Removal of Cu2+ ions with 2-phosphonobutane-1,2,4-tricarboxylic acid–modified nanoscale zero-valent iron

Applications of nanoscale zero-valent iron (N-Fe0) and modified Fe0 with 2-phosphonobutane-1,2,4-tricarboxylic acid (P-Fe0) prepared by borohydride reduction for removal of Cu2+ in water are investigated under a variety of experimental conditions. Characterizations with X-ray diffractometer, scanning electron microscopy and transmission electron microscopy confirm that N-Fe0 and P-Fe0 have a core shell structure similarly. The uptake experiments investigated the effects of the dosages of N-Fe0 and P-Fe0, pH and the adsorption kinetics. The results showed that the ratio of removal efficiencies is more than 90% with the condition of initial concentrations of 10.0–70.0 mg/L, pH of 7 at 25 °C and the adsorbent of 0.4 g/L N-Fe0 and P-Fe0. Within the applied conditions, the order rate of Cu2+ adsorption kinetics equation on the N-Fe0 and P-Fe0 was the pseudo-second. According to X-ray photoelectron spectroscopy results, Cu2+ ions were removed primarily via a redox mechanism that resulted in the formation of Cu0 and Cu2O. The contact of N-Fe0 and P-Fe0 with aqueous media caused extensive formation of iron oxide. The research reveals that Cu2+ can be efficiently removed by the means of N-Fe0 and P-Fe0 in solution, and the appropriate factors, involving pH value and the dosages of Fe0, were important keys in the process, and the modified Fe0 will be extensively utilized for the removal of Cu2+ from wastewater.