Toxics
·
2025
·Vol. 13
·期 6
·458
·
IF 4.1
Hang Liu,Runlin Yao,Mingling Yu,Zongda Ye,Yingrui Lu,Xiaolong Yu,Jin Tang,Jianteng Sun
Hexavalent chromium (Cr(VI)) is of significant interest in the environmental field due to its high toxicity. Biochar is commonly used as an adsorbent for Cr(VI) removal from wastewater. However, its lower removal efficiency remains a persistent challenge. This study develops an iron-modified rice straw biochar through a simple precipitation and pyrolysis method and applies it for Cr(VI) removal in wastewater, which could convert waste into treasure and improve the adsorption performance of adsorbent. In the adsorption experiments, the results revealed that the adsorption efficiency of Cr(VI) reached 95.54% within 480 min (conditions: adsorbent dosage 2.67 g/L, pH 2.5, temperature 25 ± 2 °C). The Langmuir isotherm model was more suitable to describe the adsorption behavior of Cr(VI) by Fe-BC, and the fitted adsorption capacity achieved 10.03 mg/g. The experimental process was better described by the pseudo-second-order kinetic model, indicating that the adsorption process chemical adsorption was the rate-limiting step. The thermodynamic experiments revealed that the adsorption process of Cr(VI) by Fe-BC was spontaneous and endothermic. Column experiments demonstrated that a lower flow speed was beneficial to adsorption performance. Mechanistic studies highlighted the synergistic roles of electrostatic attraction, ion exchange, and reduction in Cr(VI) removal. These findings provide novel perspectives and innovative approaches for the development and application of adsorbents.
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COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2025
·
IF 5.4
Qianyu Wang,Changchang Ma,Dandan Liu,Shushan Song,Ziheng Song,Weijie Zhang,Huarui Han,Jiasheng Zhu,Kai Wei,Sheng Feng
Confining nano zero-valent iron (nZVI) into porous materials could prevent its aggregation and passivation. In this study, we confined nZVI into the cavity of zeolitic imidazolate framework-8 (ZIF-8) via sequential pre-adsorption ferric ion (Fe(III)) and NaBH 4 reduction processes. The optimized Cr(VI) removal rate of ZIF-8 confined nZVI (nZVI@ZIF-8) reached 1.2 × 10 −1 min −1 , 9.2- and 37.5-fold that of nZVI and ZIF-8, respectively. Interestingly, the removal rate constants of nZVI@ZIF-8 toward Cr(VI) still reached 9.6 × 10 −2 min −1 and 6.7 × 10 −2 min −1 with initial pH of 7.0 and 9.0, respectively, 13.0 (7.4 ×10 −4 min −1 ) and 23.9 times that of nZVI. More importantly, channels confinement significantly improved the reactive lifetime of nZVI for Cr(VI) removal. The electro-donating -NH 2 provided positive charge sites for CrO 4 2- or HCrO 4 - adsorption. Subsequently, the difference of Fermi level between nZVI and ZIF-8 drove electrons transfer from nZVI to ZIF-8 for surface Cr(VI) reduction. This study provides an avenue to enhance the performance of nZVI toward heavy metal ions removal by coupling surface adsorption and nano confinement.
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ANALYTICAL CHEMISTRY
·
2011
·
IF 5.874
Cheng-Xiong Yang,Xiu-Ping Yan
The diverse structures and pore topologies, accessible cages and tunnels, and high surface areas make metal–organic frameworks attractive as novel media in separation sciences. Here we report the slurry-packed MIL-101(Cr) column for high-performance liquid chromatographic separation of substituted aromatics. The MIL-101(Cr) packed column (5 cm long × 4.6 mm i.d.) offered high-resolution separation of ethylbenzene (EB) and xylene, dichlorobenzene and chlorotoluene isomers, and EB and styrene. The typical impurities of toluene and o-xylene in EB and styrene mixtures were also efficiently separated on the MIL-101(Cr) packed column. The column efficiencies for EB, m-dichlorobenzene, and m-chlorotoluene are 20000, 13000, and 10000 plates m–1, respectively. The relative standard deviation for five replicate separations of the substituted aromatics was 0.2–0.7%, 0.9–2.9%, 0.5–2.1%, and 0.6–2.7% for the retention time, peak area, peak height, and half peak width, respectively. The MIL-101(Cr) offered high affinity for the ortho-isomer, allowing fast and selective separation of the ortho-isomer from the other isomers within 3 min using dichloromethane as the mobile phase. The effects of the mobile phase composition, injected sample mass, and temperature were investigated. The separation of xylene, dichlorobenzene, and chlorotoluene on MIL-101(Cr) was controlled by entropy change, while the separation of EB and styrene on MIL-101(Cr) was governed by enthalpy change.
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MICROCHEMICAL JOURNAL
·
2025
·
IF 5.1
Ruiqing Sun,Jing Yuan,Tong Zhou,Yujuan Xie,Qilong Zhan,Shiyi Lu,Haoran Fan,Yangyang Wen,Hongyan Li
Cr(VI), a highly toxic and carcinogenic contaminant, presents significant risks to ecological and human health due to its pervasive presence in food and environmental systems. Even minimal exposure can induce oxidative stress and genotoxicity, underscoring the urgent need for rapid, sensitive, and field-deployable analytical methods. In this study, we developed a ratiometric fluorescence probe based on a blue-emitting metal-organic framework (MOF) as the reference signal and a red-emitting CdTe quantum dot (QDs) as the responsive element. Upon Cr(VI) exposure, red fluorescence is quenched through inner filter effect (IFE) and electrostatic interaction (EI), while blue fluorescence remains unaltered, resulting in a visible color change from pink to blue. To achieve precise quantification, the ratiometric system was integrated with three representative ML algorithms—Random Forest (RF), Support Vector Regression (SVR), and BP Neural Network (BPNN). Smartphone-captured fluorescence images were processed by extracting RGB values to train and validate the ML models. Among them, the RF algorithm demonstrated superior performance, achieving an R 2 value of 0.9942, root mean square error of prediction of 3.5842, mean absolute error of prediction of 2.1893, and 93.31 % prediction accuracy. The proposed method achieved satisfactory recovery rates of 98.81–134.00 % and relative standard deviations below 4.32 % in real food and environmental samples. This study presents an intelligent, dual-mode strategy integrating ratiometric fluorescence sensing with machine learning for trace Cr(VI) detection. The approach offers high sensitivity, accuracy, and visual recognition, providing a generalizable platform for automated, on-site, and visualized analysis in complex food and environmental matrices.
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LANGMUIR
·
2025
·
IF 3.9
Hongxing He,Shunfei Li,Xintao Yang,Ying Xu,Siqing Ye,Haonan Dong,Mengye Yang,Ni Yang,Yi Zhang,Zhifeng Nie
Due to the low adsorption capacity, slow adsorption kinetics, and insufficient selectivity of conventional adsorbents in highly acidic environments, therefore, the removal of highly toxic Cr(VI) from industrial metallurgical wastewater remains a great challenge. Herein, a novel superhydrophilic quaternized nanofiber adsorbent was synthesized using electrospinning technology. The superhydrophilic nanofiber adsorbent facilitated water molecule movement during the adsorption process, which increased the system’s free energy and thus promoted the efficient and rapid selective removal of Cr(VI). The adsorbent was completely wetted within 0.06 s and reached a maximum adsorption capacity of 450.33 mg/g in a Cr(VI) solution with an initial concentration of 400 mg/L and equilibrated within 20 min. Adsorption experiments showed that the correlation coefficients of the pseudo-secondary kinetics and Langmuir model of the process were as high as R22 = 0.994 and RL2 = 0.971–0.993, respectively, suggesting that the adsorption process is mainly surface adsorption driven by chemisorption. Moreover, the adsorption mechanism by Zeta potential analysis and XPS and DFT simulations revealed that the selective adsorption for Cr(VI) is the synergistic action of ion exchange and coordination by electrostatic attraction. In addition, the dynamic column adsorption test demonstrated that the adsorbent could adsorb 6000 times its own mass of Cr(VI) ions in metallurgical wastewater, the recovery of Cr(VI) by nanofibers could still reach 89.7% after five cycles, and the removal efficiency was as high as 95.64% in real metallurgical wastewater, which highlighted the potential of its practical application.
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CERAMICS INTERNATIONAL
·
2025
·Vol. 51
·期 30
·65388-65397
·
IF 5.6
Jiahao Zha,Chongjun He,Fangzhou Chen,Xianhong Li,Jiayin Song,Chenguang Deng,Qian Li,Lijuan Liu,Mingjun Xia,Yuangang Lu
The fluorescence intensity ratio (FIR) technique has emerged as a pivotal approach in non-contact optical thermometry, offering substantial application potential. In this study, Y 3 Al 5 O 12 (YAG) phosphors co-activated with Ce 3+ and Cr 3+ ions were successfully synthesized through a high-temperature solid-state reaction method. Spectroscopic analysis revealed efficient energy transfer between the dopant ions, manifesting as distinct luminescence intensity variations compared to their single-doped counterparts. Under 450 nm excitation, the system demonstrates prominently yellow-green emission from Ce 3+ ions and well-resolved red emission from Cr 3+ ions, ensuring excellent spectral discrimination. Capitalizing on the differential thermal response between the two luminescent centers, the developed system achieves remarkable temperature sensing performance. The FIR method yields a maximum relative sensitivity of 0.845 % K −1 , maintaining sensitivity above 0.6 % K −1 throughout the 340–580 K range, coupled with exceptional temperature resolution below 0.03 K. Furthermore, we have engineered a novel FIR thermometry system incorporating 3D-printed spectral modules and fiber-optic phosphor encapsulation. The integrated system demonstrates superior sensing capabilities, reaching sensitivity values of 1.23 % K −1 in Cr 3+ lifetime mode and 4.64 % K −1 in FIR mode. These results indicate that Ce/Cr co-doped YAG has exceptional potential in multimodal optical thermometry applications.
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高影响因子
MICROCHEMICAL JOURNAL
·
2019
·
IF 3.206
Junling Duan,Li Zhao,Wei Lv,YiJing Li,Yuanhong Zhang,Shiyun Ai,Lusheng Zhu
The g-C 3 N 4 /Fe 3 O 4 nanocomposites with good fluorescence and magnetic property were designed and prepared for simultaneous detection and separation of trace Cr(VI) in water. The g-C 3 N 4 /Fe 3 O 4 nanocomposites based fluorescent sensor for Cr(VI) showed high sensitivity and selectivity. The linear response range of Cr(VI) was found to be 0 to 600 μM with a detection limit of 0.5 μM. In addition, the g-C 3 N 4 /Fe 3 O 4 as a novel adsorbent had effective removal towards Cr(VI). The adsorption capacity could reach 59.2 mg/ g. Furthermore, the g-C 3 N 4 /Fe 3 O 4 nanocomposites displayed superparamagnetic properties, allowing them to be easily separated from the liquid phase via an external magnetic field .
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SEPARATION SCIENCE AND TECHNOLOGY
·
2018
·
IF 1.2
Xuezhen Feng,Chunyan Liang,Jingang Yu,Xinyu Jiang
A binary composite consisting of graphene oxide (GO) and polyethylenimine (PEI) was fabricated by a facile physical mixing. Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Zeta potential were used to characterize the prepared graphene oxide-polyethylenimine composite (GOPC). A series of experiments were carried out to investigate the effects of some important parameters, such as molecular weight of PEI, pH, time and temperature, on the adsorption efficiency of GOPC. Due to the high amine density of GOPC, its adsorption for Cr(VI) occurred more easily at lower pH mainly via electrostatic interaction. The adsorption process matched well with the Langmuir isotherm model and the pseudo-second-order kinetic model. The maximum adsorption capacity from the Langmuir model was 370.37 mg/g at pH 2.0 and 45°C for GOPC. Thermodynamic parameters revealed spontaneous and endothermic nature of the Cr(VI) adsorption onto GOPC. The main adsorption mechanism of GOPC toward Cr(VI) was electrostatic interaction. The adsorption-desorption experiments suggested GOPC was easily recycled and its stable adsorption capacity endowed it great potential as an adsorbent of Cr(VI) from wastewater.
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Desalination and Water Treatment
·
2024
·
IF 1
Pan Hu,Jing Wang,Ruihua Huang
In this study, batch adsorption study was utilized in evaluating the potential suitability of quaternized chitosan immobilized bentonite (BT) as an adsorbent in the adsorption of anionic pollutants, Cr(VI), and methyl orange (MO) from aqueous solutions. The adsorptive behaviors of Cr(VI) and MO were examined as a function of the ratio of quaternized chitosan to BT, adsorbent dosage, solution pH, initial Cr(VI) (or MO) concentration, and contact time. The adsorption equilibrium for both Cr(VI) and MO was reached quickly. Adsorption isotherms for Cr(VI) and MO were well described by the Langmuir isotherm, while the pseudo-second-order kinetic model provided good kinetic data fitting. Furthermore, the results show that this adsorbent exhibited higher adsorption capacity for MO than Cr(VI). It appears that this anionic Cr(VI) favored the electrostatic interactions with this adsorbent while the anionic MO dye may interact with this adsorbent by electrostatic interactions and the hydrogen bonding.
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KEY ENGINEERING MATERIALS
·
2022
·
IF 0
Wen Hao Peng,Bin Bin Li,Kai Xuan Shi,Ping Chen
The intermediate band semiconductor of AgGa1-xCrxS2 is investigated by the first principles calculations and further confirmed by the experimental results. The band structures of pure and Cr-doped crystals were calculated and it is shown that the crystal with a direct energy band gap of about 0.95 eV for AgGaS2. Because of Cr dopant, a metallic intermediate band (IB) is successfully formed in the host. From the partial density of states (PDOS) of Cr-doped AgGaS2, the IB mainly comes from the hybridization of the Cr-3d and S-3p states. Based on the theoretical predications, the Cr-doped AgGaS2 is synthesized by the high-temperature solid state reaction. Two extra absorption responses are detected in the absorption spectra. The optical absorption coefficients are enhanced in the visible radiation range due to the formation of metallic and isolated IB. Therefore, Cr-doped AgGaS2 with an intermediate band is suggested as a potential material to enhance the efficiency of solar cells.
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RSC Advances
·
2025
·Vol. 15
·期 49
·41351-41363
·
IF 4.6
Meijuan Kuang,Qi Qin,Yun Li,Jiayi Lian,Changjiang Yu,Hui Yu,Tiantian Peng,Zhenya Jia,Xiaomao Song,Liantong Wang
Nanoscale zero-valent iron–biochar (BC@Fe) composites were synthesised via a one-step carbothermal method, followed by sulphidation to obtain sulphided BC@Fe (S-nZVI/BC-C-X) composites. Sulphidated nanoscale zero-valent iron–biochar (S-nZVI/BC-B-X) was also prepared using a one-step sodium borohydride reduction method. Batch experiments were conducted to investigate the effects of adsorption time, initial Cr(VI) concentration, pH and background ions on the Cr(VI) removal performance of S-nZVI/BC-C-X and S-nZVI/BC-B-X. A comparative analysis of their adsorption characteristics and removal efficiencies was conducted. The adsorption mechanisms were further elucidated through kinetic and isotherm model fitting, masking experiments and characterisation of the composites before and after Cr(VI) adsorption. The findings revealed that Cr(VI) removal by S-nZVI/BC-C-5 primarily occurred via (i) reduction of Cr(VI) to Cr(III) by FeS, FeS2 and Fe0, (ii) reduction of Cr(VI) to Cr(III) by Fe2+, (iii) reduction of Cr(VI) to Cr(III) by HS− released from FeS corrosion and (iv) adsorption of Cr(VI) by S-nZVI/BC-C-5.
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CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Bohan Zheng,Guangxu Yin,Shuang Yang,Lvping Fu,Meijie Zhang,Ao Huang,Huazhi Gu
Typically, advanced solar absorber coatings containing chromium (Cr) achieve high solar absorption efficiencies. However, large-scale applications raise concerns regarding the safety and cost due to the potential toxicity of Cr. This study develops a Cr-free (Fe x Co 0.25 Mn 0.25 Cu 0.25 ) 3 O 4 spinel coating based on tuning Fe content, which exhibits enhanced solar absorption and thermal stability. As Fe content increases, a single spinel structure is stabilized, accompanied by lattice expansion. Meanwhile, the covalent competition among cations at the tetrahedral sites in the structure is enhanced, facilitating the migration of Co and Mn ions from tetrahedral to octahedral sites. This process alters the valence distribution and lattice symmetry, leading to a reduction in oxygen vacancies (O V ) and an increase in the bandgap. Consequently, the solar absorptance was enhanced from 90.6 % to 93.2 % by decreasing Fe content in the single spinel structure, while infrared emissivity exhibits a significant increase in emissivity at 2.5–7.8 μm. After 60 thermal cycles at 750 °C, the (Fe 0.25 Co 0.25 Mn 0.25 Cu 0.25 ) 3 O 4 coating exhibits improved solar absorptance (94.9 %) and reduced thermal emissivity (90.2 %), ultimately enhancing the thermal efficiency to 89.3 %. This work provides a new option for Cr-free solar absorption coatings with tailored performance in high-temperature concentrated solar power (CSP) systems.
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