Zeolite Y-carbonaceous composite membrane with a pseudo solid foam T structure assessed by nanofiltration of aqueous dye solutions

Abstract

This work invents a composite membrane constituted by the granular NaY zeolite as the major phase (~ 74 vol %), which is integrated with carbonaceous (~ 23 vol%) and glass-fiber phases. The zeolite particles are in- timately bonded by carbonaceous to constitute a dendritic distribution of zeolite-carbonaceous amalgam frames (ZCF) that enclose micron-scaled voids, thus resembling a solid foam. These copious voids act virtually as tiny separation cells so as to favor permeance. The membrane shows high rejection to traces of water-soluble dyes, namely Methylene Blue (MB), Rhodamine-B (RB) and Methyl Orange (MO). Rejection to the probe dye molecules relies on electrostatic-interactions between the molecules and ZCF along carbonaceous pores. The interactions are influenced by the pH of feed since it affects magnitude and sign of charge on both ZCF and the dyes. Sterically, since NaY allows only water to penetrate, the dye molecules could crossover the carbonaceous phase in the filtrate if there are no rejection mechanisms. Typically, the membrane manifests a stable rejection (99%) and permeance (88 L/h m2 bar) for the 10 ppm MB solution. Attaching a stable surfactant thin layer on the pore wall allows the membrane to handle higher MB concentrations.