Green hydrophilic modification of PE hollow fiber membranes in a module scale via long-distance and dynamic low-temperature H ₂ O plasma flow

A green chemistry process, long-distance and dynamic low-temperature (LDDLT) H ₂ O plasma, was developed to modify PE hollow fiber membranes in a module scale using our modified LDDLT plasma setup. The modification degree of LDDLT-H ₂ O plasma was 2 times greater than that of Ar plasma, but the effective treatment distance achieved by LDDLT-Ar plasma was about two times of that obtained by LDDLT-H ₂ O plasma (22 cm). Under the suitable conditions, the effective treatment distance can reach over 54 cm after LDDLT-H ₂ O plasma treatment from the double inlets, closed to some industrial module sizes. The improvement in surface hydrophilicity was because of the introduction of numerous oxygen-containing groups. High concentrations of OH radicals in H ₂ O plasma played a major role in the membrane surface hydroxylation. This directly resulted in a great enhancement in the pure water flux. It increased from about 6 L m ^-2 h ^-1 to 45 L m ^-2 h ^-1 after treatment. Also, the H ₂ O plasma-treated membrane module exhibited good hydrophilic stability during 285 days storage.