title: Tailoring the Separation Behavior of Polymer-Supported Organosilica Layered-Hybrid Membranes via Facile Post-Treatment Using HCl and HN3 Vapors.
abstract: A promising layered-hybrid membrane consisting of a microporous organosilica active layer deposited onto a porous polymer support was prepared via a facile sol-gel spin-coating process. Subsequently, the pore sizes and structures of the organosilica top layers on the membrane surface were tuned at mild temperature combined with vapor treatment from either hydrochloric acid (HVT) or ammonia (AVT), thereby tailoring the desalination performance of the membranes during reverse osmosis (RO) processing. The effects of HVT and AVT on the pore size, structure, and morphology of organosilica layers and on the separation performances of membranes were investigated in detail. We confirmed that both HVT and AVT processes accelerated the condensation of silanol (Si-OH) in the organosilica layer, which led to dense silica networks. The layered-hybrid membranes after HVT showed an improved salt rejection and reduced water flux, while membranes after AVT exhibited a decrease in both salt rejection and water permeability. We found that HVT gave rise to smoother and denser organosilica layers, while AVT produced large voids and formed pinholes due to Ostwald ripening. These conclusions were supported by a comparative analysis of the results obtained via FTIR, TG-MS, SPM, and RO desalination.
authors.affiliation: Department of Chemical Engineering, Hiroshima University , Higashi-Hiroshima 739-8527, Japan.
authors.forename: Genghao
authors.initials: G
authors.lastname: Gong
authors.affiliation: Department of Chemical Engineering, Hiroshima University , Higashi-Hiroshima 739-8527, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Nagasawa
authors.affiliation: Department of Chemical Engineering, Hiroshima University , Higashi-Hiroshima 739-8527, Japan.
authors.forename: Masakoto
authors.initials: M
authors.lastname: Kanezashi
authors.affiliation: Department of Chemical Engineering, Hiroshima University , Higashi-Hiroshima 739-8527, Japan.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Tsuru
keywords: ammonia vapor treatment; hydrochloric acid vapor treatment; layered-hybrid membrane; organosilica; reverse osmosis