Development of Low Pressure Brackish-Water Reverse Osmosis Membranes.

摘要

Flat-sheet reverse osmosis membranes were developed for low pressure,brackish-water desalination from a novel,aromatic polymer polybenzimidazolone (PBIL). This polymer,developed in Japan,had been previously shown to have potential when formed into a seawater desalting membrane. Membrane formation conditions were systematically varied in order to tailor membrane characteristics to applications in brackish-water desalting. This work resulted in the formation of membranes with initial fluxes of 15-16 gfd and salt rejections of 90-95% using 0.5% sodium chloride at 250psig and 25 C. Following the laboratory work,flat-sheet membrane was manufactured for fabrication of 2-inch diameter spiral-wound reverse osmosis modules. Although newly-manufactured membrane gave fluxes of 13 gfd or greater and rejections of 90%,results for modules were typically 5-7 gfd and 80-85%. Membrane performance losses during shipment,storage and module fabrication appeared to predominate in determining module performance although structural considerations in the modules themselves were also a factor.