摘要：
Objective To compare the effectiveness of two kinds of defluorinating agents (bone char and modified clay) for removal of fluoride in drinking water,and to analyze their application feasibility in small towns.Methods Influencing factors on defluorinating efficiencies of the two kinds of defluorinating agents under the same conditions were studied,namely the effects of adsorption time,temperature,pH,common anions and cations,and solid-liquid ratio on defluorinating efficiencies were studied.The defluorinating efficiencies of the two kinds of defluorinating agents were validated by original groundwater in Jilin Province.The homemade bone char defluorinating agent and modified clay defluorinating agent were regenerated by NaOH and Al2(SO4)3,respectively,and their regeneration abilities were investigated.Results The adsorption data of the two kinds of defluorinating agents were fitted Langmuir model well,and the maximum adsorption capacities were 10.225 g/kg(bone char) and 0.587 g/kg(modified clay).The effect of temperature on defluorinating efficiencies was limited,with increasing temperature(10-35 °C),the adsorption capacity of bone char and modified clay for fluoride ranged from 1.568 g/kg to 1.598 g/kg and 0.423 g/kg to 0.470 g/kg,respectively.Fluoride could be easily removed under low pH conditions,with increasing of pH(4-10),the adsorption capacity of bone char and modified clay for fluoride decreased from 1.598 g/kg to 1.523 g/kg and 0.724 g/kg to 0.320 g/kg,respectively.The defluorinating efficiencies were improved by common cations(Ca2+) in groundwater,and the adsorption capacity of bone char and modified clay for fluoride increased to 1.713 g/kg and 0.485 g/kg,respectively.Whereas,the defluorinating efficiencies were inhibited by common anions(HCO3-,SO42-) at a certain degree,and the adsorption capacities of bone char and modified clay for fluoride were decreased to 1.158 g/kg(HCO3-) and 0.237 g/kg(SO42),respectively.Defluoridation bone char could be regenerated by soaking in NaOH,and modified clay by immersion in Al2(SO4)3.The adsorption capacities of the two defluorinating agents that had been regenerated for three times still reached 94.6％ and 97.3％ of their original capacities.Conclusions Both of the homemade bone char defluorinating agent and modified clay defluorinating agent have good defluorinating efficiencies and can be regenerated for many times,which are perfectly suitable for application in small towns since they are simple and can be easily applied.The homemade bone char defluorinating agent is suitable for family drinking water and the homemade modified clay defluorinating agent would be more suitable for centralized drinking water.%目的 对比两种除氟剂(骨炭、改性黏土)的除氟效果,分析两种除氟剂在小城镇地区饮水除氟应用的可行性.方法 对骨炭、改性黏土两种除氟剂在相同条件下进行除氟效果影响因素研究,观察吸附时间、温度、pH值、阴阳离子、固液比对除氟效果的影响.采用地下水源水对两种除氟剂的除氟效果进行验证.对骨炭和改性黏土除氟剂分别采用氢氧化钠(NaOH)和硫酸铝[Al2(SO4)3]进行再生实验,观察再生效果.结果 两种除氟剂对氟的吸附过程符合Langmuir吸附等温线,对氟理论最大吸附容量分别为10.225 g/kg(骨炭)和0.587g/kg(改性黏土).温度对两种除氟剂除氟效果影响不大,随温度的升高(10～ 35°C),骨炭对氟的吸附容量变化范围为1.568～ 1.598g/kg,改性黏土对氟的吸附容量变化范围为0.423～0.470g/kg.低pH条件下有利于两种除氟剂对氟的去除,随着pH值的升高(4～ 10),骨炭对氟的吸附容量由1.598g/kg下降至1.523g/kg,改性黏土对氟的吸附容量由0.724g/kg下降至0.320 g/kg.地下水中常见阳离子钙(Ca2+)对除氟效果起到一定的促进作用,随含量增加,骨炭对氟的吸附容量可升高至1.713 g/kg,改性黏土对氟的吸附容量可升高至0.485g/kg;阴离子碳酸氢根(HCO3-)和硫酸根(SO42-)随含量增加对除氟有不同程度的抑制作用,骨炭对氟的吸附容量可最低降至1.158 g/kg(HCO3-),改性黏土对氟的吸附容量可最低降至0.237 g/kg(SO2-).除氟后的骨炭可通过NaOH浸泡的方式再生,改性黏土可通过Al2(SO4)3浸泡的方式再生,3次再生后两种除氟剂的吸附效率仍可达原来的94.6％和97.3％.结论 骨炭除氟剂和改性黏土除氟剂均具有良好的除氟效果并可多次再生使用,简便易行,完全适合在小城镇地区应用.骨炭除氟剂适合家庭式除氟,改性黏土除氟剂适合集中式饮用水除氟.
