INORGANICA CHIMICA ACTA
·
2022
·
IF 3.118
Mingyan Chen,Dehua Zhang,Ziying Wang,Yao Zhang,Yucheng Liu
UiO-66 loading carboxyl and phosphotungstic acid has a good affinity to thiophene (TH). The synthesized catalyst, changed its original structure, which can increase its reactive site and enhance the interaction with thiophene (TH) in order to improve the adsorption performance. Then the structural changes were analyzed by XRD, FT-IR, SEM, BET, EDS and other characterization methods. Through static experiments of adsorption desulfurization, it is found that when the adsorption time is 240 min, the adsorption temperature is 30 ℃ and the oil-to-agent ratio is 100:1, the adsorption effect: UiO-66-(COOH) 2 (UC2) > UiO-66, the highest adsorption capacity can reach 89.99 mg/g; while PTA@UiO-66 (PAU) can reach adsorption equilibrium at 210 min, it has better desulfurization performance than UiO-66. After being recycled for 5 times, the adsorption effect is only slightly decreased: the adsorption capacity of UC2 was still 78.02% of the initial adsorption capacity, while that of PAU was 76.07% of the initial adsorption capacity. According to the adsorption kinetics, the adsorption process of thiophene on the adsorbent UC2 is more consistent with W-M model, and the adsorption of PAU is more in line with the pseudo-first order kinetic equation. In addition, it also includes the process of intraparticle diffusion and liquid film diffusion.
研究领域:
化学工程
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材料科学
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DOI
高影响因子
CELLULOSE
·
2017
·Vol. 24
·期 6
·2415-2425
·
IF 3.417
Sang Xiankui,Qin Chengrong,Tong Zhangfa,Kong Song,Jia Zhuan,Wan Guangcong,Liu Xinliang
2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO) can selectively oxidize primary hydroxyl groups of cellulose to carboxyl groups. However, the depolymerization also occurs during the process. The kinetics and mechanism of carboxyl group formation on the surface of cellulose fiber oxidized by TEMPO/NaClO 2 /NaClO were discussed. The oxidization and depolymerization of cellulose occurred simultaneously, according to analysis of FTIR and 13 C CP/MAS NMR. The glucuronic acid and some small molecular fragments, formed by hydrolysis or β-elimination during the oxidation, are also discussed. The crystallization index increased and crystal size decreased, as shown by X-ray analysis. The degradation steps in the TEMPO/NaClO 2 /NaClO system was discussed, according to carbon conversion analyzed by 13 C CP/MAS NMR. The oxidation of cellulose can be described well by the kinetics model established based on the degradation of cellulose. It was found that temperature is one of the key parameters for controlling the oxdation and degradation level. The possible mechanism for oxidation of cellulose was composed.
研究领域:
化学
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材料科学
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2024
·Vol. 48
·期 12
·5419-5428
·
IF 2.7
Zhou Zhou,Guo-Lei Zhang,Yue-Xin Song,Ying-Hui Zhang
Porphyrins have been widely used in designing photocatalyst systems. However, finding an effective strategy to improve the intrinsic photocatalytic activity of porphyrin molecules remains a challenge. Here, two new porphyrins, meso-tetra(5-carboxyfuryl)porphyrin (H2TCFP) and meso-tetra(5-carboxythienyl)porphyrin (H2TCTP), were successfully synthesized and compared with meso-tetra(m-carboxyphenyl)porphyrin (H2TmCPP), to clarify the influence of the organic unit bridging the carboxyl acid group with the porphine ring on the photocatalytic activity of porphyrin for H2 evolution from water splitting. The H2 evolution rates of 10.8 mmol g−1 h−1 observed for H2TCFP and 9.7 mmol g−1 h−1 for H2TCTP are both larger than 8.0 mmol g−1 h−1 observed for H2TmCTP under optimal conditions. The best photocatalytic activity observed for H2TCFP was investigated through experiments and density functional theory (DFT) calculations and was interpreted in terms of the combined effect of several key factors of the entire photocatalytic process, including the high absorptivity of UV light, high separation efficiency of photogenerated carriers, and low Gibbs energy required for associated water splitting. Meanwhile, the concentration-dependent performance of photocatalytic activity was analyzed and attributed to the aggregation and light-bleaching effect exerted on porphyrins.
研究领域:
化学
·
材料科学
·
催化
·
可再生能源
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2013
·
IF 3.473
Ning Pan,Debin Guan,Yuntao Yang,Zhenling Huang,Ruibing Wang,Yongdong Jin,Chuanqin Xia
We report a rapid, environmentally-friendly and cost-effective route for the preparation of a graphene-based nanomaterial, carboxyl graphene (aka. reduced graphene oxide , RGO) from graphene oxide (GO). Carboxyl graphene was prepared on the scale of several grams through the reduction of GO by thiourea dioxide (TUD) at a relatively low temperature (40 °C) in an alkaline medium (pH = 10). The reduction of GO was confirmed by FT-IR, UV–vis, X-ray photoelectron, and Raman spectroscopy. In addition, this reduction was also confirmed by thermal gravimetric analysis, X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Characterizations of these materials demonstrated that selective reduction of the epoxy and carbonyl groups occurred on the surface of GO, while carboxyl groups were left behind. In addition, the conjugation of the carbons in the structure was restored through this reduction and a single-layer of carboxyl graphene (with a thickness of 0.80 nm, as observed by AFM) was obtained under these conditions. Carboxyl graphene had a high surface area (of 454.52 m 2 g −1 ) and contained approximately 6.9 ± 1.6 mmol of carboxyl groups per gram of material, as determined via Boehm titration. The mechanism for selective reduction of the epoxy and carbonyl groups on GO to form carboxyl graphene by TUD is proposed and discussed in detail.
研究领域:
纳米材料化学
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材料科学
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表面化学
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碳基纳米材料
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功能化纳米材料
✓ 已验证
DOI
高影响因子
Catalysts
·
2017
·Vol. 7
·期 5
·131
·
IF 3.082
Xiaowei Liu,Lili Wang,Zhe Sun,Yu Shao,Tingchao Yu
Bromate (BrO3−) contamination in drinking water is a growing concern. Advanced reduction processes (ARPs) are reportedly promising in relieving this concern. In this work, UV/superparamagnetic BiOCl (BiOCl loaded onto superparamagnetic hydroxyapatite) assisted with small molecule carboxylic acid (formate, citrate, and acetate), a carboxyl anion radical (CO2•−)-based ARP, was proposed to eliminate aqueousBrO3−. Formate and citrate were found to be idealCO2•−precursor, and the latter was found to be safe for practical use.BrO3−(10 μg·L−1, WHO guideline for drinking water) can be completely degraded within 3 min under oxygen-free conditions. In this process,BrO3−degradation was realized by the reduction ofCO2•−(major role) and formyloxyl radical (minor role) in bulk solution. The formation mechanism of radicals and the transformation pathway ofBrO3−were proposed based on data on electron paramagnetic resonance monitoring, competitive kinetics, and degradation product analysis. The process provided a sustainable decontamination performance (<5% deterioration for 10 cycles) and appeared to be more resistant to common electron acceptors (O2,NO3−, and Fe3+) than hydrated electron based-ARPs. Phosphate based-superparamagnetic hydroxyapatite, used to support BiOCl in this work, was believed to be applicable for resolving the recycling problem of other metal-containing catalyst.Keywords:bromate;carboxyl anion radical;reduction;magnetic recovering
研究领域:
环境科学
·
水处理工程
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DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2021
·Vol. 39
·期 8
·966-974
·
IF 3.603
Feng Li-Dong,Bian Xin-Chao,Li Gao,Chen Xue-Si
The effect of exogenous hydroxyl, carboxyl groups and/or Sn 2+ on pyrolysis reactions of poly(L-lactide) (PLLA) was investigated by thermogravimetric analysis (TGA). The activation energy ( E a ) of pyrolysis reactions was estimated by the Kissinger-Akahira-Sunose method. The kinetic models were also explored by the Malek method, and the random degradation behavior was determined by comparing the plots of In{-In[1 - (1 - w ) 0.5 ]} versus 1/ T for experimental data from TGA with model reactions. The pyrolysis reaction rate of PLLA was affected slightly by exogenous hydroxyl and carboxyl groups at lower levels of Sn with 65–70 mg·kg -1 but increased appreciably in the presence of extraneous Sn 2+ , -COOH/Sn 2+ , or -OH/Sn 2+ . The E a values for the pyrolysis reactions of the PLLAs that provided lactide were different under the catalysis of Sn 2+ in different chemical environments because Sn 2+ can form the new Sn-carboxylate and Sn-alkoxide with exogenous carboxyl and hydroxyl groups, which were different in steric hindrance for the formation of activated complex between Sn 2+ and PLLA. Under the catalysis of Sn 2+ , a lactide molecule can be directly eliminated selectively at a random position of PLLA molecular chains, and the molecular chain of PLLA cannot change two PLLA fragments at the elimination site of lactide. However, it was regenerated into a new PLLA molecule with the molecular weight reduced by 144 g·mol -1 .
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
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2021
·
IF 6.953
Xiaotong Fu,Fulong Zhang,Cuihua Dong,Wenyuan Zhu,Kaifeng Xiong,Zhiqiang Pang
An appropriate cellulose-dissolving solvent is critical for the homogeneous oxidation of cellulose using TEMPO (2, 2, 6, 6-tetramethylpiperidine-1-oxyl)-mediated system. Herein, TEMPO/NaClO/NaClO 2 system in lithium bromide hydrates (LBHs) was developed for the homogeneous selective-oxidation of cellulose, which was two-stage protocol involving cellulose dissolution and homogeneous oxidation. Specifically, cellulose was firstly dissolved in LiBr·3.5H 2 O and offered the optimal pH (5.6) for the subsequent TEMPO/NaClO/NaClO 2 oxidation without precipitation of the cellulose chains. Effect of reaction conditions on cellulose oxidation was investigated. The results showed that high degree of oxidation (DO) and evenly distributed carboxyl could be achieved. The particle size gradually decreased with DO, and oxidized cellulose with high water solubility and amorphous structure could be obtained. Furthermore, FT-IR, 13 C NMR and fractionation analysis verified that cellulose was successfully converted and the carboxyl uniformly distributed onto the cellulose chains. This TEMPO-mediated system using LBHs as solvent presented an efficient method on the homogeneous selective oxidation of primary hydroxyl in cellulose.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF ORGANIC CHEMISTRY
·
2023
·
IF 3.6
Fenfen Xie,Fen Han,Yunying Yan,Haiqiong Li,Jianjun Hao,Linhai Jing,Pan Han
It is significant to develop novel difluoromethylation methods because of the important roles of difluoromethyl groups in the medicinal chemistry and material industries. Here, we developed a novel difluoromethylation–carboxylation and difluoromethylation–deuteration method triggered by a difluoromethyl radical generated by electroreduction of stable and easily available difluoromethyltriphenylphosphonium bromide. Various molecules containing difluoromethyl and carboxyl or deuterium groups can be synthesized through this method. The establishment of this method will provide an alternative to radical difluoromethylation reactions.
研究领域:
有机化学
·
药物化学
✓ 已验证
DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Chunlai Liu,Na Wang,Zelin Meng,Mingyang Song,Heming Zhao,Jianglei Hu,Fengwei Shi
The Knoevenagel reaction is one of the most significant reactions in the industrial synthesis of organic materials, pharmaceuticals, and biological compounds. In this study, 2-cyanoethyltriethoxysilane (CTES) was employed as a functionalizing agent to prepare carboxyl-functionalized silica (SBA-16-Cx) using a one-pot method. Subsequently, carboxyl groups served as anchoring points for Cr³⁺, and MOFs-modified SBA-16 (SBA-16-Cx@MIL) was obtained by in situ synthesis. The resulting materials were characterized using FT-IR, XPS, XRD, N 2 adsorption-desorption analysis, SEM, TEM, 13 C MAS NMR, and TG, which confirmed the successful synthesis of MIL-101 on the support. Meanwhile, the pore size of the composite was reduced from 5.1 nm (SBA-16) to 0.6 nm (SBA-16-C1.0@MIL). The condensation reaction of benzaldehyde with malononitrile was selected as a model reaction. The effects of various factors, including solvents, reactants molar ratios, temperature, catalyst dosage, and reaction time, on the reaction were studied. Under optimized conditions, the conversion rate of benzaldehyde reached 100 % and the catalyst demonstrated excellent stability for repeated use. The reaction follows second-order kinetics (R 2 >0.99), and the activation energy of the reaction was 17.18 kJ/mol. Finally, the mechanism of the catalytic process was proposed. This work provides a green catalytic route for the synthesis of α,β-unsaturated carbonyl compounds.
研究领域:
材料科学
·
催化化学
·
有机合成
✓ 已验证
产品关联
DOI
高影响因子
FUEL PROCESSING TECHNOLOGY
·
2016
·
IF 3.847
Yan-Na Han,Zong-Qing Bai,Jun-Jie Liao,Jin Bai,Xin Dai,Xiao Li,Jun-Li Xu,Wen Li
Oxygen functional groups as primary adsorption site of water are one of key factors controlling water re-adsorption and drying behaviors of brown coal . The dewatering energy of brown coal because of different oxygen functional groups is still unclear. Thus, two kinds of oxidized brown coal samples carrying more phenolic hydroxyl or carboxyl groups with similar pore structures were chosen. The concentrations of different water forms of the samples were determined from the moisture holding capacity at constant humidity and temperature and from the results of dewatering experiments analyzed by thermogravimetry coupled with differential scanning calorimetry . The results showed that the concentrations of three forms of water, i.e. free water, capillary water , and molecular water, showed good correlations with concentration of carboxyl groups. Comparison of 1 H NMR analysis of dried and moisturized samples showed that the types of oxygen functional groups predominantly affected the water environment in coal. IR spectra of dried and adsorbed D 2 O samples showed that OH–π hydrogen bond due to carboxyl groups was easier broken than that due to phenolic hydroxyl groups . The water desorption energy of primary site and dewatering energy of samples with more carboxyl groups were lower than that of samples with more phenolic hydroxyl groups, because hydrogen bonding energy of water bonded to hydroxyl oxygen of carboxyl groups was lower than that of water bonded to hydroxyl oxygen of phenolic hydroxyl groups.
研究领域:
能源科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Haiyan Luo,Haoyu Yao,Min Li,Fanfang Meng,Hui Zhao,Changjiang Yu,Xiangfeng Liang,Huizhou Liu
Efficient extraction of uranium from seawater is of great significance to the stable development of nuclear energy. The graft modification of pectin is expected to realize the efficient extraction of uranium through the dual action of aminoxime and carboxyl groups. In this work, novel biomimetic pectin adsorbents were developed and their performance on the adsorption performance of uranium from seawater was investigated. The physical structure and morphology were characterized by employing FT-IR, BET, SEM and elemental analysis. The skeleton structure and surface functional groups of the pectin-derived adsorbents, which were modified to improve the adsorption selectivity, favored the adsorption of uranium in simulated seawater. The modified apple pectin (MPA) adsorbents exhibited the highest adsorption capacity of 212.27 mg/g at optimal conditions. The thermodynamic results showed that the adsorption of uranium on MPA surface followed the Langmuir single-layer model, and the theoretical maximum adsorption capacity could reach up to 296.25 mg/g. The adsorption process conformed to the pseudo-second-order model. Furthermore, the synergistic mechanism between aminoxime and carboxyl groups of the pectin-based adsorbents was proposed. In conclusion, this work provides a new bio-based adsorbent with high efficiency for uranium extraction from concentrated seawater.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Yangqin Liu,Lei Chen,Lin Liu,Pengfei Shi,Junhui Sun,Yang Wang,Linmao Qian
Reducing wear and even achieving superlubrication in industrial applications using simple yet effective methodologies has been a longstanding research objective. In this study, we propose a convenient approach by employing a combination of carboxylated graphene (Gr-COOH) coating with glycerol as lubricants. Compared to the non-lubricated state, this strategy enabled the achievement of superlubrication with an exceptionally low friction coefficient of 0.002, while simultaneously reducing wear volume of substrate by 4 orders of magnitude, and the wear of the counterpart balls are nearly zero. The transfer of Gr-COOH to the ball surface led to the formation of a low shear resistance interface with the Gr-COOH present on the substrate. Nanoscopic experiments with atomic force microscopy revealed that the substrate surface lubricated by this method exhibited more hydrophilic properties. The formation of a featured hydrophilic interface enables the persistence of glycerol molecules in the contact region for an extended duration, thereby facilitating continuous elastohydrodynamic lubrication. This proposed lubrication methodology holds broad utilization potential as a wear-reduction strategy across various industrial fields.
研究领域:
材料科学
·
摩擦学
✓ 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）