Heavy metals adsorption by nanozeolites: effect of sodium hexametaphosphate

In this study, for the first time, sodium hexametaphosphate (SHMP) was used as a dispersant in the production of nanozeolites. In addition, the effect of SHMP on the adsorption of ion metals by nanozeolite was investigated. In order to characterize the prepared nanozeolite by a planetary mill, the scanning electron microscope (SEM) was used. The SEM photographs showed that the planetary mill could produce the nanoparticles of zeolites. Furthermore, according to the SEM and X-ray diffraction (XRD) results, the zeolite samples milled with SHMP have regular and fine particles in comparison with nanozeolites produced without SHMP. On the other hand, the nanozeolites produced with SHMP have high qualification. According to the size fraction results, in the presence of SHMP, less than 15 % (3 g) of the milled sample remained on the 20-micron sieve, while 70 % (14 g) of the milled sample without SHMP remained on the 20-micron sieve. Finally, a series of experiments was performed to study the effect of SHMP on the adsorption of nickel, cadmium and copper ions using nanoparticles of zeolite. As a result, the adsorption percentage of nickel and cadmium on nanozeolites pretreated by SHMP is higher for times less than 2 h and more than 6 h in comparison with nanozeolites not pretreated by SHMP. On the other hand, the effect of SHMP on the adsorption of copper by nanozeolite is not significant. This insignificant effect probably occurs due to the stronger interaction of Cu²⁺ and AlO⁴⁻ than that of Cu²⁺ and SHMP.