摘要
通过柱淋溶实验结合数值模拟,研究不同热解温度(500和800℃)制备的纳米铁复合生物炭(nFe/BC)自身迁移以及与砷(As)在污染土壤中的共迁移行为.结果表明,相较于原始生物炭(BC500和BC800),生物炭复合Fe后在As土壤中的迁移能力显著降低,分别减弱了约57.8%(nFe/BC500)和45.5%(nFe/BC800).这一结果归因于生物炭复合Fe后,颗粒表面Zeta电位变小(负电荷减少),减弱了nFe/BC与土壤颗粒之间的排斥势垒,导致nFe/BC的迁移能力较弱.并且随着热解温度升高,nFe/BC表面含氧官能团减少,颗粒表面负电荷减少,与土壤颗粒之间作用能减弱,颗粒迁移能力降低.两点动力学滞留模型较好地拟合了nFe/BC在污染土壤中的穿透曲线,且进一步说明了nFe/BC的迁移特征.此外,原始生物炭迁移过程中竞争土壤表面吸附位点,促进As迁移;而nFe/BC先抑制As在土壤中迁移,再促进其迁移.分析原因是由于nFe/BC表面的铁单质或Fe3O4与As反应并将其固定,但完全反应后会失去其原本的抑制作用,反而作为载体促进As在土壤中迁移,对地下水环境产生潜在危害.
Packed column experiments and numerical simulations were conducted to investigate the co-transport behavior of nanoscale iron supported on biochar(nFe/BC)pyrolyzed at 500°C and 800°C,respectively,with arsenic(As)in contaminated soil.The results showed that the mobility of nFe/BC(nFe/BC500 and nFe/BC800)in As-contaminated soil was obviously lower than that of pristine biochars(BC500 and BC800),decreasing by about 57.8%and 45.5%in As-contaminated soil,respectively.This is likely because zeta potentials of nFe/BC became less negative due to the adherence of positively charged Fe onto the BC.Therefore,electrostatic repulsion between nFe/BC and soil grain was weakened,resulting in a lower mobility of nFe/BC.Also the mobility of nFe/BC was reduced with an increase in pyrolysis temperature.This is likely because that the surface charge of nFe/BC produced at high temperature was less negative,due to the lower density of O-containing functional groups.Therefore,the total repulsive interaction energies between nFe/BC and soil grain were reduced.A two-site kinetic retention model was successfully employed to simulate the transport of nFe/BC in soils,further illustrating the co-transport characteristics of nFe/BC.Additionally,pristine BCs facilitated the transport of As due to the competition between BCs and As for the available sorption sites on the soil surface.However,nFe/BC first inhibited the transport of As,and then promoted it.The main reason could be because the iron substance or Fe3O4 on the surface of nFe/BC reacted with As,and then fixed it in soil.Once the reaction between nFe/BC and As was completed,nFe/BC lost its original inhibitory effect,and instead acted as a carrier to promote As transport in soil.This could cause potential risks of As to the groundwater environment.
作者
谢丽梅
韩欣妍
刘亦嘉
陈子阳
王禹
陈明
XIE Li-mei;HAN Xin-yan;LIU Yi-jia;CHEN Zi-yang;WANG Yu;CHEN Ming(School of Environmental Science and Engineering,Suzhou University of Science and Technology,Suzhou 215009,China)
出处
《中国环境科学》
北大核心
2025年第6期3199-3208,共10页
China Environmental Science
基金
国家自然科学基金资助项目(42007130,42407306)。
关键词
纳米铁复合生物炭
砷
污染土壤
共迁移
数值模拟
nanoscale iron supported on biochar
arsenic
contaminated soil
co-transport
numerical simulation
作者简介
陈明,讲师,chenming@usts.edu.cn;谢丽梅(1999-),女,江西赣州人,苏州科技大学硕士研究生,主要从事土壤污染物的迁移转化与归趋等环境化学行为方面研究.发表论文2篇.2211021023@post.usts.edu.cn.
