Impact of surface modification of green algal biomass by phosphorylation on the removal of copper(II) ions from water

A series of batch lab-scale experiments were performed to investigate the performance of dead phosphorylated algal biomass of Spirogyra species for the bioadsorption of Cu+2 ions from aqueous solutions. FT-IR and SEM analyses were performed to characterize the phosphorylated and raw algae. The SEM analysis indicated that the phosphorus content increases by about 5 times. The isotherm equilibrium data indicated that phosphorylation enhances the removal of Cu+2 from water by about 20%. The experimental isotherms fit well to Langmuir models with R-2 values close to 0.99. Adsorption kinetic study was conducted to investigate the effect of initial Cu+2 concentrations, pH, and adsorbent dose on the loading capacity of algal biomass. The optimum pH for the process was around 6 and the corresponding maximum loading capacity was 65 mg/g. The pseudo second-order kinetics successfully modeled the kinetic results with R-2 values closed to 0.99. The thermodynamic results indicated that the bioadsorption process is endothermic and spontaneous at initial Cu+2 concentrations lower than 100 mg/L. The results were promising and encourage the design of a continuous process using algal biomass to remediate water polluted with heavy metals.