新型生物质炭吸附剂对地下水中氟的去除作用

Removal of Fluoride from Groundwater Using New Biochar Adsorbents

摘要:

本文选用花生壳、栗子壳、核桃壳、橘子皮等生物质原料在不同温度下制备得生物质炭。通过对不同条件制备的生物质炭的除氟效果的比较，结果发现，以花生壳为原料在650 ℃热解所得生物质炭除氟效果最好。并对花生壳生物质炭进行了表面结构表征。在此基础上，研究了吸附时间、生物质炭投加量、pH值、氟离子初始浓度等因素对花生壳生物质炭除氟效果的影响。结果表明，最佳炭投加量为1 g/100 mL，最佳pH为5.5~6，吸附60 min左右达吸附平衡，此时去除率达到82.25%，吸附量容量达0.82 mg/g；随着氟离子初始浓度的增加生物质炭对氟的去除率成下降趋势，吸附容量随含氟量浓度的增加成上升趋势。花生壳生物质炭对氟离子的吸附等温线模拟结果表明，Freundlich型和Langmuir型均较为符合。该花生壳生物质炭对地下水氟的最大吸附容量为1.11 mg/g。该研究为农业废弃物资源化利用以及地下水氟污染治理提供了一条新的思路。

Abstract:

In this study, new biochar adsorbents were first prepared from the peanut shell, chestnut shell, walnut shell, and orange peel under different pyrolysis temperatures, and then the fluoride removal effects of these new biochar adsorbents were compared. The results showed that the biochar derived from the peanut shell with pyrolysis at 650 ℃ provided the best defluoridation effect. The surface structure of the peanut shell-derived biochar was then characterized and the effects of factors such as the adsorption equilibrium time, dosage of biochar, pH value, and initial concentration of fluoride ions on the defluoridation of the peanut shell-derived biochar were investigated. The results indicated that the optimum dosage of the biochar was 1 g/100 mL, the optimum pH was approximately 5.5~6, the adsorption equilibrium was attained after approximately 60 min when the removal rate was 82.25%, and that the adsorption capacity was 0.82 mg/g. With an increasing initial concentration of fluoride, the fluoride removal rate showed a declining trend. However, the adsorption capacity showed an increasing trend with increasing fluoride concentration. The simulated results of the adsorption isotherm of fluoride on the peanut shell-derived biochar indicated that the experimental data fitted well with both the Langmuir and Freundlich models. The maximum absorption capacity of this peanut shell-derived biochar on fluoride in groundwater was 1.11 mg/g. This study therefore provides new prospects in the recycling use of waste agricultural biomass and defluoridation of groundwater.