Synthesis And Application Of Novel Magnetic Polyacrylic Anion Exchange Resin

The widely exist of dissolved organic pollutants in biological effluents from waste water and natural water systems have negative effects on the safety of drinking water and ecology.It is difficult to remove by the traditional methods of water treatment because of its high solubility and biological refractory.Anion exchange is considered to be an effective method due to most of dissolved organic pollutants are negative charged.However,the conventional anion exchange resins cannot meet the demand in water treatment due to the limited flux by the fixed-bed volume and the resistance.MIEX resin,a magnetic ion exchange resin developed by Orica,Australia,can avoid this problem because it can be used in completely-mixed contactor due to their fast kinetics and easy separation,which can increase the flux and reduce the cost.MIEX have been increasingly used in the removal of dissolved organic matters all over the word in recent years,and the MIEX technology was crowned as the best model of water treatment in the recent 50 years.However,there are some shortages of MIEX,including 1)the high cost,2)the low exchange capacity,the exchange capacity are lower than conventional resins and 3)the poor mechanical strength,MIEX beads are susceptible to mechanical break-up,causing the lost problem.At present,magnetic resins used in china totally depend on import.Based on the above-mentioned background,this thesis focused on the preparation of new magnetic anion exchange resin and the study on their advance treatment of dissolved organic matter,which exits in biological effluent from industrial discharge and municipal sewage,also in drinking water in china.The main results and conclusions are as follows.1)The ingredient for preparation of the new magnetic anion exchange resin,comprising of?-methacryloxypropyltrimethoxysilane(MPS)-coated Fe3O4,methyl acrylate,divinylbenzene was established through optimizing the modifying agent,monomer and crosslinking agent.The processes for the preparation are co-polymerization,ammonolysis,alkylation,and the conditions of each process were optimized suitable for industrial production,respectively.The prepared magnetic anion exchange resin(NDMP-1)is around 100?m in diameter,and incorporated homogenously with Fe3O4 particles with a good performance of magnetic separation.The anion exchange capacity and the mechanical strength of NDMP-1 are both superior to that of MIEX resin.2)The effects of physicochemical properties of anion exchange resin(AER)on adsorption of humic acid(HA)and regeneration behavior were investigated,and the most important factor for HA adsorption is found to be the chemical structure of resin matrix,which influence the adsorption and regeneration much greater than the pore structure and resin size.Since the different adsorption mechanism caused by the different hydrophilicity of resin matrix,polyacrylic AERs have advantages over polystyrenic AERs on both adsorption capacity and adsorption kinetics.Porous resin is limited easily by intraparticle diffusion,leading to a slower kinetics.Thus,the resin size has small effect on the kinetics due to the limited process of intraparticle diffusion.The effects of pore structure and resin size on adsorption capacity are relevant to the initial concentration.Under low initial concentration,AER with small size is superior to AER with large size,while the pore structure has little effect on adsorption.Under high initial concentration,porous resins have their advantages on adsorption capacity,while resin size has little effect.The investigation on regeneration performance revealed that the importance follows the order:chemical structure of matrix,pore structure and resin size.The desorption efficiency for polyacrylic AER is obviously larger than that for polystyrenic AER.The larger pore diameter,or large resin size take disadvantages on desorption.The increased amount of Fe3O4 could significantly enlarged the water content and pore volume of NDMP resin,which are benefit for HA adsorption and desorption.3)Due to the hydrophilic matrix and small size,NDMP-1 exhibited an excellent performance for adsorption kinetics and regeneration by comparing with conventional resins and MIEX.For HA adsorption,NDMP has the adsorption capacity of 570 mg/g,which is 4-5 times as large as the conventional AER D201 and is obviously larger than MIEX(307 mg/g).NDMP is easier to regenerate with stable performance of regeneration cycle for adsorption.And for sulfonic DOM,the adsorption capacities of both reactive dye(RD)with large MW(RWO)and RD with small MW(OG)on NDMP are twice larger as that on MIEX.Especially for the RD with large MW,the good performance of regeneration for NDMP was observed.4)The effects of HA properties on their adsorption onto NDMP resins were explored.The HA fractions with different molecular weight(MW)were separated by membrane technique.The characterization of HA fractions indicated that the aromaticity increased as the MW increasing,while there are no relationships between MW and electronegativity of HA fractions.The adsorption results revealed that electronegativity is the determinant for the adsorption behavior,while the effects of MW are not observed.Because of the most electronegativity of HA fraction with MW ranged from 2500 to 10000 Da,their adsorption amount on NDMP is the largest.However,there are little interactions between NDMP and HA fraction with MW smaller than 1000 Da due to the smallest electronegativity of this HA fraction.It is noted that the HA fraction of 1000-2500 Da is most difficult to desorption,which is likely due to the complex mechanism of adsorption.5)The treatment of surface water,biological effluent of municipal sewage and biological effluent from printing and dyeing wastewater by NDMP-1 adsorption were all investigated.And the online-measurement of water quality in industrial treatment was recorded.The removal efficiency of NDMP-1 was larger than that of MIEX and activated carbon(F400D);industrial treatment reveals that NDMP-1 technique steadily improve water quality with a obvious removal of dissolved organic matter,chroma and other contaminants(total nitrogen,total phosphorus),and with a relatively low cost.