TALANTA
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2019
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IF 4.916
Hui-Min Zhai,Ting Zhou,Fang Fang,Zhi-Yong Wu
In this work, a paper-based analytical device (PAD) for sensitive speciation detection of chromium (Cr) by smartphone camera was introduced. In anion electrokinetic stacking mode, Cr (VI) in the form of CrO4 2− was firstly enriched into a narrow band on a paper fluidic channel, and then the band was visualized by 1,5-diphenylcarbazide (DPC). Colorimetric detection of Cr (VI) was based on the gray intensity of stacking bands. Detection of Cr (III) was achieved by subtraction of the detection results of Cr (VI) before and after the sample was oxidized. Under optimized conditions, the detection limit of Cr (VI) and Cr (III) of 0.20 μM (~10.4 μg L −1 ) and 0.30 μM (~14.6 μg L −1 ) were achieved with a linear response in the range of 0.67–5.00 μM and 0.93–6.00 μM, respectively. The detection performance of PAD is close to that obtained by desktop spectrophotometry , thanks to the online stacking effect. Meanwhile, this PAD also exhibited a good selectivity over coexisting cations and anions, thanks to the charge selectivity of the stacking mode and the selective visualization reaction of DPC. Speciation detection of Cr from tap water, river water, surface water, and electroplating wastewater was demonstrated. This work shows the potential of PADs for on-site detection of Cr (VI) in environmental water samples.
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ENVIRONMENTAL SCIENCE & TECHNOLOGY
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2019
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IF 7.149
Yue Hu,Xing Peng,Zhihui Ai,Falong Jia,Lizhi Zhang
In this study, we report that liquid nitrogen treatment is a promising zero-valent iron activation method that does not remove the iron oxide shell; this can improve the apparent Cr(VI) removal rate constant of zero-valent iron by about 4–120 times, depending on the particle sizes and the suppliers of zero-valent iron. It was found that liquid nitrogen, with its low temperature of 77 K, could crack the iron oxide shell of zero-valent iron to produce abundant fractures because of the different thermal expansion coefficients of iron oxide and iron. These fractures provided suitable mass transfer channels for the inward transfer of water/oxygen molecules to the iron core and the subsequent in situ generation of Fe(II) for the reduction of Cr(VI) to Cr(III). More importantly, systematic characterizations confirmed the generation of an Fe(III)/Cr(III)/Cr(VI) composite on the surface of zero-valent iron during the removal, suggesting its environmental benignancy. This study provides a novel physical zero-valent iron activation method, sheds light on the importance of the iron oxide shell of zero-valent iron on Cr(VI) removal, and clarifies the intrinsic Cr(VI) removal mechanism of zero-valent iron.
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BIORESOURCE TECHNOLOGY
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2018
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IF 5.807
Chaofan Zheng,Huaili Zheng,Yongjuan Wang,Yili Wang,Wenqi Qu,Qiang An,Yongzhi Liu
Novel adsorbents, poly([2-(methacryloxy)ethyl]trimethylammonium chloride) modified magnetic chitosan particles (DMCPs), were synthesized via free radical polymerization and applied to adsorb Cr(VI) from aqueous solution. The effects of pH (2–11), Cr(VI) concentration (10–200 mg/L) and contact time (0–420 min) on the adsorption performance were evaluated. The results showed that the adsorption capacity of DMCPs was much larger than that of magnetic chitosan particles (MCPs) in the examined pH range and decreased with Cl − concentration increasing, indicating that electrostatic interaction and ion exchange are the governing mechanisms of Cr(VI) adsorption by DMCPs. The Langmuir isotherm model and pseudo-second-order kinetic model fitted the experimental data well. The maximum adsorption capacity of DMCPs is 153.85 mg/g. Besides, Cr(VI)-loaded DMCPs could be easily separated and efficiently regenerated. Therefore, DMCPs are promising candidates for Cr(VI) adsorption owing to their excellent performance in a wide pH range, easy separation and good reusability.
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CHEMICAL ENGINEERING JOURNAL
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2013
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IF 3.473
Lei Wang,Wen Liu,Ting Wang,Jinren Ni
For highly efficient removal of Cr(VI) from aqueous solutions, amino-functionalized titanate nanotubes (NH 2 -TNTs) with excellent adsorption performance have been synthesized by covalently grafting [1-(2-amino-ethyl)-3-aminopropyl]trimethoxysilane (AAPTS) onto protonated titanate nanotubes (HTNTs) with great amounts of surface hydroxyl groups. TEM and XRD results confirmed that the nanotubular morphology and crystal structure of HTNTs and NH 2 -TNTs were preserved. FTIR spectra demonstrated that AAPTS was covalently bonded on the surface of HTNTs. Batch adsorption experiments showed that pseudo-second-order kinetics model and Langmuir isotherm model fitted the adsorption data very well for both materials, and the Cr(VI) adsorption capacity on NH 2 -TNTs calculated by Langmuir model was up to 153.85 mg g −1 at initial pH 5.4 and 30 °C, much larger than that on HTNTs (26.60 mg g −1 ). Moreover, uptake of Cr(VI) ions onto NH 2 -TNTs could be completed within only 5 min for 95% adsorption of the maximum. Influence of different species of Cr(VI) under varying pH was also considered. FTIR and XPS analysis indicated that Cr(VI) ions were first exchanged with NO 3 - linked on the positively charged amino groups and then partially reduced to Cr(III). Afterwards, Cr(III) were then totally chelated with amino groups and no Cr(III) was detected in the solution after Cr(VI) adsorption at pH range of 1–12.
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
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2015
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IF 2.723
Wenzhe Song,Taihong Shi,Di Yang,Jinpeng Ye,Yi Zhou,Yuxiang Feng
Adsorption of Cr(VI) onto different pretreated zeolites modified with cetylpyridinium chloride (CPC) is investigated using batch studies, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM). The results indicate that acidification after alkalization is the most effective pretreatment method, and only alkalization would significantly reduce the sorption capability. This behavior is due to the precipitates, such as CaCO 3 and MgCO 3 , generated after alkalization on zeolite surface interfere the formation of the CPC bilayer, which provides active sites for sorbing Cr(VI). The schematic of the adsorption mechanism is presented. The results indicate that developing a better understanding of the influence of different pretreatments is quite helpful and suggest that the content of Ca/Mg/Fe could be a good indication of the effectiveness of preprocessing.
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SCIENCE OF THE TOTAL ENVIRONMENT
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2017
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IF 4.9
Ziling Peng,Chunmei Xiong,Wei Wang,Fatang Tan,Yang Xu,Xinyun Wang,Xueliang Qiao
In this study, a highly stable nanoscale zero-valent iron composite (HS-NZVI) was obtained via modifying nanoscale zero-valent iron (NZVI) with tetraethyl orthosilicate (TEOS) and hexadecyltrimethoxysilane (HDTMOS), and used for Cr(VI) remediation in aqueous solution. The obtained HS-NZVI remained stable in water without being oxidized for over 12 h. After four consecutive runs, the Cr(VI) removal efficiency of HS-NZVI maintained a value of more than 82%. Moreover, the Cr(VI) removal capacity per unit weight of NZVI in HS-NZVI reached 292.8 mg/g within 60 min at the initial Cr(VI) concentration of 120 mg/L at pH 5. The Cr(VI) removal efficiency of HS-NZVI increased with decreasing solution pH, and the experimental data for Cr(VI) removal by HS-NZVI were well-described by the pseudo-first-order reaction model. Additionally, scanning electron microscope (SEM) images, X-ray diffraction (XRD) patterns and X-ray photoelectron spectroscopy (XPS) measurements of the product after reaction revealed that the mechanism of Cr(VI) remediation by HS-NZVI mainly involved adsorption, reduction and co-precipitation. Considering the advantages of easy preparation, excellent stability and reusability, and high Cr(VI) removal capacity as well as the magnetic recovery property, HS-NZVI is expected to have notably promising applications for the remediation of Cr(VI) contaminated sites.
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APPLIED SURFACE SCIENCE
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2017
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IF 3.387
Chao Liu,Ru-Na Jin,Xiao-kun Ouyang,Yang-Guang Wang
In this study, a composite adsorbent (CCN-PEI) composed of carboxylated cellulose nanocrystals (CCN) and polyethyleneimine (PEI) was prepared through an amidation reaction between the carboxyl groups of the CCN and the amine groups of the PEI. The adsorption performance of the CCN-PEI was tested by removing Cr(VI) ions from aqueous solutions. The physicochemical properties of the CCN and the Cr(VI) ion-loaded CCN-PEI were studied using scanning electron microscopy (SEM), transmission electron microscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. To investigate the adsorption kinetics of Cr(VI) ions onto this newly developed CCN-PEI, we performed experiments under different adsorption conditions, by varying the contact time, solution pH, initial Cr(VI) ion concentration, and adsorption temperature. The prepared CCN-PEI exhibited an encouraging uptake capacity of 358.42 mg × g −1 . The adsorption process was fast: within the first 100 min, Cr(VI) ion adsorption onto the CCN-PEI was about 65%, and the adsorption equilibrium was reached within 250 min. Kinetics experiments indicated that the adsorption process could be described by a pseudo-second-order kinetic model. Furthermore, our adsorption equilibrium data fit the Langmuir isotherms well. The calculated thermodynamic parameters, such as the free energy change ( ΔG = −2.93 kJ × mol −1 ), enthalpy change ( ΔH = −5.69 kJ × mol −1 ), and entropy change ( ΔS = −9.14 kJ × mol −1 ), indicate that the adsorption of Cr(VI) ions onto CCN-PEI was a spontaneous exothermic process. Regeneration tests indicated that CCN-PEI showed good durability and good efficiency for repeated Cr(VI) adsorptions. Based on the results obtained in this work, it can be concluded that CCN-PEI is a potentially effective adsorbent for removing Cr(VI) ions from aqueous solutions.
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INORGANICA CHIMICA ACTA
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2017
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IF 2.002
Tian Zhao,Ling Yang,Peiyong Feng,Irina Gruber,Christoph Janiak,Yuejun Liu
MIL-101(Cr), one of the best investigated and widely used metal–organic frameworks, has been easily synthesized with particle diameters in the range from 387(28) nm to 90(10) nm by using acetic acid as a modulator . The particle size of MIL-101(Cr) decreased with increasing acetic acid concentration. The decrease of size in high concentration of acetic acid may be explained with the efficient suppression of the framework extension. In a selected condition, MIL-101(Cr) possessing an average diameter of about 90 nm can be prepared easily and reproducibly in gram-scale, with high BET-surface areas (3200–3500 m 2 /g) and fairly good yield (60–75%).
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NEW JOURNAL OF CHEMISTRY
·
2025
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IF 2.5
Runhong Zhu,Yunlong Shi,Yi Zhou,Yi Xia,Qin Qi,Xiaojie Liang,Meijuan Kuang,Zhenya Jia,Mengyue Wang,Changjiang Yu
In this study, a type of FeNi alloy embedded in biochar (BC) was prepared by a simple, efficient, and pollution-free method to form core–shell type BC@FeNi magnetic materials (BC@FeNi-T-X). The reduction behavior of Fe3+ and Ni2+ during preparation was analyzed, showing their transformation from ionic states to oxidized states, forming metal monomers and alloys. Increasing the Ni content in the SA–Fe3+/Ni2+ gel led to the formation of Fe0.64Ni0.36 and (Fe,Ni) alloys. Mechanistic insights were obtained through adsorption kinetics and isotherm data fitting and by analyzing composite changes before and after Cr(VI) adsorption. BC@FeNi-900-3 exhibited superior corrosion performance compared to the Fe biochar composite (BC@Fe-900-3), enhancing Cr(VI) reduction. Mechanistic studies revealed that Cr(VI) removal by BC@FeNi-900-3 primarily involved (i) Cr(VI) reduction to Cr(III) by Fe0.64Ni0.36 and Fe, (ii) Cr(VI) reduction to Cr(III) by Fe2+, (iii) Cr(VI) reduction to Cr(III) by H˙ generated via Fe0.64Ni0.36 corrosion, and (iv) Cr(VI) adsorption by BC@FeNi-900-3.
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APPLIED SURFACE SCIENCE
·
2024
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IF 6.3
Xuanqi Hao,Xiao Zhang,Chenchen Liu,Ping Yang
Metal element doping often can improve the photoluminescence (PL) of carbon dots (CDs). In this paper, blue and green emitting CDs (BCDs and GCDs) were synthesized by using phenylenediamine as the carbon and nitrogen sources. Cu-doped CDs (Cu-CDs) were fabricated by using copper acetylacetone as a precursor. The PL peak wavelengths of sample Cu-doped blue CDs (Cu-BCDs) and green CDs (Cu-GCDs) were 450 and 543 nm, respectively. The full width at half maximum of PL spectra were 67.31 and 93.13 nm, the PL quantum yields (PLQYs) were 13.6 and 38.7 %, and the average fluorescence lifetimes were 4.34 and 20.97 ns, respectively. The PL intensity of the Cu-CDs samples was enhanced with the photostability, and thermal stability test results showed that the Cu-CDs samples also had excellent stability. The Cu-BCDs and Cu-GCDs were employed in the field of sensing applications due to their excellent selectivity towards Cr (VI) and tetracycline hydrochloride (TC) detection. The detection limits for Cr (VI) and TC using Cu-BCDs were 0.34 and 0.86 μM, while Cu-GCDs showed detection limits of 0.47 and 0.50 μM, respectively, demonstrating the broad application prospect for Cu-CDs in sensing applications.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2024
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IF 9.4
Meng Lan,Xiaoli Dong,Nan Zheng,Jialin Gou,Yu Wang
The development of environmentally friendly and cost-effective photocatalysts is of vital significance for the effective removal of heavy metal contamination in water, but it is still a crucial challenge. Herein, the novel Sb x Bi 2-x S 3 solid solution photocatalysts with a certain amount of sulfur vacancy were prepared by adjusting the molar ratio of Sb to Bi through a simple hydrothermal strategy, and was applied to the effective photocatalytic reduction of hexavalent chromium (Cr(VI)). Sb 1.75 Bi 0.25 S 3 with optimized ratio has superior reduction performance of Cr(VI), and the photocatalytic efficiency of Cr(VI) can achieve 91.9 % within 1 h of visible light illumination. The remarkable catalytic efficiency is due to the more applicable band structure of the solid solution photocatalyst, which is conducive for the photocatalytic reaction. Moreover, the substitution of Bi causes the crystal distortion of Sb 2 S 3 and induce the generation of sulfur defects, which can effectively capture photoelectrons, accelerate the carriers separation, and improve the reduction performance. This study provides a hopeful photocatalyst for wastewater purification and promotes the exploration of solid solution photocatalyst in water environment remediation.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2025
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IF 6.3
Qingguo Yu,Yimin Liu,Qingru Zeng,Yuxiang Yang,Shunyan Ning,Yuezhou Wei,Xinpeng Wang,Deqian Zeng
Photocatalytic technology provides key benefits in utilizing solar energy for H 2 production and pollutant removal, making the pursuit of efficient photocatalysts a vital area of focus. Herein, a novel p-n heterojunction photocatalyst was synthesized by loading ZnSe nanoparticles onto Cu 2−x Se nanoplates, creating an internal electric field that facilitates the efficient separation of charge carriers and significantly enhances photocatalytic activity. The 14 % Cu 2−x Se/ZnSe nanocomposite exhibits excellent photocatalytic performance, achieving an H 2 production rate of 1846 μmol·g −1 ·h −1 , roughly 34 times that of pure ZnSe. Additionally, the Cr(VI) reduction rate constant of nanocomposite was 0.0277 min⁻¹ , which is 20 times and 5 times higher than those of ZnSe and Cu 2−x Se, respectively. The Cu 2−x Se/ZnSe photocatalyst demonstrated exceptional stability and reusability during multiple cycles of H 2 production and Cr(VI) reduction. An in-depth examination of experimental data and density functional theory (DFT) calculations led to proposing a potential mechanism. This work introduces a simple synthesis method for ZnSe-based photocatalysts, offering a novel approach for the effective application of solar energy in environmental and energy fields.
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