Biosorption potential of Gracillaria corticata in the sequestration of malachite green from aqueous solutions

Abstract

Gracillaria corticata, a red alga, has been tested for its ability to remove malachite green (MG) from aqueous phase. The surface morphology of G. corticata is studied using Scanning Electron Microscopy (SEM). The analytical evidence from FTIR spectra confirms the involvement of amine group in the biosorption of malachite green. The effects of biosorbent concentration, initial pH, temperature, adsorption time and initial dye concentration are studied for the biosorption of MG using G. corticata. At various initial MG concentrations (20 - 100 mg/L), batch sorption equilibriumhave been attained within 1 h. However the equilibrium is slow as the time progresses. Kinetics of MG biosorptionhas beenanalyzed using pseudo second order model. The experimental data is also analyzed using Langmuir, Freundlich and Temkin isotherm models. Out of which, Langmuir model describes the isotherm data with high coefficient of determination (R² = 0.996). So, based on Langmuir model the maximum dye uptake of 76.92 mg/g is reported at pH 10.0 and temperature 303K. Different thermodynamic parameters such as ΔH ^°, ΔG^°, ΔS^° are evaluated and it is found that the present system is spontaneous, endothermic and increased randomness in nature. Thus, the investigation has proved Gracillaria biomass to be an effective low cost, eco-friendly biosorbent for the treatment of dye-bearing wastewater.