The Preparation Of Zr/Ti-MMT And Its Adsorption For Nitrobenzene

In this study,Zr/Ti-MMT composite was prepared using sodium-montmorillonite?Na-MMT?as matrix clay and hydrolysates of zirconium oxychloride?ZrOCl₂·8H2O?and titanium tetrachloride as precursors.Then,the physical and chemical properties of Zr/Ti-MMT was characterized by XRD,FT-IR,SEM,etc.Finally,the adsorption performance of the pillared material for nitrobenzene was investigated,and the thermodynamics and kinetics of the adsorption process were also analyzed.The XRD results showed that the interplanar spacing increased from 1.25 nm of Na-MMT to 3.29 nm of Zr/Ti-MMT,and thus a good pillaring effect was obtained.FT-IR showed that covalent bonds may also be formed besides ion exchange in Zr/Ti-MMT layers.The results of SEM and pore structure analysis indicated that the pillared Zr/Ti-MMT has a compact structure whose specific surface area increased significatly compared with Na-MMT.Also,the pores distribution was more uniform,and the average pore size became smaller which changed from macropores of Na-MMT to mesopores or micropores of Zr/Ti-MMT.Thus,the surface activity of Na-MMT enhanced after pillaring which might show a good adsorption properties.Zeta potential results showed that the Zeta potential of the surface of Na-MMT was negative,and Zr/Ti-MMT after pillaring was positively charged.The results of adsorption of Zr/Ti-MMT for nitrobenzene showed that the max removal rate of 52.42%and adsorption capacity of 83.08%could be obtained under the conditions of pH 2,adsorbent dosage 0.15 g,temperature 50°C and adsorption time 180 min.The XRD and FT-IR analyses for the Zr/Ti-MMT after adsorbing nitrobenzene indicated that the nitrobenzene has been adsorbed into the framework of Zr/Ti-MMT,and the adsorption process was physical adsorption.Langmuir,Freundlich and Dubinin-Radushkasevich isotherms were all suitable for describing the adsorption process,and the adsorption was easy to carried out.Adsorption of nitrobenzene onto Zr/Ti-MMT materials was a spontaneous and endothermic process and the entropy was positive.A first-order kinetic equation was developed for the process,and the Weber-Morris pore diffusion model showed that the adsorption of nitrobenzene by Zr/Ti-MMT was controlled by membrane diffusion.