Biosorption of Corafix Yellow GD3R using Halimeda gracilis and its Toxicological Assessments

Abstract

The elimination of CYGDR3 with H. gracilis was performed under in vitro conditions. Optimization of process variables affecting the adsorption capacity of CYGD3R including dye concentrations, biosorbent concentrations, pH, incubation time and temperature were performed to assess the well suited optimal conditions for the extreme removal of dye. By calculating the kinetics and thermodynamics, the mechanism and feasibility of adsorption process was evaluated. The elution of the dye from the biosorbent was recorded in terms of desorption percentage using different eluents. The treated dye solution was assessed to test its toxicity against green gram seedlings and selected microbes. The results revealed that maximum dye removal (88%) was recorded at pH 6 in the medium amended with 300mg/L of dye with 200mg/L of biosorbent at 25oC within 72hrs of incubation. Moreover application of H.gracilis for CYGDR3 removal confirmed the process of biosorption strongly comply the pseudo-second order kinetic model assisted through chemisorption. The adsorption remained endothermal, feasible and spontaneous as evident from thermodynamic study. Desorption using the eluent 0.1N HNO3 revealed 60% recovery of the dye from the biosorbent in the first cycle and a decrease was noted in further cycle. The process of dye decolorization by H.gracilis was confirmed by UV-Visible spectral analysis. The phytotoxicity study revealed significant growth on green gram seedlings grown with CYGDR3 treated solution, thereby proving its non-hazardous nature. Absence of inhibition of zone in the CYGDR3 treated solution proves its non-toxicity towards microbes. Thus, biosorption using H. gracilis proves to be a sustainable strategy for dye removal from waste water through ecofriendly approach.