硫酸铁改性活性氧化铝除氟性能及机理探究

采用浸渍法制备质量分数为1.0%、2.5%的硫酸铁溶液改性活性氧化铝（1.0% Fe₂（SO₄）₃-MGAA、2.5% Fe₂（SO₄）₃-MGAA），根据吸附等温实验和吸附动力学实验研究其对氟的吸附性能，从BET表征、零质子电荷点（pH_zpc）和pH缓冲强度等角度探讨吸附剂除氟机理。实验结果表明：活性氧化铝GAA、1.0% Fe₂（SO₄）₃-MGAA、2.5% Fe₂（SO₄）₃-MGAA 3种吸附剂除氟的吸附等温线均更好地符合Langmuir吸附，最大吸附量分别为8.78、14.08、16.78 mg/g，对20 mg/L高氟水去除率分别为34.5%、54.5%、66.5%；3种吸附剂对水中氟的吸附动力学符合准二级吸附速率方程；改性活性氧化铝表面存在的SO₄^2-和OH^-与F^-发生离子交换作用，SOFe²⁺与F^-产生配位作用，并存在一定的静电作用。改性后活性氧化铝pH缓冲强度均显著增强，数据分析发现pH缓冲强度与吸附性能呈正相关，因此可以从pH缓冲强度的角度初步预测改性效果。

Defluorination performance of activated alumina modified by ferric sulfate

Modified granular activated aluminas (MGAA) (1.0% Fe₂(SO₄)₃-MGAA and 2.5% Fe₂(SO₄)₃-MGAA) have been prepared by impregnation of granular activated alumina (GAA) with ferric sulfate solution having a mass fraction of 1.0% or 2.5%. The performance of the resulting materials in the adsorption of fluoride ions was studied by adsorption isothermal experiments and the adsorption kinetics experiments. The mechanism of fluoride removal is discussed from the perspectives of BET characterization, zero point charge point (pH_zpc) and pH buffer measurements. The results showed that the adsorption isotherms of GAA, 1.0% Fe₂(SO₄)₃-MGAA and 2.5% Fe₂(SO₄)₃-MGAA fitted the Langmuir isotherm equation, with the maximum adsorption capacities and removal ratios being 8.78, 14.08, and 16.78 mg/g and 34.5%, 54.5% and 66.5% respectively. The adsorption kinetics fitted a pseudo-second order kinetic equation. The SO₄^2- and OH^- ions present on the surface of the MGAA samples could be replaced by F^-. The SOFe²⁺ moieties present on the surface of MGAA could complex with F^-, and a significant electrostatic effect was observed. The pH buffering was significantly improved after modification, and the results showed a positive relationship between the pH buffering and the adsorption, indicating that the effects of modification can be understood from the viewpoint of pH buffering.