The main anions in papermaking wastewater are sulfate and chloride. In this paper, a strongly basic gel-type anion exchange resin (201×7) loaded with 20 ∼ 200 nm hydrated ferric oxide was prepared by dispersion impregnation with ethanol. The modified resin enhances the ability to remove sulfate by complexation of ligands to cause sulfate to form outer and inner sphere complexes on hydrated ferric oxide. The modified resin was dependent on acidic conditions, and the maximum exchange capacity for sulfate was enhanced by 14.2 % under the optimal pH, exchange time, and ion concentration conditions. Competitive exchange experiments showed that the removal effect of the modified resin on chloride was almost unchanged under different chloride, sulfate ratios, and the degree of improvement of the removal effect on sulfate decreased from 9.5 ∼ 5.5 % with the increase of chloride ratio. The removal of sulfate by the modified resin was consistent with the proposed secondary kinetics and Langmuir adsorption model. In addition, the modified resin maintained 88 % reuse after four desorption-adsorption cycles and achieved a regeneration rate of 93.1 % after was eluted with HCl and reloaded with hydrated ferric oxide. The expected removal effect was well achieved when the resin was applied to the actual wastewater treatment. The above results indicate that the hydrated ferric oxide modification can improve the ability of the 201×7 resin to remove sulfate from water, and is a promising method for removing anions from papermaking wastewater.
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