摘要
低分子量有机酸常对矿物的表面反应(吸附/沉淀)产生影响,从而影响矿物的溶解、矿化等过程,进而影响环境地球化学进程中元素的迁移稳定性。苹果酸作为一种广泛存在于自然界中的有机酸,是植物通过代谢过程分泌的副产品。通过批量平衡法开展了苹果酸对方解石-氟的吸附/沉淀反应的影响研究,旨在深入理解有机酸在地球化学过程中的作用。结果表明:①初始pH值为7.7条件下,对于低浓度氟(≤5 mg·L^(-1)),随着苹果酸浓度的升高,其对氟去除的抑制作用呈增强趋势;对于中、高浓度氟(25或60 mg·L^(-1)),氟去除主导机制为CaF 2沉淀反应,苹果酸的抑制作用对其影响不大,但其表面吸附反应导致pH值升高和钙浓度下降。②初始pH值为8.3条件下,对于低浓度氟(≤20 mg·L^(-1)),苹果酸对氟去除仍有抑制作用;苹果酸与Ca 2+的络合反应促使pH值和钙浓度上升;对于中浓度氟(60 mg·L^(-1)),氟去除主导机制为CaF 2沉淀反应,20 mg·L^(-1)苹果酸已对其产生抑制作用,随着苹果酸浓度继续升高,pH值先降后升,钙浓度持续上升,彰显了苹果酸络合反应的效应;对于高浓度氟(100 mg·L^(-1)),100 mg·L^(-1)苹果酸能极大抑制CaF 2沉淀反应,对应的pH值未超过无苹果酸时,对应的钙浓度仍低于其空白背景值,暗示了CaF 2沉淀反应的主导性。③初始pH值为8.7条件下,对于低浓度氟(≤5 mg·L^(-1)),苹果酸对氟去除的抑制作用有所减弱,但其络合反应产生的效应十分显著,导致pH值和钙浓度上升;对于高浓度氟(240 mg·L^(-1)),氟去除主导机制为CaF 2沉淀反应,该反应随着苹果酸浓度的升高而受到抑制,对应的钙浓度不断上升彰显苹果酸络合反应的效应,而pH值的下降也表明了CaF 2沉淀反应的主导性。本研究深入探讨了氟元素在方解石矿物界面上的吸附、迁移和转化过程,为理解氟的迁移稳定性提供了新的视角和理论基础,同时对富含有机酸环境中方解石矿物的稳定性评估具有重要意义,也为氟在其他矿物上的迁移转化研究提供借鉴。
Low molecular weight organic acids often influence the surface reactions(adsorption/precipitation)of minerals,which in turn affect the stability of elemental transport in environmental geochemical processes.The effect of malic acid on calcite-fluorine adsorption/precipitation reactions was investigated.The results show that①at the initial pH of 7.7 and lower F concentrations(≤5 mg·L^(-1)),as the concentration of malic acid increases,its surface adsorption capacity becomes stronger and exhibits the inhibitory effects on F removal;at the F concentrations of 25 or 60 mg·L^(-1),the dominant mechanism of F removal is CaF 2 precipitation;the intervention of malic acid shows little inhibition of the CaF 2 precipitation reaction;the stronger adsorption reaction of malic acid results in an increase of pH and a decrease in Ca concentration.②At the initial pH of 8.3 and low F concentration(≤20 mg·L^(-1)),malic acid still inhibits F removal through its competitive adsorption;as the concentration of malic acid increases,its effect of complexation with Ca 2+results in a constant increase in pH and Ca concentration;at the medium F concentration of 60 mg·L^(-1),the dominant mechanism of F removal has been shifted to CaF 2 precipitation;20 mg·L^(-1)malic acid has inhibited it,and as the malic acid continues to increase,the pH value decreases and then increases,and the Ca concentration continues to increase,highlighting the effect of the malic acid complexation reaction;At high F concentration of 100 mg·L^(-1),100 mg·L^(-1)malic acid greatly inhibits the CaF 2 precipitation reaction,corresponding to a pH value that do not exceed that of the malic acid-free condition;the corresponding Ca concentration is still lower than its blank background value,implying the dominance of the CaF 2 precipitation reaction.③At the initial pH of 8.7,malic acid has a weak inhibition to F removal at low F concentration(≤5 mg·L^(-1));however,as the concentration of malic acid increases,the effect of its complexation reaction becomes much clearer,which results in a significant increase in both pH and Ca concentration;at high F concentration of 240 mg·L^(-1),the dominant mechanism for F removal is the CaF 2 precipitation reaction,which is inhibited with increasing malic acid concentration,with increasing Ca concentration showing the effect of malic acid complexation,and decreasing pH values indicating the dominance of the CaF 2 precipitation reaction.This study is important for the stability assessment of calcite minerals in organic acid-rich environments,and also provides a reference for the study of fluorine transport transformation on other minerals.
作者
李振炫
冯添禧
吴超越
张大鹏
王逸
朱珠
桂尉竣
向育斌
David DECROOCQ
LI Zhen-xuan;FENG Tian-xi;WU Chao-yue;ZHANG Da-peng;WANG Yi;ZHU Zhu;GUI Wei-jun;XIANG Yu-bin;David DECROOCQ(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,Jiangsu,China;Joint International Research Laboratory of Climate and Environment Change(ILCEC),Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China;Nanjing Institute of Environmental Sciences,Ministry of Ecology and Environment,Nanjing 210042,Jiangsu,China;School of Chemistry and Materials,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China;Département des Sciences de la Terre,Universitéde Lille,Lille 59650,Nord,France)
出处
《地球科学与环境学报》
CAS
北大核心
2024年第4期499-512,共14页
Journal of Earth Sciences and Environment
基金
国家自然科学基金项目(41303096,41201515)
江苏省环保项目(2022016)
教育部留学回国人员科研启动基金项目(S131304001)
江苏省自然科学基金项目(BK20210655)。
关键词
方解石
氟
苹果酸
溶液化学
吸附
溶解
络合
沉淀
calcite
fluorine
malic acid
solution chemistry
adsorption
dissolution
complex
precipitation
