ABSTRACT

The fluoride with high-concentration in industrial wastewater will cause great harm to the environment and calcium-modified biochar is an effective adsorbent for the removal of fluoride. Biochar composites were prepared from mature and dried dead leaves and eggshell to remove fluoride from the aqueous solution. The effects of raw material ratio, pH, contact time, adsorbent dosage, temperature, initial concentration of fluoride, and the coexisting ions on the removal efficiency of fluoride were explored. The biochar composites before and after fluoride removal were characterized by the SEM, FTIR, XRD, and XPS, which showed CaF₂ precipitation was formed during the adsorption. The kinetics and isotherm study showed that chemical adsorption was the primary step for the fluoride adsorption of the biochar composites. The removal efficiency of fluoride can reach 98.53% when the amount of adsorbent was 1.6 g/L and the fluoride concentration was 500 mg/L. The BET-specific surface area of platanus acerifoli leaves biochar was 410.14 m²/g, which was suitable for the adsorption carrier. The adsorption capacity of the biochar composite materials was as high as 308 mg/g. The platanus acerifoli leaves-eggshell biochar composite with large pore size and high removal efficiency may be used as an efficient and low-cost adsorbent for treating high-concentration fluoride-containing wastewater.

摘要

工业废水中高浓度的氟化物会对环境造成极大的危害，钙改性生物炭是一种有效的除氟吸附剂。生物炭复合材料由成熟和干燥的枯叶和蛋壳制备，以去除水溶液中的氟化物。考察了原料配比、pH值、接触时间、吸附剂用量、温度、氟化物初始浓度、共存离子对氟化物去除效率的影响。通过 SEM、FTIR、XRD 和 XPS 对除氟前后的生物炭复合材料进行表征，结果表明 CaF ₂吸附过程中形成沉淀。动力学和等温线研究表明，化学吸附是生物炭复合材料吸附氟化物的主要步骤。当吸附剂用量为1.6 g/L，氟化物浓度为500 mg/L时，氟化物去除率可达98.53%。悬铃木叶生物炭的BET比表面积为410.14 m ² /g，适合作为吸附载体。生物炭复合材料的吸附容量高达308 mg/g。悬铃木叶-蛋壳生物炭复合材料具有大孔径和高去除效率，可作为一种高效、低成本的吸附剂处理高浓度含氟废水。