Fe_3O_4-TiO_2·nH_2O·Al吸附剂去除水中氟离子

Removal of fluoride ions from wastewaters by sorbent Fe_3O_4-TiO_2·nH_2O·Al

以实验室制备的Fe_3O_4-TiO_2·n H_2O·Al吸附剂处理模拟和实际含氟废水,探讨了吸附剂用量、体系p H、吸附温度和吸附时间等因素对F-吸附效果的影响。结果表明：在初始F-浓度16.1 mg/L,起始p H 8.0,吸附剂投加量5 g/L,室温（约25℃）下吸附15 min时,模拟和实际废水的出水F-均可达到〈10 mg/L的《电镀污染物排放标准》和《污水综合排放标准》,且吸附剂的容量都在1.6 mg/g左右,显示Fe_3O_4-TiO_2·n H_2O·Al具有一定的实际应用价值。含氟水溶液初始p H对Fe_3O_4-TiO_2·n H_2O·Al吸附F-性能影响较大。在p H介于3.0~5.0时,吸附容量较大,过高或过低都会导致吸附容量降低。Fe_3O_4-TiO_2·n H_2O·Al吸附F-的过程为放热反应,升温不利于F-的吸附。该吸附剂吸附F-的过程为化学吸附,符合准二级动力学模型,等温线拟合接近Freundlich吸附等温线。

An adsorbent of Fe_3O_4-TiO_2·n H_2O·Al synthesized in the lab was applied for water defluoridation with simulated and practical fluoride wastewater. The impacts of the experiment parameters,such as adsorbent dosage,p H value,adsorption temperature,and adsorption time on the defluoridation process were discussed. The results showed that： under p H 8. 0,an initial fluoride concentration of 16. 1 mg / L,an adsorbent of5 g / L,and 15 min of adsorption at room temperature（ about 25 ℃）,the adsorption capacities of adsorbent were around 1. 6 mg / g for the simulated and practical fluoride wastewater. The effluent fluorine（ F-） concentration was lower than 10 mg / L,which can meet the integrated wastewater discharge standards and discharge standard of pollutants for electroplating. The results suggested that the adsorbent has a potential in fluoride wastewater treatment. The initial p H value had a great effect on defluoridation. The adsorption capacity could reach its highest value when the p H was between 3. 0 and 5. 0,but it decreased if the p H value was outside this range. The adsorption of F-by the adsorbent was an exothermic process. An elevated temperature was not beneficial to the adsorption. The defluoridation of the adsorbent was a chemical adsorption process,and it was consistent with the pseudo-second-order model and Freundlich isotherm.