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Mengfang Chen
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China

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Journal article
Published: 17 April 2021 in Science of The Total Environment
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The multiple injections of nanoscale zero valent iron (nZVI) slurry, an efficient method to remediate contaminated groundwater, requires an accurate assessment of the transport and risks of these particles in saturated porous medium. However, the influencing mechanism of nZVI transport under multiple injection conditions is not fully understood. In this experimental study, one-dimensional sand columns were used to evaluate the effects of injection concentrations, particle sizes and surface chemical corrosion on the transport of carboxymethyl cellulose modified nZVI (CMC-nZVI) under triple injection conditions, where the different volumes of NaCl solution were flushed through the columns between the injections. Based on the breakthrough curves and retention profiles under flushing 4 pore volumes of NaCl solution between the injections, the transport of CMC-nZVI particles was gradually enhanced attributable to the exclusion among these particles at injection concentration of 200 mg/L, but the opposite was observed due to large aggregation caused by strong magnetic force among particles at 500 mg/L. However, the magnitudes of enhancement or reduction on maximum C/C0 under the above injection concentrations were related to the smallest particle size of Dh = 3.926 μm because of high particle number concentrations leading to intense competition on depositional sites at 200 mg/L and significant aggregation at 500 mg/L. Conversely, the transport of CMC-nZVI was reduced under flushing 76 pore volumes of NaCl solution between the injections because of pronounced corrosion of CMC-nZVI in water as evidenced by the XPS and XRD analyses of particles. This corrosion could cause the decrease in repulsion among particles due to the increase in surface negative zeta potential and the CMC desorption from nZVI. Accordingly, this study revealed that relative high injection concentrations and chemical corrosion in groundwater could restrain the mobility of nZVI under multiple injection conditions and the potential risks posed by CMC-nZVI are controllable.

ACS Style

Wenpei Wu; Lu Han; Xiang Nie; Mingyue Gu; Jing Li; Mengfang Chen. Effects of multiple injections on the transport of CMC-nZVI in saturated sand columns. Science of The Total Environment 2021, 784, 147160 .

AMA Style

Wenpei Wu, Lu Han, Xiang Nie, Mingyue Gu, Jing Li, Mengfang Chen. Effects of multiple injections on the transport of CMC-nZVI in saturated sand columns. Science of The Total Environment. 2021; 784 ():147160.

Chicago/Turabian Style

Wenpei Wu; Lu Han; Xiang Nie; Mingyue Gu; Jing Li; Mengfang Chen. 2021. "Effects of multiple injections on the transport of CMC-nZVI in saturated sand columns." Science of The Total Environment 784, no. : 147160.

Journal article
Published: 10 December 2020 in Journal of Hazardous Materials
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Layered double hydroxide (LDH) with the metal composition of Cu(II)Mg(II)Fe(III) was prepared as an adsorbent for fast adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA). 84% of PFOS and 48% of PFOA in relation to the equilibrium state were adsorbed in the first minutes of contact with 0.1 g/L of suspended µm-sized LDH particles. The adsorption mechanisms of PFOS and PFOA on the CuMgFe-LDH were interpreted. Hydrophobic interactions were primarily responsible for the adsorption of these compounds in accordance with the different adsorption affinities of long-chain (C8, Kd = 105 L/kg) and short-chain (C4, Kd = 102 L/kg) perfluorinated carboxylic acids. PFOA adsorption on CuMgFe-LDH was strongly suppressed under alkaline conditions while PFOS uptake was only slightly affected in the pH range from 4.3 to 10.7, indicating a significant role of electrostatic interactions for PFOA adsorption. The adsorption of PFOS and PFOA was rather insensitive to competition by monovalent anions. The previously reported ‘memory effect’ of calcined CuMgFe-LDH for sorption of organic anions was not confirmed in the present study. Spent CuMgFe-LDH could be easily regenerated by extraction with 50 vol% methanol in water within 1 h and maintained a high PFOS removal in subsequent usage cycles.

ACS Style

Yun Chen; Anett Georgi; Wenying Zhang; Frank-Dieter Kopinke; Jingchun Yan; Navid Saeidi; Jing Li; Mingyue Gu; Mengfang Chen. Mechanistic insights into fast adsorption of perfluoroalkyl substances on carbonate-layered double hydroxides. Journal of Hazardous Materials 2020, 408, 124815 .

AMA Style

Yun Chen, Anett Georgi, Wenying Zhang, Frank-Dieter Kopinke, Jingchun Yan, Navid Saeidi, Jing Li, Mingyue Gu, Mengfang Chen. Mechanistic insights into fast adsorption of perfluoroalkyl substances on carbonate-layered double hydroxides. Journal of Hazardous Materials. 2020; 408 ():124815.

Chicago/Turabian Style

Yun Chen; Anett Georgi; Wenying Zhang; Frank-Dieter Kopinke; Jingchun Yan; Navid Saeidi; Jing Li; Mingyue Gu; Mengfang Chen. 2020. "Mechanistic insights into fast adsorption of perfluoroalkyl substances on carbonate-layered double hydroxides." Journal of Hazardous Materials 408, no. : 124815.

Journal article
Published: 02 December 2020 in Chemosphere
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The attapulgite of different morphologies and mineral compositions were successfully obtained following the treatment by HCl and HF with different concentrations. Variations of morphologies, elemental and mineral components of the pristine and modified attapulgite were investigated and assessed in detail by a series of characterization methods. The SEM-EDS results indicated significant variations on the contents and morphologies of silicon after acid modification. The Cr(VI) removal efficiencies under pristine and modified attapulgite-supported nZVI composites were evaluated with the removal rate in case of 0.5HAT-nZVI being 69.2% more superior than that of 6FAT-nZVI. The reaction kinetic is well fitted with pseudo second order kinetics model. The correlation analysis indicated that Cr(VI) removal efficiency was positively correlated with the content of active silicon in the attapulgite-nZVI composites (R2 = 0.979∗∗). Additionally, the reduction of Cr(VI) is more likely to occur in silicon-rich composites based on the analysis of XPS spectra and Cr concentration changes, which were mainly attributed to the enhanced Si–O–Fe coupling mediated by silicon. Attapulgite with more exposure sites of silicon enhanced the Cr(VI) reduction process and promoted crystallization of the reaction products. Simultaneously, the nZVI consumption caused by oxidation and aggregation were improved by silicon in attapulgite. It is concluded that silicon played a significant role on Cr(VI) removal through the reductive precipitation by Si–O–Fe coupling.

ACS Style

Wenying Zhang; Linbo Qian; Yun Chen; Da Ouyang; Lu Han; Xiao Shang; Jing Li; Mingyue Gu; Mengfang Chen. Nanoscale zero-valent iron supported by attapulgite produced at different acid modification: Synthesis mechanism and the role of silicon on Cr(VI) removal. Chemosphere 2020, 267, 129183 .

AMA Style

Wenying Zhang, Linbo Qian, Yun Chen, Da Ouyang, Lu Han, Xiao Shang, Jing Li, Mingyue Gu, Mengfang Chen. Nanoscale zero-valent iron supported by attapulgite produced at different acid modification: Synthesis mechanism and the role of silicon on Cr(VI) removal. Chemosphere. 2020; 267 ():129183.

Chicago/Turabian Style

Wenying Zhang; Linbo Qian; Yun Chen; Da Ouyang; Lu Han; Xiao Shang; Jing Li; Mingyue Gu; Mengfang Chen. 2020. "Nanoscale zero-valent iron supported by attapulgite produced at different acid modification: Synthesis mechanism and the role of silicon on Cr(VI) removal." Chemosphere 267, no. : 129183.

Journal article
Published: 04 August 2020 in Science of The Total Environment
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Dissolved black carbon (DBC) is becoming increasingly concerned by researchers due to its unique environmental behavior. However, understanding of the influence mechanism of biopolymer compositions of cellulose (CEL), hemicellulose (HEM) and lignin (LIG) on the formation and physiochemical characteristics of DBC from lignocellulose-based biochar is limited. This study therefore examined the formation of DBCs derived from the biopolymer compositions, corn straw (CS), corncob (CC), bamboo sawdust (BS) and pinewood sawdust (PS) under the heat treatment temperatures (HTTs) of 300–500 °C. Zeta potential and hydrodynamic diameters (Dh) of DBCs produced under 300 °C were further investigated. DBC formation may be closely associated with the HTT-dependent heterogeneities of biopolymer compositions, in which significant effects of CEL and HEM charring on physiochemical properties of DBCs were identified under the HTT of 300 and 400 °C, while the formation of DBCs was closely related to LIG and its proportions in biomass under high HTT (>500 °C). On the rise of the HTT, the carbonaceous structures of biopolymer compositions were reorganized and converted to graphitic structures in biochar accompanied by the large decomposition or carbonization of CEL and HEM, leading to the reduced carbon content, surface functional groups, aromaticity and molecular weight of DBCs, as well as the decrease of protein-like and relative increase of fulvic-like fluorescent substances in most DBCs. LIG in biomass may facilitate the migration of DBCs due to abundant surface negative charges and the formation of low Dh. This study offered new insights into our understanding of influencing mechanisms of biopolymer compositions on the characteristic of DBCs under different HTTs.

ACS Style

Lu Han; Xiang Nie; Jing Wei; Mingyue Gu; Wenpei Wu; Mengfang Chen. Effects of feedstock biopolymer compositions on the physiochemical characteristics of dissolved black carbon from lignocellulose-based biochar. Science of The Total Environment 2020, 751, 141491 .

AMA Style

Lu Han, Xiang Nie, Jing Wei, Mingyue Gu, Wenpei Wu, Mengfang Chen. Effects of feedstock biopolymer compositions on the physiochemical characteristics of dissolved black carbon from lignocellulose-based biochar. Science of The Total Environment. 2020; 751 ():141491.

Chicago/Turabian Style

Lu Han; Xiang Nie; Jing Wei; Mingyue Gu; Wenpei Wu; Mengfang Chen. 2020. "Effects of feedstock biopolymer compositions on the physiochemical characteristics of dissolved black carbon from lignocellulose-based biochar." Science of The Total Environment 751, no. : 141491.

Journal article
Published: 21 January 2020 in Environmental Pollution
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Nano-magnetite supported by biochar (nFe3O4/BC) pyrolyzed at temperatures of 300 °C–600 °C was developed to activate hydrogen peroxide (H2O2) for the efficient degradation of ethylbenzene in aqueous solution. It was revealed that the degradation efficiency of ethylbenzene and TOC removal were 96.9% and 36.2% respectively after the reaction for 40 min in the presence of initial concentration of 0.1 mmol L−1 ethylbenzene, 2.76 g L−1 nFe3O4/BC500 with the mass ratio of nFe3O4 to BC500 of 4:1 and 2.0 mmol L−1 H2O2 at pH 7.0. Based on electron paramagnetic resonance (EPR), quenching experiment and X-ray photoelectron spectroscopy (XPS) data, both OH and O2- radicals were generated in the nFe3O4/BC500 activated H2O2 system, and the OH radicals were the predominant species for the degradation of ethylbenzene. Through electron transfer process, mechanisms of Fe(II), phenolic hydroxyl group and persistent free radicals (PFRs) on BC surfaces accounted for the generation of OH radicals, and Fe(III) in nFe3O4 and formed from Fe(II) oxidation responsible for the generation of O2- radicals in the nFe3O4/BC activated H2O2 system were proposed.

ACS Style

Jingchun Yan; Lei Yang; Linbo Qian; Lu Han; Mengfang Chen. Nano-magnetite supported by biochar pyrolyzed at different temperatures as hydrogen peroxide activator: Synthesis mechanism and the effects on ethylbenzene removal. Environmental Pollution 2020, 261, 114020 .

AMA Style

Jingchun Yan, Lei Yang, Linbo Qian, Lu Han, Mengfang Chen. Nano-magnetite supported by biochar pyrolyzed at different temperatures as hydrogen peroxide activator: Synthesis mechanism and the effects on ethylbenzene removal. Environmental Pollution. 2020; 261 ():114020.

Chicago/Turabian Style

Jingchun Yan; Lei Yang; Linbo Qian; Lu Han; Mengfang Chen. 2020. "Nano-magnetite supported by biochar pyrolyzed at different temperatures as hydrogen peroxide activator: Synthesis mechanism and the effects on ethylbenzene removal." Environmental Pollution 261, no. : 114020.

Journal article
Published: 09 December 2019 in International Journal of Environmental Research and Public Health
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With abundant oxygen-containing functional groups, a humic substance (HS) has a high potential to remediate soils contaminated by heavy metals. Here, HS was first extracted from a leonardite and analyzed for its chemical compositions and spectroscopic characteristics. Then it was assessed for its ability as a washing agent to remove Cd and As from three types of soils (red soil, black soil, and fluvo-aquic soil) that were spiked with those contaminants (Cd: 40.5–49.1 mg/kg; As: 451–584 mg/kg). The operational washing conditions, including the pH and concentration of the HS, washing time and cycles, and liquid–soil ratio, were assessed for Cd and As removal efficiency. At pH 7, with an HS concentration (3672 mg C/L) higher than its critical micelle concentration and a liquid–soil ratio of 30, a single washing for 6–12 h removed 41.9 mg Cd/kg and 199.3 mg As/kg from red soil, 33.5 mg Cd/kg and 291.5 mg As/kg from black soil, and 30.4 mg Cd/kg and 325.5 mg As/kg from fluvo-aquic soil. The removal of Cd and As from the contaminated soils involved the complexation of Cd and As with the carboxyl and phenolic groups of HS. Outcomes from this research could be used to develop a tailor-made HS washing agent for the remediation of Cd- and As-contaminated soils with different properties.

ACS Style

Dongxue Bi; Guodong Yuan; Jing Wei; Liang Xiao; Lirong Feng; Fande Meng; Jie Wang. A Soluble Humic Substance for the Simultaneous Removal of Cadmium and Arsenic from Contaminated Soils. International Journal of Environmental Research and Public Health 2019, 16, 4999 .

AMA Style

Dongxue Bi, Guodong Yuan, Jing Wei, Liang Xiao, Lirong Feng, Fande Meng, Jie Wang. A Soluble Humic Substance for the Simultaneous Removal of Cadmium and Arsenic from Contaminated Soils. International Journal of Environmental Research and Public Health. 2019; 16 (24):4999.

Chicago/Turabian Style

Dongxue Bi; Guodong Yuan; Jing Wei; Liang Xiao; Lirong Feng; Fande Meng; Jie Wang. 2019. "A Soluble Humic Substance for the Simultaneous Removal of Cadmium and Arsenic from Contaminated Soils." International Journal of Environmental Research and Public Health 16, no. 24: 4999.

Journal article
Published: 31 August 2019 in Science of The Total Environment
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The application of biochar-supported nanoscale zero-valent iron (biochar-nZVI) was successfully implemented in a field demonstration for the first time. To overcome the significant shortcomings of nZVI agglomeration for in-situ groundwater remediation, biochar-nZVI was injected into groundwater using direct-push and water pressure driven packer techniques for a site impacted by chlorinated solvents in the North China Plain. The field demonstration comprising two-step injections was implemented to demonstrate the effectiveness of nZVI and biochar-nZVI respectively. The outcome of the demonstration revealed a sharp reduction of contaminant concentrations of chlorinated solvents in 24 h following the first injection of nZVI, but the rebound of the concentrations of these contaminants in groundwater has occurred within the next two weeks. However, application of biochar-nZVI greatly enhanced the removal of chlorinated solvents in groundwater over the longer period of 42 days. The enhanced removal of chlorinated solvents in groundwater by biochar-nZVI is mainly attributed to the synergistic effects of adsorption and reduction. The adsorption by biochar significantly reduced the level of chlorinated solvents in groundwater. Overall increases in ferrous iron and chloride concentrations after the injections indicated that the reduction has occurred during the removal of chlorinated solvents in groundwater. In summary, biochar-supported nZVI could be potentially used for the effective remediation of chlorinated solvents in groundwater.

ACS Style

Linbo Qian; Yun Chen; Da Ouyang; Wenying Zhang; Lu Han; Jingchun Yan; Petr Kvapil; Mengfang Chen. Field demonstration of enhanced removal of chlorinated solvents in groundwater using biochar-supported nanoscale zero-valent iron. Science of The Total Environment 2019, 698, 134215 .

AMA Style

Linbo Qian, Yun Chen, Da Ouyang, Wenying Zhang, Lu Han, Jingchun Yan, Petr Kvapil, Mengfang Chen. Field demonstration of enhanced removal of chlorinated solvents in groundwater using biochar-supported nanoscale zero-valent iron. Science of The Total Environment. 2019; 698 ():134215.

Chicago/Turabian Style

Linbo Qian; Yun Chen; Da Ouyang; Wenying Zhang; Lu Han; Jingchun Yan; Petr Kvapil; Mengfang Chen. 2019. "Field demonstration of enhanced removal of chlorinated solvents in groundwater using biochar-supported nanoscale zero-valent iron." Science of The Total Environment 698, no. : 134215.

Journal article
Published: 30 May 2019 in Journal of Environmental Management
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To elucidate the effect of structure and property of biochar on the structure-activity relationship among the composites of biochar supported Pd/Fe and 1,2,4-trichlorobenzene (1,2,4-TCB) and its dechlorination products, biochar supported Pd/Fe nanoparticles with different mass ratios were investigated for the enhanced removal of 1,2,4-TCB (52 μmol/L) and its dechlorination products. 1,2,4-TCB was removed through the electrochemical dechlorination by Pd/Fe and adsorption by biochar simultaneously. As the mass ratio of CS700 to Pd/Fe was 0.1:1, biochar within the Pd/Fe-CS7000.1 system played a significant role in the adsorption of 1,2,4-TCB. However, there is little adsorption to biochar for dechlorination products due to strong competition by 1,2,4-TCB. As the mass ratio of CS700 to Pd/Fe was increased to 5:1, 1,2,4-TCB was completely removed from the solution by the composites within 0.5 h. The dechlorination products (1,2-DCB, MCB, benzene and trace 1,3-DCB) were completely sequestered on solid phase but absent in aqueous solution. However, the excessive biochar increased the inaccessibility of 1,2,4-TCB or decreased the reactive sites of Pd/Fe leading to the less dechlorination of 1,2,4-TCB. The alkaline biochar did not influence the chemical reactivity of Pd/Fe in the composites and buffered the acid and alkaline solutions with pH being maintained at neutral conditions under initial pH ranging from 3.07 to 10.03. The highly hydrophobicity of biochar could maintain the affinity of the composite for the chlorinated compounds even if the concentration of 1,2,4-TCB was up to 80.9% of its aqueous solubility. This study provides efficient synergistic removal support for the treatment of TCB affected groundwater.

ACS Style

Lu Han; Jingchun Yan; Linbo Qian; Wenying Zhang; Mengfang Chen. Multifunctional Pd/Fe-biochar composites for the complete removal of trichlorobenzene and its degradation products. Journal of Environmental Management 2019, 245, 238 -244.

AMA Style

Lu Han, Jingchun Yan, Linbo Qian, Wenying Zhang, Mengfang Chen. Multifunctional Pd/Fe-biochar composites for the complete removal of trichlorobenzene and its degradation products. Journal of Environmental Management. 2019; 245 ():238-244.

Chicago/Turabian Style

Lu Han; Jingchun Yan; Linbo Qian; Wenying Zhang; Mengfang Chen. 2019. "Multifunctional Pd/Fe-biochar composites for the complete removal of trichlorobenzene and its degradation products." Journal of Environmental Management 245, no. : 238-244.

Journal article
Published: 26 March 2019 in Chemical Engineering Journal
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Carbonaceous materials have been emerged as promising metal-free catalysts to activate peroxymonosulfate (PMS) for the degradation of organic contaminants. In the present study, a low-cost carbonaceous material, pine needle biochar was prepared under the oxygen limited pyrolyzation process and applied to activate PMS for the catalytic degradation of potentially carcinogenic 1,4-dioxane. Based on the batch experiments, the pyrolysis temperature has a significant influence on the potency of biochar to activate PMS. Within the biochar/PMS system, the degradation efficiencies of 1,4-dioxane were increased from 4.1 to 84.2% when the biochar pyrolysis temperatures were increased from 300 oC to 800 oC. Electron paramagnetic resonance (EPR) study and the quenching experiment verified that the dominant free radical within the system of biochar/PMS was •OH. The EPR combined X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) and Raman analysis implied that the defect of biochar contributed to the generation of SO4•- and •OH and high pyrolysis temperatures would eliminate the excess of oxygen functional groups in biochar, which could modulate and transform sp3 carbons, generating more defect structures, therefore, enhancing the activation potency of biochar towards PMS. Simultaneously, five major intermediates were identified and three possible degradation pathways were proposed in this study. In addition, 71.4% and 57.5% of 1,4-dioxane removal rates were achieved in 1,4-dioxane contaminated tap water and groundwater, indicating that biochar activating PMS is a promising technique for the remediation of 1,4-dioxane contaminated water.

ACS Style

Da Ouyang; Yun Chen; Jingchun Yan; Linbo Qian; Lu Han; Mengfang Chen. Activation mechanism of peroxymonosulfate by biochar for catalytic degradation of 1,4-dioxane: Important role of biochar defect structures. Chemical Engineering Journal 2019, 370, 614 -624.

AMA Style

Da Ouyang, Yun Chen, Jingchun Yan, Linbo Qian, Lu Han, Mengfang Chen. Activation mechanism of peroxymonosulfate by biochar for catalytic degradation of 1,4-dioxane: Important role of biochar defect structures. Chemical Engineering Journal. 2019; 370 ():614-624.

Chicago/Turabian Style

Da Ouyang; Yun Chen; Jingchun Yan; Linbo Qian; Lu Han; Mengfang Chen. 2019. "Activation mechanism of peroxymonosulfate by biochar for catalytic degradation of 1,4-dioxane: Important role of biochar defect structures." Chemical Engineering Journal 370, no. : 614-624.

Journal article
Published: 27 February 2019 in Chemosphere
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A high catalytic system using Cu layered double hydrotalcite (Cu(II)-Mg(II)-Fe(III)LDHs) and hydrogen peroxide (H2O2) was developed for the degradation of ethylbenzene. It was identified that the degradation efficiency of ethylbenzene (0.08 mmol L−1) and TOC removal were 96.1% and 39.7% respectively in the presence of 0.1 g L−1 Cu(II)-Mg(II)-Fe(III)LDHs with (Cu2+ + Mg2+)/Fe3+ molar ratio of 5.0 and 0.16 mmol L−1 H2O2 in 6.0 h. Based on ESR and XPS data, hydroxyl radicals (•OH) were the predominant free radical specials generated from the catalytic decomposition of H2O2 for the degradation of ethylbenzene. The redox of Cu(II)/Cu(III) on the layered Cu(II)-Mg(II)-Fe(III)LDHs surface active sites accounted for the formation of •OH radicals and the cycle of Cu(II) in the Cu(II)-Mg(II)-Fe(III)LDHs/H2O2 system were proposed.

ACS Style

Jingchun Yan; Yudong Chen; Weiguo Gao; Yun Chen; Linbo Qian; Lu Han; Mengfang Chen. Catalysis of hydrogen peroxide with Cu layered double hydrotalcite for the degradation of ethylbenzene. Chemosphere 2019, 225, 157 -165.

AMA Style

Jingchun Yan, Yudong Chen, Weiguo Gao, Yun Chen, Linbo Qian, Lu Han, Mengfang Chen. Catalysis of hydrogen peroxide with Cu layered double hydrotalcite for the degradation of ethylbenzene. Chemosphere. 2019; 225 ():157-165.

Chicago/Turabian Style

Jingchun Yan; Yudong Chen; Weiguo Gao; Yun Chen; Linbo Qian; Lu Han; Mengfang Chen. 2019. "Catalysis of hydrogen peroxide with Cu layered double hydrotalcite for the degradation of ethylbenzene." Chemosphere 225, no. : 157-165.

Journal article
Published: 12 January 2019 in Chemosphere
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The attapulgite supported nanoscale zero-valent iron composite (AT-nZVI) was synthesized and used for Cr(VI) removal. X-ray diffraction (XRD) and transmission electron microscope (TEM) indicated that nZVI particles were well distributed and immobilized on the attapulgite surface. Batch experiments of Cr(VI) removal were conducted at varying mass ratios, initial Cr(VI) concentrations and kinetics. The results indicated that the removal efficiency of Cr(VI) by AT-nZVI approaches 90.6%, being greater than that by non-supported nZVI (62.9%). The removal kinetics could be more accurately explained using the pseudo second order kinetics model. The composite exhibited a synergistic interaction instead of simple mixture of AT and nZVI. Reduction was the dominant mechanism at low concentrations as opposed to adsorption at high concentrations. FeCr2O4 was the main reduction product by AT-nZVI, which was attributed to the reduction of Cr(VI) by nZVI and co-precipitation of CrFe oxides on the surface of AT. In the meantime, Fe(II) ion contributed to 64% for the Cr(VI) removal, which resulted from the dissolution of nZVI during the removal process. From the analysis of XRD and XPS results, the crystallization of FeCr2O4 is believed to be formed easily after the reaction of the AT-nZVI composite with Cr(VI) which is more stable and greatly reduce the risk of secondary pollution compared with nZVI. The introduction of AT enhanced adsorption of Cr(VI) and crystallization of the products. The above results suggested that AT-nZVI could be a promising remediation material for Cr(VI)-contaminated groundwater.

ACS Style

Wenying Zhang; Linbo Qian; Da Ouyang; Yun Chen; Lu Han; Mengfang Chen. Effective removal of Cr(VI) by attapulgite-supported nanoscale zero-valent iron from aqueous solution: Enhanced adsorption and crystallization. Chemosphere 2019, 221, 683 -692.

AMA Style

Wenying Zhang, Linbo Qian, Da Ouyang, Yun Chen, Lu Han, Mengfang Chen. Effective removal of Cr(VI) by attapulgite-supported nanoscale zero-valent iron from aqueous solution: Enhanced adsorption and crystallization. Chemosphere. 2019; 221 ():683-692.

Chicago/Turabian Style

Wenying Zhang; Linbo Qian; Da Ouyang; Yun Chen; Lu Han; Mengfang Chen. 2019. "Effective removal of Cr(VI) by attapulgite-supported nanoscale zero-valent iron from aqueous solution: Enhanced adsorption and crystallization." Chemosphere 221, no. : 683-692.

Journal article
Published: 12 October 2018 in Chemosphere
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Silicon-rich biochar-supported nanoscale zero-valent iron (nZVI) was studied to evaluate enhanced removal of hexavalent chromium (Cr(VI)) in solution. The compositional structures of the nZVI and biochar-supported nZVI were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectra before and after Cr(VI) reaction. The removal amount of Cr(VI) by nZVI-RS700 (rice straw pyrolyzed at 700 °C) was considerably greater than that by nZVI and other biochar-supported nZVI samples. Upon the silicon was removed from RS700 (nZVI-RS700(-Si)), a significant decreased removal of Cr(VI) was observed. It was revealed that nZVI supported by silicate particles of biochar and the promotion of iron oxidation by SiO2 both contribute to the enhanced Cr(VI) removal. We found that the reduction and adsorption both contributed to the removal of Cr(VI), ferrous chromite (FeCr2O4) was observed on the surface of the nZVI-RS700 composite. The formation of FeCr2O4 is attributed to the reduction of Cr(VI) by nZVI and the adsorption of chromium oxide with iron on the surface of RS700. Therefore, RS700-supported nZVI can be used as a potential remediation reagent to treat Cr(VI)-contaminated groundwater.

ACS Style

Linbo Qian; Xiao Shang; Bo Zhang; Wenying Zhang; Anqi Su; Yun Chen; Da Ouyang; Lu Han; Jingchun Yan; Mengfang Chen. Enhanced removal of Cr(VI) by silicon rich biochar-supported nanoscale zero-valent iron. Chemosphere 2018, 215, 739 -745.

AMA Style

Linbo Qian, Xiao Shang, Bo Zhang, Wenying Zhang, Anqi Su, Yun Chen, Da Ouyang, Lu Han, Jingchun Yan, Mengfang Chen. Enhanced removal of Cr(VI) by silicon rich biochar-supported nanoscale zero-valent iron. Chemosphere. 2018; 215 ():739-745.

Chicago/Turabian Style

Linbo Qian; Xiao Shang; Bo Zhang; Wenying Zhang; Anqi Su; Yun Chen; Da Ouyang; Lu Han; Jingchun Yan; Mengfang Chen. 2018. "Enhanced removal of Cr(VI) by silicon rich biochar-supported nanoscale zero-valent iron." Chemosphere 215, no. : 739-745.

Journal article
Published: 23 August 2018 in Journal of Colloid and Interface Science
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The potential of silicon-rich biochar and Pd were evaluated for the enhanced removal of Cr(VI) in solution by nanoscale zero-valent iron (nZVI) composites. The composition and structures of the nZVI, RS700-supported nZVI, and Pd-doped samples were analyzed by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy before and after reaction with Cr(VI). The amount of Cr(VI) removed by nZVI-RS700-Pd was considerably greater than the removal by nZVI, nZVI-Pd, or nZVI-RS700. This was mainly due to the enhanced reduction and adsorption of Cr(VI) by silicon-rich biochar and Pd. Silicon and Pd promoted the reduction of Cr(VI) due to the Fe0 crystallinity in the nZVI structures. The significantly decreased removal of Cr(VI) by the silicon-removed sample (nZVI-RS700 (-Si)) further confirmed that silicon played a significant role in the removal of Cr(VI). Cr(VI) adsorption was enhanced by the dispersion and adsorption of RS700. Following the reaction of RS700-supported nZVI with Cr(VI), ferrous chromite (FeCr2O4) was observed on the nZVI-RS700 composite surface. The formation of FeCr2O4 can be attributed to the reduction of Cr(VI) by the nZVI and coprecipitation of chromium oxide with iron on the RS700 surface. Therefore, nZVI-RS700-Pd is a potential remediation reagent that can be used to effectively treat Cr(VI)-contaminated groundwater.

ACS Style

Linbo Qian; Sining Liu; Wenying Zhang; Yun Chen; Da Ouyang; Lu Han; Jingchun Yan; Mengfang Chen. Enhanced reduction and adsorption of hexavalent chromium by palladium and silicon rich biochar supported nanoscale zero-valent iron. Journal of Colloid and Interface Science 2018, 533, 428 -436.

AMA Style

Linbo Qian, Sining Liu, Wenying Zhang, Yun Chen, Da Ouyang, Lu Han, Jingchun Yan, Mengfang Chen. Enhanced reduction and adsorption of hexavalent chromium by palladium and silicon rich biochar supported nanoscale zero-valent iron. Journal of Colloid and Interface Science. 2018; 533 ():428-436.

Chicago/Turabian Style

Linbo Qian; Sining Liu; Wenying Zhang; Yun Chen; Da Ouyang; Lu Han; Jingchun Yan; Mengfang Chen. 2018. "Enhanced reduction and adsorption of hexavalent chromium by palladium and silicon rich biochar supported nanoscale zero-valent iron." Journal of Colloid and Interface Science 533, no. : 428-436.

Journal article
Published: 01 October 2017 in Chemosphere
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Nano magnetite biochar composite (nFe3O4/biochar) was synthesized and used to activate persulfate for the degradation of 1,4-dioxane. Analytical techniques using X-ray diffraction (XRD), fourier transform infrared analysis (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated that nFe3O4 was spherical and successfully loaded onto the surface of biochar. The results of batch-scale experiments illustrated that the 1,4-dioxane degradation efficiency in aqueous phase was 98.0% after 120 min reaction with the composite mass ratio of 1:1 between nFe3O4 and the pine needle biochar pyrolyzed at 400 °C (P400) under the initial neutral pH. An electron paramagnetic resonance (EPR) study, free radical quenching experiment and XPS analysis were undertaken to illustrate the mechanism of persulfate activation by nFe3O4/biochar. Under acidic and neutral conditions, the predominant free radical was SO4(-) whereas OH and SO4(-) predominated when the initial pH was 9.0. The XPS analysis indicated that Fe(II) and oxygenated functional groups activated persulfate. In addition, carbon-carbon double bonds would be transformed into ketone and quinone which could activate persulfate during the reaction.

ACS Style

Da Ouyang; Jingchun Yan; Linbo Qian; Yun Chen; Lu Han; Anqi Su; Wenying Zhang; Hao Ni; Mengfang Chen. Degradation of 1,4-dioxane by biochar supported nano magnetite particles activating persulfate. Chemosphere 2017, 184, 609 -617.

AMA Style

Da Ouyang, Jingchun Yan, Linbo Qian, Yun Chen, Lu Han, Anqi Su, Wenying Zhang, Hao Ni, Mengfang Chen. Degradation of 1,4-dioxane by biochar supported nano magnetite particles activating persulfate. Chemosphere. 2017; 184 ():609-617.

Chicago/Turabian Style

Da Ouyang; Jingchun Yan; Linbo Qian; Yun Chen; Lu Han; Anqi Su; Wenying Zhang; Hao Ni; Mengfang Chen. 2017. "Degradation of 1,4-dioxane by biochar supported nano magnetite particles activating persulfate." Chemosphere 184, no. : 609-617.

Research article
Published: 03 September 2017 in Environmental Science and Pollution Research
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Biochar produced from rice straw at 400 °C (RS400) was prepared to determine its alleviating effect on Cd phytotoxicity to wheat seedlings under different cultivation temperatures and pH. A hydroponic system (pH 4.3) and a loam soil slurry system were designed to respectively simulate acidic and neutral soil condition, and cultivation at increasing temperatures (20, 25, and 30 °C) were performed to evaluate the greenhouse effect. The root and shoot elongation and the Cd concentration in root and solution were measured; furthermore, batch experiments for Cd adsorption were undertaken. An increasing inhibition of the root by Cd addition was observed at increasing temperatures. The inhibition rate was 50.50 and 20.80% in hydroponic system and slurry system at 25 °C, respectively; however, the corresponding inhibition rates of root were significantly decreased to 25.5 and 3.5% with addition of RS400. This is mainly attributed to the reduction of Cd migration into the roots by RS400, which decreased Cd bioavailability. The mechanism behind the reduced Cd bioavailability is attributed to the Cd adsorption and the strong buffering capacity of acidity by RS400. Therefore, biochar could be a potential amendment for the remediation of Cd-contaminated soil even at increasing culturing temperatures.

ACS Style

Linbo Qian; Baoliang Chen; Lu Han; Jingchun Yan; Wenying Zhang; Anqi Su; Mengfang Chen. Effect of culturing temperatures on cadmium phytotoxicity alleviation by biochar. Environmental Science and Pollution Research 2017, 24, 23843 -23849.

AMA Style

Linbo Qian, Baoliang Chen, Lu Han, Jingchun Yan, Wenying Zhang, Anqi Su, Mengfang Chen. Effect of culturing temperatures on cadmium phytotoxicity alleviation by biochar. Environmental Science and Pollution Research. 2017; 24 (30):23843-23849.

Chicago/Turabian Style

Linbo Qian; Baoliang Chen; Lu Han; Jingchun Yan; Wenying Zhang; Anqi Su; Mengfang Chen. 2017. "Effect of culturing temperatures on cadmium phytotoxicity alleviation by biochar." Environmental Science and Pollution Research 24, no. 30: 23843-23849.

Journal article
Published: 01 September 2017 in Journal of Hazardous Materials
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CuMgFe layered double hydroxide (CuMgFe-LDH) was successfully synthesized and characterized as an efficient catalyst of persulfate (PS) for the degradation of ethylbenzene. Under the conditions of 0.2gL CuMgFe-LDH and 4.0mmolL persulfate at pH 7.6, the degradation efficiency of 0.08mmolL ethylbenzene was 93.7% with TOC removal efficiency of 65.2% in 24h, and the concentration of Cu leached into the solution was as low as 0.095mgL after the reaction. The reuse of CuMgFe-LDH showed that the catalyst was highly stable after 5 recycles. Electron Spin Resonance (ESR) test and free radical quenching experiment indicated that SO and OH radicals were the dominant species accounted for the degradation of ethylbenzene in the CuMgFe-LDH/persulfate system. Catalytic mechanism of the formation of a complex of Cu(II)OSOOSO and the subsequent redox cycle of Cu(II)/Cu(III) accounted for the generation of radicals was proposed.

ACS Style

Jingchun Yan; Yun Chen; Linbo Qian; Weiguo Gao; Da Ouyang; Mengfang Chen. Heterogeneously catalyzed persulfate with a CuMgFe layered double hydroxide for the degradation of ethylbenzene. Journal of Hazardous Materials 2017, 338, 372 -380.

AMA Style

Jingchun Yan, Yun Chen, Linbo Qian, Weiguo Gao, Da Ouyang, Mengfang Chen. Heterogeneously catalyzed persulfate with a CuMgFe layered double hydroxide for the degradation of ethylbenzene. Journal of Hazardous Materials. 2017; 338 ():372-380.

Chicago/Turabian Style

Jingchun Yan; Yun Chen; Linbo Qian; Weiguo Gao; Da Ouyang; Mengfang Chen. 2017. "Heterogeneously catalyzed persulfate with a CuMgFe layered double hydroxide for the degradation of ethylbenzene." Journal of Hazardous Materials 338, no. : 372-380.

Journals
Published: 22 August 2017 in RSC Advances
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In situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy was used to study the molecular kinetics of Cr(vi) reduction by citric acid at the α-Fe2O3–water interface.

ACS Style

W. G. Gao; X. C. Liu; M. F. Chen. In situ ATR-FTIR investigation and theoretical calculation of the interactions of chromate and citrate on the surface of haematite (α-Fe2O3). RSC Advances 2017, 7, 41011 -41016.

AMA Style

W. G. Gao, X. C. Liu, M. F. Chen. In situ ATR-FTIR investigation and theoretical calculation of the interactions of chromate and citrate on the surface of haematite (α-Fe2O3). RSC Advances. 2017; 7 (65):41011-41016.

Chicago/Turabian Style

W. G. Gao; X. C. Liu; M. F. Chen. 2017. "In situ ATR-FTIR investigation and theoretical calculation of the interactions of chromate and citrate on the surface of haematite (α-Fe2O3)." RSC Advances 7, no. 65: 41011-41016.

Journal article
Published: 01 April 2017 in Environmental Pollution
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Biochar-supported nanoscale zero-valent iron (nZVI) produced under different temperatures was studied to evaluate the effect of the nZVI-biochar composite on the removal of hexavalent chromium (Cr(VI)) in solution. The structure of biochar-supported nZVI and its roles in Cr(VI) removal were investigated by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and batch experiments. The XRD revealed that the removal rate of Cr(VI) for the nZVI supported by rice straw pyrolyzed at 400 °C (RS400) was much greater than that for other supporting biochar, and the FTIR further indicated that the carboxyl groups and silicon mineral within the biochar served as dual support sites for nZVI. NZVI-RS400 exhibited the highest removal amount of Cr(VI) at approximately 40.0 mg/g under an initial pH of 4.0, possibly due to both the reduction and adsorption processes. Therefore, the RS400-supported nanoscale zero-valent iron could be a preferable material for Cr(VI)-contaminated groundwater.

ACS Style

Linbo Qian; Wenying Zhang; Jingchun Yan; Lu Han; Yun Chen; Da Ouyang; Mengfang Chen. Nanoscale zero-valent iron supported by biochars produced at different temperatures: Synthesis mechanism and effect on Cr(VI) removal. Environmental Pollution 2017, 223, 153 -160.

AMA Style

Linbo Qian, Wenying Zhang, Jingchun Yan, Lu Han, Yun Chen, Da Ouyang, Mengfang Chen. Nanoscale zero-valent iron supported by biochars produced at different temperatures: Synthesis mechanism and effect on Cr(VI) removal. Environmental Pollution. 2017; 223 ():153-160.

Chicago/Turabian Style

Linbo Qian; Wenying Zhang; Jingchun Yan; Lu Han; Yun Chen; Da Ouyang; Mengfang Chen. 2017. "Nanoscale zero-valent iron supported by biochars produced at different temperatures: Synthesis mechanism and effect on Cr(VI) removal." Environmental Pollution 223, no. : 153-160.

Research article
Published: 28 December 2016 in Environmental Science and Pollution Research
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Adsorption behaviors of the chlorinated organic compounds (COCs) (i.e., trichloroethylene (TCE), 1,2,4-trichlorobenzene (1,2,4-TCB); 1,2-dichlorobenzene (1,2-DCB); and monochlorobenzene (MCB)) by the commercial rice husk-based biochar (RH500) and the laboratory-prepared biochars from corn stalks under different pyrolytic temperatures (i.e., CS300, CS500, CS700) were examined and interpreted by the pseudo-first-order kinetic model, the double layer model with two energies, and the Freundlich model. It is identified that the first-order adsorption rate constants (k 1 = 0.06∼0.51 h-1) were proportional to the high aromaticity and/or low polarity of biochars and the strong hydrophobicity of the COCs. The saturated adsorption capacity for the COCs was followed by the order of RH500 > CS500 > CS700 > CS300. RH500 showed the highest adsorption capacity for the COCs due to its high surface area (SA) and total pore volume (TPV). However, CS500 with low SA and TPV development highlighted the important roles of the aromaticity and/or low polarity on the COCs adsorption. In addition, 1,2,4-TCB showed the highest saturated adsorption capacity on all biochars, followed by TCE, 1,2-DCB, and MCB. The results further revealed the positive effects of the physical properties (α, N M, ε 1, and ε 2), the hydrophobicity and electrostatic forces (i.e., π-π interaction and electron donor-acceptor interaction) between the adsorbates and the aromatic moieties of biochar surfaces on the adsorption of COCs.

ACS Style

Lu Han; Linbo Qian; Jingchun Yan; Mengfang Chen. Effects of the biochar aromaticity and molecular structures of the chlorinated organic compounds on the adsorption characteristics. Environmental Science and Pollution Research 2016, 24, 5554 -5565.

AMA Style

Lu Han, Linbo Qian, Jingchun Yan, Mengfang Chen. Effects of the biochar aromaticity and molecular structures of the chlorinated organic compounds on the adsorption characteristics. Environmental Science and Pollution Research. 2016; 24 (6):5554-5565.

Chicago/Turabian Style

Lu Han; Linbo Qian; Jingchun Yan; Mengfang Chen. 2016. "Effects of the biochar aromaticity and molecular structures of the chlorinated organic compounds on the adsorption characteristics." Environmental Science and Pollution Research 24, no. 6: 5554-5565.

Journal article
Published: 01 August 2016 in Chemosphere
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In order to investigate contributions of cellulose (CEL), hemicellulose (HEM), lignin (LIG) to the sorption capacity of biochar derived from lignocellulose, the individual component and their artificially modeled biomass mixture (C-H-L) were pyrolyzed under oxygen-limited condition at various pyrolytic temperatures (i.e. 250, 350, 500, 700 °C). The characterization analysis of biochars and sorption batch experiments were carried out. Variations in physiochemical property of different component biochars resulted in discrepancies in their ability to function as sorbents to 1,2,4-trichlorobenzene (1,2,4-TCB). The maximum mass sorption capacity (Qfm) of 1,2,4-TCB was the greatest on CEL biochars ranging from 58.31 to 601.20 mg g(-1), and can be best explained by their huge surface area and micropore volume. Hydrophobic partitioning-sorption into 'soft' amorphous alkyl carbon may account for the second greatest Qfm (45.09-56.57 mg g(-1)) on HEM biochars under low pyrolytic temperatures (250-350 °C) with the lowest surface area. LIG biochars with more compact and smooth aromatic structure surface may undergo a surface monolayer specific adsorption. The Qfm (87.86-196.53 mg g(-1)) on C-H-L biochars were largely dependent on CEL and HEM components for their outstanding sorption capacity and higher content in biomass. Therefore, the results highlighted the importance of CEL and HEM components for 1,2,4-TCB sorption to biochar.

ACS Style

Lu Han; Linbo Qian; Jingchun Yan; Mengfang Chen. Contributions of different biomass components to the sorption of 1,2,4-trichlorobenzene under a series of pyrolytic temperatures. Chemosphere 2016, 156, 262 -271.

AMA Style

Lu Han, Linbo Qian, Jingchun Yan, Mengfang Chen. Contributions of different biomass components to the sorption of 1,2,4-trichlorobenzene under a series of pyrolytic temperatures. Chemosphere. 2016; 156 ():262-271.

Chicago/Turabian Style

Lu Han; Linbo Qian; Jingchun Yan; Mengfang Chen. 2016. "Contributions of different biomass components to the sorption of 1,2,4-trichlorobenzene under a series of pyrolytic temperatures." Chemosphere 156, no. : 262-271.