ABSTRACT The contamination of water by heavy metals such as Cr(VI), Cd(II), and Pb(II) poses significant risks to human health and ecosystems. In this study, NaP zeolite synthesized from rice husk ash is evaluated as an efficient and eco‐friendly adsorbent for the removal of these toxic ions. The adsorption behavior of NaP zeolite is examined in both single‐ion and competitive adsorption systems, considering variables like pH, contact time, ion concentration, and adsorbent dosage. The results indicate that NaP zeolite is highly effective in removing Cr(VI) under acidic conditions, while it efficiently adsorbs Cd(II) and Pb(II) in neutral to alkaline environments. In competitive systems, ion interactions are influenced by properties such as speciation, hydrated radius, and hydration enthalpy. Kinetic studies show that the adsorption process follows a pseudo‐second‐order rate law, suggesting chemisorption as a key mechanism. Adsorption isotherms, analyzed using the Freundlich model, suggest a multilayer adsorption process, while the Temkin and Dubinin–Radushkevich models indicate spontaneous and endothermic adsorption. These findings demonstrate that NaP zeolite is a promising material for heavy metal removal, providing valuable insights into its adsorption properties and potential for real‐world water treatment applications.
Lương et al. (Sun,) studied this question.