Biosorption for removal of hexavalent chromium using microalgae Scenedesmus sp (original) (raw)
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2012
In this study, the adsorption capacity of free and loofa sponge-entrapped microalga Kirchneriella contorta to remove Cr 6+ from aqueous solution was investigated. This is the first reported study of biosorption by K. contorta. The effects of the experimental conditions, such as pH, initial Cr 6+ concentration, sorbent-sorbate contact time, and quantity of sorbent mass, on Cr 6+ removal efficiency were studied. The Cr 6+ sorption on K. contorta was found to be highly pH dependent and the maximum uptake capacity was achieved at pH 1.0. The adsorption isotherms study showed the maximum sorption capacity of the loofa sponge-immobilized biomass of K. contorta (LIBKC) of 100.84 mg g -1 , which was much higher than 80.61 mg g -1 of the free biomass of K. contorta (FBKC). The adsorption equilibrium data showed a better fit on the monolayer Langmuir adsorption isotherms model with the regression coefficient (r 2 ) greater than 0.99 for both FBKC and LIBKC. The rate of Cr 6+ removal followed ...
Biosorption of hexavalent chromium from aqueous solution by six brown macroalgae
The biosorption potential of six brown macroalgae viz. Nizamuddina zanardinii, Stoechospermum marginatum, Cystoseira indica, Dictyota cervicornis, Padina australis, and Sargassum glaucescens, for the removal of hexavalent chromium (Cr(VI)) was investigated in the present study. Optimum conditions were determined by studying the effect of initial solution pH, biomass dosage, initial Cr(VI) concentration, and contact time on Cr(VI) removal by the macroalgae. Cr(VI) sorp-tion was found to be highly pH dependent and maximum sorption was obtained at pH 1.0. Freundlich isotherm model showed the best fit with the equilibrium data. The removal rate of Cr(VI) was relatively rapid during the first 30 min, although the rate decreased gradually and the sorption reached equilibrium in about 70 min for S. marginatum, 90 min for N. zanardinii, and 150 min for D. cervicornis, P. australis, S. glaucescens, and C. indica. Different kinetic models such as pseudo-first-order, pseudo-second-order, and intra-particle diffusion model were tested, and the experimental data was in agreement with the pseudo-second-order model. The results of the present study suggest that brown macroalgae could be used as effective biosor-bents for Cr(VI) removal from aqueous solution.
2012
Microalga, Isochrysis galbana, biomass was entrapped into alginate gel by liquid curing method in the presence of Ca(II) ions. The biosorption of chromium(III) by the entrapped live algal biomass was studied in a batch system. The effect of initial cadmium concentration, pH, temperature and liquid and solid ratio on Cr(III) removal was investigated. The maximum experimental biosorption capacities for entrapped live algal biomass were found to be 335.27 mg Cr(III) g−1 of dry algal biomass. The kinetics of chromium biosorption was slow; approximately 75 % of biosorption took place in 2 h. The percent adsorption increased with increase in pH; pH 5 of the solution was found to favor adsorption very strongly. The equilibrium biosorption data were evaluated by Langmuir and Freundlich isotherm models, and was best described by Langmuir and Freundlich isotherms. The biosorbent was characterized and evaluated, the functional groups –OH, –COOH and C=O were involved in the biosorption process....
Biosorption studies for removal of chromium using immobilized marine alga Isochrysis galbana
2006
A new biosorbent material marine micro alga Isochrysis galbana, from marine sources Bay of Bengal, was immobilized and used as an adsorbent for removal of chromium. It was found that the increase in aqueous metal concentration increased metal uptake within the range of present study. The presence of acid decreased metal uptake probably due to the preferential adsorption of hydrogen ion compared to chromium ion. The immobilized calcium alginate beads were also found to adsorb chromium in absence of biomass as well and presence of biomass increased the metal adsorption by 3-4 fold. This immobilized biomass was very effective for the removal of chromium. Isochrysis galbana was found to adsorb chromium more strongly when compared to another marine micro alga, Chaetoceros calcitrans, probably due to presence of polysilicate layers over Chaetoceros cells and also due to larger size of Chaetoceros cells. Equilibrium distribution data were best correlated by Freundlich type of equation for ...