Simultaneous recovery of phosphorus with nickel purification in nickel-plating wastewater via Fe/C activated H2O2 oxidation

Abstract

The recovery of phosphorus (P) from wastewater has attracted substantial attention with the atrophy of global P resource. In the current work, the simultaneous recovery of P with the removal of nickel (Ni) via iron/activated carbon (Fe/AC) and hydrogen peroxide (H2O2) form nickel-plating wastewater was achieved. The isotherm reaction showed a maximum P recovery of 99.99% with an equilibrium concentration of P of 0.12 mg/L, which was lower than the limitation of discharge regulation (China national regulation, 0.5 mg/L). The optimal conditions for P recovery were 0.25 mol/L H2O2, a Fe/AC mass ratio of 1:1, an at 60 °C, which led to the ratio of P in the form of FePO4 in the residue to be 77%. Moreover, the Fe/AC microelectrolysis coupling to H2O2 promoted Fe2+ production from Fe0 and improved the circulation of Fe2+, which improved the production of hydroxyl radicals with increasing pH and consequently enhanced oxidation efficiency of hypophosphite. The FePO4 was found the major form of phosphate in the precipitate. The highest removal rate of nickel was 89%, which was attributed to its precipitation at high pH and adsorption on to iron hydroxides and activated carbon. Nickel purification was achieved by further coagulation as the equilibrium concentration of Ni was lower than 0.1 mg/L. Therefore, our work provides a promising approach for simultaneous recovery of P and removal of Ni from electroplating wastewater.