteamine hydrochloride or cystamine dihydrochloride was investigated in acidic pH. The zeolitic minerals were characterized by thermogravimetric analysis, scanning electron microscopy, X-ray diffraction and FTIR. The sorption kinetics behavior and the retention isotherms for mercury were determined in the natural and treated zeolitic mineral samples. It was found that the amounts of sulfur on the modified zeolitic minerals were 0.375 (cysteamine hydrochloride) and 0.475 (cystamine dihydrochloride) mmol g^-1, which were not saturated to their total capacities of adsorption for the maximum concentration used (0.310 mM). Under the experimental conditions, the retention of mercury was the highest for the zeolitic minerals treated with the organic compounds, with adsorption capacities ranging from 0.0107 to 0.0509 mmol Hg g^-1. The retention was not affected by the presence of others heavy metals studied in this work as expected.

Keywords: Adsorption, Cysteamine HCl, Cystamine HCl, Mercury, Modified Zeolites, Natural Zeolites, Heavy-Metals, Mexican Erionite, Adsorption, Sorption, Clinoptilolite, Surfactant, Microscopy, Exchange, Water

Oğuz, E., Gürses, A. and Yalcin, M. (2003), Removal of phosphate from waste waters by adsorption. Water Air and Soil Pollution, 148 (1-4), 279-287.

Full Text: W\Wat Air Soi Pol148, 279.pdf

Abstract: In this study, the adsorption of phosphate on gas concrete from aqueous solutions has been studied as functions of temperature, mixing rates and suspension pH. Over 99% of phosphate removal was found. The chemical composition of the gas concrete has been defined by X-ray analysis. Experimental data was fitted to the Langmuir equation in order to Langmuir coefficients. After calculating Langmuir coefficients, adsorption free energy (DeltaG(ads.)(0)) has been determined. In order to gather information about adsorption mechanism, electrophoretic mobilites of particles were measured at various pHs by using Zeta meter 3.0+. It has been found that the adsorption is driven by the interactions between the ionizations of CaO and Al₂O₃ and the formation of AlPO₄. According to the BET (N₂) measurements, the specific surface area of gas concrete was found as 22 m² g^-1. The surface area after adsorption has been found as 17 m² g^-1. The surface area covered by adsorbate has been found as 5.23 m² g^-1 by using a(s) = n(m)(s) . a(m) . N-A. These two areas determined by BET and Langmuir model were close to each other (BET: 22 m² g^-1-17 m² g^-1).

Keywords: Gas Concrete, Removal of Phosphate, Adsorption Isotherm, Variables, TNSAC

Vinod, V.P. and Anirudhan, T.S. (2003), Adsorption behaviour of basic dyes on the humic acid immobilized pillared clay. Water Air and Soil Pollution, 150 (1-4), 193-217.

Full Text: W\Wat Air Soi Pol150, 193.pdf

Abstract: In this work, the adsorption of three basic dyes, namely Methylene blue (MB), crystal violet (CV) and rhodamine B (RB) on the humic acid (HA) immobilized pillared clay (PILC) (HA-PILC) was studied. The adsorption capacity of dyes at 30degreesC using HA-PILC was found to be 2.6, 2.0 and 2.3 times greater than that using PILC for the removal of MB, CV and RB, respectively for an initial concentration of 250 mol dm^-3. The adsorption process was pH dependent. The maximum dye adsorption on HA-PILC was observed at a pH of 5.0-7.0 (removal of 95.2-99.2% for MB, 92.7-97.3% for CV and 83.4-91.0% for RB) with no significant increase in removals beyond a pH of 7.0. The adsorption process could be best described by the Urano and Tachikawa model showing that particle diffusion controlled adsorption. Equilibrium adsorption data were analyzed using the Langmuir, Freundlich and Redlich-Peterson isotherms. Dye adsorption was best described by the Freundlich model. The monolayer adsorption capacities of HA-PILC calculated using the Langmuir isotherm were 608.4, 484.7 and 413.1 mumol g^-1 for MB, CV and RB, respectively. The linear Sheindorf-Rebhun-Sheintuch equation (Multicomponent Freundlich-type), was applied to the isotherm data obtained for each binary-solute combination of MB, CV and RB. The study showed that HA-PILC was an excellent media for the removal of basic dyes from aqueous solutions, based on adsorption kinetics and capacity.

Keywords: Adsorption Kinetics, Competitive Coefficients, Dye Adsorption, Equilibrium Isotherms, Pillared Clay, Low-Cost Materials, Aqueous-Solutions, Activated Carbon, Metal-Ions, Removal, Sorption, Phenol, Montmorillonite, Equilibrium, Isotherms

Darbi, A., Viraraghavan, T., Butler, R. and Corkal, D. (2003), Column studies on nitrate removal from potable water. Water Air and Soil Pollution,