An investigation into the sorption of benzoic acids by polyurethane membrane

The extraction mechanism of organic compounds by ether- and ester-type polyurethane membrane has been investigated through a detailed study of sorption of monobromobenzoic acids. The effects of solution concentration, extraction time, surface area, pH, salts, and temperature on extraction were studied. It was found that monobromobenzoic acids are extracted in their neutral form, and that the extraction is controlled primarily by the relative strength of intra- and intermolecular hydrogen bonding. The ether-type polyurethane membrane allows a more efficient removal of monobromobenzoic acids from solution than the ester-type membrane. The extraction of benzoic acids with the ether-type membrane decreases as the temperature increases. When the ester-type polyurethane membrane is used, an extraction maximum is observed at room temperature with a decrease in extraction at lower and higher temperatures.