ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
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2022
·Vol. 30
·期 3
·6544-6558
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IF 5.19
Gao Jianlei,Feng Mengyuan,Yan Yixin,Zhao Zixu,Wang Yingchun
In this research, a new composite adsorbent (SC@ZVI@CS-AA) was designed and synthesized, and its application for the removal of Cr(VI) in groundwater was investigated. The interaction between SC@ZVI@CS-AA and Cr(VI) conformed to a pseudo-second-order model, and the adsorption process was dominated by chemisorption. The effects of material ratios, pH, temperature, SC@ZVI@CS-AA dosage, and coexisting ions on the removal of Cr(VI) were investigated. The removal efficiency of Cr(VI) by SC@ZVI@CS-AA reached 95%, and the reaction was significantly inhibited when SO 4 2− was present. Thermodynamically, the adsorption of Cr(VI) proceeded spontaneously above 35 °C ( ΔG θ < 0). According to scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometry, and synchronous thermal analysis, the removal mechanism of Cr(VI) by SC@ZVI@CS-AA was attributed to electrostatic attraction and reduction. In addition, SC@ZVI@CS-AA had good cyclic adsorption performance. Overall, the SC@ZVI@CS-AA composite showed great potential in the remediation of Cr(VI)-contaminated groundwater.
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JOURNAL OF MOLECULAR LIQUIDS
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2022
·
IF 6.633
Shiyao Li,Rong Cheng,Jiahao Li,Haobo Hou,Yi Wang,Jiaao Chen,Yuwei Xiang,Min Zhou
The efficient removal of hexavalent chromium from solution is a challenging task, in this paper, the nZVI and nitrogen co-doped magnetic carbon aerogel microsphere composites (nZVI@NCAs) were prepared via the microemulsion polymerization and subsequent carbonization process, and were expected to satisfactory performance in the removal of Cr(VI). From batch experiments, the Cr(VI) removal process by nZVI@NCA900 fitted better with the pseudo-second-order model. The optimal nZVI@NCA900 was superior to that of most magnetic carbon-substrate composites, displaying high Cr(VI) adsorption capacity of 266.79 mg·g −1 at 318 K. Additionally, it was found that Cr(VI) was reduced to the low-toxicity Cr(III) from the results analyzed by XPS, and nZVI@NCA900 exhibited Cr(VI) reduction performance of 33.92% Cr(VI) reduced to Cr(III). The reaction between the nZVI@NCAs and Cr(VI) was pH-dependence, endothermic and spontaneous. Removal mechanisms might involve multiple processes. The nZVI particles on the surface acted as reductants to reduce Cr(VI) to Cr(III) and form Cr(III)/Fe(III) hydroxides to precipitate on nZVI@NCAs. Simulation results by DFT prove that N is an active site and show positive effect in the adsorption system. N atoms were used as active sites to stabilize the interaction with Cr(VI) via adsorption attributed to electrostatic and act as electron donors for reduction of Cr(VI). The nZVI particles encapsulated by carbon aerogels could provide magnetic stability after acid reaction, which was beneficial to the separation of adsorbents after reaction and reuse for many cycles. These results provide a new view for developing magnetic carbon materials to remove Cr(VI) from contaminated water.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2022
·
IF 6.371
Qiang Gao,Junxi Li,Bin Liu,Chenguang Liu
The rationally designed semiconductor photocatalytic materials have attracted significant attention because of their huge advantages in the use of solar light. Herein, a series of direct Z-scheme heterojunction nanocomposites were synthesized via in situ growth of zinc indium sulfide nanosheets on ceria nanosheets (ZnIn 2 S 4 @CeO 2 ) and employed for effective photodegradation and Cr(VI) reduction. Advanced characterizations such as XPS , EPR spectra, and DFT calculations verified that the formation of direct Z-scheme charges transfer mechanism promoted rapid charge separation and retained strong redox capacity. As a result, the optimized ZnIn 2 S 4 @CeO 2 sample showed significantly promoted photocatalytic removal rates for tetracycline (TC) and Cr(VI) at a 3.7 and 4.5 times enhancement by comparison with the pristine ZnIn 2 S 4 , respectively. Additionally, after four consecutive cyclic tests, the as-synthesized nanocomposite exhibited remarkable photocatalytic activity and stability. The present work provides an integrated engineering strategy for Z-scheme photocatalyst systems with high photocatalytic efficiency and extensive applications.
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RARE METALS
·
2021
·Vol. 41
·期 4
·1265-1275
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IF 4.003
Tian Kang-Hui,Duan Chan-Qin,Ma Qun,Li Xing-Long,Wang Zhi-Yuan,Sun Hong-Yu,Luo Shao-Hua,Wang Dan,Liu Yan-Guo
High entropy oxides (HEOs), as a new type of single-phase multielement solid solution materials, have shown many attractive features and promising application prospect in the energy storage field. Herein, six-element HEOs (CoNiZnFeMnLi) 3 O 4 and (CoNiZnCrMnLi) 3 O 4 with spinel structure are successfully prepared by conventional solid-phase method and present outstanding lithium storage performances due to the synergy effect of various electrochemically active elements and the entropy stabilization. By contrast, (CoNiZnFeMnLi) 3 O 4 delivers higher initial discharge specific capacity of 1104.3 mAh·g −1 , better cycle stability (84% capacity retention after 100 cycles at 100 mA·g −1 ) and rate performance (293 mAh·g −1 at 2000 mA·g −1 ) in the half-cell. Moreover, the full-cell assembled with (CoNiZnFeMnLi) 3 O 4 and LiCoO 2 provides a reversible specific capacity of 260.2 mAh·g −1 after 100 cycles at 500 mA·g −1 . Ex situ X-ray diffraction reveals the electrochemical reaction mechanism of HEOs (CoNiZnFeMnLi) 3 O 4 , and the amorphous phase and the large amount of oxygen vacancies were obtained after the initial discharge process, which are responsible for the excellent cycle and rate performance. This research puts forward fresh insights for the development of advanced energy storage materials for high-performance batteries. Graphical Abstract
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CHEMOSPHERE
·
2021
·
IF 7.086
Fenglei Liu,Shan Hua,Chao Wang,Baowei Hu
Herein, using dialdehyde waste paper (DAWP) as a cross-linking agent to immobilize persimmon tannin (PT) was first used to remove the U(VI) and Cr(VI) via the “waste control by waste” concept. The microscopic and macroscopic surface properties of the as-prepared adsorbent was characterized by the advanced characterization techniques. Factors that affected the elimination process such as variable pH, coexistence ions and equilibrium time were investigated by batch techniques. The results showed that the maximal removal capacities of U(VI) and Cr(VI) on DAWP-PT were 242.3 mg/g (pH = 6.0) and 178.7 mg/g (pH = 2.0) at 298 K, which exhibited competitiveness with most of the reported solid materials. Meanwhile, adsorption data were fitted perfectly to the Langmuir and Pseudo-second-order equations, which indicated that the monolayer and homogenous chemisorption dominated the removal process. The SEM-EDX, DFT and XPS analysis conformed that adsorption of U(VI) was mainly via surface complexation, while the elimination of Cr(VI) was a redox reaction process, and about 65.33% of Cr(III) and 34.67% of Cr(VI) co-existed onto the surface of DAWP-PT. Thus, this study would provide a high-efficiency and low-cost adsorbent for radionuclide and heavy metal treatment.
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CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Tianwu Hu,Lifan Zeng,Yaqin Li,Yajing Wu,Zece Zhu,Yanbo Zhang,Di Tian,Chao Gao,Wei Li
A novel terylene carbon dots (TCDs) were successfully synthesized by a one-step solvothermal method, and further modified onto chitosan non-woven fabrics (CNF) for selective detection and effective removal of Cr(VI). Compared with TCDs, chitosan non-woven fabrics modified by carbon dots (CNF-TCDs3) exhibited higher selectivity and lower detection limit for Cr(VI) (The limit of detection (LOD) is 0.15 mg/L). In addition, CNF-TCDs3 showed a rapid and effective removal of Cr(VI), and still maintain a high relative removal rate (above 92%) after five times recirculation. The adsorption equilibrium could be reached in only 8 min, and the maximum adsorption capacity was 203 mg/g. The adsorption process conformed to the Langmuir model, and the fitting correlation is R 2 = 0.99. The fluorescence response and efficient adsorption mechanisms of the CNF-TCDs3 toward Cr(VI) were mainly attributed to the internal filtering effect and the amino and hydroxyl groups in chitosan. Significantly, this functionalized fabrics CNF-TCDs3 were successfully applied to semi-quantitatively detect on a smartphone-integrated-device and efficiently remove Cr(VI) in real samples.
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RSC Advances
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2021
·Vol. 11
·期 50
·31795-31806
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IF 3.361
Run Fang,Bing-Chiuan Shiu,Yuansong Ye,Yuchi Zhang,Hanyu Xue,Ching-Wen Lou,Jia-Horng Lin
In this study, a novel cationic nanofiber membrane with various functional groups, good structural stability, and high adsorption capacity of Cr(VI) is presented. This nanofiber membrane is prepared by electrospinning a mixed aqueous solution of a cationic polycondensate (CP) and polyvinyl alcohol (PVA). With the aid of PVA, CP can be smoothly electrospun without using any organic solvents, and the cross-linking between CP and PVA improves the stability of membrane in acidic solution. Chemical and morphology characterization reveals that the CP/PVA membrane is composed of interwoven nanofibers that contain numerous cationic groups. Due to its high cationicity and hydrophilicity, the CP/PVA membrane shows great affinity for HCr2O7− and Cr2O72−. Adsorption experiments indicate that the CP/PVA membrane can remove Cr(VI) from simulated wastewater rapidly and efficiently in both batch and continuous mode. Besides, the presence of most coexisting ions will not interfere with the adsorption. Due to the redox reaction between the CP/PVA membrane and adsorbed Cr(VI), the CP/PVA membrane exhibits distinct color change after Cr(VI) adsorption and the discoloration is highly dependent on the adsorption amount. Therefore, in addition to serving as a highly efficient adsorbent, the CP/PVA membrane is also expected to be a convenient and low-cost method for semi-quantitative determination of Cr(VI) in wastewater.
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JOURNAL OF HAZARDOUS MATERIALS
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2021
·
IF 10.588
Hui Wang,Min Zhuang,Liang Shan,Jie Wu,Guixiang Quan,Liqiang Cui,Yonghao Zhang,Jinlong Yan
Nano zero-valent iron (nZVI) is an effective material for Cr(VI) treatment, however excessive agglomeration and surface oxidation limit its application. Herein, straw derived hierarchically porous carbon supported FeNi bimetallic nanoparticles (FeNi@HPC) was prepared for effective removal of Cr(VI) from water. FeNi nanoparticles were successfully loaded onto HPC with good dispersibility, and HPC caused an increase in specific surface area of FeNi nanoparticles. FeNi@HPC exhibited a significantly enhanced removal efficiency for Cr(VI) in comparison to Fe@HPC and FeNi NPs. The Ni doping content was further optimized, and the best Ni content in bimetallic NPs was estimated as 10 wt%. The conditions optimal for the activity of FeNi@HPC were assessed, and the highest removal efficiency equivalent to 30 mg L −1 of Cr(VI) was achieved at pH= 4.0 in 360 min with a dosage of 0.5 g L −1 . Higher temperatures favored the removal of Cr(VI) and FeNi@HPC manifested the lowest activation energy as compared to Fe@HPC and FeNi NPs. The action mechanisms of FeNi@HPC presumably involved electron transfer from Fe 0 , Fe 2+ and atomic hydrogen. This work not only provide a cost-effective and available HPC material to stabilize nZVI but also revealed that using FeNi@HPC is a promising approach for the remediation of water pollution .
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Weichun Yang,Dongdong Xi,Chaofang Li,Zhihui Yang,Zhang Lin,Mengying Si
Anionic Cr(VI) and cationic heavy metals generally co-exist in industrial effluents and threaten the public health. Zero-valent iron (ZVI) particles tent to passivate rapidly, which results in a gradual drop in its reactivity. In this work, a strategy of “in-situ synthesized” iron-based bimetal was first developed to stimulate the self-activation of passivated ZVI. During this process, ZVI-loaded hydroxyapatite (ZVI/HAP) was prepared to enhance the affinity for co-existing Cu 2+ , which promoted the in-situ Cu 0 deposition on ZVI/HAP to form a Fe–Cu bimetal. The deposited Cu 0 significantly decreased the activation energy (E a ) of Cr(VI) reduction by 24.9%, and its corresponding Cr(VI) removal (96.53%) was much higher that of single Cr(VI) system (68.67%) within 9 h. More importantly, the removal of Cr(VI) and Cu 2+ were synchronously achieved. Systematical electrochemical characterizations were first introduced to explore the galvanic behaviors of iron-based bimetal. The charge transfer resistance and the negative open circuit potential of ZVI/HAP significantly decreased with the Cu 0 deposition, thereby accelerating the electron transfer from Fe 0 to Cu 2+ . The enhanced electron transfer further facilitated the Fe(II) release to promote Cr(VI) reduction. This “in-situ synthesized” iron-based bimetal strategy provides a novel pattern for ZVI activation and exhibits practical application in remediation of combined contaminant.
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Analytical Methods
·
2021
·Vol. 13
·期 32
·3561-3568
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IF 2.896
Lihong Shi,Xiaorui Dong,Guomei Zhang,Yan Zhang,Caihong Zhang,Chuan Dong,Shaomin Shuang
N-doped blue-fluorescence carbon dots (N-CDs) were fabricated via a one-pot hydrothermal method using folic acid and p-phenylenediamine. The obtained N-CDs exhibited strong fluorescence (FL) with a considerable quantum yield (QY) of 21.8% and exceptional optical stability under different conditions. Upon introducing Cr(VI), blue FL of N-CDs was distinctly quenched. On subsequent addition of L-AA, the FL of N-CDs could be partially recovered. The fluorescence changes of N-CDs have been utilized to detect Cr(VI) and L-AA in aqueous solutions with linear ranges of 0.10–150 μM and 0.75–2.25 mM, respectively, as well as limit of detection values of 9.4 nM and 25 μM, respectively. Furthermore, as-obtained N-CDs can be extended to monitor the fluctuation of intracellular Cr(VI) and L-AA. More intriguingly, N-CDs can target lysosomes with a satisfactory Pearson correction coefficient of 0.87, which indicates a promising application prospect in the biomedical field.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
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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Journal of Environmental Chemical Engineering
·
2021
·
IF 5.909
Malcom Frimpong Dapaah,Baojian Liu,Liang Cheng
Metal-organic frameworks (MOFs) are of particular interest in the adsorption of organic pollutants . This study investigated the adsorption of aniline (ANI), furfural (FUR), and bisphenol A (BPA) in aqueous solution using MIL-101(Cr)-X (X = –H, –NO 2 , –NH 2 and, –N-2-pyc), MIL-100(Cr, Fe), HKUST-1, and ZIF-8. For the first time, an imino-functionalized MOF was used to adsorb organic compounds in water. MOFs were characterized by XRD, N 2 adsorption-desorption, SEM , TEM, elemental analysis, and FTIR. MIL-101-N-2-pyc demonstrated the highest adsorption capacity of 460.8, 126.5, and 100.7 mg/g towards 500 mg/L BPA, ANI, and FUR respectively. The adsorption isotherms better suited the Langmuir model than the Freundlich model. Importantly, 98% of BPA (100 mg/L) was removed and the kinetic data correlated well with the pseudo-second-order model (R 2 > 0.998). Binary adsorption of FUR and acetic acid (AA) were determined for industrial relevance. MIL-101-N-2-pyc outperformed commercial activated carbon and the other MIL-101s with an impressive co-adsorption of 66.1 mg/g FUR and 62.5 mg/g AA. Overall, the adsorption mechanism was due to hydrogen bonding, π-π interaction, and electrostatic attraction. Moreover, MIL-101-N-2-pyc exhibited remarkable structural stability and less than 0.01 wt% Cr leached into water. The adsorbent regeneration was improved after 4 cycles in methanol.
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