-
滴滴涕(DDT)是一类具有很强迁移性和生物富集性的持久性有机污染物(POPs)[1],广泛分布于各个国家和地区,甚至通过食物链和食物网富集到人体内,因此早已被列入各国优先控制污染物的名单。
机械化学球磨法通过剪切、磨擦、冲击、挤压等机械力作用,降低反应活化能,从而轻易地诱发化学反应[2-3],相比于传统的焚烧和非焚烧处置技术,其具有操作简单、适用范围广、二次污染少等诸多优点[4]。如今,机械化学球磨法能够实现POPs的高效脱氯,且大部分球磨产物可直接填埋,但高效球磨药剂中存在的少量金属单质仍未得到充分利用。为此,不少学者展开研究。例如,有学者利用机械化学球磨PVC后的产物制氢[5-6];也有学者利用Fe-Ni-SiO2混合药剂球磨降解五氯硝基苯(PCNB)的球磨产物对水相中的4-氯酚实现催化脱氯[7];此外,Cagnetta等[8]利用La2O3药剂球磨处理全氟化合物(PFCs),并利用球磨产物制备发光材料;同时提出利用Bi2O3和La2O3混合药剂球磨溴化持久性有机污染物,以此制备具有催化和电性能的化合物(如铋或镧溴氧化物)[9-10],从而探索出机械化学球磨法处理溴化持久性有机污染物“从废物到材料”的新方法[11-12]。
Cagnetta等[13]发现,行星球磨仪降解污染物的工艺参数中物料比(m球磨药剂:m污染物)非常高,本团队前期研究[14—15]同样发现,Fe-Zn药剂降解DDTs所用的物料比也很高,大约为10∶1到50∶1(m药剂∶m滴滴涕)。过量的药剂易造成浪费和二次污染,为此本研究拟对铁锌双金属球磨产物开展资源化利用,机械化学球磨降解高浓度DDTs污染土壤后的球磨产物可对水相中四氯化碳(CCl4)的有效去除。
1994年,Gillham等[16]发现零价铁粉可还原降解水相中氯代烃;近年来,零价铁降解水相中的氯代烃的研究已发展至纳米双金属领域[17]。此外,Tseng等[18]发现使用活性炭和零价铁的复合材料能够更加高效地去除水相中三氯乙烯。因此,本研究以CCl4作为重质非水相液体(DNAPL)代表成分,选择Fe-Zn双金属球磨处理高浓度DDTs污染土壤后的球磨产物作为修复材料,发现球磨产物中剩余的铁粉以及球磨过程产生的石墨和不定型碳可以成功去除水相中的CCl4。
目前,国内的机械化学球磨技术仍处于实验室阶段,而国外已经实现商用。例如,德国Tribochem公司于1996年在挪威利用机械化学法处理了多氯联苯(PCBs)污染土壤;于1998年在德国处理了PCBs变压器油;新西兰EDL公司更是在近年来研发了机械化学脱卤(MCD)工艺技术[19],成功在多国修复了多个POPs高浓度污染场地,处理效率达到15 t·h−1,修复效果达到新西兰相关用地标准[20]。因此,当我国的机械化学球磨技术完全投入到规模化应用后,球磨产物的安全处置和资源化利用必定是值得考虑的问题。
本文主要研究了球磨产物对水相中CCl4的降解与吸附,以此探索了机械化学球磨产物再利用的途径,为处理机械化学技术商业化应用后产生的大量残渣提供了理论基础和研究方向。
Fe-Zn双金属球磨法处置污染土壤后的球磨产物去除水中四氯化碳
Removal of carbon tetrachloride in water by ball milling products after disposal of contaminated soil with Fe-Zn bimetal ball milling
-
摘要: 机械化学球磨是一种高效处理POPs污染土壤的非焚烧处置方式,具有操作简易性和广泛适用性等独特优势。当机械化学球磨法投入到实际污染场地的土壤修复工程,产生的大量球磨产物如何处置是值得研究的问题。根据现有文献和本团队之前的研究发现,添加的球磨药剂(如铁、锌和氧化钙等)总是过量的。由于零价铁去除水相中氯代烃的研究较为成熟,因此本研究拟利用球磨产物中剩余的零价铁去除水中CCl4,一方面发现球磨产物中的剩余零价铁能对CCl4逐级脱氯至二氯甲烷;另一方面对零价铁降解CCl4的中间产物分析,发现CCl4降解产物的总量并不守恒,存在吸附现象。因此,本研究以球磨高浓度DDTs污染土壤和添加SiO2的高浓度污染土壤的球磨产物作为对照,考察铁锌双金属球磨产物对水中CCl4及其降解产物的吸附情况,研究发现铁锌双金属在机械化学球磨过程中反应较为激烈,从而产生了更多的含氧官能团能(主要为羟基)与水相中强极性的氯仿形成微弱氢键,发生吸附。Abstract: Mechanochemical ball milling is an efficient non-incineration disposal method with unique advantages such as easy operation and wide applicability. When the mechanochemical ball milling is put into the actual contaminated site, how to dispose of the ball milling products will be a problem worthy of study. According to the existing literature and previous research, the added ball milling agents (such as iron, zinc, calcium oxide, etc.) are always in excess. Due to the large amount of research on the removal of chlorinated hydrocarbons in aqueous phase by zero valent iron (ZVI), this experiment mainly used the remaining ZVI in the ball milling product to remove CCl4 in aqueous phase. On one hand, it was found that the residual ZVI in ball milling products can dechlorinate CCl4 to dichloromethane step by step; on the other hand, intermediate product of CCl4 was analyzed, and it was found that the total amount of degradation products of CCl4 was not conserved and there was adsorption. Therefore, in this study, the contaminated soil without reagent and contaminated soil with added SiO2 were used as controls to investigate the adsorption of Fe-Zn bimetal ball milling products on CCl4 and its by-products in water. At the same time, it was found that the Fe-Zn bimetal reaction was more intense during the mechanochemical ball milling, and the degradation of DDTs in contaminated soil was more thorough. As a result, more oxygen functionality (hydroxyl) was generated and weak hydrogen bonds were formed with strong polar chloroform in the aqueous phase, and adsorption occured.
-
表 1 DDT污染土壤中各衍生物的浓度
Table 1. The concentration of derivative in DDT contaminated soil
单体
Monomerp, p’-DDE o, p’-DDE o, p’-DDD p, p’-DDD o, p’-DDT p, p’-DDT 合计
Total含量/(mg·kg−1) 1451.04 1224.42 205.71 0 3913.47 782.62 7577.27 表 2 3种球磨产物的比表面积及孔隙度
Table 2. Specific surface area and porosity of the three ball milling products
指标Index 土壤 Soil Fe+Zn+Soil SiO2+Soil as, BET/(m2·g−1) 23.70 10.74 35.28 Vp /(cm3·g−1) 0.04 0.02 0.04 Mean pore diameter /nm 8.12 8.93 8.67 -
[1] 栾晓琳, 乔田峰, 吕敏, 等. 近百年来大辽河口潮间带中滴滴涕(DDTs)的沉积记录及其对人类活动的响应 [J]. 环境化学, 2020, 39(1): 119-127. doi: 10.7524/j.issn.0254-6108.2019043001 LUAN X L, QIAO T F, LV M, et al. Sediment records of DDTs in intertidal sediment core of Daliao River Estuary and their respones to anthropogenic activities in the past century [J]. Environmental Chemistry, 2020, 39(1): 119-127(in Chinese). doi: 10.7524/j.issn.0254-6108.2019043001
[2] 李冷, 曾宪滨. 粉碎机械力化学的进展及其在材料开发中的应用 [J]. 武汉工业大学学报, 1993, 15(1): 23-26. LI L, ZENG X B. Progress of mechanochemistry in comminution and its application in material development [J]. Journal of Wuhan University of Technology, 1993, 15(1): 23-26(in Chinese).
[3] 杨南如. 机械力化学过程及效应(Ⅰ)——机械力化学效应 [J]. 建筑材料学报, 2000, 3(1): 26-33. YANG N R. Mechanochemical process and effect (Ⅰ) - mechanochemical effect [J]. Journal of Buliding and Materials, 2000, 3(1): 26-33(in Chinese).
[4] 陈志良, 陆胜勇, 毛琼晶, 等. 水平式球磨机用于POPs机械化学处置的能量传递 [J]. 环境化学, 2016, 35(10): 2134-2145. doi: 10.7524/j.issn.0254-6108.2016.10.2016031603 CHEN Z L, LU S Y, MAO Q J, et al. Energy transfer in mechanochemical treatment of POPs in a horizontal ball mill [J]. Environmental Chemistry, 2016, 35(10): 2134-2145(in Chinese). doi: 10.7524/j.issn.0254-6108.2016.10.2016031603
[5] TONGAMP W, ZHANG Q, SAITO F. Mechanochemical decomposition of PVC by using La2O3 as additive [J]. Journal of Hazardous Materials, 2006, 137(2): 1226-1230. doi: 10.1016/j.jhazmat.2006.04.013 [6] TONGAMP W, ZHANG Q, SHOKO M, et al. Generation of hydrogen from polyvinyl chloride by milling and heating with CaO and Ni(OH)2 [J]. Journal of Hazardous Materials, 2009, 167(1): 1002-1006. [7] ZHANG T, HUANG J, ZHANG W, et al. Coupling the dechlorination of aqueous 4-CP with the mechanochemical destruction of solid PCNB using Fe–Ni–SiO2 [J]. Journal of Hazardous Materials, 2013, 250-251: 175-180. doi: 10.1016/j.jhazmat.2013.01.072 [8] CAGNETTA G, ZHANG Q, HUANG J, et al. Mechanochemical destruction of perfluorinated pollutants and mechanosynthesis of lanthanum oxyfluoride: A Waste-to-Materials process [J]. Chemical Engineering Journal, 2017, 316: 1078-1090. doi: 10.1016/j.cej.2017.02.050 [9] HUANG S T, JIANG Y R, CHOU S Y, et al. Synthesis, characterization, photocatalytic activity of visible-light-responsive photocatalysts BiOxCly/BiOmBrn by controlled hydrothermal method [J]. Journal of Molecular Catalysis a-Chemical, 2014, 391: 105-120. doi: 10.1016/j.molcata.2014.04.020 [10] YAN D, LEI B, CHEN B, et al. Synthesis of high-quality lanthanide oxybromides nanocrystals with single-source precursor for promising applications in cancer cells imaging [J]. Applied Materials Today, 2015, 1(1): 20-26. doi: 10.1016/j.apmt.2015.06.001 [11] CAGNETTA G, LIU H, ZHANG K, et al. Mechanochemical conversion of brominated POPs into useful oxybromides: a greener approach [J]. Scientific Reports, 2016, 6: 28394. doi: 10.1038/srep28394 [12] ZHANG K, HUANG J, WANG H, et al. Mechanochemical destruction of decabromodiphenyl ether into visible light photocatalyst BiOBr [J]. Rsc Advances, 2014, 4(28): 14719-14724. doi: 10.1039/C3RA47738J [13] CAGNETTA G, ROBERTSON J, HUANG J, et al. Mechanochemical destruction of halogenated organic pollutants: A critical review [J]. Journal of Hazardous Materials, 2016, 313: 85-102. doi: 10.1016/j.jhazmat.2016.03.076 [14] 隋红, 李海波, 宋静, 等. 高浓度DDTs污染土壤机械化学球磨试剂筛选 [J]. 环境科学研究, 2015, 28(8): 1227-1233. SUI H, LI H B, SONG J, et al. Selection of milling reagents for mechanochemical degradation of high concentrations of DDTs in contaminated soil [J]. Research of Environmental Sciences, 2015, 28(8): 1227-1233(in Chinese).
[15] 张冬格, 隋红, 宋静, 等. CaO机械化学法去除土壤中DDTs的工艺参数优化 [J]. 环境科学研究, 2016, 29(9): 1336-1343. ZHANG D G, SUI H, SONG J, et al. Optimization of the operational parameters for mechanochemical degradation of DDTs in containated soil with calcium oxide [J]. Research of Environmental Sciences, 2016, 29(9): 1336-1343(in Chinese).
[16] GILLHAM R W, MAJOR L, WADLEY S L, et al. Advances in the application of zero-valent iron for the treatment of groundwater containing VOCs [J]. IAHS Publication(International Association of Hydrological Sciences), 1998, 250: 475-481. [17] O’CARROLL D, SLEEP B, KROL M, et al. Nanoscale zero valent iron and bimetallic particles for contaminated site remediation [J]. Advances in Water Resources, 2013, 51: 104-122. doi: 10.1016/j.advwatres.2012.02.005 [18] TSENG H H, SU J G, LIANG C. Synthesis of granular activated carbon/zero valent iron composites for simultaneous adsorption/dechlorination of trichloroethylene [J]. Journal of hazardous materials, 2011, 192(2): 500-506. doi: 10.1016/j.jhazmat.2011.05.047 [19] 毛琼晶, 陆胜勇, 卫樱蕾, 等. 水平球磨机械化学法处置多氯联苯污染土壤的试验 [J]. 环境化学, 2016, 35(4): 607-614. doi: 10.7524/j.issn.0254-6108.2016.04.2015090101 MAO Q J, LU S Y, WEI Y L, et al. Mechanochemical decomposition of polychlorinated biphenyls contaminated soil using a horizontal ball mill [J]. Environmental Chemistry, 2016, 35(4): 607-614(in Chinese). doi: 10.7524/j.issn.0254-6108.2016.04.2015090101
[20] 肖松文, 肖骁. 持久性有机污染物机械化学无害化处理的研究进展 [J]. 矿冶工程, 2006, 26(2): 53-56. doi: 10.3969/j.issn.0253-6099.2006.02.014 XIAO S W, XIAO X. Advances in study of mechanochemical process for persistent organic pollutants treatments [J]. Mining and Metallurgical Engineering, 2006, 26(2): 53-56(in Chinese). doi: 10.3969/j.issn.0253-6099.2006.02.014
[21] 戎宇舟. 铁-锌双金属机械化学法处理土壤中滴滴涕的过程机理及再利用研究[D]. 天津: 天津大学, 2018: 80. RONG Y Z. Process, mechanism and reuse study on the mechanochemical treatment of DDT in soil with iron-zinc bimetal[D]. Tianjin: Tianjin University, 2018: 80 (in Chinese).
[22] SUI H, RONG Y, SONG J, et al. Mechanochemical destruction of DDTs with Fe-Zn bimetal in a high-energy planetary ball mill [J]. Journal of hazardous materials, 2018, 342: 201-209. doi: 10.1016/j.jhazmat.2017.08.025 [23] SONG J, GAO X, RONG Y, et al. Mechanism for degradation of dichlorodiphenyltrichloroethane by mechano-chemical ball milling with Fe-Zn bimetal [J]. Journal of environmental management, 2019, 247: 681-687. [24] MATHESON L J, TRATNYEK P G. Reductive dehalogenation of chlorinated methanes by iron metal [J]. Environmental Science & Technology, 1994, 28(12): 2045-2053. [25] 张望. 基于Fe-SiO2的POPs废物机械化学处置工艺及机理研究[D]. 北京: 清华大学, 2012: 115. ZHANG W. Process and mechanism study of mechanochemical destruction of POPs wastes using Fe-SiO2[D]. Beijing: Tsinghua University, 2012: 115 ( in Chinese) .
[26] TANAKA Y, ZHANG Q, SAITO† F. Mechanochemical dechlorination of trichlorobenzene on oxide surfaces [J]. Journal of Physical Chemistry B, 2003, 107(40): 11091-11097. doi: 10.1021/jp0276808 [27] LIU C-C, TSENG D-H. WANG C-Y. Effects of ferrous ions on the reductive dechlorination of trichloroethylene by zero-valent iron [J]. Journal of Hazardous Materials, 2006, 136(3): 706-713. doi: 10.1016/j.jhazmat.2005.12.045 [28] LOOKMAN R, BASTIAENS L, BORREMANS B, et al. Batch-test study on the dechlorination of 1, 1, 1-trichloroethane in contaminated aquifer material by zero-valent iron [J]. Journal of Contaminant Hydrology, 2004, 74(1-4): 133-144. doi: 10.1016/j.jconhyd.2004.02.007 [29] 陈静, 陈海, 金歆, 等. 纳米零价铁降解水中四氯化碳的试验研究 [J]. 环境科学学报, 2017, 37(2): 610-616. CHEN J, CHEN H, JIN X, et al. Degradation of aqueous carbon tetrachloride by nanoscale zero-valent iron [J]. Acta Scientiae Circumstantiae, 2017, 37(2): 610-616(in Chinese).
[30] 孟亚锋. 零价铁还原降解四氯化碳废水研究[D]. 杭州: 浙江大学, 2010: 116. MENG Y F. Reduction degradation of carbon tetrachloride wastewater by zero-valent iron[D]. Hangzhou: Zhejiang University, 2010: 116 (in Chinese) .
[31] 乔本志, 张季君. 1HNMR法研究氯仿与某些化合物的氢键作用 [J]. 太原工业大学学报, 1992, 23(2): 33-36. QIAO B Z, ZHANG J J. The 1HNMR study of hydrogen-bond associations between chloroform and some compounds [J]. Journal of Taiyuan University of Technology, 1992, 23(2): 33-36(in Chinese).