The Preparation And Characterization Of Inorganic Pillared Montmorillonite And Its Application In Phosphate Removal

With Zr polycations (Zr-Mon) and mixed Al/Zr polycations (Al,Zr-Mon) were fabricated bymodificating natural montnorillonite. The synthesized (Zr-Mon and Al,Zr-Mon) exhibit increasedBET surface area and higher micropore volume, as compared to natural montmorillonite. Thedifferences of the clay texture before and after pillaring were characterized by scanning electronmicrographs (SEM). Several important parameters, such as contact time, temperature, initial pHof solution and coexisting anions were investigated in detail to evaluate the phosphate adsorptionperformance of both Zr-Mon and Al,Zr-Mon. The maximum phosphate adsorption capacitieswere found to be14.5mg/g and18.5mg/g for Zr-Mon and Al,Zr-Mon, respectively. Thephosphate adsorption kinetics followed pseudo-second-order kinetic model. The experimentalequilibrium data of both Zr-Mon and Al,Zr-Mon were fitted better with the use of the Freundlich modelthan the Langmuir model, suggesting the heterogeneity of the adsorbent surface. The positive value ofHindicated that the adsorption of phosphate onto Zr-Mon and Al,Zr-Mon were endothermic,which was supported by the increasing adsorption of phosphate with temperature. Stability of Zrstudies also showed that the risk of Zr leakage during adsorption process was negligiblysmall.The pH values of all the phosphate–adsorbent system increased from about5.09to5.60forZr-Mon system, from about5.13to5.46for Al,Zr-Mon system, indicating a ligand exchangeprocess occurred during adsorption.