Study on Heavy Metal Adsorption Capacity According to Modification Conditions with Ca-Zeolite

Abstract

This study investigated the liquid-phase adsorption reactions of heavy metal ions (Pb, Cd, Cr⁶⁺, Hg) in wastewater using post-use Li₂O-Al₂O₃-SiO₂ crystalline glass derived from induction top plate materials in which Li had been removed through a sulfuric acid heat reaction. Two types of zeolites, before and after Ca²⁺ modification, were used for heavy metal adsorption.  The amount of zeolite used as an adsorbent, adsorption time, concentration of heavy metal elements, and pH were examined for their effects on adsorption capacity. Ca-zeolite showed an average adsorption removal rate improvement of 54.5% for Cr⁶⁺ and 79.5% for Hg compared to the original lithium-removed zeolite.  As the amount of zeolite added increased, the heavy metal adsorption removal rate also increased. Adsorption reaction time significantly influenced adsorption characteristics, with a notable improvement in the removal rate of Cd. Additionally, the adsorption removal rate of Cd increased with increasing pH, while that of Pb and Cr⁶⁺ decreased. The adsorption characteristics of Hg were not significantly affected by pH.