Analytical Methods
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2016
·Vol. 8
·期 28
·5684-5689
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IF 1.915
Na Xu,Quan Zhu,Xiang-Yue Kong,Lei Meng
Polyethyleneimine protected silver nanoclusters (AgNCs@PEI) were prepared and used as high sensitive fluorescence probes for detecting Cr(VI). The mechanism worked by combining Cr(VI) with a primary amine of AgNCs@PEI causing electrostatic interaction, which led to the aggregation of AgNCs, as well as fluorescence quenching. Compared with other fluorescence sensors of Cr(VI) detection, this probe shows excellent performances: (i) The fluorescence probe responds immediately after adding Cr(VI). (ii) The fluorescence quenching efficiency of AgNCs@PEI was linearly related to the concentration of Cr(VI) over the range from 0.5 nM to 25 μM. (iii) The limit of detection is as low as 0.05 nM. (iv) High selectivity for Cr(VI) in 14 types of normal metal ions were obtained and especially the probe can be applied in both acidic and alkaline conditions (pH 2.0–11.0). (v) The probe can be used for the determination of Cr(VI) in real samples with satisfactory results. Therefore, the fluorescence probe is of practical significance and application prospects.
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RSC Advances
·
2016
·Vol. 6
·期 64
·59292-59298
·
IF 3.289
Jianqiao Zhang,Huan Chen,Zi Chen,Jiaojie He,Wenxin Shi,Dongmei Liu,Huizhong Chi,Fuyi Cui,Wei Wang
A high-performance, cost-effective and spongeous adsorbent was rationally designed for Cr(VI) removal from aqueous solution based on PPy modified natural quasi two-dimensional (2D) structures. Core of corncobs, a kind of agricultural waste composed of quasi 2D sub-micro sheets, has a unique macroporous spongeous microstructure. In consideration of the unique chemical structure of polypyrrole (PPy) and microstructure of the natural sponge, we constructed the microstructured spongeous adsorbents. The PPy active layer provided reactive sizes to detoxifies Cr(VI) ions by ion-exchange. While the spongeous microstructure provided by the microsheets could enhance the adsorption performance by increasing active areas and facilitating the access of pollutants inside the adsorbents. Compared with artificial nano-powder adsorbents, CC–PPy displayed larger advantage in separation process and fabrication/operation cost. Compared with other bulk-style PPy composites, the adsorption capacity of CC–PPy was several times higher. In addition, the regeneration and stability of CC–PPy was outstanding with no loss in the adsorption to Cr(VI) even after 3 adsorption–desorption cycles. The present development provides a solution to design highly efficient and cost-effective water treatment agents.
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JOURNAL OF HAZARDOUS MATERIALS
·
2017
·
IF 6.065
Weizhao Yin,Yongtao Li,Jinhua Wu,Guocai Chen,Gangbiao Jiang,Ping Li,Jingjing Gu,Hao Liang,Chuansheng Liu
A one-pot bio-iron system was established to investigate synergetic abiotic and biotic effects between iron and microorganisms on Cr(VI) removal. More diverse iron corrosion and reactive solids, such as green rusts, lepidocrocite and magnetite were found in the bio-iron system than in the Fe 0 -H 2 O system, leading to 4.3 times higher Cr(VI) removal efficiency in the bio-iron system than in the Fe 0 -H 2 O system. The cycling experiment also showed that the Cr(VI) removal capacity of Fe 0 in the bio-iron system was 12.4 times higher than that in the Fe 0 -H 2 O system. A 62 days of life-span could be achieved in the bio-iron system, while the Fe 0 -H 2 O system lost its efficacy after 30 days. Enhanced effects of extra Fe 2+ on Cr(VI) removal was observed, largely contributed to the adsorbed Fe 2+ on iron surface, which could function as an extra reductant for Cr(VI) and promote the electron transfer on the solid phase. The results also showed that the reduction of Cr(VI) by microorganisms was insignificant, indicating the adsorption/co-precipitation of Cr by iron oxides on iron surface was responsible for the overall Cr(VI) removal. Our study demonstrated that the bio-amended iron corrosion could improve the performance of Fe 0 for Cr(VI) removal from groundwater.
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MICROCHEMICAL JOURNAL
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2024
·
IF 4.9
Xuanqi Hao,Xiao Zhang,Jianrong Wang,Chenchen Liu,Chuanhao Li,Ping Yang
To create fluorescent sensors for Cr (VI) and l-arginine detection, blue-emitting carbon dots (CDs, named as M-CDs) were prepared via a solvothermal synthesis by using m-phenylenediamine. The introduction of sulfuric acid changed the blue-emitting of CDs into green-emitting (named as S-CDs), in which the photoluminescence (PL) peak wavelengths of samples M-CDs and S-CDs were 450 and 540 nm, while their PL efficiencies were 21.7 and 84.2 % respectively. Sulfuric acid resulted in the average fluorescent lifetime of the CDs was prolonged into 8.19 from 4.65 ns. The photo and thermal stable tests demonstrated that theses CDs revealed excellent stability. Meanwhile, CDs flexible films with bright blue- and green-emitting were prepared utilizing the favorable solubility of CDs in polar solvents. Mono-dispersed CDs as luminescent materials demonstrated it promising prospects in luminescent devices field. Furthermore, M-CDs exhibited excellent selectivity towards Cr(VI) and l-arginine. The detected limit (0.86 μM for Cr(VI) and 0.43 μM for l-arginine) was determined by assessing the response of M-CDs to various concentrations of Cr(VI) ion and l-arginine solutions. These bright CDs revealed great potential for accurate detection of Cr(VI) and l-arginine.
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Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Xu Xing,Luxin Zhang,Yue Ren,Yunfeng Li,Han Yu,Weiwei Shi
The mild, fast and green removal of hexavalent chromium (Cr(VI)) from wastewater has already attracted extensive attention due to the severe acute toxicity and carcinogenicity of Cr(VI). At present work, Bi 2 S 3 /Bi 2 MoO 6 S-scheme heterojunctions were constructed by facile solvothermal assembly and in situ anion exchange methods for visible light-driven efficient photocatalytic removal of Cr(VI). The structure-activity relationship, photoelectrochemical properties, and density functional theory (DFT) calculations revealed that the controllable construction of the heterostructure significantly expanded the light response range and remarkably enhanced the light absorption capacity. In particular, the unique charge transfer mechanism of this S-scheme heterojunction is conducive to promoting efficient separation of photogenerated charges and thus enhancing the photocatalytic performance. The results show that the total efficiency of Cr(VI) removal by the developed Bi 2 S 3 /Bi 2 MoO 6 heterojunction under visible light irradiation is 98.5% within 6 min, with a k value of 0.466 min −1 . This work provides a new route with enormous promise to construct bismuth-based S-scheme heterojunction photocatalysts for clean and efficient environmental remediation.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Xiaojie Zhang,Kangrui Ma,Liqin Zhao,Hong Peng,Yuefa Gong
To enhance the stability and adsorption performance of chitosan in Cr(VI)-contaminated acidic wastewater, a novel EDAC-modified-EDTA-crosslinked chitosan derivative (CSEC) was synthesized via a one-pot method with chitosan, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC), and Na 2 EDTA as raw materials. To further improve the mechanical strength and separation performance of CSEC, a novel composite bead (CSEP) of CSEC and imidazolium-functionalized polysulfone (IMPSF) was prepared through a phase inversion method. The chemical composition and microstructure of CSEC and CSEP were characterized by FESEM, FTIR, NMR and XPS techniques. The maximum adsorption capacities of CSEC and CSEP for Cr(VI) were 145.96 and 135.82 mg g −1 at pH 3, respectively, and the equilibrium time for Cr(VI) adsorption by CSEC and CSEP was 5 min and 8 h, respectively. The adsorption process of Cr(VI) by both CSEC and CSEP was exothermic and spontaneous. Compared to CSEC, CSEP has significantly enhanced resistance to interference from coexisting anions. The removal mechanism of Cr(VI) by CSEP might involve redox reaction as well as electrostatic attraction between Cr(VI) oxyanions and various nitrogen cations, including protonated amino groups, guanidinium groups, protonated tertiary amine groups, and imidazolium cations. The CSEP beads have potential application value in the treatment of acidic wastewater containing Cr(VI).
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LANGMUIR
·
2025
·
IF 3.9
Dandan Liu,Hui Zhang,Jinfeng Mei,Xudong Zheng,Jian Rong,Zhongyu Li
A three-dimensional porous aerogel was synthesized by combining soft chitosan oligosaccharide to hard multi-walled carbon nanotubes (MWCNTs) under mild conditions. Owing to the support of MWCNTs, mesopores can be detected on the inner surfaces of the aerogel. The cross-linking by tetraethylenepentamine forms a macropore structure after freeze drying, using water as the template. The hydrogel can bear 30% recoverable compression with the aid of hydrogen bonds between the amide groups. The aerogel exhibits excellent adsorption capabilities for Cr(VI) in water. The adsorption capacity can reach 367.6 mg/g within 100 min. Notably, the aerogel demonstrated an extremely high efficiency in removal for trace Cr(VI). Soluble Cr(VI) of 1 mg/L can be completely removed by the aerogel at a dosage of 0.2 g/L. This work provides a new strategy to synthesize adsorbents with hierarchical pores that exhibit high porosity and a fast mass transfer rate.
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RSC Advances
·
2024
·Vol. 14
·期 27
·19174-19184
·
IF 3.9
Peixin Hu,Hechao Lu,Qinting He,Fang Ren,Juan Wu,Wei Jiang
In this work, intelligent pH-sensitive sensors (Fe3O4/RhB@PAM) for Cr(VI) detection were successfully synthesized based on polyacrylamide (PAM) and Rhodamine B (RhB) co-modified Fe3O4 nanocomposites. The characterization results indicated that the sensors had many favorable properties, including suitable size, stable crystal structure and excellent magnetic response performance (47.59 emu g−1). In addition, the fluorescence changes during the detection process indicated that Fe3O4/RhB@PAM were “ON–OFF” intelligent sensors. When the Fe3O4/RhB@PAM sensors were placed in acidic Cr(VI) solution (pH 4), PAM acted as a pH-responsive “gatekeeper” releasing RhB, and the fluorescence intensity of released RhB was weakened by the complexation of Cr(VI). Furthermore, the fluorescence changes of the magnetic sensors were remarkably specific for Cr(VI) even in the presence of other competitive cations, and the limit of detection (LOD) for Cr(VI) was lower (0.347 μM) than the value recommended by the World Health Organization (0.96 μM). All the results presented in this study showed that the Fe3O4/RhB@PAM sensors had significant potential for Cr(VI) detection in acidic environmental samples.
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Journal of Water Process Engineering
·
2024
·
IF 6.3
Junlong Cai,Bin Liu,Fazhi Xie,Xin Mao,Bing Zhang
Cr(VI) in chromium-containing industrial wastewater, which is highly toxic and difficult to degrade, brings great challenges to the treatment of industrial wastewater. However, conventional chromium removal methods suffer from low efficiency and secondary contamination. This study demonstrates that the micelle-enhanced nanofiltration (MENF) process is an effective strategy for the removal of Cr(VI). Micelles generated from two commonly used cationic surfactants (cetyltrimethylammonium bromide (CTAB) and cetyltrimethylammonium chloride (CTAC)) were capable of complexing with Cr(VI), resulting in the formation of aggregates with larger hydrodynamic diameters that were effectively retained by the membrane. The results showed that CTAC had a greater performance in removing Cr(VI) compared to CTAB, and the removal rate can reach 98.55 % at an initial concentration of 100 ppm. Meanwhile, the retention rate of surfactant under each condition was more than 96.23 %, which effectively reduced the generation of secondary pollution. Even in the presence of interfering anions, Cr(VI) still had a high affinity for cationic surfactant micelles. In addition, concentration polarization and micelles deposition acted as the main fouling potential during MENF process. This study provides a new insight into technological innovation and environmental protection in the field of wastewater treatment.
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JOURNAL OF HAZARDOUS MATERIALS
·
2018
·
IF 6.434
Jianhao Qiu,Xiong-Fei Zhang,Xingguang Zhang,Yi Feng,Yuxin Li,Lvye Yang,Haiqiang Lu,Jianfeng Yao
A novel and highly efficient photocatalyst of Cd 0.5 Zn 0.5 S@ZIF-8 nanocomposite has been developed by a facile self-assembly strategy. This is the first report on the application of Cd x Zn 1−x S and metal-organic framework (MOF) nanocomposite as photocatalysts for the reduction of Cr(VI). The resulting Cd 0.5 Zn 0.5 S@ZIF-8 exhibited higher photocatalytic activity than that of pristine Cd 0.5 Zn 0.5 S and ZIF-8. Particularly, the CZS@Z60 composite with 60 wt% of ZIF-8 exhibited a photocatalytic activity that is about 1.6 times as high as that of Cd 0.5 Zn 0.5 S. The dominant reason for the improved photocatalytic reduction potential is proved to be the newly-formed interfacial S Zn bonds that firmly connect Cd 0.5 Zn 0.5 S and ZIF-8 and substantially improve the separation efficiency of photo-excited electrons and holes. The newly-formed chemical bonds are confirmed by XPS analyses, and the prolonged lifetime of photo-excited electrons is evidenced by the electrochemical measurement of photocurrent, which shows that the photocurrent on Cd 0.5 Zn 0.5 S@ZIF-8 is much higher than that of Cd 0.5 Zn 0.5 S and ZIF-8. This study clearly demonstrates that the MOF-based composite nanomaterials hold great promises for applications in the field of environmental remediation and for design of novel photocatalytic materials.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2017
·
IF 9.446
Yaxi Zhang,Mengjiao Xu,Hao Li,Hao Ge,Zhenfeng Bian
The photocatalytic reduction efficiency of hexavalent chromium (Cr 2 O 7 2− (Cr(VI)) is suffering from high recombination of photoinduced charges, poor adsorption capacity of Cr(VI), and slow desorption of product trivalent chromium (Cr 3+ (Cr(III))) from photocatalyst surface. In this work, carbon dots (CDs) was coupled with TiO 2 mesocrystals (MT), where CDs displayed both the electron collectors and the active sites. During photoreduction of Cr(VI), the as-prepared CD/MT exhibited activity about 5.4 times higher than the pure TiO 2 mesocrystals. The positive charges on the CD/MT surface favored the selective adsorption of Cr(VI) and rapid desorption of Cr(III), which has an obvious promotion on the photocatalytic reduction of Cr(VI) and retention of photoreduction activity. Meanwhile, the CDs coupled on TiO 2 mesocrystals facilitated the separation of photogenerated charges. This work provides a simple and effective adsorption-photoreduction-desorption mechanism for the photocatalytic reduction of Cr(VI).
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Yulong Xiang,Xinbin Ji,Xiaoli Dong,Yu Wang,Nan Zheng,Chundong Liu,Menglin Wang,Chumin Yan
Photoreduction of toxic Cr(VI) in wastewater to less toxic Cr(III) presents an effective approach to address the environmental issues. Nevertheless, the photocatalytic performance of these photocatalysts is severely constrained by their narrow light absorption range and the rapid recombination of photo-generated electrons and holes. Herein, DUT-67/Fe 2 O 3 heterojunction photocatalysts were prepared by a simple mechanical grinding method. The formation of DUT-67/Fe 2 O 3 heterostructures not only increased the specific surface area and light absorption range, but also improved the separation of photogenerated charge carriers. Compared to the pristine DUT-67, DUT-67/Fe 2 O 3 exhibited significantly improved photocatalytic performance in the reduction of Cr(VI), achieving a reduction efficiency of up to 94 % within 40 min. Active species trapping experiments identified that electrons served as the primary species in the photocatalytic process. Coupled with electron spin resonance and density functional theory (DFT) calculations, a comprehensive mechanism for the photocatalytic reduction of Cr(VI) by DUT-67/Fe 2 O 3 Z-scheme heterojunction was proposed. This work offers new insights into the underlying mechanisms involving in the interfacial charge transfer and Cr(VI) photoreduction processes.
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