Determination of Water-soluble Cu, Pb, Zn, Cd in Rock Salt by ICP-OES with Sulfhydryl Cotton Separation and Preconcentration

Solution mining of rock salt is one of the important methods to obtain salt, which is a necessity of human life and an important raw material of industry. In solution mining, water-soluble heavy metals within rock salt will migrate to the surface environment with mother solution and remain in subsequent salt products, which may contaminate the surface environment and endanger human health. Thus, it is of great importance to analyze water-soluble heavy metals in rock salt. However, water-soluble heavy metals, such as Cu, Pb, Zn, Cd, have much lower abundances than salt. The high content of salt will affect the atomization efficiency of Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), making it difficult to directly quantify these metals. In this study, sulfhydryl cotton was employed as the absorbent to separate and enrich Cu, Pb, Zn, Cd in rock salt. Experimental conditions such as pH, concentration and volume of eluent were optimized. The results indicated that good adsorption efficiency was achieved at pH 7, and adsorbed metals could be quantitatively eluted with 7 mL 15%HCl. Meanwhile, Na had no influences on the adsorption or desorption processes. The recoveries of Cu, Pb, Zn and Cd in desorbed solution are above 92.2%, and only 0.04% for Na, realizing the separation of heavy metals from Na and meeting the requirements for the detection of heavy metals by ICP-OES.