Experimental Study Of Phosphate Adsorption By The Modified Polyethersulfone Metal Affinity Membrane Loading With Cu(Ⅱ)

The polyethersulfone(PES) powders used as original materials were employed to prepare a metal affinity membrane bearing Cu(II), via techniques of chemical grafting and chelating adsorption. After the chemical grafting processes of chloride acetylation and amination reaction, the amino groups were anchored on the surface of PES-based membrane. The modified PES membrane after chemical grafting was prepared by a phase transfer process. Then, Cu(II) was adsorbed to the surface of the membrane; thus, the PES-based metal affinity membrane bearing Cu(II) was fabricated.In this research, the parameters for the preparation of PES-based metal affinity membrane were optimized. The pore size, water content, porosity and pure water flux of the membrane were measured by the filtration tests. The prepared membrane bearing Cu(II) was employed as an adsorbent for the removal of phosphate from aqueous solutions. The effects of p H, temperature, adsorption time, initial concentration of Cu(II) on the Cu(II) uptake of the metal affinity membrane were investigated.The influences of p H, temperature, adsorption time and initial phosphate concentration on the properties of the PES-based metal affinity membrane bearing Cu(II) towards phosphate were evaluated. The adsorption kinetics and thermodynamic properties of the metal affinity membrane towards phosphate were studied, considering the coexistence of Cl-, SO42-, Ca2+, Mg2+ ions in solutions. These four ions show the inhibitory effects on the phosphate adsorption. Adsorption experimental results show that the adsorption kinetics can be described by the secondary equation. The Langmiur model is of benefit for the description of the isotherm adsorption process. The analyzed results of D-R model show that the adsorption process of phosphate is a chemical reaction. Thermodynamic parameters are as follows: ΔG0<0, ΔH0>0, ΔS0>0, confirming that the phosphate adsorption is a spontaneous endothermic process. In the process of phosphate adsorption by the metal affinity membrane, the interference of coexisting ions on the phosphate adsorption is as follows: SO42->Mg2+>Ca2+>Cl-. The reused property of this metal affinity membrane is excellent, i.e., after 5 times of absorption/desorption processes, it still maintain the uptake of phosphate and the desorbed efficiency higher than 85%.