Application of aluminosilicate residue-based zeolite from lithium extraction in water treatment

Abstract

In a previous study, the Na-P1 type zeolites were synthesized from aluminosilicate residues using an efficient and cost-effective process, exhibiting an excellent adsorption capacity for Ca2+ in comparison to commercial zeolites 13X and A. Building upon this, the current study evaluates their performance for the adsorption of various elements, including Ca2+, Mg2+, and NH4+. The objective was to evaluate the performance of the Na-P1 type zeolites for the adsorption of various elements, including Ca2+, Mg2+, and rare earth elements, with a particular emphasis on the adsorption kinetics and water hardness removal in comparison to commercial zeolite A. The results demonstrated that the Na-P1 zeolite exhibited a satisfactory sorption capacity for Ca2+ and NH4+ ions (66 mg/g), while displaying a relatively lower effectiveness for the sorption of Mg2+ ions (5.6 mg/g). The Langmuir model is particularly well suited to the sorption of Ca2+, while the Freundlich model is more appropriate for Mg2+. Both models demonstrated satisfactory representation of NH₄ ⁺ sorption. Moreover, the pseudo-second-order kinetic model provides an excellent description of the Ca2⁺ and Mg2⁺ sorption processes, while both models effectively describe the NH₄⁺ adsorption kinetics. Additionally, Na-P1 zeolite was observed to effectively reduce water hardness from 322 to 63 mg CaCO₃/L at temperatures of 10, 20, and 38 °C, and to 18 mg/L at 58 °C. These findings suggest that Na-P1 zeolite has promising potential for applications as a water softening agent. Regarding metals and rare earths, the Na-P1 zeolite demonstrated noteworthy sorption efficiencies for Cd2+ (138 mg/g), Ce3+ (209 mg/g), Cr3+ (56.2 mg/g), and Cu2+ (60.5 mg/g). However, it demonstrated lower sorption efficiencies for Co2+, Mn2+, Ni2+ and Dy3+ (below 16 mg/g). The findings illustrate that Na-P1 zeolites are effective for the adsorption of diverse elements, offering a promising avenue for the sustainable transformation of industrial waste into valuable materials for environmental applications.