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ABSTRACT: In this study the biosorption of Yellow RL, a metal-complex anionic dye, by dried Rhizopus arrhizus, a filamentous fungus, was investigated as a function of initial solution pH, initial dye concentration and initial salt (sodium chloride) concentration. The fungus exhibited the maximal dye uptake at pH 2 in the absence and in the presence of salt. Dye uptake increased with the dye concentration up to 1000 mg l(-1) and diminished considerably in the presence of increasing concentrations of salt up to 50 g l(-1). The fungus biosorbed 85.4 mg dye g(-1)of dried biomass at 100 mg l(-1) initial dye concentration in the absence of salt. When 50 g l(-1) salt was added to the biosorption medium, this value dropped to 60.8 mg g(-1) resulting in 28.8% reduction in biosorption capacity. The Redlich-Peterson and Langmuir-Freundlich were the most suitable adsorption models for describing the biosorption equilibrium data of the dye both individually and in salt containing medium. The pseudo-second-order and saturation type kinetic models depicted the biosorption kinetics accurately for all cases studied. Equilibrium and kinetic constants varied with the level of salt were expressed as a function of salt concentration.
Journal of Environmental Management 03/2010; 91(7):1546-55. · 3.24 Impact Factor
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ABSTRACT: Some industrial wastewaters contain high quantities of salts besides heavy metal ions. The presence of salt ions leads to high ionic strength, which may significantly affect the performance of the biosorption process so the effect of salts on the biosorption of heavy metal ions should be investigated. In this study the biosorption of chromium(VI) from saline solutions on dried Rhizopus arrhizus was studied as a function of pH, initial chromium(VI) and salt (NaCl) concentrations in a batch system. The biosorption capacity of R. arrhizus strongly depended on solution pH and maximum chromium(VI) sorption capacity of sorbent was obtained at pH 2.0 both in the absence and in the presence of increasing concentrations of salt. Chromium(VI)-salt biosorption studies were performed at this pH value. Equilibrium uptakes of chromium(VI) increased with increasing chromium(VI) concentration up to 250mgl(-1) and decreased considerably by the presence of increasing concentrations of salt. At 100mgl(-1), initial chromium(VI) concentration, dried R. arrhizus biosorbed 78.0mgg(-1) of chromium(VI) in 72h without salt medium. When salt concentration was raised to 50gl(-1), this value dropped to 64.0mgg(-1) of chromium(VI) at the same conditions resulting in 17.9% decrease of biosorption capacity. The equilibrium sorption data were analysed by using Freundlich, Langmuir, Redlich-Peterson and Langmuir-Freundlich (Sips), the two and three parameters adsorption models, using non-linear regression technique and isotherm constants were evaluated depending on salt concentration. The Langmuir-Freundlich (Sips) was the best suitable adsorption model for describing the biosorption of chromium(VI) individually and in salt-containing medium. Pseudo-first-order, pseudo-second-order and saturation type kinetic models described the biosorption kinetics accurately at all chromium(VI) concentrations in the absence and in the presence of changing concentrations of salt. Isotherm and saturation type kinetic constants varied due to the level of salt were expressed as a function of initial salt concentration.
Journal of Hazardous Materials 07/2007; 145(1-2):210-20. · 4.17 Impact Factor
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ABSTRACT: The removal of 2,4-dichlorophenoxyacetic acid (2,4-D), one of the most commonly used phenoxy acid herbicides, from aqueous solution was studied by using acid-washed powdered activated carbon (PAC) as an adsorbent in a batch system. Adsorption equilibrium, kinetics, and thermodynamics were investigated as a function of initial pH, temperature, and initial 2,4-D concentration. Powdered activated carbon exhibited the highest 2,4-D uptake capacity of 333.3 mg g(-1) at 25 degrees C and an initial pH value of 2.0. Freundlich, Langmuir, and Redlich-Peterson isotherm models were used to express the equilibrium data of 2,4-D depending on temperature. Equilibrium data fitted very well to the Freundlich equilibrium model in the studied concentration range of 2,4-D at all the temperatures studied. Three simplified models including pseudo-first-order, pseudo-second-order, and saturation-type kinetic models were used to test the adsorption kinetics. It was shown that the adsorption of 2,4-D on PAC at 25, 35, and 45 degrees C could be best fitted by the saturation-type kinetic model with film and intraparticle diffusions being the essential rate-controlling steps. The activation energy of adsorption (EA) was determined as--1.69 kJ mole(-1). Using the thermodynamic equilibrium coefficients obtained at different temperatures, the thermodynamic constants of adsorption (deltaG degrees, deltaH degrees, and deltaS degrees) were also evaluated.
Journal of Environmental Science and Health Part B 02/2005; 40(4):545-70. · 0.89 Impact Factor
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ABSTRACT: The biosorption of chromium(VI) and nickel(II) ions, both singly and in combination, by dried activated sludge was investigated in a batch system as a function of initial pH and single- and dual-metal ion concentrations. The working initial pH values for single chromium(VI) and nickel(II) biosorptions were determined as 1.0 and 4.5, respectively. It was observed that the co-ion effect on the equilibrium uptake became more pronounced as the co-ion concentration in solution increased and pH level increased for chromium(VI) and decreased for nickel(II). Adsorption isotherms were developed for both the single- and dual-metal ion systems at these two pH values and expressed by the mono- and multi-component Langmuir and Freundlich adsorption models and model parameters were estimated by the non-linear regression. It was seen that the mono-component adsorption equilibrium data fitted very well to both the mono-component adsorption models for both the components and the pH values studied while the multi-component Freundlich adsorption model adequately predicted the multi-component adsorption equilibrium data at moderate ranges of initial mixture concentrations for both the studied pH values.
Water Research 08/2002; 36(12):3063-73. · 4.86 Impact Factor
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ABSTRACT: The effect of copper(II) and nickel(II) ions on the growth and bioaccumulation properties of non-adapted and adapted growing cells of a non-pathogenic Candida sp. has been tested under laboratory conditions as a function of initial pH and initial metal ion concentration. Optimum pH value for maximum metal ion accumulation was determined as 4.0 for both the metal ions. Although the copper(II) adapted Candida sp. was capable of removing of copper(II) with the maximum specific uptake capacity of 36.9 mg g-1 at 783.6 mg dm-3 initial copper(II) concentration, non-adapted Candida was only capable of bioaccumulating copper(II) with 23.1 mg g-1 maximum uptake capacity from aqueous solution at 578.7 mg dm-3 initial copper(II) concentration. The non-adapted and nickel(II) adapted Candida cells also showed the highest nickel(II) uptake capacities (46.8 and 30.8 mg g-1, respectively) at 321.5 and 300.6 mg dm-3 initial nickel(II) concentrations, respectively. For both the non-adapted and nickel(II) adapted Candida sp., the growth of cells was totally inhibited by 500 mg dm-3 of nickel(II) ions. The results also indicated that copper(II) adapted Candida sp. has been found to be more efficient to accumulate larger amounts of copper(II) than that of nickel(II) bioaccumulated by nickel(II) adapted Candida at higher initial metal ion concentrations without loosing its biological activity.
Water Research 05/2001; 35(6):1425-34. · 4.86 Impact Factor
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ABSTRACT: The potential use of dried activated sludge and fly ash as a substitute for granular activated carbon for removing mono-chlorinated phenols (o-chlorophenol and p-chlorophenol) was examined. The pollutant binding capacity of the adsorbent/biosorbent was shown to be a function of substituted group, initial pH and initial mono-chlorinated phenol concentration. The working sorption pH value was determined as 1.0 and the equilibrium uptake increased with increasing initial mono-chlorinated phenol concentration up to 500 mg dm(-3) for all the mono-chlorinated phenol-sorbent systems. The suitability of the Freundlich, Langmuir and Redlich-Peterson adsorption models to the equilibrium data were investigated for each mono-chlorinated phenol-sorbent system. The results showed that the equilibrium data for all the mono-chlorinated phenol-sorbent systems fitted the Redlich-Peterson model best within the concentration range studied.
Waste Management 02/2001; 21(8):695-702. · 2.43 Impact Factor
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ABSTRACT: Biosorption of copper(II) ions from aqueous solutions was studied to compare the binding capacities of untreated (live) or treated (dried, autoclaved, perchloric acid (HClO4)-washed, ethanol-treated, formaldehyde-treated) Candida sp. Due to the ion exchange nature of metal biosorption, copper(II) uptake was strongly affected by the solution pH and optimum adsorption pH value was determined as 5.0 for all the live and treated Candida sp. At the optimal conditions, metal ion uptake increased with increasing initial copper(II) concentration up to 300 mg l-1 for all the biomass types. It is found that all the treatment methods used to kill the yeast (except for formaldehyde treatment) increased the copper(II) biosorption capacity of Candida cells. The results also indicated that copper(II) biosorption by live, autoclaved and formaldehyde-treated yeasts was consisted of an initial, rapid surface binding of copper(II) followed by a second, slower intracellular uptake of copper(II), but copper(II) uptake by the other treated yeasts took place only via surface binding. Both the Freundlich and Langmuir adsorption models were suitable for describing the short-term biosorption of copper(II) by all the untreated and treated Candida.
Journal of Environmental Science and Health Part A 02/2001; 36(3):367-81. · 1.19 Impact Factor
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ABSTRACT: The competitive biosorption of cadmium(II) and nickel(II) onto dried Chlorella vulgaris, a green alga from binary metal mixture was studied and compared with single metal ion situation in a batch stirred system. The effects of single- and dual-metal ion concentrations on the biosorption capacity of biomass were investigated at an initial pH value of 4.0. Equilibrium uptake of cadmium(II) and nickel(II)) increased with increasing its initial metal ion concentration up to 150 mg l−1 and decreased considerably by the presence of increasing concentrations of the other metal ion. Both the Freundlich and Langmuir adsorption models were suitable for describing the biosorption equilibrium of cadmium(II) and nickel(II) ions both in single and binary systems. According to the Langmuir model the maximum biosorption capacity of dried alga was determined as 86.6 mg g−1 for cadmium(II) and as 58.4 mg g−1 for nickel(II) for single ion situation. These values dropped to 68.5 mg g−1 for cadmium(II) and to 28.3 mg g−1 for nickel(II) when co-ion concentration was kept at 150 mg l−1. For each metal ion, variation of isotherm constants due to the level of other metal ion were expressed as a function of initial co-ion concentration by non-linear regression techniques.
Process Biochemistry.
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ABSTRACT: The influence of copper(II) ions on the growth and bioaccumulation properties of adapted and growing cells of Saccharomyces cerevisiae, Kluyveromyces marxianus, Schizosaccharomycespombe and Candida sp. was studied. The level of copper(II) accumulation and microbial growth were dependent on the pH and initial copper(II) concentration. Optimum pH values for maximum copper(II) accumulation were determined as 4.0, 5.0, 4.0 and 4.0 for S. cerevisiae, K. marxianus, S. pombe and Candida sp., respectively. The results indicated that Candida sp. and K. marxianus are able to accumulate large amounts of copper(II) from feed medium at higher copper(II) concentrations without loosing their biological activities.
Process Biochemistry.
