JOURNAL OF ALLOYS AND COMPOUNDS
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2021
·
IF 5.316
Xinyu Hu,Juntao Wang,Jing Wang,Kehui Xue,Ting Yang,Yi Peng,Ying Yan,Hongbo Xiao,Wenlei Wang
Controlling the migration behavior of photogenerated carriers by designing the microstructure of materials remains a significant challenge. In this work, the solvothermal method was used to fabricate a SnO 2 /SnS 2 heterojunction anchored on biochar through −C Sn− bonds between biochar and SnS 2 , as demonstrated by X-ray photoelectron spectroscopy characterization. DFT calculations further confirmed −C Sn− bonds can shorten theoretical band gap of SnS 2 @biochar from 1.01 eV to 0.66 eV and provide a pathway for swift electron migration, which can effectively modulate the separation of photo-induced carriers and promote the generation of e − and h + . Additionally, the oxalate activated by −C Sn− bonds can effectively capture h + and produce abundant ∙CO 2 – free radicals. When the obtained composites were used as photocatalysts , Cr(VI) was thoroughly reduced by the SnO 2 /SnS 2 @biochar composite with a molar ratio of SnO 2 and SnS 2 of 2 within 20 min under visible light irradiation when oxalate was 1.0 mM (CSO-2/H 2 C 2 O 4 -1). Furthermore, CSO-2/H 2 C 2 O 4 -1 exhibited excellent reusability, and the degradation efficiency of Cr(VI) remained above 91.71% after five cycles. The remarkable photocatalytic properties can be ascribed to the synergistic effects of e − and ∙CO 2 – . This work proposes a new strategy for the preparation of an applied photocatalyst with a high separation rate of photoinduced carriers.
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高影响因子
LANGMUIR
·
2019
·
IF 3.683
Fei Xue,Hui He,Hongxiang Zhu,Huanhuan Huang,Qi Wu,Shuangfei Wang
A cellulose-based solid amine adsorbent (MCC/TEPAA) with high amino density for the detection and removal of Cr(VI) was designed and prepared through using epichlorohydrin cross-linking with MCC (microcrystalline cellulose) and tetraethylenepentamine (TEPA). The structure and amino density of the cellulose-based solid amine adsorbents could be tailored by adjusting the structure of the amines (triethylenetetramine or diethylenetriamine). The as-prepared cellulose-based solid amine adsorbents could detect and completely remove Cr(VI) from water, and the concentration of Cr(VI) solution after adsorption met the standard concentration of Cr(VI) solution for drinking water (0.05 mg/L). In particular, the MCC/TEPAA, supported by MCC with porosity as a framework, promoted the adsorption rate (adsorption equilibrium within only 10 min), removal rate (100%) of Cr(VI), and adsorption capacity (327.72 mg/g). In addition, the limit of colorimetric detection of Cr(VI) by MCC/TEPAA was 0.5 mg/L at 20 min when other interfering heavy metal ions exist. The adsorption and colorimetric detection mechanism of Cr(VI) on MCC/TEPAA was proposed to include electrostatic interactions, chelating reactions, and oxidation–reduction reactions, all of which contributed to the excellent adsorption and detection performance.
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PubMed
高影响因子
LANGMUIR
·
2019
·
IF 3.683
Jie Chen,Yan Xiong,Ming Duan,Xiang Li,Jun Li,Shenwen Fang,Sha Qin,Run Zhang
The adsorption of dye molecules is an important process for the photodegradation removal of dye pollutants. In this work, a semiconductor photocatalyst of Cr-doped ZnO nanorods (Cr–ZnO NRs) was synthesized, and its adsorption–photocatalysis synergy (APS) effect was investigated for anionic methyl orange (MO–) and cationic methylene blue (MB+). The detailed thermodynamic information (including adsorption maximum capacity qmax, adsorption equilibrium constant Kads and adsorption efficiency AE %) and dynamic information (including adsorption rate constant ka, degradation rate constant kd and degradation efficiency DE %) were obtained to evaluate the different reaction performances for MO– and MB+. With qmax(MB+) = 40.59 mg g–1 > qmax(MO–) = 15.95 mg g–1, ka(MB+) = 20.61 min–1 > ka(MO–) = 4.62 min–1, and AE(MB+) = 40% > AE(MO–) = 9%, Cr–ZnO NRs showed much superior adsorption performance for MB+ than MO–. With kd (MB+) = 0.0430 min–1 > kd (MO–) = 0.0014 min–1 and DE(MB+) = 98% > AE(MO–) = 20%, Cr–ZnO NRs also showed much superior photodegradation performance for MB+ than MO–. The APS mechanism of Cr–ZnO NRs is revealed to be multiple π–π interactions and stronger electrostatic attractions dominant for enhanced adsorption of MB+ and higher AE and more photocatalytic active species dominant for enhanced photodegradation of MB+. The APS was furthermore characterized and verified by zeta potential analysis, Fourier transform infrared investigation, and fluorescence imaging. The results indicate that Cr–ZnO NRs are promising adsorbent and photocatalyst candidates favorable for positive MB+ than negative MO–. Such an APS investigation can effectively help to improve the photodegradation treatment performance of photocatalysts for dye pollutant removal.
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高影响因子
CELLULOSE
·
2019
·Vol. 26
·期 5
·3437-3453
·
IF 3.917
Zhang Shengli,Chen Haoyu,Zhang Silue,Kai Chengcheng,Jiang Man,Wang Qun,Zhou Zuowan
Abstract A novel biosorbent PEI-HOCM was successfully prepared by grafting polyethyleneimine (PEI) onto H 2 O 2 -oxidized cellulose membrane (HOCM). The whole systhesis process occurred in aqueous solution and was environmentally friendly without any toxic cross-linkers involved. ATR-FTIR, XPS and titration analysis confirmed that the hydroxyl groups of cellulose were oxidized to carbonyl groups by H 2 O 2 and PEI was successfully introduced to the HOCM. The PEI-HOCM had positively charged surface (+ 20.6 to + 86.6 mV) at the measured pH range 3–9 according to the zeta potential analysis. The adsorption of Cr(VI) on the PEI-HOCM obeyed the pseudo-second-order kinetic model and Langmuir isotherm model. Its maximum equilibrium adsorption capacity was 147.06 mg/g at 25 °C, which was much higher than that of cellulose membrane (CM, 30.61 mg/g). According to the obtained results from the intraparticle diffusion, Body kinetic and diffusion-chemisorption models, film diffusion was the rate-limiting step and chemical adsorption was the main mechanism of Cr(VI) adsorption. The Cr(VI) adsorbed on the PEI-HOCM was completely reduced to Cr(III), suggesting that PEI-HOCM was not only useful for Cr(VI) removal but also good for its detoxification. The competitive uptakes from coexisting components (Na + , Mg 2+ , Ca 2+ , phenol, Cl − and NO 3 − ) were insignificant except H 2 PO 4 − and SO 4 2− which reduced the Cr(VI) uptake with a efficiency loss of 22–41%. Ionic strength had little effect on the adsorption in the range of 0–1000 mg/L NaCl. After five adsorption/desorption cycles, the PEI-HOCM still retained good adsorption capacity. More importantly, it can be separated easily after adsorption, which will greatly benefit the wastewater treatment by simplifying the separation procedure and reducing costs. Graphical abstract
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高影响因子
ENVIRONMENTAL TECHNOLOGY
·
2019
·
IF 1.918
Ying Li,Cheng Chen,Yao Wu,Yijie Han,Yeqing Lan
The synergism of CuS and tartaric acid (TA) in the reduction of Cr(VI) with an irradiation of simulated solar light was investigated through observing the effects of solution pH, temperature, CuS loading and TA concentration on the removal efficiency of Cr(VI). Approximately 32% and 54% of the initial Cr(VI) (100 µmol/L) were reduced within 180 min by TA and CuS with light, respectively. Under the same condition, however, almost a complete removal of the initial Cr(VI) was achieved within 130 min in the coexistence of CuS and TA. In the case, it is considered that Cr(VI) was rapidly reduced in two main pathways. One is that H2S produced from the dissolution of CuS in weak acidic solution directly reduced Cr(VI) to Cr(III). The other is that Cu(II) released from CuS reacted with TA to form complexes with photochemical activity, producing Cu(I) through ligand-to-metal electron transfer, and then the reduction of Cr(VI) was coupled with a conversion of Cu(I) to Cu(II). Thus, a cycle catalytic system was established for the reduction of Cr(VI). Moreover, it is observed that the reaction could be divided into two stages: the initial chemical reduction of Cr(VI) by H2S and the later photochemical reduction of Cr(VI) by Cu(II)–TA complexes.
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PubMed
高影响因子
ELECTROCHIMICA ACTA
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2019
·
IF 5.383
Jiangping Jing,Zhuoyuan Chen,Yuyu Bu,Mengmeng Sun,Wenqiang Zheng,Weibing Li
SrTiO 3 is a promising material for the photoelectrochemical (PEC) cathodic protection technology due to its intrinsic band structure . Its disadvantage of light absorption only in the ultraviolet region can be effectively solved by Cr doping. The Cr dopant usually exists as two states of Cr 3+ and Cr 6+ , among which the latter one usually behaves as the trapping center for the photoinduced electrons and leads to the decrease of the PEC performance. In this paper, a hydrogen treatment process is performed on the Cr-doped SrTiO 3 to reduce the Cr 6+ . It is verified that hydrogen treatment reduces Cr 6+ to Cr 3+ , leading to the increase of the concentration of the charge carriers and the decrease of the charge transfer resistance. And also, hydrogen treatment induces the formation of oxygen vacancy , which leads to the negative shift of conduction band potential and the increase of the concentration of the charge carriers. The effect of the hydrogen treatment temperature is further studied in this work. Higher temperature will promote the reduction degree of Cr 6+ and increase the concentration of oxygen vacancy . However, hydrogen treatment with excessively high temperature will induce too high concentration of oxygen vacancy, which would act as the recombination centers of the photogenerated charge carriers, suppress the mobility conduction and thus lead to the decrease of the PEC performance. Therefore, benefiting from the Cr 6+ reduction and modification with appropriate concentration of oxygen vacancy, the Cr-doped SrTiO 3 with hydrogen treatment at 250 °C shows the optimal PEC cathodic protection performance in NaCl solution.
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高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
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2019
·
IF 4.978
Zhenjiang He,Yuxi Yang,Peng Bai,Xianghai Guo
Selective adsorption and separation of three xylene isomers of seven stable metal-organic frameworks (MOFs) were investigated, where MIL-53(Cr) manifested the highest adsorption capacity and apparent preference for o -xylene. Further detailed studies with MIL-53(Cr) showed that pseudo-second-order model fit best with adsorption kinetics of xylene isomers, and the isotherms were perfectly fitted by Langmuir isotherm model. The adsorption was proved to be a quick process, and both the changes of entropy and enthalpy contributed to the o -xylene selectivity, but which mainly resulted from the entropy effect. The adsorption capacity of preferable isomer o -xylene, on account of better packing efficiency, was record-breaking 8.19 mmol/g, and selectivity of OX/PX, OX/MX and MX/PX were 13.75, 8.01 and 1.72, respectively. Both the adsorption capacity and OX selectivity on MIL-53(Cr) in liquid phase adsorption and breakthrough experiments were super high, which discriminated it from zeolites and other materials reported so far. Combined with extremely short equilibrium time and high stability, MIL-53(Cr) can be a promising adsorbent for separation of xylenes in industrial process.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 26
·期 28
·28898-28908
·
IF 2.914
Zhang Yakun,Chen Sisi,Feng Xuezhen,Yu Jingang,Jiang Xinyu
The assembly of graphene oxide with biomass or polymers to form 3D hydrogels with excellent mechanical properties has become a research hotspot. In this work, the sponge-like kaolin/chitosan (CS)/reduced graphene oxide (rGO) composite was prepared for adsorption by simple self-assembly without cross-linking agent. The morphology, composition, surface properties, and pore size of as-prepared materials were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), zeta potential analyzer, Brunauer-Emmett-Teller surface area measurement (BET), and scanning electron microscopy (SEM). The effects of raw material ratio, contact time, temperature, pH, ionic strength, and recycling times on adsorption performance were investigated in detail. The results indicate that the composite has good absorption capacity for Cr(VI) and alizarin yellow R (AYR). Besides, composite hydrogel also exhibits excellent flexibility and good repeatability, which confirms its great potential as an adsorbent to remove pollutants in the water environment.
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高影响因子
APPLIED CLAY SCIENCE
·
2019
·
IF 3.89
Shifeng Zhao,Mi Wu,Ruisen Jing,Xijuan Liu,Yifei Shao,Qian Zhang,Fengzhu Lv,Aiju Liu,Zilin Meng
Magnetic ZnAl-LDH composite materials (Fe 3 O 4 @LDH) based on the electrostatic attraction was manufactured by self-assembly method to remove Cr(VI) from wastewater simultaneously. Fe 3 O 4 microspheres with suitable size can be surrounded by the LDH layers in the formation process to separate easily and reduce the dosage of Fe 3 O 4 . The removal behaviors of Cr(VI) from wastewater were investigated and the obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopic (TEM) and molecular simulation. Equilibrium studies indicated that the experimental data was well described by Langmuir models and the removal was a charge-limited process. Compared with other reported papers, the removal capacity for Cr(VI) by this method was larger, revealing a maximum utilization of charges on LDH. By molecular simulation, the relationship among chemical bond, electron transfer and energy was explained microscopically and the removal mechanism was proved that Cr(VI) trapped onto Fe 3 O 4 @LDH involved ion electrostatic interaction. The reusability of Fe 3 O 4 @LDH composite was tested and illustrated that it can be reused for several times.
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高影响因子
CELLULOSE
·
2018
·Vol. 25
·期 6
·3471-3486
·
IF 3.809
Li Qiaoping,Xu Bin,Zhuang Linghua,Xu Xiaoqing,Wang Guowei,Zhang Xinghua,Chen Jing,Tang Yang
Tetracarboxylic acid ester was synthesized with diethyl malonate and methyl acrylate, and an amino terminated hyperbranched polymer (HBP-NH 2 ) was prepared by reaction of a tetracarboxylic acid ester with diethylenetriamine (DETA). Hyperbranched polymer grafted chitosan (HBP-g-chitosan), a novel adsorbent material for Cr(VI) removal, was prepared from HBP-NH 2 and chitosan with epichlorohydrin as crosslinking agent. The adsorbent was characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectrophotometry, and X-ray diffraction. The influence of the initial concentration of Cr(VI), the dosage of adsorbent, pH value and the coexisting anions on the adsorption performance were studied. An isotherm of the adsorption process was generated and studied by Langmuir and Freundlich models. The results showed that the Freundlich model proved to be more suitable than the Langmuir model. The adsorption kinetics were determined by pseudo-first order and pseudo-second order kinetics. In doing so, it was found that the pseudo-second order kinetic model was more reliable than the pseudo-first order kinetic model.
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高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Ying Lü,Zhanfeng Li,Jianfa Li,Kun Chen,Huaping Dong,Jianxin Shou,Yimin Li
In this work, a novel combination of pyrite with zero valent iron (ZVI) was used to enhance the efficiency of Cr(VI) removal in column experiments, simulating the operation of permeable reactive barriers (PRBs).The influence of pyrite dosage, initial pH, and the mixing manner on the removal efficiency were evaluated. The synergetic effect between pyrite and ZVI was found to contribute to enhanced Cr(VI) removal in column experiments using the ZVI/pyrite mixture, by which the Cr(VI) removal could be kept at >90% for 50–100 PVs in comparison with ∼30 PVs by using ZVI alone.The Cr(VI) removal efficiency by the ZVI/pyrite mixture was also much higher than the sum of those by ZVI and pyrite separately in the batch experiments. Mechanism investigations indicated that the synergetic effect was principally attributed to the more reactive Fe 2+ regenerated in the columns using the ZVI/pyrite mixture, due to reaction of pyrite with Fe 3+ produced during Cr(VI) reduction. In addition, pyrite could suppress the pH increase and retard the surface passivation of active materials. The by-product SO 4 2− from pyrite oxidation is also beneficial for enhanced removal efficiency. X-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy-Energy dispersive spectrometry (SEM-EDS) studies confirmed the reduction of Cr(VI) into Cr(III), and that more pyrite was consumed in the Cr(VI) reduction by the ZVI/pyrite mixture. These findings are useful for developing cost-efficient methods for enhancing the removal of pollutants by ZVI-PRBs.
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高影响因子
Catalysts
·
2018
·Vol. 8
·期 12
·628
·
IF 3.465
Lei Wang,Changbo Zhang,Rong Cheng,Jafar Ali,Zhenbo Wang,Gilles Mailhot,Gang Pan
Cyanobacterial blooms can cause serious damage to aquatic ecosystems. However, we have demonstrated that typical algae-blooming speciesMicrocystis aeruginosa (M. aeruginosa)combined with photocatalysts could synergistically facilitate the photodecontamination of tetracycline hydrochloride (TC) and Cr(VI). In this study, for the first time, harmful algae were successfully converted into photoreactive bionano hybrid materials by immobilizingM. aeruginosacells onto polyacrylonitrile (PAN)-TiO2/Ag hybrid nanofibers, and their photocatalytic activity was evaluated. The addition ofM. aeruginosasignificantly improved the photodecontamination, and the reaction rate constant (k) values of TC and Cr(VI) degradation byM. aeruginosa-PAN/TiO2/Ag nanofiber mats were 2.4 and 1.5-fold higher than that of bare PAN/TiO2/Ag nanofiber. Photoreaction caused damage to algae cells, but no microcystin was found that had been photodegraded simultaneously. The effects of various active species were also investigated, and the photodegradation mechanism was proposed. Recycling tests revealed that this flexibleM. aeruginosa-PAN/TiO2/Ag hybrid mat had potential application in the removal of mixed organic and inorganic pollutants with high efficiency and without secondary pollutants. Thus, harmful algae blooms could serve as an efficient materials to remove toxic pollutants in a sustainable way under visible light irradiation.Keywords:Microcystis aeruginosa;PAN nanofiber;TiO2photocatalytic;Ag nanoparticles;tetracycline;Cr(VI)
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高影响因子
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