The use of natural zeolite and chamotte clay-based sorbents for the extraction of sodium and potassium ions from saline water: a preliminary study

In this work, sorbents based on natural zeolite (Z) and chamotte clay (ChC) treated with NaCl and HNO3 solutions were obtained to extract Na+ and K+ ions from saline water. The physicochemical characteristics of the obtained sorbents were studied by SEM, EDAX, and BET methods. It was found that successive treatment with NaCl and HNO3 solutions has a positive effect on the sorption properties of the studied materials. The maximum increase in the specific surface area from 4.5 m2/g to 39.3 m2/g is observed for acid-treated Z, and the specific surface area of ChC also increases almost 2-fold from 8.4 m2/g to 15.3 m2/g. Na+ and K+ ions are extracted from water due to ion exchange with Z and ChC cations. As a result of determining the cation exchange capacity (CEC) of the studied sorbents, it was found that treatment with a NaCl solution improves the ion exchange properties of the sorbent and leads to the formation of a “homoionic” form of aluminosilicates. Due to that the sorbents more easily enter ion exchange reactions. The authors established the sorption activity of the obtained materials based on natural Z and ChC with respect to Na+ and K+ cations. The maximum recovery rate is 28.45% for Na+ ions with the ChC-Na-H sorbent and 76.28% for K+ ions with the ChC-Na sorbent. Among Z-based sorbents, the most effective forms are Z-Na-H (15.44% Na+ recovery) and Z-Na (60.47% K+ recovery).