Response surface methodology approach for optimization of biosorption process for removal of Hg(II) ions by immobilized Algal biomass Coelastrella sp.

Currently, adsorption stands as a viable technique for the effective removal of pollutants such as heavy metals from water. Within this research endeavor, adapted green algae (Coelastrella sp.) have been harnessed as a sustainable and environmentally conscious adsorbent, employed in the removal of Hg(II) ions from a simulated aqueous solution via employment of an Airlift bioreactor. The analysis of the attributes of adsorbent was conducted through the utilization of Fourier transform infrared (FTIR) spectroscopy. The examination of residual concentrations of Hg(II) ions in the treated solution was accomplished through the utilization of atomic absorption spectroscopy (AAS). The impact of various experimental factors, including the duration of contact (ranging from 10 to 90 minutes), initial concentrations of Hg(II) ions (ranging from 500 to 2000 μg/l), quantity of adsorbent introduced (ranging from 0.1 to 0.7 g per 250 ml), temperature variations (ranging from 20 to 40 °C), and airflow velocity (ranging from 200 to 300 ml/min), was systematically examined. For the optimization of adsorption efficiency, MINITAB 18 software was employed. The equilibrium data was subjected to analysis using the Langmuir, Freundlich, and Temkin isotherm models. Employing the framework recommended by MINITAB 18, the optimal parameters for adsorption were identified as 2000 μg/l for initial concentration, 90 minutes for contact time, 40 °C for temperature, and 300 ml/min for airflow rate. The Langmuir equation yielded the highest adsorption capacity, measuring 750 μg/g at a temperature of 40 °C.