摘要
进入环境的纳米材料对共存化学污染物的环境行为有重要影响.本文选择3种多壁碳纳米管,分别为石墨化多壁碳纳米管(G-MWCNT)、羟基化多壁碳纳米管(O-MWCNT)和氨基化多壁碳纳米管(N-MWCNT),通过批次实验研究其对林丹的吸附行为和催化转化作用.林丹在3种多壁碳纳米管上的吸附动力学符合准二级动力学模型(R2>0.997),吸附速率常数(k2)分别为0.73(G-MWCNT)、0.60(N-MWCNT)和0.28(O-MWCNT)g·mg^(-1)·h^(-1).林丹在3种多壁碳纳米管上吸附的等温线符合Freundlich经验模型(R2>0.979),不同p H条件下,吸附系数(KF)分别为28.0—30.0(G-MWCNT)、21.3—24.6(N-MWCNT)和9.1—10.2(O-MWCNT)mg1-n·Ln·g^(-1).平衡浓度为8.5 mg·L^(-1),在不同p H条件下林丹在3种多壁碳纳米管上的分配常数(Kd)分别为12.7—14.4(G-MWCNT)、8.7—9.8(N-MWCNT)和3.9—4.2(O-MWCNT)L·g^(-1).林丹是非离子型有机化合物,疏水作用在吸附过程中起主导作用,表面引入亲水性强的氨基和羟基后,N-MWCNT和O-MWCNT的吸附作用相比具有疏水性表面的G-MWCNT明显减弱.溶液的p H值(5.0—9.0)对同种多壁碳纳米管的吸附作用影响不显著.均相溶液中,林丹发生β-消去反应的准一级动力学表观速率常数kobs(0.017—10.2 d^(-1))随溶液p H值(7.0—12.0)升高而增大.N-MWCNT对林丹发生β-消去反应起催化作用,这种催化作用随p H值(7.0—9.0)升高而增强.当N-MWCNT存在时,林丹的去除率分别增加了7.5%(p H=7.0)、29.3%(p H=8.0)和30.1%(p H=9.0).在均相溶液和N-MWCNT体系中都检测到γ^(-1),3,4,5,6-五氯环己烯、1,2,4-三氯苯和1,2,3-三氯苯转化产物.
Nanomaterials in the environment have great impacts on the environmental processes of co-existing chemistry contaminats. In this paper,three types of multi-walled carbon nanotubes（ MWCNTs） including graphitized MWCNT（ G-MWCNT）,hydroxylated MWCNT（ O-MWCNT）and aminated MWCNT（ N-MWCNT） were studied for their adsorption and catalytic transformation of lindane using batch experiments. Adsorption kinetics of lindane on the three MWCNTs followed pseudo-second-order kinetic model（ R^2〉 0. 997）,and the adsorption rate constants（ k2） of G-,Nand O-MWCNT were 0. 73,0. 60 and 0. 28 g·mg^-1·h^-1,respectively. Freundlich model could welldescribe the adsorption isotherms of lindane on the three MWCNTs（ R^2〉 0. 979）. The Freundlich affinity coefficients（ KF） of G-,N- and O-MWCNT were 28. 0—30. 0,21. 3—24. 6 and 9. 1—10. 2 mg1- n·Ln·g^-1,respectively,under different pH. The distribution coefficients（ Kd） of lindane on G-,N- and O-MWCNT were 12. 7—14. 4,8. 7—9. 8 and 3. 9—4. 2 L·g^-1,respectively,at lindane equilibrium concentration of 8. 5 mg·L^-1under different pH. Lindane was a typical nonionic organic chemical,and hydrophobic interactions dominantly controlled its adsorption on MWCNTs.The adsorption of lindane by N- and O-MWCNTs with hydrophilic moieties was weaker than the graphitized MWCNT with higher surface hydrophobicity. Changing the pH value of solution from 5. 0to 9. 0 didn＇ t affect the adsorption of lindane significantly. The pseudo-first-order rate constant（ kobs） of β-elimination in homogeneous aqueous solution increased from 0. 017 to 10. 2 d^（-1）with increasing pH in the range of 7. 0—12. 0. The N-MWCNT had catalytic effects on the β-elimination of lindane at moderate to slight alkaline pH values（ 7. 0—9. 0）,and catalysis became faster with increasing pH value from 7. 0 to 9. 0. The removal rates of lindane were increased by 7. 5%,29.3% and 30. 1% in the presence of N-MWCNT at pH value of 7. 0,8. 0 and 9. 0,respectively.Several transform
出处
《环境化学》
CAS
CSCD
北大核心
2016年第4期629-638,共10页
Environmental Chemistry
基金
教育部创新团队发展计划(IRT13024)资助~~
关键词
碳纳米管
林丹
吸附
催化转化
carbon nanotubes
lindane
adsorption
catalytic transformation
