Removal of Copper from Aqueous Solutions with Zeolites and Possible Treatment of Exhaust Materials

Abstract

The mechanism of Cu 2+ loading into commercially available natural HEU-type and synthetic LTA-type zeolites for their possible use in environmental processes, such as water and air treatment applications, was studied. Elemental analysis, SEM/EDXS, XRD, XAS and XPS analyses revealed 4-fold coordination of Cu 2+ cations with oxygen atoms in the pores, a predominant location of copper atoms on the surface of crystallites and retained crystallinity of zeolites throughout the processes. The post-treatment of Cu 2+ -loaded samples with HCl and/or NaCl solutions confirmed the predominantly reversible sorption of copper on zeolites from aqueous solutions by ion-exchange mechanism and, therefore, excellent regeneration possibilities for both types of zeolites. Furthermore, with the calcination of exhaust metal-loaded zeolites, catalysts for total toluene oxidation reaction, as a model VOC pollutant, were obtained.

Utilisation of waste Cu-, Mn- and Fe-loaded zeolites generated after wastewater treatment as catalysts for air treatment

“…Possible explanation for this result would be that the migration of metal cations loaded in the pores of zeolite A out of the pores to form metal oxides on the surface of zeolite is limited due to smaller pore openings and stronger interaction of metal cations to more electronegative zeolite A framework, if compared to clinoptilolite sample. For example, stronger interaction of Cu 2+ with zeolite A framework than with clinoptilolite framework in Cu-modified zeolites was shown by X-ray absorption analysis (Logar et al, 2021). However, the formation of small metaloxo clusters in the pores after calcination may be supported by the wide peak at 702 cm −1 (Figure 6D).…”

“…In Supplementary Table S1 0.1 some literature data on sorption performance of natural and synthetic zeolites is summarized, which reveals comparable uptakes [e.g. Logar et al, 2021;Mokrzycki et al, 2022].…”

“…In all test reactions, CO 2 and water were the only reaction products, confirming that total oxidation of toluene is the only reaction taking place. To evaluate possible synergistic effects of the three metals, as it was reported for MnNi clinoptilolite system (Ahmadi et al, 2017), we also performed the same catalytic tests for single metal modified samples of the two zeolites, i.e., calc-Cu-NaZ-n, already reported in (Logar et al, 2021), calc-Mn-NaZ-n and calc-Fe-NaZ-n (n = 50 mg and 150 mg) as well as calc-Cu-4A-n (Logar et al, 2021), calc-Mn-4A-n and calc-Fe-4A-n (n = 50 mg and 150 mg) (Supplementary Table S6).…”