Abstract

Dissolved Mn2+ in groundwater is dangerous for human health since it may act as a neurotoxin. To address this issue, sorption has emerged as an environmentally-friendly technology for Mn2+ removal. This study aimed to assess the effect of activation of Chilean natural zeolite, by modification of its compensating cations with NaCl, on its capacity for Mn2+ removal using batch and fixed-bed column studies. The natural and activated zeolites were characterized by SEM-EDS, TXRF, XRD, and N2 adsorption assays. The results of batch studies demonstrate that Na+ enhances the Mn2+ removal capacity of these zeolites from 4.55 to 5.9?1, with negligible changes in the pore structure. The experimental data fitted well with the pseudo-second-order kinetic and Langmuir adsorption models. Furthermore, MnOx(s) formed during the Mn2+ removal was identified on the surface of the zeolite by XRD and SEM-EDS analysis. The fixed-bed column studies were conducted at two bed heights: H1 (5 cm) and H2 (10 cm). The breakthrough curves adjusted to models of Thomas and Dose-response. The dose-response model adequately described both experimental data with an R2 > 0.90. The Mn2+ adsorption capacity of the system (qmdr) was 2.38 and 5.13 mg g?1, for H1 and H2, respectively. The regeneration of the activated zeolite was achieved using NaCl solution improving the efficiency of Mn2+ removal after reuse. This work highlights natural zeolite potential as an effective material for Mn2+ removal and as a viable technology to improve the water quality affected by geogenic contamination. © 2023 The Authors