Preparation And Performance Study Of Magnetic Anion Exchange Resin

Drinking water sources contain large amounts of inorganic compounds and dissolved organic carbon（DOC）.They will generate disinfection by-products that endanger human health after conventional process treatment and disinfection in water treatment plants.Ion-exchange technique is widely used in industrial water treatment because of its high selectivity and water treatment efficiency.Traditional ion exchange resin is generally a fixed bed process with high equipment costs and low water treatment volume;whereas the magnetic anion exchange resin（MIEX）developed by Orica Company in Australia has a fast mass transfer rate and can be rapidly separated from water using a fluidized bed process.The MIEX has the advantages of low equipment and operating costs,simplicity of operation,and so on,and occupies a portion of the domestic market.However,because there are no substitute products in China at the moment,it has become a key product that holds back our ion-exchange technology development.Based on the background above,two magnetic materials,namely Fe₂O₃ and Fe₃O₄,are used in this paper to synthesize resin by suspension polymerization.The influence of preparation conditions on the structure and properties of magnetic anion exchange resin are also studied to obtain magnetic resin products with excellent performance.The magnetic resin synthesized in this paper can successfully replace imported products（MIEX）and showed even better removal efficiency after optimization.The study came to the following conclusions:1.The effects of magnetic material type,degree of crosslinking,magnetic material proportion,oil-water ratio,degree of functionalization,and porogen type on resin properties were investigated.According to the research findings,Fe₃O₄/resin is a paramagnetic material that settles quickly in a magnetic field and is difficult to be separated from water without an external magnetic field.The particle size of Fe₂O₃/resin is about 200μm～300μm,which is a ferromagnetic material with good sedimentation performance without an external magnetic field.Increasing the degree of crosslinking and functionalization improves the sedimentation performance and exchange performance of the resin respectively.The rise of the proportion of magnetic materials within a certain range improves the magnetic properties and the exchange performance of the resin.A higher oil-water ratio causes resin agglomeration,and also influences the particle size distribution of the resin.According to BET analysis and characterization,the porogen is beneficial to the formation of the pore structure in the resin,and adding a mixed porogen is more conducive to increasing the specific surface area of the resin than adding a single porogen,thereby improving the resin properties.2.The adsorption kinetics and thermodynamic properties of the optimized resin,the effect of p H on the resin’s adsorption performance as well as the regeneration conditions of the resin were studied.The results show that the adsorption process of tannic acid on the resin surface fits the pseudo-second-order kinetic model well,and the adsorption isotherm conforms to the Langmuir model,which means the adsorption behavior on the Fe₂O₃/resin surface of tannic acid is monolayer adsorption.3.The optimized resin formulation was developed by optimizing the resin preparation conditions.Compared with MIEX resin,the product shows good adsorption performance and sedimentation performance,and the overall performance is comparable to MIEX.The resin product with excellent performance can be produced consistently when using the optimized formula in pilot testing.When compared to MIEX,the preparation cost is lowered by 20,000 RMB/m³,resulting in a significant price advantage and the ability to replace imported items.