Publications by authors named "Shengsen Wang"

25 Publications

  • Page 1 of 1

Modification of ordered mesoporous carbon for removal of environmental contaminants from aqueous phase: A review.

J Hazard Mater 2021 May 30;418:126266. Epub 2021 May 30.

College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou 225127, Jiangsu, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, China. Electronic address:

Contamination of water bodies by potentially toxic elements and organic pollutants has aroused extensive concerns worldwide. Thus it is significant to develop effective adsorbents for removing these contaminants. As a new member of carbonaceous material families (activated carbon, biochar, and graphene), ordered mesoporous carbon (OMC) with larger specific surface area, ordered pore structure, and higher pore volume are being evaluated for their use in contaminant removal. In this paper, modification techniques of OMC were systematically reviewed for the first time. These include nonmetallic doping modification (nitrogen, sulfur, and boron) and the impregnation of nano-metals and metal oxides (iron, copper, cobalt, nickel, magnesium, and rare earth element). Reaction conditions (solution pH, reaction temperature, sorbent dosage, and contact time) are of critical importance for the removal performance of contaminants onto OMC. In addition, the pristine and modified OMC have been investigated for the removal of a range of contaminants, including cationic/anionic toxic elements and organic contaminants (synthetic dye, phenol, and others), and involving different and specific mechanisms of interaction with contaminants. The future research directions of the application of pristine and modified OMC were proposed. Overall, this review can provide sights into the modification techniques of OMC for removal of environmental contaminants.
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http://dx.doi.org/10.1016/j.jhazmat.2021.126266DOI Listing
May 2021

ZVI impregnation altered arsenic sorption by ordered mesoporous carbon in presence of Cr(Ⅵ): A mechanistic investigation.

J Hazard Mater 2021 07 24;414:125507. Epub 2021 Feb 24.

College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou 225127, PR China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, PR China. Electronic address:

It is challenging to efficiently remove arsenate (As(Ⅴ)) and chromate (Cr(Ⅵ)) simultaneously. Herein, ordered mesoporous carbon (OMC) was fabricated with averaged pore diameter of 6.5 nm and surface area of 997 m g. Zerovalent iron (ZVI) impregnation reduced surface area of ZVI/OMC (432 m g) and increased I/I ratio by 13%. Maximal Cr(Ⅵ) and As(Ⅴ) sorption capacities at pH 3 were 0.66 and 0.019 mmol g by OMC, and 0.71 and 0.39 mmol g by ZVI/OMC, respectively. Reduction accounted for over 55% for Cr(Ⅵ) and As(Ⅴ) removal followed by complexation and precipitation. Better ZVI/OMC performance was ascribed to higher electron transfer rate and lower electrical resistance than OMC as per electrochemical analysis. Upon Cr(Ⅵ) introduction, As(Ⅴ) removal increased to 0.28 mmol g by OMC, but decreased to 0.16 mmol g by ZVI/OMC. OMC could preferably reduce CrO to Cr by hydroxyl group, which enhanced its zeta potential facilitating As(Ⅴ) sorption. Regarding ZVI/OMC, Fe and Fe oxide in ZVI/OMC exhibited better affinity to As(Ⅴ), but the competition for the similar active sites resulted in compromised As(Ⅴ) and Cr(Ⅵ) removal. Thus, the novel OMC is advantageous for removal of binary As(Ⅴ) and Cr(Ⅵ), but ZVI/OMC is robust to detoxify single heavy metal.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125507DOI Listing
July 2021

Preparation of biochar-interpenetrated iron-alginate hydrogel as a pH-independent sorbent for removal of Cr(VI) and Pb(II).

Environ Pollut 2021 May 10;287:117303. Epub 2021 May 10.

Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops/Agricultural College, Yangzhou University, Yangzhou, 225009, PR China.

Herein, a pH-independent interpenetrating polymeric networks (Fe-SA-C) were fabricated from graphitic biochar (BC) and iron-alginate hydrogel (Fe-SA) for removal of Cr(VI) and Pb(II) in aqueous solution. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and scanning electron microscope (SEM) results demonstrated that graphitic BC interpenetration increased surface porosity and distorted surfaces of Fe-SA, which boosted availability of hydroxyl (-OH) group. Fe as a cross-linking agent of the alginate endowed Fe-SA-C with positive surfaces (positive zeta potential) and excellent pH buffering capacity, while excessive Fe was soldered on Fe-SA-C matrix as FeO(OH) and FeO. Cr(VI) removal at pH of 3 by Fe-SA-C (20.3 mg g) were 30.3% and 410.6% greater than that by Fe-SA and BC, respectively. Fe-SA-C exhibited minor pH dependence over pH range of 2-7 towards Cr(VI) retention. Greater zeta potential of Fe-SA-C over Fe-SA conferred a better electrostatic attraction with Cr(VI). FTIR and XPS of spent sorbents confirmed the reduction accounted for 98.5% for Cr(VI) removal mainly due to participation of -OH. Cr(VI) reduction was further favored by conductive carbon matrix in Fe-SA-C, as evidenced by more negative Tafel corrosion potential. Reductively formed Cr(III) was subsequently complexed with carboxylic groups originating from oxidation of -OH. Thus, Cr(VI) removal invoked electrostatic attraction, reduction, and surface complexation mechanisms. Pb(II) removal with excellent pH independence was mainly ascribed to surface complexation and possible precipitation. Thus, the functionalized, conductive, and positively-charged Fe-SA-C extended its applicability for Cr(VI) and Pb(II) removal from aqueous solutions in a wide pH range. This research could expand the application of hydrogel materials for removal of both cationic and anionic heavy metals in solutions over an extended pH range.
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http://dx.doi.org/10.1016/j.envpol.2021.117303DOI Listing
May 2021

Mechanism analysis of MnFeO/FeS for removal of Cr(VI) from aqueous phase.

Ecotoxicol Environ Saf 2021 Jul 11;217:112209. Epub 2021 Apr 11.

College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225000, PR China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, PR China; Institutes of Agricultural Science and Technology Development, Yangzhou 225127, Jiangsu, PR China. Electronic address:

By using NaS as a sulfur source, sulfur-doped MnFeO was prepared using one-step solvent thermal method and utilized to remove hexavalent chromium. The materials were characterized through scanning electron microscopy, transmission electron microscopy, high-resolution TEM, X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller method, zeta potential test, vibrating sample magnetometry, and X-ray photoelectron spectroscopy. When the pH was 3, the adsorption capacity of MnFeO/FeS to Cr(VI) was 43.36 mg/g, which was roughly five times that of MnFeO (8.90 mg/g). MnFeO/FeS and MnFeO fitted the Freundlich and pseudo-second-order kinetic models well. The electrochemical test analysis results showed that MnFeO/FeS had a faster MnFeO electron transfer rate and higher electron transfer capacity than MnFeO, and thus promoted the reduction of Cr(VI) to Cr(III). This finding could be attributed to the lower electronegativity of the sulfur element than the oxygen element. In addition, the formation of additional FeS through sulfur doping improved the Cr(VI) removal ability of the prepared materials. The XPS and desorption results showed that more than 80% of the adsorbed Cr(VI) were reduced to Cr(III), which indicated that reduction was an important mechanism for Cr(VI) removal. This study verified that sulfur-doped manganese ferrite can be utilized in the high-efficiency removal of Cr(VI).
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http://dx.doi.org/10.1016/j.ecoenv.2021.112209DOI Listing
July 2021

Increased structural defects of graphene oxide compromised reductive capacity of ZVI towards hexavalent chromium.

Chemosphere 2021 Aug 18;277:130308. Epub 2021 Mar 18.

College of Environmental Science and Engineering & Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, 225127, PR China; Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China. Electronic address:

Graphene oxide (GO) was treated with irradiation beams to understand the defective degree of carbon structure of GO in relation to electron transfer property of impregnated zerovalent iron (ZVI). The GO-supported ZVI (ZVI/GO) was synthesized and then characterized by an X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The results showed that the oxygen-bearing functional groups, oxygen content and structural disorder were increased as a function of irradiation beam intensity. ZVI was dominant in the composites, but proportion of iron oxide increased with greater oxygen content. Batch sorption revealed that Cr(VI) removal decreased from 20.11 g kg to 2.30 g kg as solution pH rose from 3 to 9. Cr(VI) removal capacity was 26.39 g kg, 23.12 g kg and 12.35 g kg for ZVI/GO, ZVI/GO and ZVI/GO, respectively. The reduction capacity of sorbents followed similar trends as Cr(VI) sorption as per desorption experiment, which accounted for a major Cr(VI) detoxification mechanism by ZVI/GO composites. The electrochemical tests demonstrated that unfavorable electron transfer rate of ZVI/GO composites was aggravated by greater structural disorder of GO. Thus, higher dose of irradiations could create more disorder in graphitic carbon and promote oxidation of ZVI, which hindered Cr(VI) reduction.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130308DOI Listing
August 2021

Copper Nanoparticle Loading and F Doping of Graphene Aerogel Enhance Its Adsorption of Aqueous Perfluorooctanoic Acid.

ACS Omega 2021 Mar 4;6(10):7073-7085. Epub 2021 Mar 4.

National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Tai'an 271018, China.

Perfluorooctanoic acid (PFOA) persists in the environment for a long time due to its stable physical and chemical properties, and it is harmful to the environment and biological system. In order to effectively remove PFOA from aqueous solution, Cu nanoparticles and fluorine-modified graphene aerogel (Cu/F-rGA) were fabricated by the microbubble template method. Compared with unmodified aerogels (rGA), the adsorption rate of PFOA on Cu/F-rGA was enhanced 2.68-fold. These significant improvements were assumed to benefit from the ligand exchange reaction and hydrophobic and F-F interactions. The regeneration of Cu/F-rGA maintained 73.26% with ethanol as the desorption solvent after 10 times adsorption-desorption. The fitting results of the statistical physics model showed that PFOA tended to be parallel to the adsorption site at low temperature and perpendicular at high temperature. The number of PFOA molecules connected to each adsorption site was 0.53 to 1.41, and the number of adsorption layers of PFOA on the Cu/F-rGA was between 1.63 and 2.51. Compared with the response surface methodology and artificial neural network, an adaptive neuro-fuzzy inference system had more accurate analysis and prediction results. These results provide an effective and alternative strategy to remove PFOA from aqueous solution with environment-friendly consumption.
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http://dx.doi.org/10.1021/acsomega.1c00044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7970550PMC
March 2021

Formation and mechanisms of nano-metal oxide-biochar composites for pollutants removal: A review.

Sci Total Environ 2021 May 22;767:145305. Epub 2021 Jan 22.

School of Environmental Engineering, Jiangsu Key Laboratory of Industrial Pollution Control and Resource Reuse, Xuzhou University of Technology, Xuzhou 221018, China.

Biochar, a carbon-rich material, has been widely used to adsorb a range of pollutants because of its low cost, large specific surface area (SSA), and high ion exchange capacity. The adsorption capacity of biochar, however, is limited by its small porosity and low content of surface functional groups. Nano-metal oxides have a large SSA and high surface energy but tend to aggregate and passivate because of their fine-grained nature. In combining the positive qualities of both biochar and nano-metal oxides, nano-metal oxide-biochar composites (NMOBCs) have emerged as a group of effective and novel adsorbents. NMOBCs improve the dispersity and stability of nano-metal oxides, rich in adsorption sites and surface functional groups, maximize the adsorption capacity of biochar and nano-metal oxides respectively. Since the adsorption capacity and mechanisms of NMOBCs vary greatly amongst different preparations and application conditions, there is a need for a review of NMOBCs. Herein we firstly summarize the recent methods of preparing NMOBCs, the factors influencing their efficacy in the removal of several pollutants, mechanisms underlying the adsorption of different pollutants, and their potential applications for pollution control. Recommendations and suggestions for future studies on NMOBCs are also proposed.
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http://dx.doi.org/10.1016/j.scitotenv.2021.145305DOI Listing
May 2021

The contribution of lignocellulosic constituents to Cr(VI) reduction capacity of biochar-supported zerovalent iron.

Chemosphere 2021 Jan 18;263:127871. Epub 2020 Aug 18.

College of Resources and Environment, Shandong Agricultural University, Taian, 271018, PR China. Electronic address:

Biochars (BCs) derived from individual and blending lignocellulosic constituents were prepared to harbor zerovalent iron (ZVI/BC) in an effort to discriminate significance of each constituent or combination in ZVI/BC for Cr(VI) removal. BCs and ZVI/BC were characterized by TGA/GSC, XRD, Raman and BET analyses. Cellulose (BC) and hemicellulose (BC)-derived BCs has greater C content, H/C ratio, surface area and mass loss than BCs derived from lignin or lignin-containing biopolymer blends (BC). As per sorption and XPS analysis, ZVI/BC demonstrated greater Cr(VI) removal capacity than respective BCs, in which reduction accounted for over 77% Cr(VI) detoxification. Cr(VI) reduction by ZVI harbored by BC and BC was 19.72-16.54 g kg, compared to 5.97-4.26 g kg for BC. ZVI/BC prepared by three-biopolymer blends with (12.63 g kg) or without (12.32 g kg) mineral approximated pinewood-BC (BC) (13.02 g kg) for Cr(VI) reduction, suggesting minerals are not important constituent. Tafel analysis showed BC and BC, with lower I/I ratio owing to greater graphitization, were more conducible to transfer electron of ZVI in Cr(VI) reduction than BC. Thus, cellulose, hemicellulose and lignin can offer a good prediction of property of natural biomass, in which BC and BC favor electron transfer of ZVI but BC is not electroactive.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127871DOI Listing
January 2021

Enhance in mobility of oxytetracycline in a sandy loamy soil caused by the presence of microplastics.

Environ Pollut 2021 Jan 26;269:116151. Epub 2020 Nov 26.

Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang Agriculture and Forestry University, Hangzhou, 311300, China.

Microplastics are emerging contaminants and widely distributed in the environment. They are considered as a vector of numerous organic pollutants including antibiotics in aquatic environments and thereby influence their distribution and transport behaviors. However, the effects of microplastics on the environmental behavior of antibiotics in soils remain largely unclear. In this paper, the influence of polyamide (PA) microplastics on sorption and transport of the selected antibiotic [oxytetracycline (OTC)] in a sandy loamy soil was studied by performing batch and column experiments. Results show that PA microplastics increase the pH of reaction systems, which contributes to OTC sorption onto the tested soils. However, altering pH is not the key influencing mechanism because the overall sorption capacity decreases slightly after adding PA microplastics, which can be attributed to the dilution effect. Reduction of OTC sorption by adding microplastics promotes the migration of OTC in the tested soil, which could be demonstrated by the results of column experiments that the breakthrough of OTC occurs earlier with an increasing content of PA microplastics. According to the fitting parameters of HYDRUS-1D model, PA microplastics can affect the transport of OTC by altering the soil pore structure and dispersion coefficient. These results provide new insight into the interaction between microplastics and organic pollutants in soil environments.
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http://dx.doi.org/10.1016/j.envpol.2020.116151DOI Listing
January 2021

Carbothermal synthesis of biochar-supported metallic silver for enhanced photocatalytic removal of methylene blue and antimicrobial efficacy.

J Hazard Mater 2021 01 6;401:123382. Epub 2020 Jul 6.

College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, PR China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, 225127, Jiangsu, PR China. Electronic address:

Pinewood biochar (PBC)-supported metallic silver (Ag) was prepared via a one-step carbothermal reduction route (AgH) or a wet-chemistry reduction method (AgW). XRD and SEM confirmed Ag was soldered on PBC matrix. Low methylene blue (MB) sorption was observed for unsupported Ag nanoparticles (AgNP), AgH and AgW. Under ultraviolet (UV) light irradiation, net MB degradation by AgH (15.88 g kg) was higher than that of AgW (12.50 g kg) and AgNP (10.27 g kg). TOC removal percentages after degradation corresponded largely to reduction of MB concentrations in solution, indicating MB was dominantly mineralized. Electron paramagnetic resonance (EPR) revealed that MB was degraded by reactive oxygen species (ROS) such as hydroxyl radical (OH), superoxide radical (O-) and singlet oxygen (O). The scavenging experiments further suggested that OH scavengers suppressed MB degradation to a greater extent than other quenchers. Compared to AgW, AgH possessed greater abundance of persistent free radicals, which enhance ROS generation. PBC could also improve separation of electron-hole (e-h) pairs and enhance electron transfer ascribing to favorable carbon structure. Besides, PBC-Ag maintained good antimicrobial efficacy over E.coli DH5α. This work presented a facile carbothermal route to prepare Ag-based photocatalysts for dye removal and microbial inhibition in industrial wastewater.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123382DOI Listing
January 2021

Pinewood outperformed bamboo as feedstock to prepare biochar-supported zero-valent iron for Cr reduction.

Environ Res 2020 08 20;187:109695. Epub 2020 May 20.

College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, PR China. Electronic address:

In this work, pinewood and bamboo were pyrolyzed at 600 °C to prepare PBC and BBC-supported zerovalent iron (ZVI), respectively. Raman spectra suggested PBC was more intensively carbonized than BBC as indicated by higher I/I ratio. XRD and TEM confirmed nanoscaled ZVI was well dispersed in PBC but soldered in chain-structure in BBC. Maximal chromate (Cr(VI)) sorption capacity followed the order of PBC/ZVI (5.93 g kg)>BBC/ZVI (3.61 g kg)>BBC (3.55 g kg)>PBC (2.59 g kg). Desorption and XPS of four Cr-spent sorbents suggested reduction accounted for 79-88% of overall Cr(VI) detoxification. Greater Cr(VI) reduction of BBC than PBC indicated greater tendency of BBC to donate electrons. However, Cr(VI) reduction by PBC/ZVI was 1.7 times greater than BBC/ZVI, corresponding to greater electron transfer of PBC/ZVI (2.5 μA e) than BBC/ZVI (0.5 μA e). Thus, PBC is more conducible to transfer electrons as evidenced by Tafel and Amperometric analyses. Demineralization of pristine BC enhanced the difference between PBC/ZVI and BBC/ZVI regarding Cr(VI) reduction, suggesting the dominant role of biopolymers in biomass in terms of electron transfer capacity. Three model biopolymers were compared which indicated lignin-BC had lower electron transfer rates than cellulose-BC and hemicellulose-BC. BC prepared by lignin extracted from pinewood exhibited higher corrosion rate and lower electrical resistance than that from bamboo. Thus, unfavorable lignin in bamboo compromised electron transfer of BBC and Cr(VI) reduction by BBC/ZVI.
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http://dx.doi.org/10.1016/j.envres.2020.109695DOI Listing
August 2020

Preparation of highly-conductive pyrogenic carbon-supported zero-valent iron for enhanced Cr(Ⅵ) reduction.

J Hazard Mater 2020 Sep 18;396:122712. Epub 2020 Apr 18.

College of Resources and Environment, Shandong Agricultural University, Taian, 271018, PR China. Electronic address:

In this work, electron transfer (ET) moiety of PC was ascertained in chromate (Cr(Ⅵ)) reduction by zero-valent iron supported by pyrogenic carbon (PC) (ZVI/PC) prepared by pyrolysis of hematite (α-FeO)-treated pinewood. X-ray diffraction analysis suggested successive phase transformation of α-FeO→magnetite (FeO)→wustite (FeO)→ZVI (Fe). Raman spectra and Brunauer-Emmett-Teller analysis revealed that ZVI/PC is characterized with more ordered graphitic carbon and greater surface area than pristine PC. Maximal Cr(Ⅵ) removal capacity (pH = 3) as predicted by Langmuir isotherm model were 5.78, 36.12 and 8.39 g kg for PC, ZVI/PC and ZVI, respectively. ZVI/PC maintained significantly greater Cr(Ⅵ) removal capacity than ZVI and PC at pH 3-9, but Cr(Ⅵ) removal dropped rapidly to 6.78 g kg at pH 4 and above. X-ray photoelectron spectroscopy and successive desorption of Cr-laden ZVI/PC and ZVI showed trivalent Cr was the dominant species, suggesting reduction was an important mechanism for Cr(Ⅵ) detoxification. Electrochemical analysis demonstrated that ZVI/PC exhibited greater Tafel corrosion rate and ET quantity, with lower electrical resistance. Besides, Cr(Ⅵ) reduction showed reversal trend with electrical resistance of ZVI/PC. To conclude, ET capacity was closely associated with electrical conductivity of ZVI/PC due to intensified conductive graphitic carbon structure of PC at higher pyrogenic temperatures.
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http://dx.doi.org/10.1016/j.jhazmat.2020.122712DOI Listing
September 2020

Photocatalytic behavior of biochar-modified carbon nitride with enriched visible-light reactivity.

Chemosphere 2020 Jan 31;239:124713. Epub 2019 Aug 31.

College of Environmental Science and Engineering, Yangzhou University, Jiangsu, 225127, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, 225127, Jiangsu, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing, 210095, China. Electronic address:

Ultra-thin layered structures and modified bandgaps are two efficient strategies to increase the photocatalytic performance of various materials for the semiconductor industry. In the present study, we combined both strategies in one material to form carbon-doped graphitic carbon nitride (g-CN) nano-layered structures by the method of melamine thermal condensation, in the presence of different mass ratios of biochar. The characterization showed that the composite with the best ratio retained the g-CN polymeric framework and the bond with g-CN. The biochar was established via π-π stacking interactions and ether bond bridges. The π-conjugated electron systems provided from biochar can elevate charge separation efficiency. The ultra-thin structure also curtailed the distance of photogenerated electrons migrating to the surface and enlarge specific surface area of materials. The presence of carbon narrowed the bandgap and increased light absorption at a wider range of wavelengths of g-CN. The biochar/melamine ratio of 1:15 presented the best performance, 2.8 and 5 times faster than g-CN degradating Rhodamine and Methyl Orange, respectively. Moreover, the catalyst presented a good stability for 4 cycles. In addition to that, biochar from waste biomass can be considered a sustainable, cost-effective, and efficient option to modify g-CN-based photocatalysts.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124713DOI Listing
January 2020

Biochar-supported nZVI (nZVI/BC) for contaminant removal from soil and water: A critical review.

J Hazard Mater 2019 07 19;373:820-834. Epub 2019 Mar 19.

Korea Biochar Research Center & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, South Korea. Electronic address:

The promising characteristics of nanoscale zero-valent iron (nZVI) have not been fully exploited owing to intrinsic limitations. Carbon-enriched biochar (BC) has been widely used to overcome the limitations of nZVI and improve its reaction with environmental pollutants. This work reviews the preparation of nZVI/BC nanocomposites; the effects of BC as a supporting matrix on the nZVI crystallite size, dispersion, and oxidation and electron transfer capacity; and its interaction mechanisms with contaminants. The literature review suggests that the properties and preparation conditions of BC (e.g., pore structure, functional groups, feedstock composition, and pyrogenic temperature) play important roles in the manipulation of nZVI properties. This review discusses the interactions of nZVI/BC composites with heavy metals, nitrates, and organic compounds in soil and water. Overall, BC contributes to the removal of contaminants because it can attenuate contaminants on the surface of nZVI/BC; it also enhances electron transfer from nZVI to target contaminants owing to its good electrical conductivity and improves the crystallite size and dispersion of nZVI. This review is intended to provide insights into methods of optimizing nZVI/BC synthesis and maximizing the efficiency of nZVI in environmental cleanup.
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http://dx.doi.org/10.1016/j.jhazmat.2019.03.080DOI Listing
July 2019

Biomass facilitated phase transformation of natural hematite at high temperatures and sorption of Cd and Cu.

Environ Int 2019 03 24;124:473-481. Epub 2019 Jan 24.

College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, China. Electronic address:

Phase changes of natural hematite are often practiced to improve heavy metal removal and magnetism for easy recycling. In this work, pinewood biomass (PB) and natural hematite (H) admixtures were pyrolyzed at 300, 450 and 600 °C under N environment to prepare HBC nanocomposites (HBC300, HBC450 and HBC600). The X-ray diffraction (XRD) confirmed the reductive transformation of hematite (crystallite size ≈ 47 nm) into magnetite (25 nm) and further to wustite (25 nm) and zerovalent iron (48 nm). The Langmuir isotherms showed that the maximum sorption capacities of HBC300, HBC450, and HBC600 were 173, 138, and 130 mmol kg for Cd, and 359, 172, and 197 mmol kg for Cu, respectively. The higher pH up to 5 increased sorption of both Cd and Cu, whereas the higher ionic strength (0.05-0.4 M) decreased Cd sorption. Sorption of Cd and Cu by HBC300 was accompanied by one order of magnitude greater cation release than HBC450 and HBC600. In a binary system, Cd sorption was depressed by over four times in presence of Cu. Overall, ion exchange was more pronounced for HBC300, and Cu was more favorably retained by specific sorption than Cd. The greater magnetism of HBC nanoparticles favors separation from aqueous solutions.
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http://dx.doi.org/10.1016/j.envint.2019.01.004DOI Listing
March 2019

Carboxymethyl cellulose stabilized ZnO/biochar nanocomposites: Enhanced adsorption and inhibited photocatalytic degradation of methylene blue.

Chemosphere 2018 Apr 8;197:20-25. Epub 2018 Jan 8.

College of Resources and Environment, Key Laboratory of Agricultural Environment in Universities of Shandong, Shandong Agricultural University, Taian, 271018, PR China. Electronic address:

Biochar(BC)-supported nanoscaled zinc oxide (nZO) was encapsulated either with (nZORc/BC) or with no (nZOR/BC) sodium carboxymethyl cellulose (CMC). The X-ray diffraction and ultraviolet (UV)-visible-near infrared spectrophotometry revealed that nZO of 16, 10, and 20 nm with energy band gaps of 2.79, 3.68 and 2.62 eV were synthesized for nZOR/BC, nZORc/BC and nZO/BC, respectively. The Langmuir isotherm predicted saturated sorption of methylene blue (MB) was 17.01 g kg for nZORc/BC, over 19 times greater than nZOR/BC and nZO/BC. Under UV irradiation, 10.9, 61.6, 83.1, and 41.6% of MB were degraded for nZORc/BC, nZO/BC, nZOR/BC and BC. The scavenging experiment revealed hydroxyl radical dominated CMC degradation. Exogenous CMC (2 g L) increased MB sorption from 10.6% to 73.1%, but decreased MB degradation from 80.7% to 41.1%, relative to nZOR/BC. Thus, CMC could increase MB sorption by electrostatic attraction and other possible mechanisms. The compromised MB degradation may be ascribed to reduced availability of hydroxyl and superoxide radicals to degrade MB, and increased band gap energy of ZnO.
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http://dx.doi.org/10.1016/j.chemosphere.2018.01.022DOI Listing
April 2018

The sorptive and reductive capacities of biochar supported nanoscaled zero-valent iron (nZVI) in relation to its crystallite size.

Chemosphere 2017 Nov 7;186:495-500. Epub 2017 Aug 7.

College of Resources and Environment, Shandong Agricultural University, Taian 271018, China. Electronic address:

In this work, nZVI was immobilized by bamboo derived biochars (nZVI/BB), hydrogen peroxide (HO) (nZVI/PBB) and nitric acid (HNO) (nZVI/HBB) modified BB. HO and HNO deceased surface area and pore volume of pristine biochars. Total iron (Fe) contents were 16.50, 24.40, and 13.08% for nZVI/BB, nZVI/PBB and nZVI/HBB, respectively. The X-ray diffraction revealed that nZVI in biochar matrix was dominantly metallic Fe coated with Fe oxides. The transmission electron microscopy indicated nZVI particle sizes were 41.5, 30.5 and 6.1 nm for nZVI/BB, nZVI/HBB and nZVI/PBB, respectively. The removal capacities of arsenate (AsV) and silver ions (Ag) by nZVI nanocomposites were compared in a batch experiment. Greater reductive removal of Ag (1217 g kg nZVI) and sorptive removal of AsV (109.1 g kg nZVI) were achieved in nZVI/PBB, indicating smaller-sized nZVI was more reactive. Thus, particle size of nZVI affected the sorptive and reductive capacities for AsV and Ag.
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http://dx.doi.org/10.1016/j.chemosphere.2017.08.014DOI Listing
November 2017

Magnetic [email protected] Nanocomposite as an Efficient Fenton-Like Heterogeneous Catalyst for Degradation of Ethidium Bromide.

Sci Rep 2017 07 20;7(1):6070. Epub 2017 Jul 20.

College of Environmental Science and Engineering, Yangzhou University, Jiangsu, 225127, China.

Magnetic attapulgite-FeO nanocomposites (ATP-FeO) were prepared by coprecipitation of FeO on ATP. The composites were characterized by scanning electron microscopey, X-ray diffractometry, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, energy dispersive spectrometer and transmission electron microscopy. Surface characterization showed that FeO particles with an average size of approximately 15 nm were successfully embedded in matrix of ATP. The capacity of the FeO-activated ATP ([email protected]) composites for catalytic degradation of ethidium bromide (EtBr, 80 mg/L) at different pH values, hydrogen peroxide (HO) concentrations, temperatures, and catalyst dosages was investigated. EtBr degradation kinetics studies indicated that the pseudo-first-order kinetic constant was 2.445 min at T = 323 K and pH 2.0 with 30 mM HO, and 1.5 g/L of [email protected] Moreover, a regeneration study suggested that [email protected] maintained over 80% of its maximal EtBr degradation ability after five successive cycles. The effects of the iron concentrations and free radical scavengers on EtBr degradation were studied to reveal possible catalytic mechanisms of the [email protected] nanocomposites. Electron Paramagnetic Resonance revealed both hydroxyl (∙OH) and superoxide anion (∙O) radicals were involved in EtBr degradation. Radical scavenging experiment suggested EtBr degradation was mainly ascribed to ∙OH radicals, which was generated by reaction between Fe and HO on the surface of [email protected]
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http://dx.doi.org/10.1038/s41598-017-06398-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5519544PMC
July 2017

Biochar provides a safe and value-added solution for hyperaccumulating plant disposal: A case study of Phytolacca acinosa Roxb. (Phytolaccaceae).

Chemosphere 2017 Jul 27;178:59-64. Epub 2017 Feb 27.

School of Metallurgy and Environment, Central South University, Changsha 410083, China.

In this work, an innovative approach using biochar technology for hyperaccumulator disposal was developed and evaluated. The heavy metal enriched P. acinosa biomass (PBM) was pyrolyzed to produce biochar (PBC). Both PBM and PBC were characterized with X-ray diffraction (XRD) for crystal phases, scanning electron microscopy (SEM) for surface topography, and analyzed for elemental composition and mobility. The results revealed that whewellite, a dominant crystal form in biomass, was decomposed to calcite after pyrolysis. Elemental analysis indicated that 91-99% total non-volatile elements in the biomass were retained in the biochar. The toxicity characteristic leaching procedure (TCLP) results revealed that 94.6% and 0.15% of total Mn was extracted for biomass and biochar, respectively. This suggests that mobility and bioavailability of Mn in biochar was much lower relative to pristine biomass. Batch sorption experiment showed that excellent removal of aqueous silver, lead, cadmium, and copper ions can be achieved with PBC. Findings from this work indicated that biochar technology can provide a value-added solution for hyperaccumulator disposal.
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http://dx.doi.org/10.1016/j.chemosphere.2017.02.121DOI Listing
July 2017

Oxygen-Content-Controllable Graphene Oxide from Electron-Beam-Irradiated Graphite: Synthesis, Characterization, and Removal of Aqueous Lead [Pb(II)].

ACS Appl Mater Interfaces 2016 Sep 16;8(38):25289-96. Epub 2016 Sep 16.

Department of Agricultural and Biological Engineering, University of Florida , Gainesville, Florida 32611, United States.

A high-energy electron beam was applied to irradiate graphite for the preparation of graphene oxide (GO) with a controllable oxygen content. The obtained GO sheets were analyzed with various characterization tools. The results revealed that the oxygen-containing groups of GO increased with increasing irradiation dosages. Hence, oxygen-content-controllable synthesis of GO can be realized by changing the irradiation dosages. The GO sheets with different irradiation dosages were then used to adsorb aqueous Pb(II). The effects of contact time, pH, initial lead ion concentration, and ionic strength on Pb(II) sorption onto different GO sheets were examined. The sorption process was found to be very fast (completed within 20 min) at pH 5.0. Except ionic strength, which showed no/little effect on lead sorption, the other factors affected the sorption of aqueous Pb(II) onto GO. The maximum Pb(II) sorption capacities of GO increased with irradiation dosages, confirming that electron-beam irradiation was an effective way to increase the oxygen content of GO. These results suggested that irradiated GO with a controllable oxygen content is a promising nanomaterial for environmental cleanup, particularly for the treatment of cationic metal ions, such as Pb(II).
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http://dx.doi.org/10.1021/acsami.6b08059DOI Listing
September 2016

Adsorptive removal of arsenate from aqueous solutions by biochar supported zero-valent iron nanocomposite: Batch and continuous flow tests.

J Hazard Mater 2017 Jan 23;322(Pt A):172-181. Epub 2016 Jan 23.

College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, China.

Arsenate (As(V)) removal ability by nanoscale zero-valent iron (nZVI) is compromised by aggregation of nZVI particles. In this work, pine derived biochar (PB) was used as a supporting material to stabilize nZVI for As(V) removal. The biochar supported nZVI (nZVI/BC) was synthesized by precipitating the nanoparticles on carbon surfaces. Experiments using batch and continuous flow, completely mixed reactors (CMRs) were carried out to investigate the removal of As(V) by the nZVI/BC from aqueous solutions. Batch experiments showed that nZVI/BC had high As(V) removal capacity in a wide range of pH (3-8). Kinetic data revealed that equilibrium was reached within 1h and the isotherm data showed that the Langmuir maximum adsorption capacity of the nZVI/BC for As(V) at pH 4.1 was 124.5gkg. As(V) (100mgL) adsorption in anoxic condition was about 8% more than in oxic conditions, where As(V) reduction was observed in anoxic condition. The performance of the nZVI/BC in flowing condition was evaluated in CMRs at influent As(V) concentrations of 2.1 and 5.5mgL and the adsorbent removed 100% and 90% of the As(V), respectively. Furthermore, the nZVI/BC composite is magnetic which facilitates collection from aqueous solutions.
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http://dx.doi.org/10.1016/j.jhazmat.2016.01.052DOI Listing
January 2017

Physicochemical and sorptive properties of biochars derived from woody and herbaceous biomass.

Chemosphere 2015 Sep 15;134:257-62. Epub 2015 May 15.

Tropical Research and Education Center, Department of Agricultural and Biological Engineering, University of Florida, Homestead, FL 33031, United States.

It is unclear how the properties of biochar control its ability to sorb metals. In this work, physicochemical properties of a variety of biochars, made from four types of feedstock at three pyrolysis temperatures (300, 450 and 600°C) were compared to their ability to sorb arsenic (As) and lead (Pb) in aqueous solutions. Experimental results showed that both feedstock types and pyrolysis temperature affected biochar's production rate, i.e., ratio of mass of biochar and biomass, thermal stability, elemental composition, non-combustible component (NCC) content, pH values, surface areas and thus their sorption ability to the two metals in aqueous solution. In general, the high temperature biochars had low O/C and H/C ratios, were more carbonized with larger surface area, and were more concentrated with alkaline cations. In addition, biochars made from woody feedstocks had larger surface area, but lower NCC contents than that made from grasses under the same conditions. Although all the tested biochars removed both As and Pb from aqueous solutions, they showed different sorption abilities because of the variations in properties. Statistical analyses suggested that feedstock type affected the sorption ability of the biochars to both As and Pb significantly (p<0.001). Pyrolysis temperature, however, showed little influence on biochar sorption of Pb in aqueous solutions. Statistical analyses also showed that electrostatic interaction played an important role in controlling the sorption of both As(V) and Pb(II) onto the biochar. Other mechanisms, such as precipitation and surface complexation, could also control the sorption of Pb(II) onto the biochars.
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http://dx.doi.org/10.1016/j.chemosphere.2015.04.062DOI Listing
September 2015

Manganese oxide-modified biochars: preparation, characterization, and sorption of arsenate and lead.

Bioresour Technol 2015 Apr 17;181:13-7. Epub 2015 Jan 17.

Tropical Research and Education Center, University of Florida, Homestead, FL 33031, United States; Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, United States.

This work explored two modification methods to improve biochar's ability to sorb arsenic (As) and lead (Pb). In one, pine wood feedstock was pyrolyzed in the presence of MnCl2·4H2O (MPB) and in the other it was impregnated with birnessite via precipitation following pyrolysis (BPB). The resulting biochars were characterized using thermogravimetry, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and energy-dispersive X-ray analyses. The dominant crystalline forms of Mn oxides in the MPB and BPB were manganosite and birnessite, respectively. Batch sorption studies were carried out to determine the kinetics and magnitude of As(V) and Pb(II) onto the biochars. As(V) and Pb(II) sorption capacities of MPB (0.59 and 4.91 g/kg) and BPB (0.91 and 47.05 g/kg) were significantly higher than that of the unmodified biochar (0.20 and 2.35 g/kg). BPB showed the highest sorption enhancement because of the strong As(V) and Pb(II) affinity of its birnessite particles.
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http://dx.doi.org/10.1016/j.biortech.2015.01.044DOI Listing
April 2015

Batch and column sorption of arsenic onto iron-impregnated biochar synthesized through hydrolysis.

Water Res 2015 Jan;68:206-16

State Key Laboratory of Analytical Chemistry for Life Science, Center of Material Analysis and School of Chemistry and Chemical Engineering, 20 Hankou Road, Nanjing University, Nanjing 210093, PR China.

Iron (Fe)-impregnated biochar, prepared through a novel method that directly hydrolyzes iron salt onto hickory biochar, was investigated for its performance as a low-cost arsenic (As) sorbent. Although iron impregnation decreased the specific surface areas of the biochar, the impregnated biochar showed much better sorption of aqueous As (maximum sorption capacity of 2.16 mg g⁻¹) than the pristine biochar (no/little As sorption capacity). Scanning electron microscope equipped with an energy dispersive spectrometer and X-ray diffraction analysis indicated the presence of crystalline Fe hydroxide in the impregnated biochar but no crystal forms of arsenic were found in the post-sorption biochar samples. However, large shifts in the binding energy of Fe₂p, As₃d, O₁s and C₁s region on the following As sorption indicated a change in chemical speciation from As(V) to As(III) and Fe(II) to Fe(III) and strong As interaction with oxygen-containing function groups of the Fe-impregnated biochar. These findings suggest that the As sorption on the Fe-impregnated biochar is mainly controlled by the chemisorption mechanism. Columns packed with Fe-impregnated biochar showed good As retention, and was regenerated with 0.05 mol L⁻¹ NaHCO₃ solution. These findings indicate that Fe-impregnated biochar can be used as a low-cost filter material to remove arsenic from aqueous solutions.
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http://dx.doi.org/10.1016/j.watres.2014.10.009DOI Listing
January 2015

Removal of arsenic by magnetic biochar prepared from pinewood and natural hematite.

Bioresour Technol 2015 Jan 28;175:391-5. Epub 2014 Oct 28.

Tropical Research and Education Center, University of Florida, Homestead, FL 33031, United States; Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, United States.

There is a need for the development of low-cost adsorbents to removal arsenic (As) from aqueous solutions. In this work, a magnetic biochar was synthesized by pyrolyzing a mixture of naturally-occurring hematite mineral and pinewood biomass. The resulting biochar composite was characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDS). In comparison to the unmodified biochar, the hematite modified biochar not only had stronger magnetic property but also showed much greater ability to remove As from aqueous solution, likely because the γ-Fe2O3 particles on the carbon surface served as sorption sites through electrostatic interactions. Because the magnetized biochar can be easily isolated and removed with external magnets, it can be used in various As contaminant removal applications.
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http://dx.doi.org/10.1016/j.biortech.2014.10.104DOI Listing
January 2015
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