开放系统下方解石除氟机制的主导性界定研究  

Study on Delimiting the Dominance of the Removal Mechanisms of Fluoride by Calcite in Open System

作　　者：李振炫[1] 朱珠[1] 华辰 张帅[1] 桂尉竣 黄利东[2] 于飞 潘德勤 LI Zhenxuan;ZHU Zhu;HUA Chen;ZHANG Shuai;GUI Weijun;HUANG Lidong;YU Fei;PAN Deqin(Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology/Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control,Nanjing University of Information Science&Technology,Nanjing 210044,China;School of Applied Meteorology,Nanjing University of Information Science&Technology,Nanjing 210044,China;Nanjing Leyi Environmental Technology Co.,Ltd.,Nanjing 211135,China;Yangzhou Songquan Environmental Protection Technology Co.,Ltd.,Yangzhou 225600,China)

机构地区：[1]南京信息工程大学江苏省大气环境与装备技术协同创新中心/江苏省大气环境监测与污染控制高技术重点实验室,江苏南京210044 [2]南京信息工程大学应用气象学院,江苏南京210044 [3]南京乐翼环境科技有限公司,江苏南京211135 [4]扬州松泉环保科技有限公司,江苏扬州225600

出　　处：《环境科学与技术》2023年第5期1-9,共9页Environmental Science & Technology

基　　金：国家自然科学基金(41303096,41201515);南京信息工程大学校级大学生创新创业训练计划项目:方解石与氟的反应规律研究(2022415);教育部留学回国科研启动基金(S131304001);国家水体污染控制与治理科技重大专项(2015ZX07204-002)。

摘　　要：方解石除氟机制主要涉及表面吸附和沉淀2个方面,宏观界定以上2种机制在除氟过程中的主导性,对氟去除后的稳定性评估有重要意义。文章采用批量平衡法,在不同pH、时间、氟浓度等条件下,对开放体系中方解石除氟机制的主导性进行界定研究。结果表明:(1)在pH8.3条件下,初始氟浓度≤40 mg/L,表面吸附为氟去除的主导机制,该反应3 h内便基本完成;初始氟浓度≥60 mg/L,CaF_(2)沉淀反应作为除氟的主导机制,该主导性在3 h后已体现出来,24 h后反应仍未达到平衡;Langmuir和Freundlich模型拟合结果与上述结果一致。(2)在pH7.7条件下,初始氟浓度≤10 mg/L,表面吸附作为除氟的主导机制,反应在3 h内也基本完成;当初始氟浓度≥25mg/L时,氟去除的主导机制为CaF_(2)沉淀反应,对应Ca浓度和pH值的变化趋势印证了该沉淀反应的主导性,3 h后反应基本完成。(3)在pH7.3条件下,初始氟浓度≤5 mg/L时,氟去除的主导机制为表面吸附,该反应在3 h内也基本完成;当初始氟浓度≥10 mg/L,氟去除的主导机制已转变为沉淀反应,反应在3 h内也基本完成,与pH7.7条件时类似。对应的Ca浓度和pH值并未产生重大变化,与pH7.7时情况不同。(4)氟的去除率结果指出,不管反应3 h还是24 h后,氟的去除率曲线总出现拐点,暗示了氟去除的主导机制由表面吸附向沉淀转变,与上述氟去除动力学结果一致。通过对2种除氟机制主导性的宏观界定,为今后氟的迁移稳定性研究提供借鉴。The mechanism of fluoride removal by calcite often entails two aspects:surface adsorption and precipitation.It is of importance to find a critical range of conditions for macroscopically delimiting the dominance of these two mechanisms,for estimation of F stability after its removal.The present study aimed at macroscopically delimiting the dominance of these two removal mechanisms through batch method in open-system,by adjusting pH,reaction time and F concentration.The results indicated that at pH 8.3,the removal of fluoride was mainly by surface adsorption at initial F concentration<40 mg/L,where the reaction was completed within 3 h.At initial F concentration≥60 mg/L,the CaF_(2) precipitation was the main removal mechanism and its dominance occurred after 3 h reaction,where the reaction equilibrium wasn't achieved after 24 h.The fitting results of Langmuir and Freundlich models were consistent with the above results.At pH 7.7,surface adsorption was the key removal mechanism at initial F concentration<10 mg/L,where the reaction was accomplished within 3 h.At initial F concentration≥25 mg/L,the CaF_(2) precipitation was the main removal mechanism.The corresponding results of Ca and pH change suggested the dominance of CaF_(2) precipitation which was almost completed after 3 h.At pH 7.3,the main removal mechanism was surface adsorption at initial F conceniration<5 mg/L,where the reaction was accomplished within 3 h.At initial F concentration≥10 mg/L,the main removal mechanism shifted to the CaF_(2) precipitation and this reaction was completed within 3 h,similar to that at pH 7.7.The corresponding results of Ca and pH didn't show significant change as compared to blank value,which is different from that at pH 7.7.The occurrence of change point on the F removal percentage curve suggested that the main removal mechanism had shifted from surface adsorption to precipitation for whether 3 h or 24 h reaction,which is consistent with the above kinetic results of fluoride removal.Through macroscopically delimiting t

关 键 词：氟 方解石 吸附 沉淀 

分 类 号：X701[环境科学与工程—环境工程]