Water purification from heavy metal ions by nano-sized Fe0/kaolinite composites

Abstract

We have investigated the physicochemical features of the purification of wastewater that are complex on its content and include a mixture of heavy metal ions (Cu(II), Cd(II), Zn(II), Co(II), Cr(VI)). The phase of a composition and structural-sorption characteristics of synthesized nano-sized Fe0/kaolinite composites were studied. It was found that the obtained materials have much better sorption properties for the extraction of heavy metals from aqueous solutions in comparison with natural kaolinite. Calculations of sorption isotherms according to the Freundlich equation are done. Based on isotherms, the average values of specific sorption per unit of an active surface of the mineral at the content of heavy metal ions in the initial solutions of 300 μmol/dm3 were determined. They range from 0.42 to 17.1 μmol/g for Cr(VI) to Cu(II) ions. It has also been found that similar values for the modified samples are much larger and range from 13.8 to 80.27 μmol/g for ions from Cr(VI) to Cu(II). It is shown that composite sorbents based on nano-sized zero-valent iron and dispersed kaolinite silicate are effective sorbent materials for the purification of water contaminated with toxic heavy metal ions that are commonly found in wastewater of the galvanic and hydrometallurgical industries.