Optimization of chromium(VI) removal by indigenous microalga (Chlamydomonas sp.)‐based biosorbent using response surface methodology

Abstract

Phycoremediation of heavy metals has garnered considerable recent research interest. In this study, an indigenous microalga (Chlamydomonas sp.)‐based biosorbent was employed for biosorption of Cr(VI) dissolved solids (Cr(VI)‐DS), optimized using response surface methodology (RSM). The effects of microalga concentration, pH, and contact time were studied with 250 mg Cr(VI)‐DS L−1. The biosorption of Cr(VI)‐DS was higher at acidic pH (94.17% at pH 4) than at alkaline conditions (68.53% at pH 10). The interaction of pH and microalga concentration exerted significant (p < 0.05) influence on the biosorption. Under the optimized parameters of 1.5 g microalga L−1, pH 4, and contact time of 30 min, a predicted biosorption of 91.31% and biosorption capacity of 152 mg Cr(VI)‐DS g−1 biomass were documented. FTIR analysis attested the electronegative surface functional groups of the microalgae biomass, bracketed together with its high biosorption potency. The study evinced the potential of the indigenous microalga for remediation of hexavalent chromium. Practitioner points Indigenous Ethiopian microalga (Chlamydomonas sp.) exhibited 94% Cr(VI) abatement with biosorption capacity of 152 mg Cr(VI) g−1. FTIR analysis of the biosorbent divulged the presence of electronegative functional groups (amino, carboxyl, hydroxyl, and carbonyl groups). Higher biosorption of Cr(VI)‐DS under acidic pH (94.17% at pH 4) than alkaline pH (68.53% at pH 10). Significant (p < 0.05) interaction effect of pH and biomass concentration on the biosorption, evinced in RSM optimization 91% Cr(VI) removal achieved under optimal conditions of 1.5 g biosorbent L−1, 30 min of contact time, and pH 4.

Study on the Preparation of Nano-FeS Loaded on Fly Ash and Its Cr Removal Performance

“…The correction determination coefficients R adj 2 of the two models were 0.9629 and 0.9750, respectively, indicating that 3.71 and 2.5% of the variance, respectively, could not be explained by the model. 31 The coefficients of variation were 0.67 and 0.89, respectively, which further indicated that the model was accurate and suitable for preliminary analysis and prediction of Cr(VI) and total chromium removal efficiency.…”

“…It can be seen from Tables and that the p values of the regression model of Cr­(VI) and total chromium removal efficiencies are both <0.0001, indicating that the model is extremely significant; p values of misfit terms are all >0.05, and it shows that the model fits well with the experiment, and the regression equation can be used to analyze the experimental results instead of the real points. The correction determination coefficients R adj 2 of the two models were 0.9629 and 0.9750, respectively, indicating that 3.71 and 2.5% of the variance, respectively, could not be explained by the model . The coefficients of variation were 0.67 and 0.89, respectively, which further indicated that the model was accurate and suitable for preliminary analysis and prediction of Cr­(VI) and total chromium removal efficiency.…”

A Study on multiple isotherms of Cr6+ions usingBrevibacillus brevisUS575 isolated from tannery effluents

“…However in another study using microalga Chlamydomonas sp., nearly 90% biosorption has been observed in 30 mins of contact time. [21]. Although various studies have have highlighted much more longer contact time to get maximum biosorption, studies by Zhang et.al showed that using a contact time of 60 mins using Bacillus subtilis, nearly 90% biosorption has been observed [22].…”

Biosorption of Hexavalent Chromium by Freshwater Microalgae Craticula subminuscula from Aqueous Solutions

“…(92.89%) [65], higher than that by Planothidium lanceolatum (about 87%) [26], Chlamydomonas sp. (91.31%) [66], Scenedesmus quadricauda (47.6%) [67], and Chlorella vulgaris (43%) [41], and lower than that by Chlorella sorokiniana (99.67%) [68], and Scenedesmus quadricauda (98.1%) [69]. It is clear from the table above that this alga has high metal binding capacities.…”