Study On Preparation Of Ion Imprinted Polymers And Their Application In Selective Removal Of Pb(â…¡) And Recycle Li(â… ) From Waste Water

The environmental pollution of heavy metal ions has already become serious problems that influence the survival environment of human being and development of social economy. Among the water pollution, the heavy metal Pb(II) ions pollution and waste of Li(I) resource problem are prominent issues at present. However, the traditional processing of metal ions recovery exist the deficiencies and limitations,their inherent drawbacks including stringent requirements of equipments, hard operation conditions and great energy consumption make it urgent to look for alternative strategies. Therefore,in this paper, we developed several new specificity nano adsorbent materials by using ion imprinting technology, applied them to remove harmful heavy metal Pb(II) from waste water, and recycle Li(I) resource from aqueous solution. The details are summarized as follows:1. A magnetic ion-imprinted polymer(Fe3O4@Si O2-IIP) functionalized with –SH groups for the selective removal of Pb(II) ions from aqueous samples was synthesized by surface imprinting technique combined with a sol-gel process using3-mercaptopropyl trimethoxysilane as monomer, tetraethyl orthosilicate as cross-linking agent, and Pb(II) ion as template. The Fe3O4@Si O2-IIP was characterized by infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrometry. Fe3O4@Si O2-IIP showed higher capacity and selectivity than that of Fe3O4@Si O2-NIP. The experimental data fits well with the Langmuir adsorption isotherm. The maximum Pb(II)-sorption capacity calculated from Langmuir isotherm is 32.58 and 16.50 mg/g for Fe3O4@Si O2-IIP and Fe3O4@Si O2-NIP, respectively. Kinetics studies show that the adsorption process obeys a pseudo-second-order kinetic model with high correlation coef?cient(R2=0.9982). The separation factor of Fe3O4@Si O2-IIP for Pb(II)/Cu(II),Pb(II)/Zn(II), and Pb(II)/Co(II) are 50.54, 52.14, and 37.39, respectively. In addition,the spent Fe3O4@Si O2-IIP can be refreshed by simple washing with aqueous HCl solution, and there is no significant decrease in adsorption capacity after a test of up to five cycles, demonstrating that the Fe3O4@Si O2-IIP is stable and reusable.2. The recovery of lithium from spent lithium batteries is a growing problem and newtechnologies are needed to recover the lithium. Currently, there is a lack of highly selective adsorption/ ion exchange materials, which can be used to recover lithium.We have developed a novel crown ether which is comprised of a lithium ion imprinted polymer(IIP) and is coated with magnetic particles(Li-IIP).The Li-IIP has been prepared by a surface imprinting technique using our newly synthesized 2-(allyloxy)methyl-12-crown-4 as functional monomer. The Li-IIP was characterized by Fourier infrared spectroscopy(FT-IR), scanning electron microscopy(SEM), and X-ray diffraction(XRD). The optimum p H for adsorption is p H = 6. The material shows fast binding kinetics for lithium ion(complete equilibrium is reach within 10 min) and the saturation adsorption capacity is 0.586 mmol/g. Homogeneous binding sites are confirmed by the Langmuir isotherm. The Li-IIP has excellent selectivity for Li(I)because the selectivity separation factor of Li(I) with respect to Na(I), K(I), Cu(II) and Zn(II) are 50.88, 42.38, 22.5, and 22.2, respectively. The adsorption capacity of sorbent remained above 92% after five cycles. Fixed-bed column adsorption experiment indicate that the effective treatment volume was 140 bed volumes(BV)for the first run for a breakthrough of 10% of the inlet concentration for an inlet concentration of 0.5 mmol/L,and 110 BV was treated for the second run under identical conditions. We also conducted an experiment with a real wastewater and validated great potential of Fe3O4@Si O2-IIP in advanced wastewater treatment.Accordingly, we have developed a new method for wastewater treatment that meets Li emission standards and recovery of Li creates economic value.3. We had prepared Li ion imprinted polymers(IIPs) with hydrophilic polymer brushes on the surface using precipitation polymerization technology and Reversible Addition-Fragmentation chain Transfer(RAFT) polymerization. The G-IIP were confirmed by IR analysis, contact angle analysis and SEM. The absorption performance of G-IIP was investigated. It was showed in the results that it possessed good anti-interference, compatibility in aqueous solution and regenerability owing to the hydrophilic brush.