Feasibility of mercury (II) ion removal by nitrated polycarbonate derived from waste optical discs

Advanced technology has led to the generation of the massive amount of electrical and electronic wastes, including compact discs and digital versatile discs. These optical discs are often ended up in landfills and incinerators, resulting in severe environmental degradation. This research aims to recover polycarbonate from waste optical discs and exploring its potential as a sorbent for the removal of mercury in water. The recovered polycarbonate was nitrated to enhance its efficiency in removing mercury (II) ion. The nitrated polycarbonate was characterized using Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis, energy-dispersive X-ray spectroscopy and Brunauer-Emmett-Teller surface area analysis. Response surface methodology was employed to investigate the effects of agitation rate, contact time, pH, initial concentration, sorbent dosage on the mercury (II) ion removal efficiency via a central composite design. According to the quadratic model, an optimum response can be achieved at 188.6 rpm of agitation, 150 min of contact time, pH 7.55 and 1.50 mg/L of initial mercury (II) ion concentration. The adsorption process was found to follow the Freundlich isotherm model, and the adsorption mechanism was found to obey the pseudo-second-order kinetic model that indicates the chemisorption process. The results of this study showed that the nitrated PC with a maximum adsorption capacity of 0.289 mg/g has the potential to be used as a sorbent in water treatment for the removal of mercury (II) ion in water.