Method Of Monitoring Phenolics By Diffusive Gradients In Thin Film Technique In Aqueous Solutions

Diffusive gradients in thin film (DGT) technique is a kind of in situ, continuous passive sampling technique, and has been widely applied to sampling pollutants in water, soil and sediments in the past 20 years. The quantitative basis of DGT techqinque is Fick's first law of diffusion, its sampling process includes that the analyte passes through the diffusion layer with a certain diffusion coefficient, and is bound in the binding layer. The main components in the DGT device are diffusion layer and binding layer. The diffusion layer plays roles of separating the binding layer from the bulk solution and controlling the diffusion of the analyte, it is the quantative basis of the sampling technique. The binding layer acts as a sink of the diffused analyte, making sure the concentration of the analyte between the interface of the diffusion layer and the binding layer is negligible, it is a necessary condition of DGT device. In this paper, several new materials were prepared by molecular imprinting technique, and the adsorption behaviors of phenol or 4-chlorophenol (4-CP) were studied, and the materials were used in the DGT technique as the binding layer; meanwhile, nylon membrane which has relative inert interaction with phenol and 4-CP, is used in DGT technique as diffusion layer. The investigation of the diffusion coefficients of phenol and 4-chlorophenol through nylon membrane were measured by diffusion cell method. Sampling methods of DGT for the free form of phenol and 4-chlorophenol were developed and preliminary application was studied. The main work is as follows.In Chapter 1, passive sampling techniques of organic matters, DGT technique, and analysis methods of phenolics were introduced. The configuration of DGT device, working principle and applicaiton were described. The purpose and innovation of this paper are presented.In Chaper 2, a series of imprinted and non imprinted polymer were prepraed. Infrared spestoscopy (IR), scanning electron microscope (SEM) and thermal analysis were used to characterize the structure, surface morphology and thermal satbility of the imprinted materials. The adsorption behaviors of phenol and/or 4-CP on the imprinted or non-imprinted materials were studied and the adsorption mechanism were analyzed.In the 2nd part, polymers were prepared by precipitation polymerization using 4-CP or phenol as template, acrylamide or methacrylic acid as monomer, ethylene glyco dimethyl acrylate (EDMA) or N,N'-methlene bis acrylamide as crosslinking agent, and azo-iso-butyroitrile (AIBN) as initiator. The UV-Vis spectra is used to study the interaction between the monomer and the template.In the 3rd part, phenol surface imprinted silica materials were prepared using phenol as template, silane coupling agent, such as ?-aminopropyl triethoxy silane, mercaptopropyltriethoxysiane and chlrorpropyl trimethoxy silane for the modification of silica surface, then adding epichlorohydrin or EDMA as crosslinker.In the 4th part,4-CP imprinted composite membrane was prepared with 4-CP as template, polyvinylidene fluoride membrane as supporting base in the presence of acrylamide or methacrylic acid as monomer, EDMA as crosslinker.In the 5th part,4-CP and phenol molecularly imprinted gel were prpared by immobilizing its corresponding molecularly imprinted polymer prepared by MAA as monomer in polyacrylamide gel using AM as the monomer, N, N'-methylene bisacrylamide as crosslinking agent. A detailed study of the gel properties including water absorption under different pH values and salinity conditions was carried out.In Chapter 3, the simple equation of DGT technique was deduced, and the negligible conditions were discussed, a matching relation equation between the diffuison layer and the binding layer was put forward.In the 6th part, from the view of dynamics, the DGT equation was deduced on the basis of Fick's first law of diffusion, a balance was established between the accumulated mass of the analyte on the binding phase and the diffused mass through a ceratain volume of the diffusion phase. When the binding rate constant, k, of the analyte on the binding phase was much greater than the ratio of the diffusion coefficient, D, of the analyte through the diffusion layrer over square of its thickness, ?g2, which was k>>D/?g2, the concentration of the analyte at the the interficial diffusion phase and the binding phase was negligible.In the 7th part, sampling free form of phenol by DGT technique was established, using nylon membrane as the diffusion phase, the imprinted gel as the bindning phase. Linear relationship was obtained with time to accumulated mass of phenol on the binding phase. The effects of pH, ionic strength and dissolved organic carbon (DOC) of the bulk solution spiked with 1.0 mg L-1 of phenol on the accuracy of sampling phenol by DGT technique were studied. And 0.54 mg L-1 of phenol was obtained by DGT in the industrial wastewater spiked with 1.0 mg L-1 of phenol.In the 8th part, sampling free form of 4-CP by DGT technique was estabilshed, using nylon membrane as the diffusion phase, the imprinted gel as the bindning phase. Linear relationship was obtained with time to accumulated mass of 4-CP on the binding phase. The effects of pH, ionic strength and DOC of the bulk solution spiked with 1.0 mg L-1 of 4-CP on the accuracy of sampling 4-CP by DGT technique were studied. And 1.8 mg L-1 of 4-CP was obtained by DGT in the industrial wastewater, and occupied 39.1% of the total concentiation of 4-CP, which might be complexed by the DOC, or part of 4-CP was sorbed on the ferric hydroxide colloid.