Alcohols assisted in-situ growth of MoS2 membrane on tubular ceramic substrate for nanofiltration

Abstract

Molybdenum disulfide-based membranes have received wide attention for their excellent performance in chemical separation field. Yet, manipulating the structure of MoS2 membranes still remains an unprecedented challenge. In this work, the tubular MoS2 ceramic membranes were prepared by in-situ hydrothermal method using aqueous solution of thiourea and ammonium molybdate as precursor solution. The structure and morphology of the membranes were manipulated by introducing different alcohols into the precursor solution. The results indicated that the presence of alcohols drove the transformation of MoS2 morphology from nanosheets to spherical aggregates. As the molecular weight of the alcohols decreased, more small-sized molybdenum disulfide spheres were formed on the tubular ceramic substrate, which resulted in the formation of a great number of large transportation channels and promotion of surface area, and thereby improved the permeability of the membrane. Moreover, the addition of different alcohols enhanced the negative charge of the membrane surface, which ensured an effective rejection while enhancing the membrane permeability. The results demonstrate that the membranes prepared in a water-ethanol mixed solvent possess an excellent permeability for water (33.2 L/(m2 h bar)) and methanol (52.2 L/(m2 h bar)), with a rejection of more than 97% for Eriochrome black T, and an excellent pressure resistance as well as long-term running stability under cross-flow filtration. In addition, such membrane exhibited a below 30% rejection for salts, which can be utilized for dye desalination.