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近年来,由于农业灌溉、化肥使用、工业“三废”和生活污水排放,地下水和地表水中的NO3−-N污染令人担忧。在我国山东潍坊,饮用水井中NO3−-N质量浓度高达150 mg·L−1 [1],石家庄市浅层地下水NO3−-N质量浓度更是高达184 mg·L−1[2],同时我国部分河流也出现NO3−-N污染问题[3]。NO3−-N污染不仅会引起水体富营养化、生物多样性丧失等生态环境问题[4],还会对人类健康产生潜在威胁,如引发癌症和高铁血红蛋白血症等[5]。
目前,去除NO3−-N的方法主要有生物反硝化法、离子交换法、膜法、催化还原法等。其中,催化还原法具有转化率高、反应速率快等特点,是一种很有前途的NO3−-N脱除技术[6]。在众多催化还原材料中,纳米零价铁由于比表面积大、反应活性高、毒性低等优点已被运用到NO3−-N去除领域,但其尺寸小、表面能高、加上固有的磁性,使其易于团聚,导致表面活性位减少,进而降低NO3−-N的还原效率[7]。为了解决上述问题,国内外学者提出了一些改进方法。例如,以沸石、凹凸棒土、生物炭、聚合树脂等为载体制备负载型纳米零价铁,抑制纳米零价铁的团聚;在纳米零价铁中引入Pd、Pt、Ag、Au等贵金属和其他过渡金属(Al、Ni、Cu等),提高反应速率、减少氨氮生成量等[8-10]。
本研究以果壳活性炭为基体,采用硼氢化钠还原法一步制备铁/镍双金属负载活性炭(AC-Fe/Ni),优化了活性炭与金属铁、镍的最佳掺杂比,考察了初始pH、AC-Fe/Ni投加量、NO3−-N初始质量浓度、共存离子和有机物对NO3−-N去除效果和反应产物的影响;分析了AC-Fe/Ni去除NO3−-N过程中含氮物种的浓度变换,探究了AC-Fe/Ni还原NO3−-N的机理。同时,采用次氯酸钠氧化法去除出水中的氨氮,达到有效控制NO3−-N污染的目的。
AC-Fe/Ni联合次氯酸钠去除水中硝酸盐氮
Removal of nitrate nitrogen from water by AC-Fe/Ni combining sodium hypochlorite
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摘要: 随着工业、农业的快速发展,硝酸盐氮(NO3−-N)的污染范围不断扩大、污染程度不断加深,因此,有效去除水中的NO3−-N具有重要意义。本研究通过在活性炭上原位负载零价铁和镍,制备了载铁/镍双金属活性炭(AC-Fe/Ni),并联合次氯酸钠去除水中的NO3−-N。结果表明,AC-Fe/Ni能够快速还原NO3−-N,反应20 min时NO3−-N的去除率为99.29%,比AC-Fe提高40%,且N2选择性提高8%。AC-Fe/Ni在酸性和碱性条件下均能有效还原NO3−-N,但碱性条件更有利于形成N2。减少材料投加量或提高NO3−-N初始质量浓度均会降低NO3−-N的去除率;共存阴离子、阳离子、有机物对NO3−-N的去除无明显影响。NO3−-N的还原过程总铁释出量仅为0.28 mg·L−1,总镍浓度低于0.05 mg·L−1。与此同时,次氯酸钠联用能有效去除出水中的NH4+-N,反应60 min时溶液中残余氨氮仅为0.28 mg·L−1。Abstract: With the rapid development of industry and agriculture, the scope of nitrate nitrogen (NO3−-N) pollution continues to expand and the pollution degree becomes increasingly severe. Therefore, it is of great significance to effectively remove NO3−-N in water. In this study, iron/nickel bimetallic nanoparticles loaded activated carbon (AC-Fe/Ni) was prepared by a in-situ reduction method. Subsequently, the AC-Fe/Ni was combined with sodium hypochlorite for the NO3−-N removal. The results show that AC-Fe/Ni could quickly reduce NO3−-N. The removal rate of NO3−-N reached 99.29% after 20 min of reaction, which was 40% higher than the AC-Fe, and the N2 selectivity increased by 8%. AC-Fe/Ni could effectively reduce NO3−-N under both acidic and alkaline conditions, but alkaline condition was more conducive to the formation of N2. Reducing the AC-Fe/Ni dosage or increasing the initial NO3−-N concentration decreased the removal rate of NO3−-N. Coexist anions, cations and organic matter had no significant effect on the removal of NO3−-N. The total iron released in the solution was only 0.28 mg·L−1 during the reduction process of NO3−-N, and the total nickel concentration was less than 0.05 mg·L−1. At the same time, the combination of sodium hypochlorite could effectively remove NH4+-N in the effluent, and the residual NH4-N in the solution after 60 min of reaction was only 0.28 mg·L−1.
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Key words:
- nitrate nitrogen /
- activated carbon /
- iron/nickel bimetal /
- sodium hypochlorite
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表 1 AC-Fe/Ni去除NO3−-N的动力学拟合参数
Table 1. Kinetic fitting parameters of NO3−-N removal by AC-Fe/Ni
NO3−-N初始浓度/
(mg·L−1)一级动力学 二级动力学 k1/ min−1 R2 k2/(g·(L·min)−1) R2 20 0.305 0.865 1.173 0.950 30 0.184 0.968 0.070 0.927 40 0.163 0.920 0.035 0.976 50 0.108 0.862 0.009 0.998 -
[1] 徐春英, 李玉中, 李巧珍, 等. 山东潍坊地下水硝酸盐污染现状及δ^(15)N溯源[J]. 生态学报, 2011, 31(21): 6579-6587. [2] 赵俊玲, 曹李靖, 赵雪莲, 等. 石家庄市浅层地下水中硝酸盐氮污染现状及原因分析[J]. 洛阳工业高等专科学校学报, 2005, 15(2): 6-7,44. [3] ZHANG X, ZHANG Y, SHI P, et al. The deep challenge of nitrate pollution in river water of China[J]. Science Of The Total Environment, 2021, 770: 144674. doi: 10.1016/j.scitotenv.2020.144674 [4] BIJAY S, GRASWELL E. Fertilizers and nitrate pollution of surface and ground water: an increasingly pervasive global problem[J]. SN Applied Sciences, 2021, 3(4): 1-24. [5] SHI J L, YI S N, HE H L, et al. Preparation of nanoscale zero-valent iron supported on chelating resin with nitrogen donor atoms for simultaneous reduction of Pb and NO3−[J]. Chemical Engineering Journal, 2013, 230: 166-171. doi: 10.1016/j.cej.2013.06.088 [6] ABASCAL E, GOMEZ-COMA L, ORTIZ I, et al. Global diagnosis of nitrate pollution in groundwater and review of removal technologies[J]. Science of the Total Environment, 2022, 810: 152233. doi: 10.1016/j.scitotenv.2021.152233 [7] RYU A, JEONG S, JANG A, et al. Reduction of highly concentrated nitrate using nanoscale zero-valent iron: Effects of aggregation and catalyst on reactivity[J]. Applied Catalysis B- Environmental, 2011, 105(1-2): 128-135. doi: 10.1016/j.apcatb.2011.04.002 [8] 吕晓书, 王霞玲, 蒋光明, 等. 纳米零价铁基材料去除水中硝酸盐污染的研究进展[J]. 材料导报, 2023, 37(4): 58-67. [9] XU J, PU Y, QI W K, et al. Chemical removal of nitrate from water by aluminum-iron alloys[J]. Chemosphere, 2017, 166: 197-202. doi: 10.1016/j.chemosphere.2016.09.102 [10] LIOU Y H, LO S L, LIN C J, et al. Chemical reduction of an unbuffered nitrate solution using catalyzed and uncatalyzed nanoscale iron particles[J]. Journal of Hazardous Materials, 2005, 127(1-3): 102-110. doi: 10.1016/j.jhazmat.2005.06.029 [11] 汪虹西, 廖兵, 卢涛, 等. 零价铁-生物炭复合材料对地下水中硝酸盐的去除[J]. 环境工程学报, 2020, 14(12): 3317-3328. doi: 10.12030/j.cjee.201912045 [12] SHI L N, DU J H, CHEN Z L, et al. Functional kaolinite supported Fe/Ni nanoparticles for simultaneous catalytic remediation of mixed contaminants (lead and nitrate) from wastewater[J]. Journal of Colloid and Interface Science, 2014, 428: 302-307. doi: 10.1016/j.jcis.2014.04.059 [13] HE Y H, LIN H, DONG Y B, et al. Zeolite supported Fe/Ni bimetallic nanoparticles for simultaneous removal of nitrate and phosphate: Synergistic effect and mechanism[J]. Chemical Engineering Journal, 2018, 347: 669-681. doi: 10.1016/j.cej.2018.04.088 [14] KIM D G, HWANG Y H, SHIN H S, et al. Kinetics of nitrate adsorption and reduction by nano-scale zero valent iron (NZVI): Effect of ionic strength and initial pH[J]. KSCE Journal of Civil Engineering, 2016, 20(1): 175-187. doi: 10.1007/s12205-015-0464-3 [15] LV X S, PENG H H , WANG X L, et al. Nitrate reduction by nanoscale zero valent iron (nFe0)-based systems: Mechanism, reaction pathway and strategy for enhanced N2 formation[J]. Chemical Engineering Journal, 2022, 430: 4. [16] 邱思远, 高芳, 王金霞, 等. 生物炭零价铁去除水中硝酸盐氮影响因素探究[J]. 当代化工研究, 2023(11): 33-35. [17] LIU Y, PHENRAT T, LOWRY, G V. Effect of TCE concentration and dissolved groundwater solutes on NZVI-promoted TCE dechlorination and H2 evolution[J]. Environmental Science & Technology, 2007, 41(22): 7881-7887. [18] SHEN Z H, LIU D R, DONG X Y, et al. Nitrate reduction using iron and copper bimetallic nanoparticles supported by chelating resin: effect of solution chemistry, mechanism, and regeneration[J]. Journal of Environmental Engineering, 2020, 146(4): 04020011. doi: 10.1061/(ASCE)EE.1943-7870.0001671 [19] HOU M T, TANG Y, XU J, et al. Nitrate reduction in water by aluminum-iron alloy particles catalyzed by copper[J]. Journal of Environmental Chemical Engineering, 2015, 3(4): 2401-2407. doi: 10.1016/j.jece.2015.08.014 [20] LIU Y L, GONG X B, YANG W J, et al. Selective reduction of nitrate into nitrogen using Cu/Fe bimetal combined with sodium sulfite[J]. Industrial & Engineering Chemistry Research, 2019, 58(13): 5175-5185. [21] TANG T T, XING Q J, ZHANG S H, et al. High selective reduction of nitrate into nitrogen by novel Fe-Cu/D407 composite with excellent stability and activity[J]. Environmental Pollution, 2019, 252: 888-896. doi: 10.1016/j.envpol.2019.05.071 [22] 张胜利, 刘丹, 曹臣. 次氯酸钠氧化脱除废水中氨氮的研究[J]. 工业用水与废水, 2009, 40(3): 23-26. doi: 10.3969/j.issn.1009-2455.2009.03.006 [23] 方小琴, 胡君杰, 夏俊方. NaClO氧化去除高盐废水中氨氮的影响因素及其动力学研究[J]. 工业用水与废水, 2017, 48(2): 18-23. doi: 10.3969/j.issn.1009-2455.2017.02.006