Preparation Of Toxic Anionic Surface Molecularly Imprinted Material And Studies On Its Molecule Recognition And Binding Character

With the development of China’s printing industry, dye wastewater has become oneof industrial waste water which is difficult to deal with. Most dyes are toxic refractoryorganic compounds. They possess strong chemical stability and they have carcinogenic,teratogenic and mutagenic effects. These toxic organic compounds seep intounderground aquifers by surface, which makes groundwater contaminated and leads to adirect impact on drinking water sources. Moreover, drinking water disinfection alsoproduces another kind of disinfection by-product which has carcinogenic and teratogeniceffects for human when it kills pathogenic microorganisms of water. Both of above havebeen a serious threat to human health and safety. Therefore, it is a major issue ofenvironmental management and protection that developing high-performance solidmaterial as solid-phase extraction agent to effectively adsorb and remove disinfectionbyproducts of drinking water and toxic anionic of dye wastewater.In this study, disinfection by-products trichloroacetic acid, acid dye reactivebrilliant red X-3B and acid red-14molecule surface-imprinted materials were preparedby using the novel surface-imprinting technique of “synchronously graft-polymerizingand imprinting”, in which the acryloyloxyethyl trimethy-lammonium chloride （DAC）was used as the functional monomer. The surface imprinted materials can selectivelyadsorb trichloroacetic acid of disinfection by-products and acid dye residue of waterefficiently. Obviously, the results of this research has potential application value in thegovernance, protection and monitoring of water environment.Firstly, micron-sized silica gel particles were surface-modified with γ-aminopropyltrimethoxysilane （AMPS） as silane coupling agent, and the modifiedparticles AMPS-SiO₂were obtained, on which amino groups were bond. In aqueoussolution, a redox initiating system was constructed by the amino groups on AMPS-SiO₂and ammonium persulphate in the solution, and the surface-initiated graft-polymerization of cationic monomer DAC was performed, obtaining the graftedparticles PDAC/SiO₂. The interaction between PDAC/SiO₂and Trichloroacetic acid（TCAA） was studied and FITR characterization for PDAC/SiO₂was carried out. On thisbasis, the cationic monomer DAC were first combined around the TCAA by selectingTCAA as template molecule through ion exchange action （electrostatic interaction）. Asurface-initiated graft-polymerization system was constructed by the amino groups onAMPS-SiO₂and ammonium persulphate in the solution, and free radicals were producedon the surfaces of silica gel particles. These free radicals initiated the crosslinkingcopolymerization of the monomer DAC and the crosslinker N,N-methylenebisacrylamide （MBA）, which synchronously carried out with the surface-imprinting ofTCAA. After removing the template ions, TCAA anion surface-imprinted materialIIP-PDAC/SiO₂was obtained. Both static and dynamic methods were adopted to studythe binding properties and ion recognition character of IIP-PDAC/SiO₂for TCAA ion.The experiment results show that static and dynamic binding capacity of IIP-PDAC/SiO₂for TCAA ion are0.93mmol/g and0.963mmol/g, respectively. With MCAA ion asreference material, its selectivity coefficients for TCAA ion is3.6. IIP-PDAC/SiO₂hasexcellent elution property and the desorption ratio of TCAA ion reaches to99.6％in21BV with a mixed solution of NaCl and NaOH as the eluent.Then, reactive brilliant red X-3B （RBR） surface-imprinted material MIP-PDAC/SiO₂was prepared by using the similar method. The Zeta potential of the PDAC/SiO₂was determined and the effect of the pH of adsorption solution on adsorption of graftedparticles PDAC/SiO₂was studied. The reasearch show that PDAC/SiO₂for RBR has thegreatest adsorption capacity when pH is7. Based on this, in neutral aqueous solution, thesurface-imprinting of reactive brilliant red molecule was conducted on the surface of gel particles by using DAC as the functional monomer and MBA as the crosslinking agent.After removing the template molecule, reactive brilliant red molecule surface-imprintedmaterial MIP-PDAC/SiO₂was obtained. With reactive yellow X-RG （RY） and reactivelight yellow X-6G （RLY） as reference materials, both static and dynamic methods wereadopted to study the binding properties and molecule recognition character ofMIP-PDAC/SiO₂for RBR. The experiment results show that static and dynamic bindingcapacity of MIP-PDAC/SiO₂for RBR are1.032mmol/g and1.058mmol/g, respectively.Relative to RY and RLY, the selectivity coefficients of MIP-PDAC/SiO₂for RBR are8.1and8.9, respectively. MIP-PDAC/SiO₂has excellent elution property and the desorptionratio of RBR molecule reaches to96.2％in20BV with a mixed solution of NaCl andNaOH as the eluent.Last, the surface-imprinting of acid Red-14（AR） molecule was conducted on thesurface of gel particles via “ion exchange” and “surface-initiated graft-polymerization”.After removing the template molecule, AR molecule surface-imprinted materialMIP-PDAC/SiO₂was obtained. The effect of imprinted reaction conditions on bindingproperties of MIP-PDAC/SiO₂was investigated. The results show that the imprintedmaterial for AR has the greatest combination capacity when the feed ratio of DAC withAR and MBA are4:1and8:1, respectively. With acid orange Ⅱ （AO） and acid lightyellow G （ALY） as reference material, static and dynamic binding capacity of imprintedmaterial for AR are1.147mmol/g and1.155mmol/g, respectively. Relative to AO andALY, the selectivity coefficients of MIP-PDAC/SiO₂for AR are5.3and6.5, respectively.MIP-PDAC/SiO₂has excellent elution property and the desorption ratio of AR moleculereach96.8％in20BV with a mixed solution of NaCl and NaOH as the eluent.