Abstract:
The main objective of this research is to evaluate removal efficiency of nalidixic acid (NAL) residues in synthetic wastewater at high concentration (0-30 mg/L) by adsorption on functionalized superpapramagnetic mesoporous silicates (F-HMS-SP) and to study effect of magnetic field on cake formation of adsorbents removal by ultrafiltration(UF). Five types of surface functional groups (3-aminopropyltrimethoxy-, 3-mercaptopropyltrimethoxy-, n-octyldimethyl-, 4-triethoxysilyl butyronitrile- and phenyltrimethoxy functional group) were grafted on pristine superpapramagnetic mesoporous silicates (HMS-SP) via post-grafting method denoted as A-HMS-SP, M-HMS-SP, OD-HMS-SP, N-HMS-SP and PTM-HMS-SP respectively. NAL adsorption kinetic of all adsorbents were compatible with the pseudo-second order model and implied the intraparticle diffusion as a rate limiting step. Hydrophobic surface of OD-HMS-SP and PTM-HMS-SP provided highest adsorption capacity comparing with hydrophilic adsorbents; however, it was still lower than PAC. Moreover, electrostatic interaction played an important role for NAL adsorption mechanism. Greatly reduction of cake resistance (Rc) was observed due to magnetic system which caused a slow-down of the cake built-up. Moreover, electrostatic interaction between adsorbent and membrane surface was found to affect on Rc value. The presence of NAL adsorbed on F-HMS-SP can affect electrostatic interaction between adsorpbent and UF membrane surface.