| Nickel, which is widely used in many fields, has caused a major pollution to the environment. The conventional methods of removal of nickel ions are ion exchange and electrochemical process, etc. However, these methods have same drawbacks, such as energy wasting and the need for additional reagents, etc. The modified ceramic membrane, ion-imprinted and dynamic membrane technique will be used to remove nickel ions from aqueous solution in this article.First of all, the inorganic ceramic membrane(CM) was modified to prepare modified ceramic membrane(CM-SiO2-A) to treat the wastewater containing nickel ions. Then the preparation parameters were optimized and the CM-SiO2-A was characterized by SEM, EDX, XRD, etc. Meanwhile, the water flux and rejection rate of Ni2+ of CM-SiO2-A were studied. The results are as follows. At first, SiO2 and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane(AAAPTS) have successfully deposited and grafted onto the surface of ceramic membrane. Then, the pore diameter of CM-SiO2-A is reduced to about 1.25 ?m, as a result of which the water flux of CM-SiO2-A is decreased by 84.79% compared with CM. Finally, the rejection rate of Ni2+ of CM-SiO2-A is much higher than that of ceramic membrane deposited with SiO2 when filtering 10 mg L-1 Ni2+ solution. With the increase of Ni2+ solution from 10 mg L-1 to 30 mg L-1, the rejection rate of Ni2+ of CM-Si O2-A will be gradually decreased.Secondly, an ion-imprinted silica gel sorbent(IIP) and non-imprinted silica gel(NIP) were synthesized by using Ni2+ as template, AAAPTS as functional monomer, and epichlorohydrin as cross-linking agent. Then IIP and NIP were characterized by FT-IR and TGA and the preparation parameters of IIP were optimized. At the same time, the adsorption ability and reusable property were studied. The results are as follows. For one thing, the optimized preparation parameters are firstly combining Ni2+ with AAAPTS, and the optimized reaction time and temperature are 20 h and 80? respectively. For another, the IIP shows a higher adsorption capacity for Ni2+(14.93 mg g-1) than that of NIP(5.80 mg g-1) and the IIP shows a higher adsorption capacity when pH is about 6.0. The adsorption equilibrium time of IIP to Ni2+ is about 30 min. The adsorption affinity of IIP is about six times larger than that of NIP. Besides, after 10 times adsorption-elution of IIP, its adsorption capacity is decreased by 9.14%. The adsorption capacity of IIP is still maintained a higher level, its reusable property is superiority.Finally, IIP/NIP dynamic membranes which were based on ceramic membrane were prepared and the preparation parameters were optimized. Meanwhile, the water flux change and the rejection ability for Ni2+ were studied in the process of treatment of wastewater containing Ni2+ by CM, IIP and NIP dynamic membranes. The results are as follows. First, the optimized transmembrane pressure, concentrations of IIP suspension, cross-flow velocity and coating time are 0.10 MPa, 1.0 g L-1, 1.0 m s-1 and 30 min respectively. Second, during the treatment process of wastewater containing Ni2+ by CM, IIP and NIP dynamic membranes, the flux decay ratio of CM is about 86.46%, while that of IIP and NIP dynamic membranes are about 60%. The IIP and NIP dynamic membranes perform much higher steady water flux than CM. Last, with the increase of the permeate volume, the Ni2+ concentration in the total permeate(Cp) of CM remains relatively stable at about 13.26 mg L-1, while the Cp of IIP and NIP dynamic membranes show a tendency that increase from 0/1.2 mg L-1 to 13.26 mg L-1/13.26 mg L-1, and the NIP dynamic membrane reach to 13.26 mg L-1 faster than IIP dynamic membrane. All the IIP and NIP dynamic membranes show ability to reject Ni2+, but the rejection ability of IIP dynamic membrane is much better than NIP dynamic membrane. |
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