污泥基生物炭负载纳米零价铁去除Cr(VI)的性能与机制

曾涛涛; 农海杜; 沙海超; 陈胜兵; 张晓玲; 刘金香

污泥基生物炭负载纳米零价铁去除Cr(VI)的性能与机制

南华大学　污染控制与资源化技术湖南省高校重点实验室, 湖南衡阳 421001

基金项目: 国家自然科学基金项目(52170164)；湖南省教育厅创新平台开放基金项目(19K081)

详细信息

通讯作者:
刘金香，博士，教授，硕士生导师，研究方向为水处理理论与技术及污染控制　 E-mail：cafardworm@163.com

中图分类号: X703
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- 被引次数: 0
出版历程
- 收稿日期: 2022-01-10
- 录用日期: 2022-03-13
- 修回日期: 2022-03-08
- 网络出版日期: 2022-04-01

Performance and mechanism of Cr(VI) removal by sludge-derived biochar loaded with nanoscale zero-valent iron

Hunan Province Key Laboratory of Pollution Control and Resource Reuse Technology, University of South China, Hengyang 421001, Hunan, China

摘要

摘要: 针对电镀、冶金、印染等行业产生的含铬废水所导致的环境污染难题，以城市污泥热解获得的污泥基生物炭(SB)为载体，制备了污泥基生物炭负载纳米零价铁(nZVI-SB)材料用于去除水中的Cr(VI)，探究了铁炭质量比、初始pH值、投加量、温度等因素对去除Cr(VI)的影响。通过扫描电镜-能谱分析(SEM-EDS)、X衍射分析仪(XRD)和X射线光电子能谱(XPS)等手段对nZVI-SB去除Cr(VI)的机制进行分析。结果表明，nZVI-SB对Cr(VI)废水具有较好的去除能力。在投加量0.5 g/L、初始pH值2、温度40℃条件下，nZVI-SB(1:1)对Cr(VI)吸附量最大为150.60 mg/g。Cr(VI)去除过程可通过Langmuir吸附等温式与准二级动力学方程进行拟合。nZVI-SB对Cr(VI)去除机制主要包括吸附、还原和共沉淀。本研究表明污泥基生物炭与纳米零价铁可以协同发挥除Cr(VI)作用。
- 污泥基生物炭 /
- 纳米零价铁 /
- Cr(VI) /
- 吸附量 /
- 机制 /
- 还原
Abstract: Chromium-containing wastewater was generated in electroplating, metallurgy, printing and dyeing industries, which caused environmental pollution. The sludge-derived biochar (SB) was obtained from the pyrolysis of municipal sludge, and then loaded with nanoscale zero-valent iron (nZVI) to prepare sludge-derived biochar loaded with nanoscale zero-valent iron (nZVI-SB) for the removal of Cr(VI) from water. The effect of the iron to carbon mass ratio, initial pH value, dosage and temperature on the removal of Cr(VI) were explored. Scanning electron microscope and energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the mechanisms of Cr(VI) removal. The results show that nZVI-SB has a desirable removal capacity for Cr(VI). Under the conditions of dosage 0.5 g/L, pH 2 and 40℃, the maximum adsorption capacity of Cr(VI) by nZVI-SB (1:1) is 150.60 mg/g. The Cr(Ⅵ) removal process can be fitted by Langmuir adsorption isotherm and pseudo-second-order kinetic equations. The removal mechanisms of Cr(VI) mainly include adsorption, reduction and co-precipitation. The present study confirms SB and nZVI can synergically remove Cr(VI).
- Sludge-derived biochar /
- nanoscale zero-valent iron /
- Cr(VI) /
- adsorption capacity /
- mechanism /
- reduction

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图 1 SB (a)和污泥基生物炭负载纳米零价铁(nZVI-SB) (1:1)处理Cr(VI)前(b)、后(c)的SEM-EDS图

Figure 1. SEM-EDS images of SB (a) and sludge-derived biochar loaded with nanoscale zero-valent iron (nZVI-SB) (1:1) before (b) and after (c) treatment of Cr(VI)

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图 3 SB和nZVI-SB(1:1)的N₂吸附-脱附等温线(a)和孔径分布(b)

Figure 3. The N₂ adsorption-desorption isotherms (a) and pore size distributions (b) of SB and nZVI-SB (1:1)

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图 2 nZVI-SB(1:1)处理Cr(VI)前(a)、后(b)的TEM图

Figure 2. TEM images of nZVI-SB(1:1) before (a) and after (b) treatment of Cr(VI)

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图 4 SB和nZVI-SB(1:1)去除Cr(VI)前、后的XRD图(a)以及nZVI-SB(1:1)的XPS全谱图(b)

Figure 4. XRD patterns of SB and nZVI-SB(1:1) before and after adsorption of Cr(VI) (a) and XPS full spectrum of nZVI-SB(1:1) (b)

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图 5 不同Fe:C质量比对Cr(VI)去除的影响

Figure 5. The effect of Fe:C mass ratio on Cr(VI) removal

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图 6 初始pH对nZVI-SB(1:1)去除Cr(Ⅵ)的影响

Figure 6. The effect of initial pH on the removal of Cr(Ⅵ) by nZVI-SB(1:1)

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图 7 不同pH值下Cr(VI)形态分布曲线图

Figure 7. Cr(VI) form distribution curve under different pH values

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图 8 投加量对nZVI-SB(1:1)去除Cr (VI)的影响

Figure 8. The influence of dosage on the removal of Cr (VI) by nZVI-SB(1:1)

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图 9 吸附时间对nZVI-SB(1:1)去除Cr(Ⅵ)的影响(a)；准一级(b)、准二级(c)动力学拟合曲线和颗粒内扩散拟合曲线(d)

Figure 9. The effect of adsorption time on the removal of Cr(Ⅵ) by nZVI-SB(1:1) (a); Quasi-first (b), quasi-second (c) kinetic fitting curves and intra-particle diffusion fitting curve (d)

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图 10 温度对nZVI-SB(1:1)去除Cr(Ⅵ)的影响(a)；Langmuir吸附等温线(b)和Freundlich吸附等温线(c)

Figure 10. The influence of temperature on the removal of Cr(Ⅵ) by nZVI-SB(1:1) (a); Langmuir adsorption isotherm (b) and Freundlich adsorption isotherm (c)

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图 11 nZVI-SB(1:1)的XPS图：(a)C 1s精细谱；(b)O 1s精细谱；(c)Fe 2p精细谱；(d)Cr 2p精细谱

Figure 11. XPS spectra of nZVI-SB(1:1): (a) C 1s spectrum; (b) O 1s spectrum; (c) Fe 2p spectrum; (d) Cr 2p spectrum

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图 12 nZVI-SB(1:1)对Cr(VI)去除机制图^[15]

Figure 12. Schematic of Cr(VI) removal mechanisms by nZVI-SB(1:1)

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图 13 nZVI-SB(1:1)洗脱再生试验

Figure 13. nZVI-SB(1:1) regeneration test

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表 1 污泥及污泥基生物炭消解液中重金属浓度/(mg·L⁻¹)

Table 1. Heavy metal concentrations in digestion solution of sludge and sludge-based biochar /(mg·L⁻¹)

sample	Zn	Pb	Cu	Ba	Cd	Cr
sludge	5.28	0.34	2.37	7.32	0.06	0.14
SB	7.81	0.51	3.01	8.67	0.09	0.13
Specified value in GB 5085.3—2007^[18]	100	5	100	100	1	15

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表 2 SB和nZVI-SB(1∶4、1∶2、1∶1、2∶1)的元素组成

Table 2. Elemental composition of SB and nZVI-SB (1∶4, 1∶2, 1∶1, 2∶1)

Mass percentage /wt%
	C	N	O	Na	Mg	Al	Si	K	Ca	Cr	Fe
SB	40.48	8.46	34.94	0.19	0.39	3.26	6.43	0.88	3.05	0.33	1.59
1:4	36.63	7.56	33.05	0.22	0.48	0.63	0.76	0.28	0.30	0.22	19.87
1:2	30.41	6.41	27.55	0.18	0.36	0.51	0.62	0.23	0.24	0.18	33.31
1:1	23.92	3.11	21.45	0.14	0.27	0.28	0.35	0.19	0.21	0.16	49.92
2:1	16.48	1.76	14.45	0.06	0.13	0.11	0.16	0.08	0.08	0.06	66.63

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表 3 nZVI-SB(1:1)对Cr(Ⅵ)的吸附动力学参数

Table 3. Adsorption kinetic parameters of Cr(VI) adsorption by nZVI-SB(1:1)

Quasi-first order dynamics model			Quasi-two-stage dynamics model
q_e/(mg·g⁻¹)	K₁/(min⁻¹)	R²	q_e/(mg·g⁻¹)	K₂/(min⁻¹)	R²
38.57	0.0113	0.855	103.07	0.0005	0.999
Intraparticle diffusion model
Kd1/(mg·(m·min^0.5)⁻¹)	C₁	R²	Kd2/(mg·(m·min^0.5)⁻¹)	C₂	R²
5.858	22.731	0.971	0.038	98.551	0.946
Notes: q_e is equilibrium adsorption capacity; K₁ is the quasi-first order adsorption rate constant; K₂ is the quasi-second order adsorption rate constant; R² is linear correlation coefficient; K_d1 and K_d2 are particle diffusion constants.

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表 4 nZVI-SB(1:1)对Cr(Ⅵ)的吸附等温线拟合参数

Table 4. Adsorption isotherm fitting parameters of Cr(VI) by nZVI-SB(1:1)

Temperature/℃	Langmuir			Freundlich
Temperature/℃	q_max(mg·g⁻¹)	K_L	R²	K_F	n	R²
20	141.55	0.457	0.999	98.48	8.93	0.821
30	143.84	0.338	0.999	104.73	9.99	0.744
40	151.23	0.433	0.999	106.38	9.07	0.766
Notes: q_m is the maximum adsorption capacity; K_L is the adsorption equilibrium constant of the Langmuir model; K_F is the adsorption equilibrium constant of Freundlich model; 1/n is an empirical parameter related to the adsorption strength; R² is linear correlation coefficient.

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表 5 nZVI-SB(1:1)和其他吸附剂对Cr(VI)的吸附能力比较

Table 5. Comparison of the adsorption capacity of Cr(VI) by nZVI-SB (1:1) and other adsorbents

Adsorbent	pH	Temperature/℃	Adsorption capacity/(mg·g⁻¹)	References
Sludge biochar(500℃)	7	25	7.93	[13]
bentonite-supported nanoscale zero-valent iron (B-nZVI)	5	25	39.48	[23]
Ficus carica biosorbent	3	30	19.68	[36]
Magnetic nanoparticle-Phosphorene-Titanium nano tubes(MNP-PN-TNT)	9	25	35.00	[2]
nanoscale zero-valent iron grafted on acid-activated attapulgite (A-nZVI)	7	27	4.94	[31]
HNO₃ modified quinoa biochar	4	/	55.85	[37]
ZnO modified hyacinth biochar	/	25	43.48	[38]
halloysite nanotubes/ploy composites	2	25	855.66	[39]
nZVI-SB(1:1)	2	40	150.60	This study

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表 6 nZVI-SB(1:1)去除Cr(VI)前、后的C 1s、O 1s、Fe 2p 和 Cr 2p XPS光谱的成分和相应的相对百分比

Table 6. Composition and relative percents of C 1s, O 1s, Fe 2p and Cr 2p XPS spectra before and after Cr(VI) removal by nZVI-SB(1:1)

	Components	Relative percentage/%		Binding energy/eV
	Components	Before	After	Before	After
C 1s	C−C	58.99	59.78	284.64	284.69
	C−O	26.24	24.00	286.06	286.27
	C=O	14.77	16.22	288.54	288. 72
O 1s	Fe−O	32.07	30.05	529.95	529.99
	C−O	29.94	57.76	531.17	531.40
	C=O	37.99	12.19	532.04	532.58
Fe 2p	Fe⁰	0.36	0	706.7	-
	Fe(II)	70.31	67.96	711.10/724.39	711.11/724.45
	Fe(III)	29.33	32.04	714.41/728.15	714.44/728.55
Cr 2p	Cr(III)	-	84.39	-	577.01/586.85
Cr 2p	Cr(VI)	-	15.61	-	580.40/590.28

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[1]	GAO Q Y, LIN D G, FAN Y J, et al. Visible light induced photocatalytic reduction of Cr(VI) by self-assembled and amorphous Fe-2MI[J]. Chemical Engineering Journal,2019,374:10-19. doi: 10.1016/j.cej.2019.05.151
[2]	LIN Y J, CHEN J J, CAO W Z, et al. Novel materials for Cr(VI) adsorption by magnetic titanium nanotubes coated phosphorene[J]. Journal of Molecular Liquids,2019,287:110826. doi: 10.1016/j.molliq.2019.04.103
[3]	GHADIKOLAEI N F, KOWSARI E, BALOU S, et al. Preparation of porous biomass-derived hydrothermal carbon modified with terminal amino hyperbranched polymer for prominent Cr(VI) removal from water[J]. Bioresource Technology,2019,288:121545. doi: 10.1016/j.biortech.2019.121545
[4]	ZHANG W Y, QIAN L B, OUYANG D, et al. Effective removal of Cr(VI) by attapulgite-supported nanoscale zero-valent iron from aqueous solution: Enhanced adsorption and crystallization[J]. Chemosphere,2019,221:683-692. doi: 10.1016/j.chemosphere.2019.01.070
[5]	孙建德. 含铬废水的处理现状[J]. 湖南有色金属, 2013, 29(5):59-62. doi: 10.3969/j.issn.1003-5540.2013.05.017 SUN J D. Current situation on the treatment for chromium-containing wastewater[J]. Hunan Nonferrous Metals,2013,29(5):59-62(in Chinese). doi: 10.3969/j.issn.1003-5540.2013.05.017
[6]	秦泽敏, 董黎明, 刘平, 等. 零价纳米铁吸附去除水中六价铬的研究[J]. 中国环境科学, 2014, 34(12):3106-3111. QIN Z M, DONG L M, LIU P, et al. Removal Cr⁶⁺ from water using nanoscale zero-valent iron[J]. China Environmental Science,2014,34(12):3106-3111(in Chinese).
[7]	GUAN X H, SUN Y K, QIN H J, et al. The limitations of applying zero-valent iron technology in contaminants sequestration and the corresponding countermeasures: The development in zero-valent iron technology in the last two decades (1994-2014)[J]. Water Research,2015,75:224-248. doi: 10.1016/j.watres.2015.02.034
[8]	SHI L N, ZHANG X, CHEN Z L. Removal of Chromium (VI) from wastewater using bentonite-supported nanoscale zero-valent iron[J]. Water Research,2011,45(2):886-892. doi: 10.1016/j.watres.2010.09.025
[9]	PETALA E, DIMOS K, DOUVALIS A, et al. Nanoscale zero-valent iron supported on mesoporous silica: Characterization and reactivity for Cr(VI) removal from aqueous solution[J]. Journal of Hazardous Materials,2013,261:295-306. doi: 10.1016/j.jhazmat.2013.07.046
[10]	ZHU H J, JIA Y F, WU X, et al. Removal of arsenic from water by supported nano zero-valent iron on activated carbon[J]. Journal of Hazardous Materials,2009,172(2-3):1591-1596. doi: 10.1016/j.jhazmat.2009.08.031
[11]	SU H J, FANG Z Q, TSANG P E, et al. Remediation of hexavalent chromium contaminated soil by biochar-supported zero-valent iron nanoparticles[J]. Journal of Hazardous Materials,2016,318:533-540. doi: 10.1016/j.jhazmat.2016.07.039
[12]	刘剑, 黄莉, 彭钢, 等. 颗粒活性炭载纳米零价铁去除水中的Cr(Ⅵ)[J]. 过程工程学报, 2019, 19(4):714-720. LIU J, HUANG L, PENG G, et al. Removal of Cr(VI) from water by granular activated carbon supported nanoscale zero-valent iron[J]. The Chinese Journal of Process Engineering,2019,19(4):714-720(in Chinese).
[13]	陈林, 平巍, 闫彬, 等. 不同制备温度下污泥生物炭对Cr(Ⅵ)的吸附特性[J]. 环境工程, 2020, 38(8):119-124. CHEN L, PING W, YAN B, et al. Adsorption characteristics of Cr(Ⅵ) by sludge biochar under different pyrolysis temperatures[J]. Environmental Engineering,2020,38(8):119-124(in Chinese).
[14]	莫官海, 谢水波, 曾涛涛, 等. 污泥基生物炭处理酸性含U(Ⅵ)废水的效能与机理[J]. 化工学报, 2020, 71(5):2352-2362. MO G H, XIE S B, ZENG T T, et al. The efficiency and mechanism of U(VI) removal from acidic wastewater by sewage sludge-derived biochar[J]. CIESC Journal,2020,71(5):2352-2362(in Chinese).
[15]	CHEN X, FAN G J, LI H B, et al. Nanoscale zero-valent iron particles supported on sludge-based biochar for the removal of chromium (VI) from aqueous system[J]. Environmental Science and Pollution Research,2021,29(3):3853-3863.
[16]	ZHOU M, ZHANG C G, YUAN Y F, et al. Pinewood outperformed bamboo as feedstock to prepare biochar-supported zero-valent iron for Cr⁶⁺ reduction[J]. Environmental Research,2020,187:109695. doi: 10.1016/j.envres.2020.109695
[17]	DIAO Z H, DU J J, JIANG D, et al. Insights into the simultaneous removal of Cr⁶⁺ and Pb²⁺ by a novel sewage sludge-derived biochar immobilized nanoscale zero valent iron: Coexistence effect and mechanism[J]. Science of the Total Environment,2018,642:505-515. doi: 10.1016/j.scitotenv.2018.06.093
[18]	危险废物鉴别标准浸出毒性鉴别: GB 5085.3-2007 [S]. 北京: 中国环境科学出版社. 2007. Identification standards for hazardous wastes Identification for extraction toxicity: GB 5085.3-2007 [S]. Beijing: China Environmental Science Press, 2007(in Chinese).
[19]	ZHANG Y T, JIAO X Q, LIU N, et al. Enhanced removal of aqueous Cr(VI) by a green synthesized nanoscale zero-valent iron supported on oak wood biochar[J]. Chemosphere,2020,245:125542. doi: 10.1016/j.chemosphere.2019.125542
[20]	MA F F, PHILIPPE B, ZHAO B W, et al. Simultaneous adsorption and reduction of hexavalent chromium on biochar-supported nanoscale zero-valent iron (nZVI) in aqueous solution[J]. Water Science and Technology,2020,82(7):1339-1349. doi: 10.2166/wst.2020.392
[21]	CHOI H, AL-ABED S R, AGARWAL S, et al. Synthesis of reactive nano-Fe/Pd bimetallic system-impregnated activated carbon for the simultaneous adsorption and dechlorination of PCBs[J]. Chem Mat,2008,20(11):3649-3655. doi: 10.1021/cm8003613
[22]	PHOUNGTHONG K, ZHANG H, SHAO L M, et al. Leaching characteristics and phytotoxic effects of sewage sludge biochar[J]. Journal of Material Cycles and Waste Management,2018,20(4):2089-2099. doi: 10.1007/s10163-018-0763-0
[23]	DIAO Z H, XU X R, JIANG D, et al. Bentonite-supported nanoscale zero-valent iron/persulfate system for the simultaneous removal of Cr(VI) and phenol from aqueous solutions[J]. Chemical Engineering Journal,2016,302:213-222. doi: 10.1016/j.cej.2016.05.062
[24]	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
[25]	YI Y, WANG X Y, MA J, et al. An efficient Egeria najas-derived biochar supported nZVI composite for Cr (VI) removal: Characterization and mechanism investigation based on visual MINTEQ model[J]. Environmental Research,2020,189:109912. doi: 10.1016/j.envres.2020.109912
[26]	DONG H R, DENG J M, XIE Y K, et al. Stabilization of nanoscale zero-valent iron (nZVI) with modified biochar for Cr(VI) removal from aqueous solution[J]. Journal of Hazardous Materials,2017,332:79-86. doi: 10.1016/j.jhazmat.2017.03.002
[27]	FANG Y, WU X G, DAI M, et al. The sequestration of aqueous Cr(VI) by zero valent iron-based materials: From synthesis to practical application[J]. Journal of Cleaner Production,2021,312:127678. doi: 10.1016/j.jclepro.2021.127678
[28]	DONG H R, ZHANG C, HOU K J, et al. Removal of trichloroethylene by biochar supported nanoscale zero-valent iron in aqueous solution[J]. Separation and Purification Technology,2017,188:188-196. doi: 10.1016/j.seppur.2017.07.033
[29]	HUANG L H, ZHOU S J, JIN F, et al. Characterization and mechanism analysis of activated carbon fiber felt-stabilized nanoscale zero-valent iron for the removal of Cr(VI) from aqueous solution[J]. Colloids and Surfaces a-Physicochemical and Engineering Aspects,2014,447:59-66.
[30]	CHOI K, LEE W. Enhanced degradation of trichloroethylene in nano-scale zero-valent iron Fenton system with Cu(II)[J]. Journal of Hazardous Materials,2012,211:146-153.
[31]	QUAN G X, ZHANG J, GUO J, et al. Removal of Cr(VI) from aqueous solution by nanoscale zero-valent iron grafted on acid-activated attapulgite[J]. Water Air and Soil Pollution,2014,225(6):2195.
[32]	QIU Y, ZHANG Q, GAO B, et al. Removal mechanisms of Cr(VI) and Cr(III) by biochar supported nanosized zero-valent iron: Synergy of adsorption, reduction and transformation[J]. Environmental Pollution,2020,265:115018. doi: 10.1016/j.envpol.2020.115018
[33]	LIU L H, LIU X, WANG D Q, et al. Removal and reduction of Cr(VI) in simulated wastewater using magnetic biochar prepared by co-pyrolysis of nano-zero-valent iron and sewage sludge[J]. Journal of Cleaner Production,2020,257:120562. doi: 10.1016/j.jclepro.2020.120562
[34]	WANG H B, CAI J Y, LIAO Z W, et al. Black liquor as biomass feedstock to prepare zero-valent iron embedded biochar with red mud for Cr(VI) removal: Mechanisms insights and engineering practicality[J]. Bioresource Technology,2020,311:123553. doi: 10.1016/j.biortech.2020.123553
[35]	AWANG N A, SALLEH W N W, ISMAIL A F, et al. Adsorption behavior of chromium(VI) onto regenerated cellulose membrane[J]. Industrial & Engineering Chemistry Research,2019,58(2):720-728.
[36]	GUPTA V K, PATHANIA D, AGARWAL S, et al. Removal of Cr(VI) onto Ficus carica biosorbent from water[J]. Environmental Science and Pollution Research,2013,20(4):2632-2644. doi: 10.1007/s11356-012-1176-6
[37]	IMRAN M, KHAN Z U, IQBAL M M, et al. Effect of biochar modified with magnetite nanoparticles and HNO₃ for efficient removal of Cr(VI) from contaminated water: A batch and column scale study[J]. Environmental Pollution,2020,261:114231. doi: 10.1016/j.envpol.2020.114231
[38]	YU J D, JIANG C Y, GUAN Q Q, et al. Enhanced removal of Cr(VI) from aqueous solution by supported ZnO nanoparticles on biochar derived from waste water hyacinth[J]. Chemosphere,2018,195:632-640. doi: 10.1016/j.chemosphere.2017.12.128
[39]	陈泽文, 周子晗, 吴美仪, 等. 埃洛石纳米管/聚间苯二胺复合材料去除Cr(Ⅵ)的性能[J]. 复合材料学报, 2020, 37(3):493-503. CHEN Z W, ZHOU Z H, WU M Y, et al. Adsorption properties of halloysite nanotubes/poly(m-phenylenediamine) composites for Cr(VI)[J]. Acta Materiae Compositae Sinica,2020,37(3):493-503(in Chinese).
[40]	席冬冬, 李晓敏, 熊子璇, 等. 生物炭负载纳米零价铁对污染土壤中铜钴镍铬的协同去除[J]. 环境工程, 2020, 38(6):58-66. XI D D, LI X M, XIONG Z X, et al. Synergistic removal of Cu, Co, Ni and Cr from contaminated soil by biochar-supported nanoscale zero-valent iron[J]. Environmental Engineering,2020,38(6):58-66(in Chinese).
[41]	YOON I H, BANG S, CHANG J S, et al. Effects of pH and dissolved oxygen on Cr(VI) removal in Fe(0)/H₂O systems[J]. Journal of Hazardous Materials,2011,186(1):855-862. doi: 10.1016/j.jhazmat.2010.11.074
[42]	WANG Z, CHEN G H, WANG X R, et al. Removal of hexavalent chromium by bentonite supported organosolv lignin -stabilized zero-valent iron nanoparticles from wastewater[J]. Journal of Cleaner Production,2020,267:122009. doi: 10.1016/j.jclepro.2020.122009