Removal of three and hexavalent chromium from aqueous solutions using a microalgae biomass‐derived biosorbent

Abstract

Dry biomass of green microalgae, Scenedesmus quadricauda (Chlorophyta), was used as a biosorbent to remove Cr(III) and Cr(VI) from aqueous solutions using batch experiments. The biomass composed of 43.5% protein, 20.2% carbohydrate, and 9.2% lipid. Different functional groups including hydroxyl, amine and sulfoxide were observed in the biosorbent. The equilibrium time for the removal of Cr(III and VI) was 120 min. The maximum adsorption was obtained at pH 6 (98.3%) and pH 1 (47.6%) for Cr(III) and Cr(VI), respectively. The kinetics data was better fitted by the pseudo‐second‐order model for both Cr species. The biosorption of Cr(III) was described by the Langmuir and that of Cr(IV) by the Freundlich isotherm models. According to the Langmuir model, the maximum biosorption capacity was 58.47 and 46.51 mg g−1 for Cr(III) and Cr(VI), respectively. The regeneration of biosorbent was achieved by HNO3 (85%) for Cr(III) and NaOH (60%) solutions for Cr(VI). The application of dry microalgae biomass could be suitable as an alternative technology for the heavy metal removal from wastewater, especially for the small and medium industry. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 949–956, 2015