Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Xiaoyu Lin,Xi He,Ling Lei,Yufeng Zhao,Longzhe Cui,Guiping Wu
Cr(VI)-contaminated water poses a serious threat to the environment. In this study, capsule-type biosorbent Aliquat-336-filled chitosan capsules (AFCCs) were prepared by a simple and gentle method for more efficient and eco-friendly removal of Cr(VI). The experimental results show that the uptake of Cr(VI) by AFCCs increased with increasing Aliquat-336 content. The AFCCs show excellent stability under acidic conditions, and the maximum adsorption capacity was reached at a pH of 2. The maximum adsorption capacity of AFCCs for Cr(VI) was 110.94 ± 5.07 mg/g at 20 °C, which was calculated based on the Langmuir model. The kinetic results show that the adsorption rate control process changed from liquid film diffusion to a chemical reaction with increasing shaking rate. In addition, the AFCCs and adsorption-reduction mechanism of Cr(VI) were characterized by digital photography, electron microscope , zeta potential , Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results indicated that the electrostatic attraction between quaternary amine groups in Aliquat-336 and Cr(VI) anions plays a major role in the removal of Cr(VI). Subsequently, the adsorbed Cr(VI) obtained electrons from C C/C H and NH 3 + / NH 2 + were reduced to Cr(III), while C C/C H and NH 3 + / NH 2 + were oxidized to C O, C O, =NH + , =N and N O, respectively.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2021
·Vol. 26
·期 2
·449-456
·
IF 2.647
Liu Shanshan,Li Chenyao,Wang Dongxin,Li Junyi,Yuan Rui,Che Yusi,He Jilin,Song Jianxun
In this research, the reduction mechanism of Nb(V) under various [F − ]/[Nb n+ ] ratios ( α ) was investigated by a series of electrochemical techniques, such as square wave voltammetry (SWV) and chronopotentiometry (CP). We previously studied the electrode reduction process of Nb(V) and revealed that was Nb(V) → Nb(III) → Nb(I) → Nb in NaCl-KCl molten salt. It was found in this research that the electrode reduction process of Nb(V) ion was shortened to Nb(V) → Nb(III) → Nb when α was equal to 1.0; furthermore, the electrode reduction process of Nb(V) ion transforms to Nb(V) → Nb(IV) → Nb when α was greater than or equal to 5.0. Moreover, the reaction mechanism was also discussed in this work. Metallic niobium was collected on a molybdenum electrode under the condition of higher fluoride content after electrolysis in the melt.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 103
·期 6
·3905-3916
·
IF 3.502
Yongjie Liu,Yue Wang,Yu Zhang,Zhixiong You,Xuewei Lv
Ammonia gas can be simultaneously used as a reductant and nitrogen source to prepare TiN from titania. In this work, the mechanisms on reduction and nitridation of micrometer-sized anatase with ammonia gas have been investigated, using both thermodynamic and experimental studies. The thermodynamic analysis indicated that reduction and nitridation of TiO 2 by NH 3 was feasible. Anatase will undergo different paths to form TiN, depending on the reaction temperature. Upon heating, NH 3 was seen to partially decompose into N 2 and H 2 , although the actual NH 3 decomposition ratio was less than the theoretical value. The experimental results indicated that the obtained titanium nitride was non-stoichiometric (TiN x O 1 −x , x ≤ 1), as it contained a certain amount of oxygen. Based on the phase transformation and X-ray photoelectron spectroscopy analysis, the reduction and nitridation routes were deduced: TiO 2 reacted with NH 3 to form TiN x O 1− x directly, at lower temperatures, and followed the path TiO 2 → Ti n O 2n−1 → TiN x O 1− x , at higher temperatures. Ti n O 2n−1 was determined to be Ti 4 O 7 and Ti 3 O 5 at 1100°C and 1200°C, respectively. Reaction temperature and time significantly affected the oxygen and nitrogen contents in TiN x O 1− x , with the lattice parameter of roasted products gradually increasing—approaching those of pure TiN—with an increase in reaction temperature and holding time. At the same time, the content of oxygen in TiN x O 1− x decreased, and its nitrogen content correspondingly increased.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Rui Huang,Yinhua Wang,Yixin Pan
Owing to industrialization, the increased generation of electronic waste, and intensified metal ore and coal extraction activities, certain geographical areas are currently confronted with widespread selenium contamination in their groundwater. Consequently, there has been a considerable surge of interest in exploring techniques for selenium removal. In this study, we propose the utilization of single-layer dispersion of Ti 3 CN to facilitate the elimination of Se(Ⅳ). The results of the spectral analysis demonstrated that the removal of Se(Ⅳ) using Ti 3 CN occurs via a combined process of adsorption and reduction reactions. These two substances collaborated to create an inner sphere complex, which facilitated the reduction of Se(Ⅳ) to Se(0), ultimately resulting in the rapid formation of a co-precipitation product. The experimental results show that the adsorption capacity of Ti 3 CN for Se(Ⅳ) was notably sensitive to pH value, showing an adsorption capacity of 871.2 mg/g at pH 2. Furthermore, it was noted that the experimental results conformed well to the quasi-second-order kinetic model, with the Langmuir model effectively representing the adsorption isotherm data of Se(Ⅳ). This indicates that the process of Se(Ⅳ) removal by Ti 3 CN operates through chemical monolayer homogeneous adsorption. Notably, the presence of multiple ions revealed that only a selected few ions were able to impede the elimination of Se(Ⅳ). These findings underscore the potential of Ti 3 CN MXene as an efficient agent for treating selenium-containing wastewater.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
POWDER TECHNOLOGY
·
2020
·
IF 4.142
Zhenggen Liu,Lifeng Zhang,Mingyu Wang,Zichuan Zhao,Lihua Gao,Mansheng Chu
A new understanding of the reduction mechanisms of ferruginous manganese ores for ferromanganese alloy smelting was reported, and this new understanding was used to produce excellent ferromanganese alloys. To fulfill this objective, the effects of the operating variables on smelting ferromanganese alloys were initially investigated. The formation mechanisms and reduction reaction behaviors of olivine (Ca x Fe y Mn 2-x-y )SiO 4 , spinel (Ca x Fe y Mn 1-y-x )Al 2 O 4 , gehlenite (Ca x Mn 2-x )SiAl 2 O 7 and wüstite Mn x Fe y Ca 1-x-y O systems were systematically discussed to understand the phase transformation and reconstruction of manganese ore at high temperatures. The spinel (Ca x Fe y Mn 1-y-x )Al 2 O 4 that originated from (Fe y Mn 1-y )Al 2 O 4 was converted to CaAl 2 O 4 and then further reduced to ferromanganese alloys. A similar expression was applied to describe how the reduction mechanism of olivine (Ca x Fe y Mn 2-x-y )SiO 4 that originated from (Fe y Mn 2-y )SiO 4 was converted to Ca 2 SiO 4 . In addition, the importance of the formation of gehlenite (Ca x Mn 2-x )SiAl 2 O 7 and wüstite Mn x Fe y Ca 1-x-y O phases in smelting ferromanganese alloys was discussed and clarified in detail. Based on the findings, recommendations are provided for the theoretical basis and technical support of smelting ferromanganese alloys.
研究领域:
冶金学
·
材料科学
✓ 已验证
DOI
高影响因子
JOM
·
2021
·Vol. 73
·期 3
·881-891
·
IF 2.474
Li Yun,Taskinen Pekka,Wang Yuejun,Yang Shenghai,Tang Chaobo,Chen Yongming,Jokilaakso Ari
A promising lead-containing waste recycling method, with sulfur conservation and reductive sulfur-fixing co-smelting process (RSFCS), is proposed. This work investigated the PbSO 4 reduction equilibrium composition, phase conversions, and microscopic transformation mechanisms during the RSFCS process at different temperatures, times, and CO-CO 2 mixtures using thermodynamic modeling, thermogravimetric analysis, x-ray diffraction, and SEM-EDS analysis techniques. At the same time, the gaseous products were collected and analyzed. The results showed that three reduction paths existed: (1) PbSO 4 \( \to ^{{ {\text{CO/CO}}_{{2}} }} \) PbO·PbSO 4 +SO 2 \(\to ^{{ {\text{CO/CO}}_{{2}} }}\) 2PbO·PbSO 4 +SO 2 \(\to ^{{ {\text{CO/CO}}_{{2}} }} \) 4PbO·PbSO 4 +SO 2 \(\to ^{{ {\text{CO/CO}}_{{2}} }} \) PbO+SO 2 \( \to ^{{ {\text{CO/CO}}_{{2}} }}\) Pb; (2) PbSO 4 \( \to ^{{ {\text{CO/CO}}_{{2}} }} \) PbS; (3) PbSO 4 → PbO·PbSO 4 +SO 3 → 2PbO·PbSO 4 +SO 3 → 4PbO·PbSO 4 +SO 3 → PbO+SO 3 . Reduction temperature and CO concentration were determined as major factors in the PbSO 4 reduction. In a relatively weak reductive atmosphere and at low temperature, x PbO·PbSO 4 ( x = 1, 2, 4), PbO, Pb, and SO 2 were the major products. When temperature and the CO concentration increased, PbSO 4 was selectively reduced to PbS, with sulfur in the PbSO 4 fixed in PbS, instead of emitting SO 2 /SO 3 .
研究领域:
冶金学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ENVIRONMENTAL MANAGEMENT
·
2022
·
IF 8.91
Xuyin Huang,Xiaojun Niu,Dongqing Zhang,Xiaoqin Li,Haoshen Li,Ziyuan Wang,Zhang Lin,Mingli Fu
While nanoscale zero-valent iron modified biochar (nZVI-BC) have been widely investigated for the removal of heavy metals , the corrosion products of nZVI and their interaction with heavy metals have not been revealed yet. In this paper, nZVI-BC was synthesized and applied for the removal of Cr(VI). Batch experiments indicated that the adsorption of Cr(VI) fit Langmuir isotherm, with the maximum removal capacity at 172.4 mg/g at pH 2.0. SEM-EDS, BET, XRD , FT-IR, Raman and XPS investigation suggested that reduction of Cr(VI) to Cr(III) was the major removal mechanism. pH played an important role on the corrosion of nZVI-BC, at pH 4.5 and 2.0, FeOOH and Fe 3 O 4 were detected as the major iron oxide , respectively. Therefore, FeOOH-BC and Fe 3 O 4 -BC were further prepared and their interaction with Cr were studied. Combining with DFT calculations, it revealed that Fe 3 O 4 has higher adsorption capacity and was responsible for the effective removal of Cr(VI) through electrostatic attraction and reduction under acidic conditions. However, Fe 3 O 4 will continue to convert to the more stable FeOOH, which is the key to for the subsequent stabilization of the reduced Cr(III). The results showed that the oxide corrosion products of nZVI-BC were subjected to the environment, which will eventually affect the fate and transport of the adsorbed heavy metal.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2012
·
IF 5.625
Xi Li,Jian Zhu,Hexing Li
The photocatalytic performances of the SnS 2 and the CdS under the irradiation of visible light were investigated by using different organic dyes as reactants. The photodegradation of organic dyes containing N N double bond on the SnS 2 followed a reduction mechanism with photoelectrons via the Sn IV /Sn II transition while the photodegradation of organic dyes containing N N double bond on the CdS and the photodegradation of organic dyes without N N double bond on either the SnS 2 or the CdS followed an oxidation mechanism with O 2 − and OH radicals. The SnS 2 exhibited much higher activity than the CdS during the photocatalytic degradation of organic dyes containing N N double bond, since the reduction of reactant molecules on the SnS 2 surface was much faster than the migration of either the O 2 − or the OH radicals. However, the SnS 2 displayed even lower activity than the CdS in the photocatalytic degradation of other organic dyes without N N double bond, since all these reactions followed the oxidation mechanism and the SnS 2 displayed a lower efficiency than the CdS in producing O 2 − or OH radicals due to the presence of the Sn IV /Sn II transition.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2020
·
IF 5.289
Chenyao Li,Shaolong Li,Yusi Che,Junyi Li,Yongchun Shu,Jilin He,Jianxun Song
The reduction mechanism of Nb(V) in molten KCl-NaCl at 1023 K was investigated by a series of electrochemical techniques such as cyclic voltammetry, square wave voltammetry and chronopotentiometry. It was found that there were three steps in the reduction of Nb(V) as Nb(V)→Nb(III)→Nb(I)→Nb, and electrochemical reaction, Nb(V)→Nb(III), is a quasi-reversible diffusion controlled process. The diffusion coefficient of Nb(V) was also obtained by cyclic voltammetry, square wave voltammetry and chronoamperometry. The relationship between current density and the square root of time shows that the nucleation of niobium belongs to the instantaneous nucleation on molybdenum electrode in molten KCl-NaCl-NbCl 5 (0.43 × 10 −3 mol/cm 3 ) at 1023 K at −3.10 V vs. Cl 2 /Cl − . Moreover, the metallic niobium was deposited on molybdenum wire by chronoamperometry, and the products were analyzed by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX). The results showed that the metallic niobium has a high purity of 99.98%.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2014
·Vol. 30
·期 2
·293-296
·
IF 1.119
Zhang Yinxu,Mao Xinbiao,Ren Shuying,Ma Chunan
Ionic liquid, 1-butyl-3-methylimidazolium acetate(BMImAc), was used in the electrochemical reduction of nitrobenzene. The electro-reduction of nitrobenzene on platinum electrode was studied by cyclic voltammetry(CV), in situ Fourier transform infrared(FTIR) spectroscopy and constant-potential electrolysis. The experimental results show that electrochemical reduction process of nitrobenzene was controlled by diffusion, the main reduction product was azobenzen at −1.45 V, and the influences of scan rate and temperature on the electrochemical behaviors were obviously. A reduction mechanism of nitrobenzene in an ionic liquid was a probable ‘nitrobenzene→nitroso-benzene→azobenzene→aniline’ main reductive reaction route.
研究领域:
化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2017
·
IF 6.216
Si-Hai Zhang,Mei-Feng Wu,Ting-Ting Tang,Qiu-Ju Xing,Cai-Qing Peng,Fei Li,Hui Liu,Xu-Biao Luo,Jian-Ping Zou,Xiao-Bo Min,Jin-Ming Luo
In this study, nanoscale zero-valent iron (nZVI) with a considerably high surface area (182.97 m 2 ·g −1 ) and featured morphology of chain structure has been synthesized and well characterized. The as-prepared nZVI on can totally remove Cr(VI) under anoxic condition after 20 min reaction, whereas only 43% of Cr(VI) was removed after 60 min reaction under oxic condition. Noteworthily, the nZVI exhibits excellent removal capacity of Cr(VI) (123.85 mg/g) and fast removal rate (0.017 g·mg −1 ·min −1 ), much better than those reported in the literatures except for that reported by Li et al. (2008) [1] . Experimental results have confirmed that only FeCr 2 O 4 with low compactness was generated under anoxic and acidic conditions in the new process. And it is evident that the formation of the passivation layer which contains oxides and hydroxides (or (oxy)hydroxides) of iron and chromium were well hindered. Furthermore, the as-prepared nZVI has shown fast removal of traced Cr(VI) from the Cr-spiked drinking water or actual Cr-contaminated lake water. Accordingly, we proposed a new reaction process of Cr(VI) reduction by nZVI under anoxic condition. And we firstly make clear the detailed process of Cr(VI) removal by the as-prepared nZVI via X-ray photoelectron spectrometer (XPS) analysis in time scale. Meanwhile, the excellent Cr(VI) removal performance of the as-prepared nZVI could be attributed to (i) the high surface area, (ii) large quantity of active sites of nZVI, and (iii) fast electron transfer from the nZVI/FeCr 2 O 4 to Cr(VI). The present work not only provides the potential materials for the application to the rapid and high-efficient removal of Cr(VI) from aqueous solution, but also proposed a new avenue for hindering the passivation of Fe 0 . And a detailed mechanism of the Cr(VI) removal by nZVI was proposed for the first time.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2020
·
IF 2.627
Jiahong Wang,Tongtong Sun,Atif Saleem,Yao Chen
Polyethyleneimine (PEI) modified palygorskite (Pal) was used for the adsorption of Cr(VI) in aqueous solution. The absorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Characterized results confirmed that the Pal has been successfully modified by PEI. The modification of PEI increased the Cr(VI) adsorption performance of the Pal by the adsorption combined reduction mechanism, and amino groups of the adsorbent play the main role in the enhanced Cr(VI) adsorption. The maximum adsorption capacity was 51.10 mg·g −1 at pH 4.0 and 25 °C. The adsorption kinetics of Cr(VI) on the adsorbent conforms to the Langmuir isotherm model. The maximum adsorption occurs at pH 3, and then the adsorption capacity of PEI-Pal was decreased with the increase of pH values. The adsorption kinetics of Cr(VI) on PEI-Pal was modeled with pseudo-second-order model. The addition of Cl − , SO 4 2− and PO 4 3− reduced the Cr(VI) adsorption by competition with Cr(VI) for the active sites of PEI-Pal. The Cr(VI) saturated PEI-Pal can be regenerated in alkaline solution, and the adsorption capacity can still be maintained at 30.44 mg·g −1 after 4 cycles. The results demonstrate that PEI-Pal can be used as a potential adsorbent of Cr(VI) in aqueous solutions.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）