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Phenols are considered as organic pollutants that are discharged into the environment causing contamination of drinking water, aquatic life, and plants, and therefore, affecting human. Various treatment technologies for removal of the pollutants from water have been used such as, liquid–liquid extraction, ionic exchange with resins, and membrane processes. In this study, removal and adsorption of phenol from aqueous solutions were studied using a polyamide thin film composite reverse osmosis membrane denoted as AG 2514 TF from Osmonics company. The influence of different parameters, such as, feed concentration, ionic strength, transmembrane pressure, and recovery on the elimination of phenol was also studied. In addition, the effect of transmembrane pressure, feed concentration, and ionic strength on the adsorption of phenol was investigated. For a better understanding of the behavior of the membrane and to get more insights into the retention of phenol, the membrane was characterized with the determination of its surface charge and also by the mechanism of transport through this membrane. The results show that the retention of phenol by AG membrane exceeds 40% and may reach 80%. This was found to depend on feed concentration, ionic strength, transmembrane pressure, and recovery. The adsorption amounts were too low and did not exceed 23%. © 2015 American Institute of Chemical Engineers Environ Prog, 34: 982–989, 2015

In natural waters, fluoride ions are necessary and beneficial for the human being. At higher level of F − in water, it is toxic and detrimental to human health, leading to serious problems such as dental and skeleton fluorosis. According to the World Health Organization, the acceptable concentrations of fluoride in potable water are in the range of 0.7-1.5 mg L −1 . Various treatment technologies for fluoride removal from water have been used such as ion exchange, adsorption and membrane processes. In the present study, removal of fluoride ions from aqueous solutions was investigated using a polyamide thin film composite nanofiltration membrane denoted as HL 2514 T from Osmonics Company. Through this membrane, the mechanism of transport was investigated. The KedemKatchelsky model was applied in order to determine phenomenological parameters σ and P s , respectively, the reflection coefficient of the membrane and the solute permeability of ions. The convective and diffusive parts of the mass transfer were quantified. The retention of monovalent and bivalent salts by this membrane shows that it is negatively charged. In the second part, retention of fluoride anions was investigated. Results show that the retention of fluoride by HL membrane exceeds 80%. The influence of the chemical parameters (feed concentration and ionic strength) and the physical parameters (applied pressure and recovery) on the elimination of fluoride was studied.

Nanofiltration and reverse osmosis are investigated as a possible alternative to the conventional methods of Cr(VI) removal from model water and industrial effluent. The influences of feed concentration, water recovery, pH, and the coexisting anions were studied. The results have shown that retention rates of hexavalent chromium can reach 99.7% using nanofiltration membrane (NF-HL) and vary from 85 to 99.9% using reverse osmosis membrane (RO-SG) depending upon the composition of the solution and operating conditions. This work was also extended to investigate the separation of Cr(VI) from car shock absorber factory effluent. The use of these membranes is very promising for Cr(VI) water treatment and desalting industry effluent. Spiegler-Kedem model was applied to experimental results in the aim to determine phenomenological parameters, the reflection coefficient of the membrane (σ), and the solute permeability coefficient (Ps). The convective and diffusive parts of the mass transfer were quantified with predominance of the diffusive contribution.