Investigation of water softening using ceramic adsorbents in a continuous adsorption process

Journal article, 2026

Ceramic adsorbents offer a sustainable and cost-effective approach to water treatment, particularly for reducing water hardness. This study aimed to evaluate the performance of natural zeolite and activated alumina, modified with NaNO3 and H2SO4 respectively, in a continuous fixed-bed column system for water softening. Adsorption experiments were conducted under varying operational conditions, including column diameters (1 and 1.5 cm), flow rates (10 and 20 mL/min), and an operation time of 600 min. The optimal setup, 1.5 cm column diameter and 10 mL/min flow rate, yielded bed saturation times of 600 min for modified zeolite and 570 min for modified alumina. NaNO3-modified zeolite achieved removal efficiencies of 99.23% for total hardness, 99.37% for calcium, and 99.17% for magnesium. Breakthrough and saturation times indicated superior performance compared to unmodified adsorbents. Kinetic models, including Thomas, Adams-Bohart, and Yoon-Nelson, were applied, with the Thomas and Yoon-Nelson models fitting best (R & sup2; approximate to 0.98). The findings demonstrate that surface modification enhances the adsorption capacity of ceramic materials, highlighting their potential for efficient and scalable water hardness treatment in continuous systems.