COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2018
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IF 2.829
Hongxia Zhang,Jieli Lü,Junxia Peng,Guanqun Du,Haonan Peng,Yu Fang
In this study, we reported that the amino-functionalized organosilica monoliths (amino-OSMs) without need post-synthesis functionalization were prepared in one-step emulsion-templated method. Herein, formation of organosilica skeleton and amino-functionalization of skeleton surface can be simultaneously realized by addition of ammonia. The SEM images showed that the amino-OSMs had a rich pore structures with high adjustability via the simple change in formulation of the emulsions. The successful graft of amino groups on the surface of the organosilica monolith was confirmed by EDS and XPS measurements. The amino-OSMs prepared in this work show the excellent Cr(VI)-removal capacity from the aqueous solution. It is demonstrated that Cr(VI) adsorption on amino-OSM-3 was best described by Langmuir models and pseudo-second-order kinetic. The adsorption efficiency of amino-OSM-3 for Cr(VI) was measured to be 92.8% at room temperature , still remained as high as 85.1% after five recycles as indicative of the good durability. Furthermore, the treated capacity of amino-OSM-3 is 4.25 kg·g −1 with initial concentration of 200 μg·L −1 through the column with a height of 0.5 cm. Correspondingly, Cr(VI) aqueous solution after treatment meet the requirement of the World Health Organization water discharge standard with Cr(VI) concentration as low as 50 μg·L −1 . This work paves the way for the scale-up production of amino-OSMs using emulsion-templated technique for potential application in heavy metal removal .
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RSC Advances
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2018
·Vol. 8
·期 23
·12870-12878
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IF 2.936
Li Tan,Hailong Li,Mengru Liu
In this study, CMC–LDH beads were prepared and characterized using SEM, FTIR and TG analysis. The beads were applied for the removal of Cr(VI) from aqueous solution. The effects of adsorbent dosage, initial pH and initial concentration of Cr(VI) solution on Cr(VI) uptake were investigated in detail. Moreover, adsorption isotherms and adsorption kinetic models were employed to analyze the adsorption process, and a preliminary study of the reusability of the adsorbent was performed. The experimental results showed that the CMC–LDH beads could remove Cr(VI) from aqueous solution efficiently. When the initial concentration of the Cr(VI) solution was 100 mg L−1 and the adsorbent dosage was 12 g L−1, the removal efficiency of Cr(VI) reached 96.2%. After the CMC–LDH beads were reused 10 times, the removal efficiency of Cr(VI) still remained at 89.6%.
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APPLIED SURFACE SCIENCE
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2018
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IF 4.439
Yixiong Pang,Lingjun Kong,Diyun Chen,Gutha Yuvaraja
Microwave-induced catalytic system has been widely used in oxidation of organic pollutants, but no report focuses on heavy metal reduction. To expand the application field of microwave-induced catalytic system, MoS 2 decorated MnFe 2 O 4 was synthesized by hydrothermal method and employed for the reduction of Cr(VI) in microwave-induced catalytic system. The morphologies, chemical compositions, and optical properties of the synthesized catalysts were investigated using SEM, XRD, FT-IR and XPS. The MoS 2 -MnFe 2 O 4 samples exhibited significantly enhanced microwave-catalytic performance for Cr(VI) reduction compared to pristine MoS 2 and MnFe 2 O 4 , among which, the MoS 2 -MnFe 2 O 4 (10 wt%) sample was most suitable for Cr(VI) reduction in aqueous solution. 85.8% of Cr(VI) removal was obtained in 16 min in the present of MoS 2 -MnFe 2 O 4 . The effect of catalyst dosage, initial pH and microwave output on Cr(VI) reduction were investigated. Mechanism of Cr(VI) removal was investigated by radical quenching experiments. The enhanced microwave-catalytic activity of MoS 2 -MnFe 2 O 4 may be owing to the fact that MoS 2 can act as an electron acceptor to suppress the recombination of microwave-excited electron-holes. These results showed that microwave-induced catalytic reduction system is promising in Cr(VI) decontamination in aqueous solution.
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Journal of Materials Chemistry A
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2018
·Vol. 6
·期 45
·22580-22589
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IF 9.931
Xiu-Qing Qiao,Zhen-Wei Zhang,Qiu-Hao Li,Dongfang Hou,Qichun Zhang,Jian Zhang,Dong-Sheng Li,Pingyun Feng,Xianhui Bu
Exploiting novel photocatalysts with high efficiency and durability for reduction of hexavalent chromium (Cr(VI)) has gained attention from fundamental science and industrial research. In this work, we synthesized novel two-dimensional (2D) n–n Bi2MoO6 & Bi2S3 heterojunctions by a facile in situ anion exchange process for remarkably efficient removal of Cr(VI). Results show that Bi2MoO6 & Bi2S3 heterojunctions with core–shell structures are formed through the intimate contact of Bi2MoO6 core and Bi2S3 shell. The prepared Bi2MoO6 & Bi2S3 heterojunctions exhibit unprecedented photocatalytic activity for reduction of Cr(VI) under visible light irradiation. The optimized BMO-S1 heterojunction displays the highest reduction efficiency (κapp = 0.164 min−1) for Cr(VI) reduction. To the best of our knowledge, it is one of the highest reduction rate achieved among reported photocatalysts for Cr(VI) reduction under visible-light irradiation. Detailed studies show that strong selective adsorption for Cr(VI) enhances this unprecedented photocatalytic activity. Moreover, the intimate heterojunction between Bi2MoO6 core and Bi2S3 shell can efficiently deteriorate the charge carrier recombination and Bi2S3 content can boost visible light harvesting, thereby contributing to the remarkable photocatalytic catalytic activity, which were proven by PL, EIS and transient photocurrent responses. Characterization of Mott–Schottky plots and DRS prove that the Bi2MoO6 & Bi2S3 heterojunctions established a type-II band alignment with intimate contact, accounting for the efficient transfer and separation of photogenerated carriers. This work provides a simple route for facial synthesis of heterojunction photocatalysts for Cr(VI) reduction in industrial applications.
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CATALYSIS TODAY
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2018
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IF 4.667
Qikun Hu,Ehsan Rezaee,Haiquan Shan,Pengfei Liu,Zong-Xiang Xu
In this study, a nanocomposite based on graphene oxide (GO) and non-peripheral octamethyl-substituted copper(II) phthalocyanine (N-CuMe 2 Pc) nanorod as photosensitizer, was synthesized and characterized by X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy, FTIR and Raman spectroscopy. For the first time, the photocatalytic activity of GO/Pc nanocomposite was tested for the reduction of aqueous chromium (VI) (10 mg/L) as a model pollutant, and the results were compared with those of pure N-CuMe 2 Pc and GO. Visible light was used as source and Cr(VI) concentration was monitored during 120 min of treatment period. Up to 95% photocatalytic reduction of toxic Cr(VI) ions confirms that GO/Pc nanocomposite photocatalyst is clearly effective for wastewater treatment. Meanwhile, neat GO and N-CuMe 2 Pc nanorod were able to reduce only less than 10% of initial Cr(VI) ions. The reusability of the developed photocatalyst was also investigated. The retained amount of Cr(VI) increased from 2% at first cycle to around 17% at third cycle, due to loss of photocatalyst during collection process and morphology changes from nanorods to nanoparticles. Our results demonstrate the remarkably improved photocatalytic performance of GO/Pc nanocomposite for the practical application in wastewater remediation.
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Journal of the Taiwan Institute of Chemical Engineers
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2018
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IF 3.849
Jie Gao,Lizhe Yang,Yingying Liu,Fengli Shao,Qianjiahua Liao,Jingge Shang
Nano scale zerovalent iron (nZVI) used in waste water treatment can be more effective when modified with sulfur. In this study, we synthesized biochar-supported sulfide-modified nZVI (S-nZVI/BC) and characterized it using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. Our results reveal that sulfidation resulted in the formation of FeS on the surface of S-nZVI/BC. The Cr(VI) removal efficiency and capacity of the above composite were investigated as a function of initial solution pH/Cr(VI) concentration, reaction time, and presence of background ions (Ca 2+ and SO 4 2– ). Batch experiments revealed that solution pH had a significant impact on Cr(VI) removal capacities, with the maximum observed at pH 2.5. From a kinetic viewpoint, Cr(VI) removal was best described by a pseudo-second-order model. Importantly, the scavenger reaction was significantly promoted in the presence of SO 4 2– , being slightly inhibited by Ca 2+ and dissolved oxygen. Thus, the sulfidised nanohybrids exhibited excellent Cr(VI) removal performance, being well suited to the remediation of Cr(VI)-polluted water.
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Nanomaterials
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2018
·Vol. 8
·期 7
·537
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IF 3.504
Haijiao Lu,Jingkang Wang,Fei Li,Xin Huang,Beiqian Tian,Hongxun Hao
Recyclable nanomaterials are in great need to develop clean technology for applications in the removal of water contaminants. In this work, easily separable montmorillonite/Fe3O4/humic acid (MFH) nanocomposites were fabricated through a facile hydrothermal route. It was found the adsorption ability and stability of MFH was significantly enhanced due to the synergistic effects between montmorillonite, Fe3O4nanoparticles and humic acid. The MFH nanocomposites are highly efficient and recyclable as they can remove at least 82.3% of Cr(VI) and 95.1% of aniline in six consecutive runs. The adsorption mechanism was investigated by analyzing the kinetic parameters of pseudo first-order, pseudo second-order, and intraparticle diffusion models and describing the equilibrium isotherms of Langmuir and Freundlich models. Results indicated different adsorption mechanisms of Cr(VI) and aniline by MFH. The readily synthesized MFH nanocomposites can act as effective and practical materials for environmental applications.Keywords:nanocomposites;wastewater;adsorption;kinetics;isotherms;reusability
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ENVIRONMENTAL POLLUTION
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2019
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IF 5.714
Zhe Wang,Fanyu Lin,Liqin Huang,Zhili Chang,Bing Yang,Shuang Liu,Maosheng Zheng,Yuexiang Lu,Jing Chen
As a useful heavy metal ion , chromium has seen its applications in various fields. While it is also a toxic contaminant in water and may cause serious threats to the environment and human health. To develop a novel material with good adsorption capacity and easy solid-liquid separation strategy was necessary and significant. In this paper, the β-cyclodextrin (β-CD) functionalized three-dimensional structured graphene foam (CDGF) was successfully synthesized with the facile and one-step hydrothermal method. The SEM , BET, XRD, FT-IR and XPS analysis were carried out and the results confirmed the successfully grafting of β-CD onto GF. The batch adsorption of Cr(VI) was also taken out and the CDGF possessed good selectivity compared with other metal ions at pH = 3. The adsorption capacity reduced gradually as the initial pH of the Cr(VI) solution grew higher, which was because the anionic species of Cr(VI) were partial to the positively charged surface of CDGF. The easy separation strategy of the CDGF was also demonstrated and the CDGF could be taken out easily with a tweezer after the adsorption of Cr(VI), which significantly simplified the separation procedure and reduced time. By comparing the FT-IR and XPD analysis results, the adsorption mechanism was explored and the hydroxyl groups on CDGF played the main role in the adsorption process. This work brings a novel material for the adsorption of Cr(VI) from water and provides an innovative direction for the easy and fast solid-liquid separation strategy in the adsorption and other application fields.
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CHEMICAL ENGINEERING JOURNAL
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2018
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IF 6.735
Jing Zhang,Ning Gao,Fulong Chen,Tao Zhang,Guilong Zhang,Dongfang Wang,Xingyong Xie,Dongqing Cai,Xijun Ma,Lifang Wu,Zhengyan Wu
In this paper, we firstly used the inorganic nano-network of palygorskite (IPAL) with multiporous structure fabricated from rigid nano-rods by ion beam bombardment to enhance the photoactivity of the graphitic carbon nitride (CN). Results of spectroscopy techniques show that the as-prepared sample (IPAL/CN) displays broader light absorption in the visible light region and low recombination of charge carriers. Photocatalytic illustrations of Cr (VI) (and methylene blue (MB)) in aqueous solution by IPAL/CN samples were investigated respectively. Results show that the IPAL/CN-1:6 composites exhibit a superior catalytic activity with 99.5% of Cr (VI) and 99.2% of MB removal efficiency in 100 min, which were almost 7.0 times and 9.5 times higher than that of pure CN, respectively. After four cycles, the IPAL/CN-1:6 exhibits great photoactivity. Moreover, the reaction can be conducted better under the low pH value of the solution, and the initial concentration can influence the reaction property. The theory of DLVO and zeta potential were used to analyze the dispersion effect on the samples. The higher photoactivity of the IPAL/CN samples could be attributed not only to the high adsorption capacity but also to the improved dispersion affected by the nano-network of IPAL. This study provides a new opportunity for the modification of photocatalyst by the inorganic nanomaterials formed easily by physical irradiation.
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JOURNAL OF HAZARDOUS MATERIALS
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2017
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IF 6.065
Jun Wu,Xian-Bin Wang,Raymond J. Zeng
The widespread distribution of chromium(VI) in the environment leads to groundwater contamination. The use of iron sulfide (FeS) to remove Cr(VI) has therefore been proposed. However, aggregation is one of the main problems associated with the use of FeS nanoparticles prepared by traditional methods In this study, we used sodium alginate (SA) to stabilize FeS nanoparticles (FeS-SA). SA could prevent aggregation of FeS by the concurrent electrostatic repulsion and steric hindrance. Homogeneously dispersed FeS-SA nanoparticles 100 nm in diameter were observed. FeS-SA showed high efficiency in Cr(VI) removal, corresponding to an enhancement of efficiency from 65% (7.50 mmol Cr(VI) per g FeS) to 100% (11.54 mmol Cr per g FeS) relative to that achieved with naked FeS. Analysis of reaction products by X-ray diffraction and X-ray photoelectron spectroscopy revealed the co-existence of α-FeOOH, S 8 , and Cr(OH) 3 that apparently were introduced by Fe(II), S(−II), and Cr(VI), respectively. In-depth analysis of the removal mechanism revealed that reduction and adsorption respectively account for 82% and 18% of the Cr removal. In addition, higher pH and CaCl 2 concentration resulted in lower removal efficiency. This study provides a promising application of SA in enhancing FeS reactivity for the remediation of groundwater pollution.
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JOURNAL OF HAZARDOUS MATERIALS
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2016
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IF 4.836
Qi Wang,Xiaodong Shi,Enqin Liu,John C. Crittenden,Xiangjuan Ma,Yi Zhang,Yanqing Cong
AgI sensitized BiOI-Bi 2 O 3 composite (AgI/BiOI-Bi 2 O 3 ) with multi-heterojunctions was prepared using simple etching-deposition process. Different characterization techniques were performed to investigate the structural, optical and electrical properties of the as-prepared photocatalysts. It was found that the ternary AgI/BiOI-Bi 2 O 3 composite exhibited: (1) improved photocurrent response, (2) smaller band gap, (3) greatly reduced charge transfer resistance and (4) negative shift of flat band potential, which finally led to easier generation and more efficient separation of photo-generated electron-hole pairs at the hetero-interfaces. Thus, for the reduction of Cr(VI), AgI/BiOI-Bi 2 O 3 exhibited excellent photocatalytic activity under visible light irradiation at near neutral pH. AgI/BiOI-Bi 2 O 3 was optimized when the initial molar ratio of KI to Bi 2 O 3 and AgNO 3 to Bi 2 O 3 was 1:1 and 10%, respectively. The estimated k Cr(VI) on optimized AgI/BiOI-Bi 2 O 3 was about 16 times that on pure Bi 2 O 3 . Good stability was also observed in cyclic runs, indicating that the current multi-heterostructured photocatalyst is highly desirable for the remediation of Cr(VI)-containing wastewater.
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TALANTA
·
2016
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IF 4.035
Jian-feng Guo,Dan-qun Huo,Mei Yang,Chang-jun Hou,Jun-jie Li,Huan-bao Fa,Hui-bo Luo,Ping Yang
Herein, we have developed a simple, sensitive and paper-based colorimetric sensor for the selective detection of Chromium (Ⅵ) ions (Cr (VI)). Silanization-titanium dioxide modified filter paper (STCP) was used to trap bovine serum albumin capped gold nanoparticles (BSA-Au NPs), leading to the fabrication of BSA-Au NPs decorated membrane (BSA-Au NPs/STCP). The BSA-Au NPs/STCP operated on the principle that BSA-Au NPs anchored on the STCP were gradually etched by Cr (VI) as the leaching process of gold in the presence of hydrobromic acid (HBr) and hence induced a visible color change. Under optimum conditions, the paper-based colorimetric sensor showed clear color change after reaction with Cr (VI) as well as with favorable selectivity to a variety of possible interfering counterparts. The amount-dependent colorimetric response was linearly correlated with the Cr (VI) concentrations ranging from 0.5 µM to 50.0 µM with a detection limit down to 280 nM. Moreover, the developed cost-effective colorimetric sensor has been successfully applied to real environmental samples which demonstrated the potential for field applications.
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