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

Abstract

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).