JOURNAL OF POROUS MATERIALS
·
2022
·Vol. 30
·期 1
·311-325
·
IF 2.523
Li Zhengjie,Zhang Lu,Li Yunlong,Zhou Lilong,Han Jilong,Xu Hong,Yun Jimmy,Shen Shufeng,Liu Runjing
In the present work, functionalized MIL-101(Cr)-X (X = –Br, –CH 3 , –HSO 3 , –NO 2 ) materials with mesoporous pores were synthesized and used for tannic acid (TA) adsorption from aqueous solutions. In comparison with MIL-101(Cr), NO 2 -substituted MIL-101(Cr) was found to have positive surface charge and only slight reduction in its specific surface area, resulting in higher TA adsorption capacity than the parent MIL-101(Cr) and the others. Effect of operating parameters such as adsorption time, temperature, pH and ionic strength on the adsorption performance of MIL-101(Cr)-NO 2 was investigated. The TA adsorption capacity remarkably increases with increasing ionic strength adjusted by CaCl 2 . MIL-101(Cr)-NO 2 exhibits an adsorption capacity of 1619 mg/g, higher than that of the reported adsorbents, probably due to electrostatic interaction, π–π stacking interaction and Cr–O complexation interaction between MOF framework and TA. Adsorption isotherms and kinetic results are in accordance with Freundlich model and pseudo-second-order model, respectively. Moreover, the thermodynamics of TA adsorption on MIL-101(Cr)-NO 2 suggests an endothermic process.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2022
·
IF 8.025
Yunquan Liu,Huimei Shan,Yanyue Pang,Hongbin Zhan,Chunya Zeng
Iron modified chitosan/coconut shell activated carbon (Fe/CSCC) composite bead is synthesized to remove Cr(VI) and is characterized to reveal the influencing factors and reaction mechanism. Results show that the adsorption capacity ( Q e ) of Cr(VI) increases with the increase of iron loading, contact time ( t ), Cr(VI) initial concentration ( C 0 ), and temperature ( T ), but decreases with the increase of pH, and mass and volume ratio ( m/v ). After 0.1 mol FeCl 3 modification, the removal efficiency of Cr(VI) by Fe/CSCC reaches as high as 97.25 % at pH = 3, m/v = 1.0 g/L, t = 2880 min, C 0 = 25 mg/L, and T = 25 °C. The coexisting ions of SO 4 2− , HPO 4 − , and Ca 2+ lead to the decrease of Q e by 7.82, 5.05, and 5.50 mg/g, respectively, and the inhibition effect increases with their increasing concentrations. Fe/CSCC adsorption for Cr(VI) is an endothermic spontaneous process, and a chemical and monolayer adsorption, which is better fitted to a pseudo-second-order kinetic. The fitted maximum Q e is 64.49 mg/g by using the Langmuir model. Moreover, after five cycles of regeneration, the Q e value only drops about 3.46 mg/g. Characterization analysis of BET, XRD , FTIR , XPS, and SEM-EDS indicates that Cr(VI) is mainly adsorbed by Fe/CSCC through electrostatic attraction and complexation, which is related to the −COOH and − NH 2 groups, and Fe − O groups, respectively.
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JOURNAL OF FLUORESCENCE
·
2022
·Vol. 32
·期 6
·2343-2350
·
IF 2.525
Liu Tao,Zhang Shuai,Fan Xiaoyu,Yang Dou,Wang Min,Shao Xiaodong,Wang Shuhao,Yue Qiaoli
Carbon dots (CDs) were used to develop a sensitive sensing technique for detecting Cr(VI). CDs were made using a hydrothermal technique from citric acid and glutamic acid. These prepared CDs emitted blue fluorescence under excitation of 350 nm (λ em = 420 nm), and the fluorescence quantum yield was 48.41%. Transmission electron microscope was used to examine the morphology of the CDs, which had an average size of 2.21 ± 0.39 nm. The elementary composition and bonding structure of the CDs were conducted by XPS and FT-IR spectrum. Cr(VI) quenched the fluorescence of CDs through a static quenching effect and an inner filter effect, allowing Cr(VI) to be detected quantitatively. This approach was used to detect Cr(VI) in two samples of water, with the findings demonstrating that it is reliable and accurate. The fluorescence intensity change was linearly related to the concentration of Cr(VI) in the range from 0.5 to 400 μM, with the detection limit being 0.10 μM. This approach has the virtues of wide detection range, low cost and fast response. The strategy has a great application prospect for detecting Cr(VI) in practical samples.
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Catalysts
·
2022
·Vol. 12
·期 11
·1429
·
IF 4.501
Yali Song,Huan Zhang,Ziyan Li,Long Huang,Junhao Xie,Long Han,Ruoying Zheng,Yuqing Zhang,Hongzhong Zhang
Previous studies have displayed various conclusions about the effect of preparation factors on the photoreduction property of ZnIn2S4. Therefore, it is not easy to figure out the optimal preparation conditions of ZnIn2S4for Cr(VI) photoreduction. To ensure Cr(VI) reduction efficiency, various ZnIn2S4photocatalysts were prepared in different solvents (i.e., water and ethylene glycol) and temperatures (i.e., 120 °C, 150 °C and 180°C). Different characterization methods were used to explain the difference in optical performance and photocatalytic property among the obtained samples. The results show that all the samples exhibit a similar band gap. The reaction solvent and temperature have a great influence on the surface morphology and optical property, leading to the different photocatalytic properties. ZnIn2S4synthesized at 120 °C in the solvothermal condition shows the optimal efficiency on Cr(VI) photoreduction due to the effective utilization of photo-induced carriers. The reasonable analysis and effective conclusion presented may provide the optimal synthesis method of ZnIn2S4to effectively remove Cr(VI) from water environment.Keywords:ZnIn2S4;Cr(VI);solvothermal;hydrothermal;photoreduction
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JOURNAL OF POLYMERS AND THE ENVIRONMENT
·
2022
·Vol. 31
·期 2
·637-647
·
IF 4.705
Li Dan,Liu Huipeng,Wang Ziwen,Zhang Zeqian,Wang Chengzhong,Zhao Biao,Pan Kai
Constructing 3-D nanomaterial-based adsorbents with good mechanical properties has attracted increasing attention. This paper reports a simple strategy to prepare ultralight and superelastic 3-D aerogels as efficient adsorbents for heavy metal Cr(VI) in wastewater by in-situ loading of polypyrrole on cellulose acetate nanofibers followed by freeze-drying method. The obtained aerogel possesses obvious 3-D porous and cross-linked structure, in which polypyrrole is uniformly coated on the nanofiber surface. Besides, the aerogel shows good mechanical properties with high compressive strength of 14.49 kPa, and can be processed into any desired shape. Especially, due to the presence of large specific surface area and high porosity, the obtained nanofiber aerogel shows significant Cr(VI) adsorption with maximum adsorption capacity of 244.65 mg/g. The present work proposes a high-quality nanofiber aerogel for efficiently adsorbing Cr(VI).
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Ling Xiong,Liying Ma,Meiqi Zhao,Haojian Zhang,Shaohua Chen
In present work, nanoscale zero-valent iron (nZVI) was successfully stabilized using fulvic acid (nZVI-FA). Shewanella oneidensis MR-1 (MR-1) was used to enhance the reactivity of the nZVI-FA. The results demonstrated that nZVI-FA combined with the MR-1 (nZVI-FA/MR-1) system could effectively solve the aggregation and surface passivation of nZVI, thereby significantly enhancing the reactivity of nZVI for Cr(VI) removal. The Cr(VI) removal efficiency of the nZVI-FA/MR-1 system (100 %) within 24 h was apparently higher than that of the ZVI-FA system (64.43 %). The enhancement of Cr(VI) removal is because fulvic acid (FA) FA can stabilize nZVI against aggregation; MR-1 could rapidly reduce the Fe(III) (hydr)oxides (FeHOs) passivation layers on the surface of nZVI-FA to biogenic Fe(II) [bio-Fe(II)], which in turn reduced Cr(VI). X-ray photoelectron spectroscopy (XPS) analysis revealed that the Fe(II)/Fe(III) ratio (1.20) and Cr(III)/Cr(VI) ratio (2.53) of the precipitates in the nZVI-FA/MR-1 system were much higher than that those in the nZVI-FA system (0.55 and 1.40, respectively). Three-dimensional excitation-emission matrix (3D-EEM) spectral analysis confirmed that tyrosine, tryptophan, and protein-like substances in extracellular polymeric substances (EPSs) from MR-1 are vital for the removal of Cr(VI). The mechanism analysis demonstrated that most Cr(VI) was reduced to Cr(III); Cr(III) existed as Cr 2 O 3 , FeCr 2 O 4 and Cr x Fe 1-x (OH) 3 precipitates, and some of the Cr(VI) was removed from the solution by adsorption and complexation. This study offers a low-cost, efficient, and environmentally friendly strategy to enhance the reactivity of nZVI for Cr(VI) removal, which has broad prospective applications.
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Materials
·
2022
·Vol. 15
·期 16
·5763
·
IF 3.748
Minmin Zou,Hexin Zhu,Ming Dong,Tian Zhao
As one of the most important prototypical chromium-based MOFs, MIL-101(Cr) is well-studied and widely employed in various scientific fields. However, due to its small capture window sizes and curved internal apertures, its application in large molecular removal is quite limited, and given its high stability and high synthetic temperature (>200 °C), it is difficult to achieve hierarchically porous MIL-101(Cr). In our study, hierarchically porous MIL-101(Cr) involving a high macro-/meso-/micropores ratio was designed and synthesized using acetic acid as an additive and silicon dioxide (SiO2) nanoparticles as a template. The optimal hierarchically porous MIL-101(Cr) (A-4) possessed a high specific surface area (2693 m2g−1) and an abundant macro-/mesoporous structure with the addition of SiO2of 200 mg. Compared with the control sample (A-0) with a less macro-/mesoporous structure, A-4 showed good adsorption properties for both coomassie brilliant blue R-250 (CBB, 82.1 mg g−1) and methylene blue (MB, 34.3 mg g−1) dyes, which were 1.36 times and 9.37 times higher than those of A-0. Moreover, A-4 also had good recyclability, and the removal rate of CBB was still higher than 85% after five cycles of adsorption.Keywords:MIL-101(Cr);SiO2;dye adsorption;template
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Small
·
2022
·Vol. 18
·期 35
·2201949
·
IF 15.153
Xiaoning Li,Meng Li,Quanyu Shi,Hongmin Guo,Lidong Wang,Xiaolin Guo,Zhijun Chen,Jonathan L. Sessler,Huining Xiao,Tony D. James
Heavy metal pollution has resulted in numerous environmental challenges. However, classic approaches, involving the use of solid adsorbents are subject to limitations, including the high energy consumption required for processing before and after use. Accordingly, strategies that facilitate the use of metal capture media that extends beyond waste remediation are attractive. Herein, a porous fluorescent aerogel (CPC aerogel) is constructed by immersing amino-based carbon dots (CDs-NH 2 ) into a polyethyleneimine (PEI)/carboxymethylated cellulose (CMC) aerogel network for the simultaneous detection and adsorption of Cr(VI). Adsorption experiments confirm that the CMC/PEI containing CDs-NH 2 aerogel (CPC aerogel) exhibits good Cr(VI) extraction capacity, and can reach a level that conforms with industrial water safety standards. In addition, the CPC aerogel can continuously detect and remove Cr(VI) at high flux. Following Cr(VI) absorption, the CPC aerogel may be vulcanized (MS x -CPC gel) and used for solar thermoelectric generation resulting in power generation. Additionally, the MS x -CPC gel can be used for solar steam generation and exhibits excellent evaporation rates of ≈1.31 kg m –2 h –1 under one sun irradiation. The results serve to underscore how materials designed for metal ion recognition and adsorption once exhausted can be exploited to provide materials for solar thermoelectric power generation and seawater desalination.
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Materials
·
2022
·Vol. 15
·期 14
·4909
·
IF 3.748
Yunquan Liu,Huimei Shan,Chunya Zeng,Hongbin Zhan,Yanyue Pang
Graphene oxide and chitosan microspheres modified with α–FeO(OH) (α–FeO(OH)/GOCS) are prepared and utilized to investigate the performance and mechanism for Cr(VI) removal from aqueous solutions and the possibility of Fe secondary pollution. Batch experiments were carried out to identify the effects of pH, mass, and volume ratio (m/v), coexisting ions, time (t), temperature (T), and Cr(VI) initial concentration (C0) on Cr(VI) removal, and to evaluate adsorption kinetics, equilibrium isotherm, and thermodynamics, as well as the possibility of Fe secondary pollution. The results showed that Cr(VI) adsorption increased withC0,t, andTbut decreased with increasing pH andm/v. Coexisting ions inhibited Cr(VI) adsorption, and this inhibition increased with increasing concentration. The influence degrees of anions and cations on the Cr(VI) adsorption in descending order were SO42−> PO42−> NO3−> Cl−and Ca2+> Mg2+> Mn2+, respectively. The equilibrium adsorption capacity of Cr(VI) was the highest at 24.16 mg/g, and the removal rate was 97.69% under pH = 3,m/v= 1.0 g/L,T= 298.15 K, andC0= 25 mg/L. Cr(VI) adsorption was well fitted to a pseudo-second-order kinetic model and was spontaneous and endothermic. The best fit of Cr(VI) adsorption with the Langmuir and Sips models indicated that it was a monolayer and heterogeneous adsorption. The fitted maximum adsorption capacity was 63.19 mg/g using the Sips model under 308.15 K. Cr(VI) removal mainly included electrostatic attraction between Cr(VI) oxyanions with surface Fe–OH2+, and the adsorbed Cr(VI) was partially reduced to Cr(III) and then precipitated on the surface. In addition, there was no Fe secondary pollution during Cr(VI) adsorption.Keywords:hydroxyl iron oxide;graphene oxide;chitosan;Cr(VI) adsorption
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Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Junlin Xie,Kun Wei,Xiaoqing Liu,De Fang
Carbon powders were used to detoxify [Cr(VI)] in metallurgical solid waste was investigated, since the presence of [Cr(VI)] had a very serious impact on the environment. Five types of carbon powders were selected as carbon sources and soluble CrO 3 was used as a hexavalent chromium source in metallurgical solid waste. Ultra-fine Cr 3 C 2 powders (about 80 nm) were synthesized by carbothermal reduction reaction to achieve the detoxification of [Cr(VI)]. The temperature plays a crucial role in the synthesis of Cr 3 C 2 according the experimental and thermodynamic results, illustrating that the synthesis temperature was in the range of 900 ℃–1200 ℃. Surface area, morphology, and surface chemistry of carbon powders were investigated to analyze the effect of carbon type on the mechanism of detoxification of hexavalent chromium [Cr(VI)] and the formation of chromium carbide . The results show that nano carbon powder with finer particle size (30–50 nm), higher specific surface area (101.5 m 2 /g) and fewer chemical bonds with carbon atoms formed by sp 2 orbital hybridization are more suitable as a carbon source for carbothermal reduction of [Cr(VI)]. Therefore, nano Cr 3 C 2 powder was achieved at the lowest synthesis temperature (900 ℃), when nano carbon powder was selected as the carbon source.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2022
·Vol. 29
·期 50
·76404-76416
·
IF 5.19
Hu Jie,Lu Songhua,Ma Jianfeng,Zhu Fang,Komarneni Sridhar
In this paper, the g-C 3 N 4 /ZnIn 2 S 4 composite was synthesized by a two-stage hydrothermal method. The microstructure, surface, and optical properties of the composite were thoroughly characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analysis, and UV-Vis absorption spectroscopic analysis. The removal capacity of Cr(VI) was optimized by using ZnIn 2 S 4 loaded in the composite. Meanwhile, the optimal pH environment for the reduction of Cr(VI) was determined to be about pH 3, and the reduction efficiency could reach more than 99% within 60 min. Further, the results of UV-Vis absorption analysis indicated the high and wide range of light absorption by composite compared with pure g-C 3 N 4 . Therefore, the enhanced photocatalytic performance of the composite could be attributed to the well-matched energy band structure between g-C 3 N 4 and ZnIn 2 S 4 , which apparently promoted the effective separation and transfer of photogenerated carriers. In addition, the composite showed good stability in the visible light catalytic reaction, and the possible mechanism of the photocatalytic activity of Cr(VI) reduction by the composite was proposed.
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APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Yu Liu,Yingying Xing,Xinyu Zheng,Shengjie Xu,Di Li,Deli Jiang
Designing high-performance and earth-abundant bifunctional catalysts for electrocatalytic water splitting remains a great challenge. Herein, a novel electrode composed of Cr-doped Co 2 P with P vacancies nanowire arrays (denoted as CrCo 2 P(V p ) NWs) grown on nickel foam was fabricated via a hydrothermal and successive calcination method. The Cr doping and vacancy engineering synergistically enable the exposure of more active sites, optimize electronic structure, and accelerate the charge transport capability, thus enhancing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances. As a result, the obtained Cr 0.4 Co 2 P(V p ) NWs catalyst exhibits superior catalytic activities in 1.0 M KOH solution with low overpotentials of 37 mV at −10 mA cm −2 for HER and 253 mV at 20 mA cm −2 for OER, respectively. Furthermore, using Cr 0.4 Co 2 P(V p ) NWs as a dual-function catalyst only requires 1.54 V voltage at 10 mA cm −2 for overall water splitting. Notably, the Cr 0.4 Co 2 P(V p ) NWs catalyst displays satisfactory stability with only a small attenuation of 3.2% after 50 h in a constant current testing. This study highlights the synergistic effect between doping and anion-vacancies in the enhancement of electrocatalytic activities and provides a feasible strategy to design effective, earth-abundant, and stable bifunctional electrocatalysts for water splitting.
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