Evaluation of quaternary phosphonium-based polymer membranes for desalination application Original Research Article

Tris(2,4,6-trimethoxyphenyl)polysulfone-methylene quaternary phosphonium-hydroxide (TPQPOH) membranes were prepared and tested for potential use as desalination membranes. The effects of the curing temperature, a plasticizer and membrane preparation conditions on desalination performance of TPQPOH membranes were studied. After being cured at 80 °C for 12 h, the TPQPOH membrane exhibited a salt rejection of 53.9% and a water permeability of 9.78 L μm m− 2 h− 1 bar− 1. When the curing temperature was increased to 120 °C, the salt rejection increased whereas there was a drop in water permeability. The addition of polyvinyl butyral (PVB) as the plasticizer was shown to effectively prevent the TPQPOH membranes from cracking, and the resulting membranes possessed increased salt rejection rate and reduced water permeation. Chlorine tolerance tests showed that the membrane prepared from dried TPQPOH was more chlorine resistant than that from wet-TPQPOH. The membrane prepared by dissolving dried TPQPOH in ethanol possessed a high salt rejection of 94.9% and a water permeability of 5.05 L μm m− 2 h− 1 bar− 1.