咖啡渣生物质炭的制备及其对矿井水中氟离子的去除研究

近年来矿井水中氟离子含量超标问题尤为突出，不仅影响矿井水处理后的回用水质，而且危害人体健康。为了同时实现固废资源化利用和矿井水中氟离子的去除，本文以废弃咖啡渣为原料，采用化学活化法制备了一种新型矿井水中氟离子的吸附剂——咖啡渣生物质炭(CRB)，通过单因素法优化了制备过程中的活化剂种类、活化温度和活化浓度；通过动力学和等温吸附实验对比分析了优化前后CRB对氟离子的吸附效能；通过表面物化特性表征探究了优化后的CRB(O-CRB)对氟离子的吸附机理。结果表明:当采用氯化锌为活化剂、浓度为4 mol/L、活化温度为400 ℃时，获得了吸附性能最优的O-CRB，其对氟离子的最大吸附量为2.20 mg/g，是活化前CRB的1.30倍；与优化前相比，O-CRB的中孔孔容量与比表面积明显增加，含氧官能基团(-COOH)含量和表面Zeta电位升高，且吸附氟离子后O-CRB表面的氯离子含量明显降低(3.27 % 至0.61 %)、氟离子含量明显增加(0.76 % 至10.34 %)，从而可推测出O-CRB吸附氟离子的主要机理为静电吸附和离子交换。

Preparation of coffee residual based biochar and its removal of fluoride ions from mine water

In recent years, the problem of excessive fluoride in mine water is particularly prominent, which not only affects the water quality of reuse after treatment, but also endangers human health.Therefore, the study herein developed a novel adsorbent for fluoride -coffee residual based biochar(CRB)by applying the waste coffee residue as raw material and chemical activation, to realize the purpose of solid waste resource utilization and fluoride removal from mine water at the same time.The authors firstly optimized the preparation protocols of CRB through single factor, including the type of activator, activator concentration and activation temperature; then evaluated the adsorption efficiency of fluoride for CRB before and after optimization by kinetic and isothermal adsorption experiments; finally investigated the adsorption mechanism of fluoride for CRB after optimization(O-CRB)by surface physicochemical characterization.The results showed that the more favorable CRB for fluoride was prepared at the ZnCl₂ concentration of 4 mol/L and the activation temperature of 400 ℃.The maximum adsorption capacity of O-CRB for fluoride was 2.20 mg/g, which was 1.30 times higher than that of CRB before activation.In addition, compared with CRB, O-CRB exhibited higher amount of mesopore volume and specific surface area, as well as more oxygen containing functional groups(-COOH)and surface Zeta potential.Thus, the amount of chloride on the O-CRB surface decreased obviously(3.27 % to 0.61 %)after fluoride adsorption, whereas the amount of fluoride increased significantly(0.76 % to 10.34 %).This suggested that the adsorption of fluoride for O-CRB was mainly attributed to the electrostatic adsorption and ion exchange.