Facile Synthesis of Organic Template-Free Chabazite Zeolite-Coated Kaolin Ceramic Membrane for Continuous Separation of Cerium from Aqueous Solutions

Abstract

Developing an organic template-free zeolite coated on a low-cost ceramic support is essential to reduce the overall cost of the membrane for heavy metal separation. In this study, a low-cost and highly durable kaolin-supported zeolite-coated composite membrane was fabricated and tested for removal of cerium metal ions from its aqueous solution. Different strategies were followed to fabricate the composite membrane through the organic template-free hydrothermal synthesis method, such as coating the ceramic tubes solely on the interior surface, exterior surface, and both sides. The results obtained from X-ray diffraction, field emission scanning electron microscopy, and field emission transmission electron microscopy indicated that the hydrothermal synthesis route produced pure, ultrafine, and uniform particles of chabazite zeolite with a cation exchange capacity of 3.96 meq/g. The effect of coating on the membrane surface(s) was investigated by measuring the weight increment, porosity, pore size, and pure water permeability; the results revealed that the ceramic tube coated on both sides has the highest amount of zeolite loading, that is, 1.82 ± 0.18 g, along with a porosity of 30.50 ± 0.50%, a water permeability of 1.74 L/m2 h bar, and an average pore diameter of 36 nm. The average pore diameter of the composite membrane (both-side-coated tubes) obtained from BET analysis (34 nm) was in good agreement with the pore size (36 nm) estimated through the pure water permeability test. Furthermore, the performance of the composite membrane coated on both sides was evaluated toward removing cerium ions from aqueous solutions. The effect of applied pressure, pH, and concentration of the feed solution was investigated. During the cross-flow filtration tests, the permeate flux decline was not observed for all the applied pressures. More than 99.9% removal of cerium was achieved under the different conditions of feed concentration and pH. This study establishes the application of the prepared composite membrane for cerium removal from aqueous solutions.