Nanomaterials
·
2018
·Vol. 8
·期 7
·472
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IF 3.504
Siyu Xu,Jun Dai,Juan Yang,Jun You,Jingyi Hao
A series of novel and efficient heterostructured composites CaIn2S4/ZnIn2S4have been synthesized using a facile hydrothermal method. XRD patterns indicate the as-prepared catalysts are two-phase composites of cubic phase CaIn2S4and hexagonal phase ZnIn2S4. FESEM (field emission scanning electron microscope) images display that the synthesized composites are composed of flower-like microspheres with wide diameter distribution. UV–Vis diffuse reflectance spectra (DRS) show that the optical absorption edges of the CaIn2S4/ZnIn2S4composites shift toward longer wavelengths with the increase of the CaIn2S4component. The photocatalytic activities of the as-synthesized composites are investigated by using the aqueous-phase Cr(VI) reduction under simulated sunlight irradiation. This is the first report on the application of the CaIn2S4/ZnIn2S4composites as stable and efficient photocatalysts for the Cr(VI) reduction. The fabricated CaIn2S4/ZnIn2S4composites possess higher photocatalytic performance in comparison with pristine CaIn2S4or ZnIn2S4. The CaIn2S4/ZnIn2S4composite with a CaIn2S4molar content of 30% exhibits the optimum photocatalytic activity. The primary reason for the significantly enhanced photoreduction activity is proved to be the substantially improved separation efficiency of photogenerated electrons/holes caused by forming the CaIn2S4/ZnIn2S4heterostructured composites. The efficient charge separation can be evidenced by steady-state photoluminescence spectra (PLs) and transient photocurrent response. Based on the charge transfer between CaIn2S4and ZnIn2S4, an enhancement mechanism of photocatalytic activity and stability for the Cr(VI) reduction is proposed.Keywords:CaIn2S4/ZnIn2S4composites;Cr(VI);photocatalysis;simulated sunlight;hydrothermal method
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CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Mithun Nath,Shengqiang Song,Hang Liu,Yawei Li
Despite huge potential, Al 2 O 3 –CaO–Cr 2 O 3 system has been one of the least investigated one due to the generation of carcinogenic and toxic Cr(VI) compounds. Herein, we investigated the system under air atmosphere varying Cr 2 O 3 while keeping Al 2 O 3 :CaO ratio constant in order to identify the Cr(VI) dominant region, eventually to avoid it. The Ca 4 Al 6 Cr VI O 16 phase predominantly formed in the air atmosphere with Cr 2 O 3 content up to ∼12 mol%. However, an unprecedented Cr(III) phase appeared under air at higher Cr 2 O 3 content (26.43 mol%). We then synthesized the new polycrystalline ternary Cr(III) compound (CaAl 2 Cr 2 O 7 ) at 1500 °C under air atmosphere for the first time. A trigonal symmetry of hexagonal crystal family with space group P3 (143), lattice parameters a = b = 7.7909 Å and c = 7.6506 Å were determined from the X-ray powder diffraction pattern study. Electron microscope studies revealed uniform hexagonal microcrystals with similar lattice parameters. Most significantly, the binding energies of 586.1 and 576.2 eV for Cr2p 1/2 and Cr2p 3/2 respectively implied the +3 oxidation state of Cr in this compound.
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RSC Advances
·
2019
·Vol. 9
·期 19
·10958-10965
·
IF 3.049
Yang Zhang,Ruixi Bai,Zhigang Zhao,Qiuxia Liao,Peng Chen,Wanghuan Guo,Chunqing Cai,Fan Yang
In this study, a variety of diglycolic acid-functionalized gold nanoparticle (Au NP) probes are reported, which are highly sensitive for the detection of chromium ions, Cr(VI) ions, at low concentrations in aqueous solutions based on the application of surface plasmon resonance (SPR) theory. Due to its outstanding affinity for Cr(VI) ions, the capped diglycolic acid would induce the aggregation of the NP probes upon encountering them; this was evidenced by the obvious red-shifting of the SPR peak and the enlarged size of the NPs. For the same reason, the selectivity of the probe for Cr(VI) against other heavy metal ions was found to be remarkable. Under optimized conditions, the probe showed the limit of detection (LOD) of 0.32 ppb for Cr(VI) and a linear detection scale ranging from 0.32 ppb to 0.1 ppm. To the best of our knowledge, this is probably the lowest LOD reported for Cr(VI) detection among those of the methods based on SPR.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
·
IF 4.175
Rongfa Ding,Hui Wang,Yan Jiang,Rui Liu,Ke Jing,Meng Sun,Ruiqian Zhang,Shaoyu Qiu,Zhuoming Xie,Haowei Deng,Xianping Wang,Mingguang Kong,Weibin Jiang,Qianfeng Fang,Changsong Liu
ZrC dispersion-strengthened FeCrAl alloys with enhanced high-temperature strength and good ductility were fabricated through spark plasma sintering (SPS) and hot-forging. Nanosized ZrC particles with an average particle size of 56 nm were homogeneously dispersed in the FeCrAl-ZrC alloys. The addition of a small proportion of ZrC nanoparticles effectively refines the grain size and improves the strength and hardness of FeCrAl alloys. However, the ductility of FeCrAl alloys decreases gradually when the ZrC content increases from 0 wt% to 2.0 wt%. The tensile strength of SPSed FeCrAl-1.0 wt% ZrC alloy at 800 °C is 91 MPa, which is about 69% higher than that of pure FeCrAl, while the percentage elongation after fracture of FeCrAl-1.0 wt% ZrC is 15.0%, which is lower than that of FeCrAl (48.2%). To improve the ductility of FeCrAl-ZrC alloys, the SPSed samples were subjected to hot forging at 1000 °C. Through hot-forging, significant enhancement in ductility of FeCrAl-ZrC alloys was achieved without reducing the strength. The mechanical properties and microstructure of FeCrAl-1.0 wt% ZrC are stable after annealing at 1000 °C for 5 h, exhibiting superior thermal stability as compared with FeCrAl.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
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2019
·Vol. 411
·期 27
·7165-7175
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IF 3.286
Zhang Meng Yuan,Huang Ren Feng,Ma Xiao Guo,Guo Li Hui,Wang Ying,Fan Yin Ming
A new fluorescence sensor (QDs-IIP), based on ion-imprinted polymers (IIP) as recognition element and Mn-doped ZnS quantum dots (QDs) as fluorophore, was synthesized for the selective and sensitive determination of hexavalent chromium (Cr(VI)) ions. The QD was first coated by SiO 2 layer, and then modified with Cr(VI)-imprinted polymer. Several parameters affecting fluorescence intensity such as tetraethylorthosilicate (TEOS) volume, ZnS:Mn@SiO 2 amount, and radiation time were investigated and optimized. The QDs-IIP was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscope (TEM), and scanning electron microscope (SEM). Furthermore, the fluorescence quenching mechanism was investigated by using UV-VIS and fluorescence spectrophotometer, and it was found that internal filtration effect was the main fluorescence quenching mechanism. The relative fluorescence intensity (F 0 /F) increased linearly with the increase of Cr(VI) concentration in the range of 20 μg L −1 –1.0 mg L −1 . The QDs-IIP sensor showed high recognition selectivity for Cr(VI) in comparison with the QDs-NIP sensor with an imprinting factor (IF) of 2.53, and it could be reused 5 times. In addition, an analytical method of Cr(VI) based on the QDs-IIP sensor was established with a limit of detection of 5.48 μg L −1 , and was then applied to actual water samples with satisfactory results. Therefore, QDs-IIP can be deemed as a practicable fluorescent sensor for trace Cr(VI) detection.
Graphical abstract
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ACS Applied Bio Materials
·
2024
·
IF 4.6
Xingli Ding,Li Sheng,Jianming Zhang,Ge Zhang,Qi Gu,Yu Li,Long Zhang,Min Ji
Portable fluorescent film sensors offer a solution to the contamination issue in homogeneous sensor detection systems. However, their special structure leads to low sensitivity and a long response time, resulting in a significant scientific challenge limiting their development and application. In this work, we propose a dual design strategy to prepare highly sensitive film sensors for rapidly detecting Cr2O72–. Specifically, P(Fmoc-Osu)-SA hydrogel films were developed by integrating the biological macromolecule sodium alginate (SA) with the conjugated polymer poly(N-(9-Fluorenylmethoxycarbonyloxy)succinimide) (P(Fmoc-Osu)), using both mold and inkjet 3D printing methods. The “molecular wire effect” of the sensing unit P(Fmoc-Osu) and the water channel within the film substrate are responsible for the improved sensitivity and the reduced response time of this thin film sensor. P(Fmoc-Osu)-SA hydrogel films prepared by these two methods can rapidly detect Cr2O72– with limits of detection of 1.18 and 0.078 nM, respectively. Considering that 3D-printed hydrogel films can be tailored to different shapes according to detection needs, the P(Fmoc-Osu)-SA hydrogel films produced from this method were effectively applied in vegetable samples. This study provides an innovative and effective strategy for the development of biocompatible hydrogel sensors that offer the potential for determining trace amounts of Cr2O72– in agriculture.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2025
·
IF 8.5
Meng Zhou,Miaomiao Chen,Yunyun Wang,Caihong Mao,Yu Zhang,Junmei Liu,Xikun Zhang,Shujie Pang,Xudong Yang
In this study, a novel nitrogen-doped carbon quantum dot/oxidized gum arabic-gelatin-based fluorescent probe (NAH) was prepared using gelatin (GL) and gum arabic (AG) biomolecules. The primary network structure of this hydrogel consisted of polyacrylamide (PAM), while a secondary network structure was constructed between oxidized gum arabic and gelatin through the reaction of the Schiff base, which significantly enhanced the mechanical properties, the stress and strain of NAH reached 266.47 KPa and 2175.75 %. Nitrogen-doped carbon dots (NCDs) with yellow fluorescence emission properties were synthesized by hydrothermal method using salicylic acid as the carbon source and o -phenylenediamine as the nitrogen source. The fluorescent sensor obtained by compounding NCDs with hydrogel was able to selectively detect Cr(VI). The linear range of its detection was 0–90 μM, and the detection limit was 0.19 μM. The maximum theoretical adsorption capacity of the NAH hydrogel was 169.4 mg/g, and its adsorption isotherm conformed to the Langmuir adsorption isotherm model, and the adsorption kinetics conformed to the quasi-secondary kinetic model. Compared with the NCDs solution, the NAH hydrogel showed superior comprehensive performance, especially in solving the problem of recovery of NCDs. Meanwhile, this hydrogel provides an effective insight into the efficient detection and adsorption of environmental pollutants.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2016
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IF 3.349
Faling Ling,Liang Fang,Yi Lu,Jiemei Gao,Fang Wu,Miao Zhou,Baoshan Hu
CoFe-nitrate-layered double hydroxides (LDHs) with Co 2+ /Fe 3+ molar ratios of 2, 3 and 4 were synthesized by a simple co-precipitation method. The as-prepared CoFe-LDHs exhibited a high adsorption activity to the methyl orange (MO) dye and Cr(VI). The adsorption characteristics including adsorption kinetics and isothermals were investigated. Structure analysis of the as-synthesized LDHs before and after adsorption revealed that adsorption proceeds in two processes: external surface adsorption and interlayer anion exchange. The results of MO adsorption experiments showed that LDHs with Co 2+ /Fe 3+ molar ratios of 4 worked best with the largest MO adsorption amount up to 1290 mg/g at an initial concentration of 300 mg/L due to the porous structures. We have also noted that Cr(VI) in a range of 2–25 mg/L can be quickly removed with the maximum adsorption capacity of 27.62 mg/g in the initial 5 min, much faster than other LDH materials. Therefore, CoFe-LDHs are potential cost-effective adsorbents for both MO dye and Cr(VI).
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CHEMICAL ENGINEERING JOURNAL
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2016
·
IF 5.31
Ting Wang,Pan Zhao,Nan Lu,Hongche Chen,Conglu Zhang,Xiaohong Hou
Attractive magnetic metal-organic framework (MOF) material Fe 3 O 4 /MIL-101(Cr) (Matérial Institute Lavoisier, MIL) was synthesized by a simple reduction–precipitation method, and applied as an effective sorbent to the removal of two acid dyes, acid red 1 (AR1) and orange G (OG), in water. The novel synthetic method avoided the oxidation of Fe 2+ and made the Fe 3 O 4 /MIL-101(Cr) composite have the advantages of strong magnetism, large surface areas and excellent dispersion effect. Parameters that influenced the adsorption process, such as solution pH, adsorbent dosage, ionic strength, and so on, were investigated. Under the optimum conditions, adsorption kinetics and isotherms were determined from the obtained experimental data. The adsorption kinetics suggested the adsorption process of Fe 3 O 4 /MIL-101(Cr) toward AR1 and OG met the pseudo-second-order kinetic model. The adsorption isotherms were fitted by Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. Compared with the Freundlich and D–R models, the Langmuir isotherm model was found to be suitable to describe the equilibrium data, suggesting that the uptake of AR1 and OG by the Fe 3 O 4 /MIL-101(Cr) would be through monolayer adsorption. The thermodynamic results demonstrated that the adsorption was a spontaneous, exothermic and entropy decreased process. In addition, the Zeta potential data with pH value of AR1 and OG indicated that the electrostatic interactions between the dyes and the adsorbent might be critical to the adsorption mechanism. The used Fe 3 O 4 /MIL-101(Cr) could be regenerated by washing with NaOH solution and reused at least six times. The maximum adsorption capacities of the magnetic composite toward AR1 and OG were up to 142.9 mg g −1 and 200.0 mg g −1 , respectively. These results demonstrated that the novel composite would be an effective and easily re-usable adsorbent for AR1 and OG.
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Journal of Physical Chemistry C
·
2016
·
IF 4.509
Jie Su,Yue Liu,Weiyuan Yao,Zhongbiao Wu
In this paper, three kinds of HZSM-5-supported transition metal (Cr, Fe, and Cu) oxide catalysts were prepared by the wet impregnation method, and their stability performances for catalytic combustion of dichloromethane (DCM) were investigated. Different behaviors were observed for these three catalysts during a 300 min catalytic reaction running at 320 °C. It was found that the Cr–O/HZSM-5 catalyst showed good catalytic stability, while both Fe–O/HZSM-5 and Cu–O/HZSM-5 suffered obvious deactivation. Characterizations using XRD, BET, XPS, O2-TG, O2-TP-MS, NH3–IR, and temperature-programmed surface reaction (TPSR) techniques were then carried out to disclose the deactivation mechanisms. The results revealed that the main cause of the deactivation over the Fe–O/HZSM-5 catalyst was coke formation, which could be mainly attributed to its lower deep oxidation capacity of the intermediate products, i.e., the methoxy groups, and it could also be obtained that the Cu–O/HZSM-5 catalyst was severely poisoned by chlorine species owing to the formation of stable Cu(OH)Cl species. Based on the results above, it could be concluded that the close proximity and synergy between acidic sites and active oxygen species were crucial to avoid coke deposition during the chlorinated volatile organic compound catalytic oxidation process.
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JOURNAL OF HAZARDOUS MATERIALS
·
2015
·
IF 4.529
Ruowen Liang,Fenfen Jing,Lijuan Shen,Na Qin,Ling Wu
A bifunctional photocatalyst-Fe-benzenedicarboxylate (MIL-53(Fe)) has been synthesized successfully via a facile solvothermal method. The resulting MIL-53(Fe) photocatalyst exhibited an excellent visible light ( λ ≥ 420 nm) photocatalytic activity for the reduction of Cr(VI), the reduction rate have reached about 100% after 40 min of visible light irradiation, which has been more efficient than that of N-doped TiO 2 (85%) under identical experimental conditions. Further experimental results have revealed that the photocatalytic activity of MIL-53(Fe) for the reduction of Cr(VI) can be drastically affected by the pH value of the reaction solution, the hole scavenger and atmosphere. Moreover, MIL-53(Fe) has exhibited considerable photocatalytic activity in the mixed systems (Cr(VI)/dyes). After 6 h of visible light illumination, the reduction ratio of Cr(VI) and the degradation ratio of dyes have been exceed 60% and 80%, respectively. More significantly, the synergistic effect can also be found during the process of photocatalytic treatment of Cr(VI) contained wastewater under the same photocatalytic reaction conditions, which makes it a potential candidate for environmental restoration. Finally, a possible reaction mechanism has also been investigated in detail.
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WATER SCIENCE AND TECHNOLOGY
·
2024
·Vol. 89
·期 9
·2384-2395
·
IF 2.5
Bing Wenrong,Li Xinyu,Liang Mingzhao,Zhou Xu,Zhang Jianfeng,Liang Jing
View large Download slide View large Download slide Close modal Cr(VI) and phenol commonly coexist in wastewater, posing a great threat to the environment and human health. However, it is still a challenge for microorganisms to degrade phenol under high Cr(VI) stress. In this study, the phenol-degrading strain Bacillus cereus ZWB3 was co-cultured with the Cr(VI)-reducing strain Bacillus licheniformis MZ-1 to enhance phenol biodegradation under Cr(Ⅵ) stress. Compared with phenol-degrading strain ZWB3, which has weak tolerance to Cr(Ⅵ), and Cr(Ⅵ)-reducing strain MZ-1, which has no phenol-degrading ability, the co-culture of two strains could significantly increase the degraded rate and capacity of phenol. In addition, the co-cultured strains exhibited phenol degradation ability over a wide pH range (7–10). The reduced content of intracellular proteins and polysaccharides produced by the co-cultured strains contributed to the enhancement of phenol degradation and Cr(Ⅵ) tolerance. The determination coefficients R 2 , RMSE, and MAPE showed that the BP-ANN model could predict the degradation of phenol under various conditions, which saved time and economic cost. The metabolic pathway of microbial degradation of phenol was deduced by metabolic analysis. This study provides a valuable strategy for wastewater treatment containing Cr(Ⅵ) and phenol. Co-culture can degrade phenol under high concentrations of Cr(VI). Co-culture improves the degraded rate and concentration of phenol under Cr(VI) stress. Co-culture synergistically enhances the ability to resist phenol and Cr(VI) toxicity. BP-ANN predicted the degradation of phenol under different conditions.
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