Nanofiltration membranes to reduce phenol concentration in wastewater

Physical, chemical and biological methods have been described to remove phenolic compounds. None of them are the definitively solution of the environmental problem caused by the discharge of this pollutants. Hybrid processes that combine pressure driven membrane processes with adsorption processes have been developed. Our research group studied the removal of phenol with three reverse osmosis membranes, the rejection percentages obtained were very low (40%), besides this parameter increases when the operating pressure decreases. For this reason, in this paper, a study of phenol removal from aqueous solutions by nanofiltration using different experimental conditions (feed phenol concentration, pressure and pH) and different membranes (NF-97, NF-99 and DSS-HR98PP) is carried out. Water permeability coefficients were also obtained. The best results are obtained with DSS-HR98PP membrane increasing the rejection percentage up to 80%.

A previous study of phenol removal from aqueous solutions by reverse osmosis using different experimental conditions and different membranes (DSS-HR98PP, SEPA-MS05 and DESAL-3B) were previously carried out in our research group. Poor rejection percentages were obtained in all cases (lower than 40%). Besides, the rejection percentage increased when pressure decrease. For this reason, the next step was to try with three nanofiltration membranes: NF-99, NF99 and DSS-HR98PP. Water permeability was determined for the three membranes. Within the three membranes, DSS-HR98PP membrane presents the best rejection percentages, being these in all the cases next to 80%. Rejection percentage that is much higher that the previously obtained with the same membrane but with pressure conditions of reverse osmosis.