E-POLYMERS
·
2023
·Vol. 23
·期 1
·
IF 3.7
Xiaoyu Jie,Bing-Chiuan Shiu,Huazhong Wu,Yuchi Zhang,Yuansong Ye,Chunxiang Lin,Run Fang
Chitosan (CS) is widely used in the treatment of wastewater containing metal ions. However, the poor stability in acidic aqueous solutions severely limits its application in many practical scenarios. In this work, a CS-based composite nanofiber membrane was prepared by electrospinning using urushiol, a natural biomaterial, as the cross-linking agent. The application of the CS-urushiol (CS-U) membrane in the adsorption and recovery of Cr( vi ) in wastewater was systematically studied. The CS-U membrane showed great resistance to strongly acidic and oxidative environments, and the adsorption process combined two mechanisms of electrostatic attraction and redox reaction. Due to the nanoscale fibers, porous structure, and strong acid resistance, the CS-U membrane adsorbed Cr( vi ) rapidly and efficiently in both batch and continuous modes. Moreover, the adsorption capacity and selectivity of the CS-U membrane for Cr( vi ) could be maximized simultaneously by adjusting the solution pH, promoting the recovery of high-purity Cr 2 O 3 .
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MICROCHEMICAL JOURNAL
·
2023
·
IF 4.8
Lanlan Li,Xiaoyu Dong,Jihong Chen,Jing Xiao,Li Zeng,Zhengwen Huang,Zhirong Zou
A rapid and easy-used colorimetric method was developed for on-site and rapid analysis of Cr(VI). Under acidic condition, Cr(VI) was reacted with 1, 5-diphenylcarbazide (DPC) and a purple-red complex was formed subsequently, inducing the color changed from colorless to purple-red, this color variance can be detected by ultraviolet–visible spectrophotometer (UV–Vis), smartphone and even naked-eye. For realizing the goal of on-site analysis, this method was integrated in a three dimensional (3D) printed analytical kit, smartphone was used as a portable detector. Under the optimized conditions, limit of detections (LODs) of 0.0014 μg/mL and 0.0016 μg/mL were obtained by smartphone and UV–Vis, respectively. Concentration of Cr(VI) as low as 0.05 μg/mL was still visible by naked-eye. This colorimetric system was further applied to the analysis of several environmental water samples, recoveries of 90–107 % were obtained. It is a promising portable analytical device/system for Cr(VI) on-site and rapid analysis.
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Nanomaterials
·
2023
·Vol. 13
·期 14
·2072
·
IF 5.3
Xu Zhang,Bo Tian,Zhiheng Ma,He Wang,Zhixuan Cheng,Jiaqiang Xu
As a volatile air pollutant, formaldehyde can enter people’s living environment through interior decoration, furniture and paint, causing serious harm to human health. Therefore, it is necessary to develop a sensor for the real-time detection of formaldehyde in low concentrations. According to the chemical interaction between amino groups and formaldehyde, a MIL-101(Cr) aminated-material-based formaldehyde cantilever sensor was prepared, of which ethylenediamine- functionalized MIL-101(Cr) named ED-MIL-101(Cr)) showed the best gas sensing performance. Using quasi-in situ infrared spectroscopy, ED-MIL-101(Cr) was found bound to formaldehyde through a Schiff base. The adsorption enthalpy of formaldehyde-bound ED-MIL-101(Cr) was −52.6 kJ/mol, which corresponds to weak chemical adsorption, so the material showed good selectivity. In addition, ED-MIL-101(Cr) has the most active sites, so its response value to formaldehyde is larger and it takes longer to reach saturation adsorption than bare MIL-101(Cr). Through the research on the gas sensing performance of functionalized MIL-101(Cr) material, we found that it has a strong application potential in the field of formaldehyde monitoring, and the material performance can be quantitatively and accurately evaluated through combining calculation and experimentation for understanding the gas sensing mechanism.
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Materials
·
2023
·Vol. 16
·期 17
·5785
·
IF 3.4
Weiran Zhang,Ziyu Li,Guohua Wu,Wei Wu,Hailan Zeng,Haiyun Jiang,Weili Zhang,Ruomei Wu,Qiong Xue
The utilization of Co-Cr-Fe-based black pigments bears considerable significance within the realm of commercial ceramic pigments, owing to their distinctive spinel structure, remarkable high-temperature stability, and exceptional chromatic attributes. This study delves into the synthesis of diverse black pigment configurations by employing the co-precipitation method, leveraging the interplay of these three metallic oxides. This investigation encompasses a comprehensive scrutiny of ion valences, crystal structures and parameters, colorimetric properties, and their interrelationships. The methodology integrates the response surface methodology (RSM) framework, using theoretical formulations to navigate the material ratios and elucidating the associations between the resultant compositions and color coordinate values, aligned with the CIE-Lab* colorimetric methodology. The derived predictive models yielded an optimized black pigment composition, characterized by heightened black intensity and a refined formulation.Keywords:black ceramic pigment;response surface methodology;co-precipitation method;chromatic properties;spinel
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Catalysts
·
2023
·Vol. 13
·期 5
·876
·
IF 3.9
Huan He,Xusheng Wang,Qin Yu,Wenbin Wu,Xinya Feng,Deyu Kong,Xiaohui Ren,Junkuo Gao
Cr(VI) is one of the most toxic heavy metals, posing multiple threats to humans and ecosystems. Photoreduction of toxic Cr(VI) to para-toxic Cr(III) is one of the most effective ways to remove heavy metal chromium but is still challenging. Herein, Ti3C2/UiO-66-NH2composites with different ratio of Ti3C2were synthesized via an in situ solvothermal process and used for the enhanced photocatalytic removal of Cr(VI) for the first time. The UiO-66-NH2nanoparticles were dispersed on the surface and slits of accordion-like Ti3C2homogeneously. A strong interfacial interaction between Ti3C2and UiO-66-NH2was formed, which was indicated by the XPS. The Fermi level of the MXene cocatalyst is lower than UiO-66-NH2; thus, Ti3C2can serve as the electron sink and accumulate photogenerated electrons from UiO-66-NH2on its surface. A depletion layer was also formed due to the different Fermi levels of UiO-66-NH2and Ti3C2, which prevents electrons from flowing back to UiO-66-NH. The strong interfacial interaction and formed depletion layer are beneficial for the following charge transfer from UiO-66-NH2to Ti3C2after light irradiation and for suppressing the photogenerated charge recombination. With suitable band positions and enhanced charge separation ability, Ti3C2/UiO-66-NH2composites exhibited better photoreduction efficiency of Cr2O72−than pure Ti3C2and UiO-66-NH2, with optimized samples reaching 100% in 40 min. The photoreduction kinetics of Cr2O72−by 2-T/U was also studied, with a photoreduction rate of 0.0871 min−1, which is about 2.6 times higher than that of the pure UiO-66-NH. This research provides a new type of efficient and environmentally friendly photocatalysts for the photoreduction of Cr2O72−.Keywords:metal–organic frameworks;photocatalysis;MXene;Cr(VI);photocatalyst;photoreduction;porous materials
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ANALYTICAL CHEMISTRY
·
2023
·
IF 7.4
Yu-Fei Li,Can-Jun Zou,Xing-Biao Liu,Feng Gan,Ping-Ping Fang
The detection of pharmaceuticals has been a matter of concern among scientists and health researchers in the past few decades. However, it is still difficult to realize the sensitivity and selectivity detection of pharmaceuticals with similar structures. Herein, the pharmaceutical molecules of 2-mercaptobenzimidazole (MBI) and 2-mercaptobenzothiazole (MBT) with so similar structures can be selectively detected by surface-enhanced Raman spectroscopy (SERS) taking advantage of the fingerprint identification on Au/MIL-101(Cr), with sensitive detection limits of 0.5 ng·mL–1 for MBI and 1 ng·mL–1 for MBT. MBI is selectively enriched by Au/MIL-101(Cr) from the mixture solution and detected by SERS below 30 ng·mL–1. MBI can also be selectively detected in the serum samples with a detection limit of 10 ng·mL–1. Density functional theory calculations combined with the SERS experiments explained that the high sensitivity and selectivity are caused by the intrinsic differences in Raman intensity and different adsorption energies from the pharmaceutical molecules adsorbed on Au/MIL-101(Cr), respectively. This study provides an effective way to enrich and detect pharmaceutical molecules with similar structures.
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Materials
·
2023
·Vol. 16
·期 11
·3994
·
IF 3.4
Qingxiang Wang,Yan Yue,Wenfei Liu,Qing Liu,Yu Song,Chengjun Ge,Hongfang Ma
Biochar can be used to address the excessive use of tetracycline and micronutrient chromium (Cr) in wastewater that potentially threatens human health. However, there is little information about how the biochar, made from different tropical biomass, facilitates tetracycline and hexavalent chromium (Cr(VI)) removal from aqueous solution. In this study, biochar was prepared from cassava stalk, rubber wood and sugarcane bagasse, then further modified with KOH to remove tetracycline and Cr(VI). Results showed that pore characteristics and redox capacity of biochar were improved after modification. KOH-modified rubber wood biochar had the highest removal of tetracycline and Cr(VI), 1.85 times and 6 times higher than unmodified biochar. Tetracycline and Cr(VI) can be removed by electrostatic adsorption, reduction reaction, π–π stacking interaction, hydrogen bonding, pore filling effect and surface complexation. These observations will improve the understanding of the simultaneous removal of tetracycline and anionic heavy metals from wastewater.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2023
·
IF 4.4
Shengwen Wang,Yu Shi,Hao Zhang,Yufeng Sun,Fangfang Wang,Leyong Zeng,Xing Li,Aiguo Wu,Yujie Zhang
Hexavalent chromium (Cr(VI)) is highly carcinogenic and mutagenic, which is seriously harmful to human health. Hence, it is important to create a probe that can detect Cr(VI) effectively. In this work, gold nanotetrapods (Au NTPs) were applied in colorimetric detection for the first time. Based on the oxidative etching principle of Cr(VI) on Au NTPs, a sensitive and multicolor response detection method for Cr(VI) was established. The oxidative etching of Au NTPs by Cr(VI) resulted in the blue shift of plasmon resonance absorption peak of Au NTPs with the change of morphology. As the etching progress processed, Au NTPs solution exhibited obvious color changes from gray-green to blue-violet and then to pink. This multicolor response design is very convenient for naked-eye detection. The limit of detection (LOD) of Cr(VI) is 3 nM for the naked eyes and 0.5 nM for UV–vis spectrum, both of which are lower than the toxicity level of Cr(VI) (0.2 μM) set by United States Environmental Protection Agency. This sensing method exhibits good linearity between the wavelength shift and Cr(VI) concentration in the range of 0.5 nM to 8 nM. The detection results of Cr(VI) in actual environmental samples demonstrate that the Au NTPs colorimetric probe (Au-N-Probe) is expected to be applied to the detection of Cr(VI) in water environmental samples such as lake water and industrial wastewater.
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Journal of Environmental Chemical Engineering
·
2023
·
IF 7.7
Jianle Wang,Xueming Liu,Hong Deng,Dongye Zhao,Qiulin Yang,Zhihua Zhu
Various sulfur- and iron-bearing materials have been shown promising for reductive immobilization of Cr(VI) in water and soil. Yet, composite Ca-Fe-S materials and the effects of water chemistry and material aging have not been investigated. In this work, we prepared a type of Ca-Fe-S microparticles under the atmospheric conditions through a facile one-pot approach, and tested the particles for reductive immobilization of Cr(VI) in solution and soil. Ca-Fe-S showed 40 % higher removal efficiency of Cr(VI) in solution than FeSO 4 and 10 % higher than CaS x on the basis of equal molar dosage. When a Cr-laden soil was amended by Ca-Fe-S, the leachable concentration of Cr per the toxicity characteristic leaching procedure remained below the regulatory limit of 5 mg L −1 after 730 days of curing, while FeSO 4 and CaS x failed to meet the regulatory threshold. Ca-Fe-S served as a slow-releasing source of Fe 2+ and S 2- , which were able to convert Cr(VI) into the stable final product of Cr(OH) 3 . Ca-Fe-S was able to perform well under a wide range of pH (3.0–9.0) and in the presence of high concentrations of coexisting ions (5 mmol L −1 of Cl - , SO 4 2- , or HCO 3 - ). Moreover, the material remained effective when aged under the atmospheric conditions for 14 days. This study showed that Ca-Fe-S is a highly effective material for efficient sequestration of Cr(VI) in soil and groundwater under various water chemistry and materials aging conditions.
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PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
·
2019
·Vol. 216
·期 22
·1900379
·
IF 1.606
Liang Ma,Xuejuan Shi,Xiaoxiao Zhang,Shunjun Dong,Lili Li
Core–shell-structured cellulose acetate–polycaprolactone/chitosan (CA–PCL/CS) nanofibers with excellent removal performance of hexavalent chromium (Cr(VI)) are developed by coaxial electrospinning. The effect of core-to-shell ratio on adsorption capability is studied. The results show that all core–shell-structured fibers possess higher adsorption capability and good durability in acidic environment compared with the CS powder adsorbent. CA–PCL/CS fibers with core-to-shell ratio of 0.442 have a maximum adsorption capability of 126 mg g −1 at room temperature. The adsorption kinetics reveals that chemisorption serves as the rate-determining step by notable electron transfer, share, or exchange between adsorbents and adsorbates. The adsorption equilibrium data of the core–shell-structured CA–PCL/CS fiber adsorbents are all well described by the Freundlich isotherm model, indicating the multilayer adsorption process. Herein, it is highlighted that the core–shell-structured CA–PCL/CS nanofibers have a promising prospect in removing Cr(VI) ions from waste water.
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BIORESOURCE TECHNOLOGY
·
2018
·
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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ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2019
·
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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