CARBON
·
2021
·
IF 9.594
Mingyan Jia,Lulin Peng,Maohua Yang,Huangzhao Wei,Mei Zhang,Yu Wang
In this article, we show that the conventional boron-nitrogen co-doped carbon dots (BNCDs) exhibit unique fluorescent ratiometricity in the detection of Cr (VI) due to their unique dual emission system. The 3D fluorescence spectrum study reveals that besides the commonplace emission centered at (360, 465) nm in blue fluorescence region, another center which may be corresponding to N-contain conjugation domains is found at (490, 535) nm. In the presence of Cr (VI) ions, the emission centered at (360, 465) nm is remarkably quenched due to inner filter effect, whereas the emission centered at (490, 535) nm is almost unchanged. By spectrally simulating inner filter effect using different excitation interferents in the 3D fluorescence spectrum study, accompanied with the fluorescence lifetime and absorption comparison, the sensing mechanism has thoroughly been illustrated. The versatile sensing capability of BNCDs in the different real samples not only provides a new way for the rapid determination of Cr (VI) in practices, but also demonstrates the great potential of the carbon-based materials with multiple emission possess in developing ratiometric sensing platform for rapid and accurate assay of different kinds of analytes.
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Nanomaterials
·
2022
·Vol. 12
·期 21
·3923
·
IF 5.719
Wen-Yi Wang,Tian Sang,Yan Zhong,Chao-Hao Hu,Dian-Hui Wang,Jun-Chen Ye,Ni-Ni Wei,Hao Liu
The surfactant modification of catalyst morphology is considered as an effective method to improve photocatalytic performance. In this work, the visible-light-driven composite photocatalyst was obtained by growing CdS nanoparticles in the cubic crystal structure of CdCO3, which, after surfactant modification, led to the formation of CdCO3elliptical spheres. This reasonable composite-structure-modification design effectively increased the specific surface area, fully exposing the catalytic-activity check point. Cd2+from CdCO3can enter the CdS crystal structure to generate lattice distortion and form hole traps, which productively promoted the separation and transfer of CdS photogenerated electron-hole pairs. The prepared 5-CdS/CdCO3@SDS exhibited excellent Cr(VI) photocatalytic activity with a reduction efficiency of 86.9% within 30 min, and the reduction rate was 0.0675 min−1, which was 15.57 and 14.46 times that of CdS and CdCO3, respectively. Finally, the main active substances during the reduction process, the photogenerated charge transfer pathways related to heterojunctions and the catalytic mechanism were proposed and analyzed.Keywords:surfactant;CdS/CdCO3;photocatalytic;Cr(VI)
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高影响因子
KOREAN JOURNAL OF CHEMICAL ENGINEERING
·
2022
·Vol. 39
·期 7
·1839-1849
·
IF 3.146
Zhang Xiaoting,Zhang Shusheng,Ouyang Gangfeng,Han Runping
A zirconium-based metal organic framework (UiO-66-NH 2 ) was prepared using a greener approach for the removal of hexavalent chromium (Cr(VI)) from solution. The characterization of UiO-66-NH 2 was performed using several methods, and the influence of the solution pH, adsorbent dosage, salt, adsorption time, Cr(VI) concentration and adsorption temperature on adsorption quantity was performed in batch mode. UiO-66-NH 2 can efficiently remove Cr(VI) through the synergistic effect of adsorption and reduction. At pH solution of 1.1 and solid-to-liquid ratio of 2 g·L −1 , the removal rate of 100 mg·L −1 Cr(VI) increased to 95.2%. The maximum adsorption capacity of UiO-66-NH 2 from Langmuir model was 252 mg·g −1 . The adsorption equilibrium process can be well described by Langmuir, Koble-Corrigan and Temkin models, while the kinetic process can be predicted by pseudo-second-order and Elovich model. UiO-66-NH 2 showed a good adsorption capacity in a wide range of pH (pH=1.1–10) and also had better regeneration performance after five cycles using 0.01 mol·L −1 NaOH; consequently, it can be a promising adsorbent for the removal of Cr(VI) from solution.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2022
·
IF 10.753
Jing Yang,Qian Guo,Lei Li,Ruixue Wang,Yucheng Chen,Xingrun Wang
Compare to the content of Cr(VI), the distribution of specific Cr(VI) species in soil is rarely paid attention to, which may lead to an inaccurate environmental risk assessment of Cr(VI) contaminated soil or inability to meet stringent requirement for soil remediation . Herein, to reveal the primary mechanisms and factors controlling the evolution of Cr(VI) species in soil, the distribution of Cr(VI) and Cr(III) species in soils with different particle sizes and textures was systematically investigated by using a modified sequential extraction procedure and spectroscopy characterizations (e.g., SEM-EDS mapping). The results show that a significant proportion of Cr(VI) can be captured by minerals containing exchangeable calcium ions and metal oxide hydrates in the soil, forming a relatively stable adsorbed Cr(VI). Also, a small fraction of Cr(VI) can precipitate as calcium chromate with free calcium ion which is the most stable Cr(VI) species in the soil. The majority of Cr(VI) discharged into soil tends to be reduced by ferrous ions or minerals containing ferrous ions with a product of Fe(III)-Cr(III) coprecipitate. Therefore, the speciation of Cr in the soil is closely correlated to Fe and Ca. After the equilibrium of adsorption, precipitation, and reduction reactions of Cr(VI), the rest of Cr(VI) retains as the form of its original water-soluble state in soil. The evolution of Cr(VI) species and the content of specific Cr species in soil are mainly determined by the contents of iron, exchangeable calcium ions and metal oxide hydrates, which effect the Cr(VI) reduction, precipitation and adsorption, respectively.
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高影响因子
ENVIRONMENTAL POLLUTION
·
2016
·
IF 4.839
Na Li,Fenglian Fu,Jianwei Lu,Zecong Ding,Bing Tang,Jiabin Pang
Chromium-contaminated water is regarded as one of the biggest threats to human health. In this study, a novel magnetic mesoporous MnFe 2 O 4 @SiO 2 −CTAB composite was prepared by a facile one-step modification method and applied to remove Cr(VI). X-ray diffraction, scanning electron microscopy, transmission electron microscopy , specific surface area, and vibrating sample magnetometer were used to characterize MnFe 2 O 4 @SiO 2 −CTAB composites. The morphology analysis showed that the composites displayed a core-shell structure. The outer shell was mesoporous silica with CTAB and the core was MnFe 2 O 4 nanoparticles , which ensured the easy separation by an external magnetic field. The performance of MnFe 2 O 4 @SiO 2 −CTAB composites in Cr(VI) removal was far better than that of bare MnFe 2 O 4 nanoparticles. There were two reasons for the effective removal of Cr(VI) by MnFe 2 O 4 @SiO 2 −CTAB composites: (1) mesoporous silica shell with abundant CTA + significantly enhanced the Cr(VI) adsorption capacity of the composites; (2) a portion of Cr(VI) was reduced to less toxic Cr(III) by MnFe 2 O 4 , followed by Cr(III) immobilized on MnFe 2 O 4 @SiO 2 −CTAB composites, which had been demonstrated by X-ray photoelectron spectroscopy results. The adsorption of Cr(VI) onto MnFe 2 O 4 @SiO 2 −CTAB followed the Freundlich isotherm model and pseudo-second-order model. Tests on the regeneration and reuse of the composites were performed. The removal efficiency of Cr(VI) still retained 92.4% in the sixth cycle. MnFe 2 O 4 @SiO 2 −CTAB composites exhibited a great potential for the removal of Cr(VI) from water.
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高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2018
·
IF 4.61
Shunquan Shi,Jiakuan Yang,Sha Liang,Mingyang Li,Quan Gan,Keke Xiao,Jingping Hu
Fe 3 O 4 @SiO 2 -NH 2 magnetic particles with core-shell structure were attached on carboxylated biochar derived from phoenix tree leaves to synthesize a novel magnetic biochar for removing Cr(VI) ions from acidic solutions. FSEM, FTEM, XRD characterizations of the synthesized magnetic biochar revealed that the Fe 3 O 4 @SiO 2 -NH 2 magnetic particles distributed uniformly on the surface or macrospores of carboxylated biochar by strong chemical bonding. The Cr(VI) ions adsorption capacity of magnetic biochar was 27.2 mg·g −1 , surpassing original carboxylated biochar (18.2 mg·g −1 ). VSM and XPS characterizations demonstrated that the attached Fe 3 O 4 @SiO 2 -NH 2 magnetic particles not only endowed biochar with perfect magnetic property (23 emu·g −1 ) but also provided complexing sites for binding Cr(III) cations reduced from Cr(VI) anions. The Cr(VI) ions removal by magnetic biochar contained three steps: (1) adsorption of Cr(VI) anions by protonated functional groups; (2) reduction of Cr(VI) anions to Cr(III) cations by electron-donor groups; and (3) chelation of Cr(III) cations by amine groups. The adsorption recycling test showed that magnetic biochar kept 85% of its initial Cr(VI) adsorption capacity at the sixth cycle, and the Fe leakage under pH 1.0 was smaller than 0.25 mg·L −1 . The results indicated that this novel magnetic biochar was applicable for the practical treatment of Cr(VI)-containing wastewater.
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高影响因子
JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2020
·Vol. 20
·期 3
·1660-1669
·
IF 1.134
Deng Yu-Ying,Xiao Xin-Feng,Wang Dan,Han Bo,Gao Yu,Xue Jian-Liang
Cu-BTC was synthesised by hydrothermal method in this study to adsorb and remove the toxic heavy metal hexavalent chromium Cr(VI) in water. The EDTA-chitosan/Cu-BTC was prepared by the surface modification of Cu-BTC with EDTA-modified chitosan. The initial concentration effects of adsorbed
chromium solution, adsorbent dosage, adsorption time, adsorption temperature and pH of chromium solution on adsorption capacity were estimated using the single-factor optimisation experiment. Results show that the adsorption capacity of the modified composite was higher than that of Cu-BTC.
Cu-BTC and EDTA-chitosan/Cu-BTC exhibited significant adsorption of Cr(VI) under acidic conditions in water and basically independent of temperature. Their adsorption processes conformed with the pseudo-second-order model. The Langmuir adsorption isotherm model obtained the adsorption isotherm,
which indicated that the adsorption process was single molecule adsorption. Isotherm fitting obtained the maximum adsorption amounts of Cr(VI) for Cu-BTC and EDTA-chitosan/Cu-BTC at 27.32 and 46.51 mg·g-1, respectively. Factor and principal component analyses show that the
main factors affecting the adsorption of Cr(VI) in the EDTA-chitosan/Cu-BTC composites are pH, initial concentration and adsorption time. Therefore, EDTA-chitosan-modified Cu-BTC was a more feasible metal-organic framework material than Cu-BTC because of better adsorption performance, which
can be used for adsorption removal of Cr(VI) in water.
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高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2022
·
IF 9.136
Qunfeng Kuang,Kun Liu,Qikun Wang,Qibing Chang
Biochar is used as adsorption material for transition metal ions based on its special high surface area. However, the ion adsorption capacity is limited by the inability through the increasing of specific surface area. Three-dimensional hierarchical pore biochar (ASPB) is prepared by pre-carbonization and KOH activation using soybean protein with gelation properties to construct a three-dimensional framework structure of biomass. The saturation level of Cr(VI) adsorption in 250 mg·L −1 Cr(VI) solution is 489.66 mg·g −1 , which is attributed to the ASPB's vast 2788 m 2 ·g −1 surface area and three-dimensional hierarchical pore structure, with pore structure data indicating an empty volume of 1.65 cm 3 ·g −1 and a 2.386 nm size average pore size. The Cr(VI) adsorption level is higher than the calculated saturated capacity according to Langmuir equation based on the specific surface area. The extra adsorption performance is contributed to the transport channels provided by the three-dimensional framework structure, the large and abundant ion riveting sites provided by micro-mesopores, and the redox and complexation of surface-active groups. The saturated adsorption capacity can keep 86.6 % after three adsorption–desorption cycles.
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高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2018
·Vol. 135
·期 30
·46530
·
IF 1.901
Kaijie Dong,Qinze Liu,Gang Wei,Tao Hu,Jinshui Yao,Xian Zhang,Tingting Gao
A novel magnetic adsorbent, poly(catechol-1,4-butanediamine)-coated Fe 3 O 4 composite (Fe 3 O 4 @PCBA), was successfully fabricated via an easy and gentle method according to the mussel-inspired adhesion property of polydopamine. Effects of many factors on the adsorption performance of Fe 3 O 4 @PCBA for Cr(VI) were investigated, including temperature, pH value, contacting time, adsorbent dosage, and initial Cr(VI) concentration. The thermodynamics, adsorption isotherm, kinetics, and intraparticle diffusion of adsorption were also studied systematically. Results indicated that the removal rate of Cr(VI) was approximately close to 100% when the initial concentration was less than 120 mg/L, and the maximum uptake capacity of Fe 3 O 4 @PCBA for Cr(VI) was 280.11 mg/g complied with Langmuir isotherm model. Accordingly, the nocuous Cr(VI) could be partially reduced to Cr(III) during the adsorption period. Hopefully, this strategy could be extended to prepare series of magnetic Fe 3 O 4 @catechol–amine adsorbents with different amino and phenolic hydroxyl groups for Cr(VI) removal. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 46530.
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JOURNAL OF HAZARDOUS MATERIALS
·
2019
·
IF 7.65
Li Song,Yuefeng Feng,Changqing Zhu,Fuqiang Liu,Aimin Li
Cr(VI) and Cd(II) are typical heavy metal ions and their co-removal is significant. Nitrogen-doped, bi-functional, and biomass-based composites (CP-BA) were successfully applied for efficient and synergistic removal of Cr(VI) and Cd(II). The mutual promotion ratios of adsorption capacity by Cr(VI) and Cd(II) were 161.32 % and 14.13 %, respectively. In addition, all coexisting inorganic anions could extremely promote the removal of Cd(II) with the best promotion ratio upon phosphate ions as high as 80.00 %. The following co-removal mechanisms were deeply revealed: (1) Cr(VI) combined with protonated imine groups could weaken the electrostatic repulsion between CP-BA and Cd(II) by electrostatic shielding, and further promoted the coordination of Cd(II) with hydroxyl, carboxyl and neutral imine groups. (2) Cd(II) which were coordinated to neutral imine groups could form cation bridges, and thus promoted the interaction with Cr(VI) because of the electrostatic attraction. Moreover, the removal capacity for Cr(VI) and Cd(II) did not display obvious reduction even after four cycles. Therefore, CP-BA showed a great potential in the co-removal of inorganic anion-cation complexes from wastewater.
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高影响因子
MICROCHEMICAL JOURNAL
·
2024
·
IF 4.9
Yi Tian,Yunlong Yue
To improve the photoluminescence (PL) and increase photostability of carbon dots (CDs), phosphorus doped CDs with bright green emitting were prepared using (NH 4 ) 2 HPO 4 and m-phenylenediamine (MPD), and terephthalic acid (TA) via a solvothermal synthesis. Compared to undoped CDs (M−CDs), the PL efficiency of P-doped sample (M−6 %P-CDs) created using optimized conditions was improved from 55.1 to 73.9 %. These bright CDs were incorporated in films to test the stability, in which the photostability in liquid and polymer films were improved by 6 and 37 %, respectively. Namely, it is found that P affected the functional groups of on the surface and inside CDs. Phosphorus promoted the dehydration condensation reaction of precursors, increased the structural defects of the CDs, separated the sp 2 structural domains, and retained more oxygen-containing functional groups. In the case of o-phenylenediamine (OPD) instead of MPD, the PL efficiency of P-doped CDs was decreased. This is ascribed to P impeding the polymerization process of OPD. These CDs were used for pH and Cr(VI) ion sensors. P-doping improved the sensitivity of CDs to pH and Cr(VI). The pKa value of sample M−6 %P-CDs was 8.32 which was much lower compared with undoped one (∼1.97). Moreover, P-doped CDs revealed significantly enhanced sensitivity response to Cr(VI). The detection range and detection limit of M−6 %P-CDs for Cr(VI) was 1–130 μM and 0.59 μM, respectively. These results are crucial for the preparation and applications of CDs.
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高影响因子
Chemical Engineering Journal Advances
·
2025
·
IF 7.1
Wuxin Hou,Jizhuang Zuo,Yongle Gao,Yao Wang,Li Liu
The generation of humins by-products in biorefinery is often unavoidable. We here report the valorization of chitosan-derived humins for removal of heavy metal ions to enhance the atomic economy of the biomass conversion. Chitosan-derived humins were synthesized by catalysis of oxalic acid (OA), whereby the adsorption performance for Cd(II), Cr(III) and Cr(VI) was explored. The adsorption data were well fitted by the pseudo-second-order kinetic model, complemented by the Freundlich and Temkin isotherm models, revealing maximum adsorption capacities of humins for heavy metal ions as follows: 358.7 mg/g for Cr(VI), 152.6 mg/g for Cd(II), and 40.2 mg/g for Cr(III). The mechanistic studies revealed that the adsorption of Cd(II) and Cr(III) by humins mainly occurs through ion exchange (carboxyl groups) and surface complexation (hydroxyl, carbonyl, and amino groups). In comparison, the adsorption of Cr(VI) by humins involves electrostatic attraction, alongside ion exchange and surface complexation. After carbonization and activation, the specific surface area increased markedly, however the adsorption capacity decreased owing to reduced oxygen- and nitrogen-containing functional groups. Competitive adsorption studies, industrial wastewater experiments, and cyclic adsorption tests demonstrate that humins exhibit remarkable adsorption performance even in complex environments. This work highlights that chitosan-derived humins are promising adsorbents for the remediation of heavy metal ions.
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