Synthesis of a hybrid organic-inorganic polyethersulfone membrane incorporated with phosphotungstic acid: Controversial performance in removal of dinitroaniline herbicides from water

Present study focused on removal of one type of highly employed and poisonous herbicides (trifluralin and ethalfluralin as dinitroaniline herbicides) from water using membrane technology. To this aim, composite membranes were prepared using polyethersulfone as base polymer and different concentrations of phosphotungstic acid as superhydrophilic additive. Scanning electron microscopy, atomic force microscopy, water contact angle, bulk porosity and mean pore size measurements as well as pure water tests were employed for characterization of membranes. To mimic real circumstances existing in surface water, experiments were conducted at acid, neutral and basic pHs, and also, effects of ionic environment on removal of herbicides was probed by controlling the sodium and calcium concentration in feed solution. Water permeability was remarkably improved due to induced changes in composite membranes. Surprisingly, fabricated membranes behaved contrarily in removal of dinitroanilines belonged to the same class of herbicides with similar size and molecular weight. According to the results, efficiency of membranes was affected by several factors relating to both membrane and herbicide as well as solution pH. Moreover, evaluation of antifouling characteristics of membranes demonstrated higher resistance of composite membranes against fouling.