水合氧化铁负载量对丙烯酸树脂基复合吸附剂的结构及除磷影响

为优化丙烯酸树脂基水合氧化铁(Hydrated ferric oxide，HFO)复合吸附剂的负载量，调节FeCl₃浓度制备出5种复合吸附剂(HFO负载量分别为5.3wt%、8.6wt%、12.1wt%、14.9wt%和18.5wt%，以Fe质量分数计)，分析其结构性能，并考察D213-HFO复合吸附剂对磷的吸附等温线、吸附动力学、pH和共存离子影响及洗脱效果。结果表明，复合吸附剂负载HFO颗粒为纳米无定型HFO，在直径方向呈U型分布。此外，随HFO负载量增加，磷吸附容量先升高后下降，负载量为14.9wt%的复合吸附剂吸附容量最大(19.04 mg·g?1)。复合吸附剂吸附磷在240 min达到平衡，更符合准一级动力学模型(R2>0.99)。磷吸附最佳pH为6~8，当SO₄2?≥600 mg·L?1树脂对磷无吸附效果，而负载HFO吸附磷不受影响。在连续4个吸附-洗脱周期内，5wt%的NaOH和5wt%的NaCl溶液对磷的洗脱率均接近100%。实验表明，复合吸附剂的吸附容量随HFO负载量增加先升高后下降，而结构性能、吸附平衡时间、pH适应范围、共存离子影响及洗脱效果无显著差异。 

Effect of hydrated ferric oxide loadings on structure and phosphate adsorption of acrylic polymer-supported composite adsorbents

In order to optimize the hydrated ferric oxide (HFO) loadings of acrylic resin-based HFO composite adsorbents, five composite adsorbents were prepared by regulating FeCl₃ concentration, and the HFO loadings were 5.3wt%, 8.6wt%, 12.1wt%, 14.9wt% and 18.5wt% (mass fraction in Fe), respectively. The structure properties of composite adsorbents were analyzed. Furthermore, the adsorption performance of composite adsorbents in removing phosphate were investigated, including adsorption isotherms, adsorption kinetics, effect of pH and coexisting anion, and elution effect. The results show that HFO nanoparticles dispersed into composite adsorbents are amorphous in nature, and the radial distribution of HFO obeys U-type distribution. Moreover, the phosphate adsorption capacity increases with the HFO loadings and then decreases, and the adsorption capacity of the composite adsorbent with HFO loading of 14.9wt% is the maximum (19.04 mg·g?1). The contact time of 240 min is long enough for composite adsorbents to achieve adsorption equilibrium, and the adsorption kinetic curves of the composite adsorbents are fitted well with pseudo-first order kinetic model (R2>0.99). The optimal pH for phosphate adsorption is 6~8. Furthermore, there is no phosphate adsorption by resin when the concentration of SO₄2? is equal or greater than 600 mg·L?1, while it does not pose any noticeable effect on phosphate adsorption by the loaded HFO nanoparticles. The regeneration efficiencies approach 100% by a binary 5wt% NaOH and 5wt% NaCl solution during 4 continuous adsorption-regeneration cycles. The experiments show that the phosphate adsorption capacity of the composite adsorbents increases with the HFO loadings and then decreases, while there is no significant difference in structure property, adsorption equilibrium time, pH range, effect of coexisting anion, and elution effect.