Manufacturing and Analysis of an Efficient Nanofiltration Membrane with TiO2-Doped ZrO2 on Clay Support for Effective Filtration of Dyes and Heavy Metal Solutions

In this investigation, the membranes are a typical example of structural composite layering that ensures high mechanical strength and low resistance to fluid passage. The flat support of bentonite clay was made by dry pressing technique. Sintered support at 950 ℃, leads to obtained porosity of 34%, water permeability of 1000 L/h.m2.bar and good mechanical resistance of 22 MPa. This support was used for development of intermediate layer by dip-coating process using nano-TiO2 and followed by sintering at 750 ℃. The average pore diameter and water permeability of the obtained layer are respectively 10 nm and 50 L/h.m2.bar. The activated layer of nanofiltration was successfully fabricated via a modified colloidal sol-gel process using a mixture of Zr-inorganic salts and Ti-alkoxide and deposited by spin-coating. The resulting TiO2-doped ZrO2 (TDZ) membrane was sintered at 550 ℃ and characterized by XRD, SEM and Nitrogen sorption. The as-prepared membrane (TDZ/TiO2/Bentonite) exhibits high performances in terms of average pore diameter (2.5 nm) and water permeability (5 L/h.m2.bar). The membrane has a high efficiency for both dyes and heavy metal removal. The rejection of methyl orange and methylene blue are respectively 94.2 and 99.36%, while the rejection of Cd(NO3)2, Pb(NO3)2 and Cr(NO3)3 are 99.6, 99.2 and 99.4% respectively.