Chlorella sorokiniana waste-based biomass for sorption of chromium ions from aqueous solution

Abstract

The present study investigates the potential of the phosphoric acid-treated Chlorella sorokiniana biomass in the adsorption of chromium ions. The Chlorella sorokiniana species used for acid modification is waste-based biomass generated from biofuel extraction. The biodiesel preparation process utilizes the C. sp grown at in situ conditions in open pond systems. The SEM imaging of the phosphoric acid-treated biomass shows an improved morphology required for the sorption of metal ions. Meanwhile, BET analysis results presented that the acid-treated biomass is macro-porous. Besides, TGA and FTIR studies captured the functional group changes occurred in the chemically modified biomass. Further, the stability of the prepared adsorbent is confirmed in the zeta potential studies. The present study also delves into the study of process parameters on the uptake of metal ions. The result shows an increased uptake efficiency of 89.5% for 100 mg/L chromium solution at a pH of 2. Another key finding in the study is the rapid sorption of metal ions in the first 10 min of contact time. In addition, the isotherm and kinetic studies establish the inclination of the studied system towards Freundlich and pseudo-second-order models, respectively. Thus, the current study unveils the possibility of reusing C. sp waste biomass to remove chromium contaminants from an aqueous solution.