Arsenic removal from water by magnetic Fe1-xCox Fe2O4 and Fe1-yNiy Fe2O4 nanoparticles

Abstract

This article studies the effects of Co and Ni replacement in Fe1-xCoxFe2O4 and Fe1-yNiyFe2O4 (x, y = 0, 0.05, 0.1, 0.2, 0.5) nanoparticles, pH, weight of nanoparticles/mL of water, and time of stirring on the arsenic removal ability. The results showed that a small amount (0.25 g L-1) of Fe3 O4 nanoparticles after stirring time of 3 min can reduce the arsenic concentration from 0.1 to 0.01 mg L-1. The removal was also affected by the pH of the water. Absorption of arsenic by nanoparticles was effective when pH was smaller than seven and reduced with the increase of pH. At pH of 13, there was a strong release of arsenic ions from arsenic-absorbed nanoparticles back to water. The time of stirring was studied from 1 min to 2 h and the optimal time was about few minutes. Co and Ni's presence was reported to keep saturation magnetisation stable under working conditions. For Co replacement, absorption does not change significantly when x ≤ 0.1 and slightly reduces when x > 0.1. The presence of Ni improved the absorption in most cases.