| With the development of living standard, more and more pharmaceutical and personal care products (PPCPs) are produced and used in our daily life. In municipal wastewater and natural waters, a considerable part of PPCPs are of negative charge, which are hydrophilic and low-molecular, so that it cannot be efficiently removed by coagulation/sedimentation or by activated carbon adsorption. The residual of PPCPs would cause ecological risk in aquatic environment after discharge. Magnetic anion ion exchange resin, which is focus on electronegative contaminant, are more and more applied in treatment of PPCPs. Until now there is few research about the mechanism of PPCPs adsorption onto magnetic ion exchange resin, especially the effect of pore structure of resins. In this thesis, different synthetic parameters were adjusted and series crylic-acid resins with different pore structure were synthesized. In order to discuss the effect of pore structure and mechanism of competing adsorption, kinetics, isotherm and regeneration performance of series resins in adsorption of typical negative-charge PPCPs (ibuprofen and clofibric acid) were investigated, together with the impact of temperature, pH, inorganic ion and co-existed organics. The main contents and conclusions of this research are listed as followed:(1) Glycidyl methacrylate (GMA) and divinylbenzene (DVB) were used as monomers, and γ-Fe2O3 was added into suspension polymerization. After optimization of synthetic parameters, series magnetic resins with different pore structure were synthesized. The results showed that resin with higher degree of crosslinking are of greater mechanical strength and faster settling rate, while water content and exchange capacity were lower. Synthesized with benign porogen (toluene), resin usually cannot meet the requirement of mechanical strength and settling rate. Synthesized with non-benign porogen (mixture with cyclohexanol and dodecanol), resin not only achieved great mechanical strength and settling rate, but also had controlled pore size distribution. The success rate of resin synthesis was satisfactory when using polyvinyl alcohol and sodium sulfate as dispersant, while it was unsatisfactory when using solsperse(?)24000 or sodium dodecyl benzene sulfonate. The more γ-Fe2O3 was used, the greater mechanical strength and faster settling rate the resin will have, while its water content and exchange capacity declined. After analysis of pore size distribution, three kinds of resins (ND-1, ND-2 and ND-3) were selected to conduct further adsorption experiments. The average pore size of these resins are 11.67,15.36 and 24.95 nm, respectively; their cumulative pore volume are 4.83,11.69 and 22.18 mm3 g-1, respectively.(2) By comparing adsorption and regeneration results of ibuprofen and clofibric acid onto series resins, the advantage of resin with larger pore structure (ND-3) was found. According channel internal diffusion equation, internal diffusion process and external diffusion process were the rate-limiting step. Freundlich model is more suitable to describe resin adsorption, which prove it a heterogeneous adsorption process with π-π, cation-π, hydrogen bond or other forces. Resin with larger pore structure had higher correlation coefficient, which showed more features of heterogeneous adsorption. Results showed that the number of adsorbed IBU (or CFA) was higher than that of released chloride ion, which indicated there existed other reaction besides ion exchange. Besides, resin with larger pore structure had greater regeneration performance, which was attributed to its less resistance force inside pore.(3) Resin adsorption was influenced by temperature, pH, inorganic ion and co-exist organics. Equilibrium absorption capacity raised with the rising of temperature, which indicated resin adsorption is an endothermic reaction. And resin with larger pore was less affected by temperature, which showed the characteristics of both chemical and physical adsorption. The optimum pH for IBU adsorption was 7 (pH=6 for CFA). Low pH would make it hard for IBU and CFA molecule to ionization, while high pH caused competing adsorption from OH-. And inorganic ion showed inhibiting effect to IBU and CFA adsorption. Co-exist organics would also cause inhibiting effect to resin adsorption. Influence by polyatomic acid is greater than monobasic acid at the same concentration because of its multiple functional groups. For mono-carboxylic acid, the influence increased with its hydrophobicity, which came from hydrophobic adsorption reaction. For mono-sulfonic acid, the influence increased with its hydrophilicity for its higher effective concentration in aqueous phase. Moreover, resin with large pore was less affected by pH, inorganic ion and co-existed organics. |
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