HYDROMETALLURGY
·
2017
·
IF 2.605
Xingyu Chen,Qiang Chen,Fuliang Guo,Yulong Liao,Zhongwei Zhao
Leaching of scheelite by adopting the sulfur-phosphorus mixed acid allowed the accompanied rare-earth elements to enter a leaching solution. The leaching solution contained ions that could be coordinated with rare-earth ions, such as phosphotungstic acid anions, sulfate anions and phosphate anions, among others. To efficiently extract rare earths from the leachate, the extraction behavior of rare-earth ions in the solution was examined. Experimental results indicated that when the solution pH was lower than 1, phosphotungstic acid existed in the form of Keggin-type (1:12) [PW 12 O 40 ] 3 − , which exhibited a relatively poor complexing ability. Thus, secondary carbon primary-amine (N1923) could only extract phosphotungstic acid anions without extracting rare earths. As pH increased, a number of WO groups were dropped from the [PW 12 O 40 ] 3 − ion to form unsaturated phosphotungstic acid. Unsaturated phosphotungstic acid anions with rare-earth ions exhibited a complexing ability stronger than that with SO 4 2 − . Rare-earth ions were mainly complex with unsaturated phosphotungstic acid to form stable anions in the solution and could be extracted completely by the anionic extractant N1923. Meanwhile, the cationic extractant P204 could hardly extract rare earths. As the pH rose and exceeded 2.75, the concentration of PO 4 3 − increased, rendering the complexation between the rare-earth ions and PO 4 3 − dominant. Hence, rare-earth ions were precipitated.
研究领域:
冶金学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Polymer Materials
·
2019
·
IF 0
Arun Saini,Chandravati Yadav,Bai-Liang Xue,Nan Wang,Lei Dai,Xinping Li
In this study, a mixed-acid-assisted system utilizing a combination of a weak acid (citric acid, CA) and strong acid (H2SO4, SA) under hydrothermal reaction conditions was proposed for simultaneous preparation and modification (carboxylation) of cellulose nanocrystals (CNCs). Bleached bamboo pulp was used as the cellulose source, and the optimized reaction conditions were further used to produce carboxylated CNCs (cCNCs) from microcrystalline cellulose and Whatman 1 filter paper. Different concentrations of CA and SA (namely, 40 wt % CA (optimized concentration) and 5, 10, 20, and 30 wt % SA) were used for the hydrolytic processing of raw cellulosic material under hydrothermal conditions. The effect of various concentrations of CA and SA on the yield, carboxylate content, microstructure, crystallinity, thermal, and rheological characteristics of cCNCs were methodically investigated and contrasted. The optimized hydrothermal reaction conditions performed for 4 h at 100 °C using a mixture of 40 wt % CA and only 20 wt % SA yielded needle-shaped cCNCs with a yield higher than 70%. The carboxyl functionalization of CNCs was affirmed through Fourier transform infrared spectroscopy and conductometric titrimetric method. The results revealed the carboxylate content of 1.18 mmol/g corresponding to an average degree of oxidation of ∼0.20. The length of nanocrystals lies in the range of 280–420 nm with diameter ranging from 10 to 20 nm, as was perceived through microstructural analytical tools like field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Dynamic light scattering analysis gives an average size of ∼200 nm. The visual inspection revealed high colloidal stability of cCNCs dispersions, which was further supported through its appreciable Zeta potential value of ca. −49.5 mV. Further, the rheological characterizations revealed typical features reminiscent of critical gels showing elastic behavior of cCNCs. Nanocomposite films of hydroxypropyl methylcellulose (HPMC) with different loadings of cCNCs were fabricated using a simple solvent casting method. The incorporation of very small amounts of cCNCs (0.1 wt %) in HPMC resulted in ∼58% increment in tensile strength, ∼10% increment in modulus, and ∼82% increment in elongation. Moreover, the composite films exhibited high transparency and appreciable water barrier properties that allow their potential application as barrier and transparent films for various applications.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
Journal of Flow Chemistry
·
2023
·Vol. 13
·期 3
·311-323
·
IF 2.7
Song Jing,Cui Yongjin,Wang Yujun,Wang Kai,Deng Jian,Luo Guangsheng
The nitration of toluene with mixed acid is one of the most representative nitration reactions. Accurate kinetic study is essential for controlling the reaction and designing reactors. Due to the characteristics of fast rate, high exothermicity and heterogeneity in toluene nitration, the effects of mass and heat transfer may result in inaccurate determination of kinetics. In this work, the adiabatic temperature rises of the reaction system were studied to provide precise ranges of experimental conditions for accurately controlling the reaction rate and heat release rate in a liquid–liquid microflow system. The adiabatic temperature rise was successfully controlled to below 0.3 °C. The effects of mass and heat transfer on the reaction rate were completely eliminated, so that the kinetic study was carried out under the control of intrinsic kinetics only. The activation energy for toluene nitration was determined to be 28.00 kJ/mol. The activation energies for the formation of o -nitrotoluene and p -nitrotoluene were obtained for the first time, which were 25.71 and 31.91 kJ/mol, respectively. The obtained kinetic models can predict the reaction performance of toluene nitration very well.
研究领域:
化学工程
·
反应动力学研究
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Ni Ai,Wenye Deng,Yi Liu,Yan Xue,Jinyang Li,Kai Ding,Pengjun Zhao,Aimin Chang,Penggao Liu,Yongxin Xie
The recovery of valuable metals from spent LIBs is essential for environmental protection and economic development. This study used a green and mild organic mixed acid to leach valuable metals from spent LIBs to prepare thermally sensitive ceramics. The effects of acid concentration, temperature, time, and S/L on the leaching efficiency were investigated during the leaching process. The effects of the elemental molar ratio on the ceramic properties were also explored. The results revealed that there was an optimum leaching efficiency at 1.25 M citric acid, 0.5 M ascorbic acid, 70 min, 353 K, 50 g/L, and 500 r/min. The characterization of the substances before and after leaching by XRD and SEM confirmed the effective leaching of valuable metals by the mixed acids. FT-IR, Raman, and UV-Vis analyses further verified that the mixed acids leached valuable metals through the synergistic effect of acidity and reduction. The leaching kinetics study revealed that the leaching process conforms to the leaching mechanism of the Arvami equation. Thermal ceramic materials were prepared by co-precipitation of mixed acid leaching spent LIBs. Mn 1.2 Co x Ni 1.8-x O 4 (x = 1.5) ceramics have excellent crystalline shapes and densification. The R-T curves confirmed that Mn 1.2 Co x Ni 1.8-x O 4 has significant thermally sensitive ceramic properties. This study is the first to use spent LIBs with valuable metals for the preparation of thermal ceramics, which provides a new way to recycle and apply valuable metals in spent LIBs.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Mingchen Yang,Yi Chen,Somia Yassin Hussain Abdalkarim,Xuefei Chen,Hou-Yong Yu
The performance of cellulose-based materials is highly dependent on the choice of solvent systems. Exceptionally, cellulose dissolution and derivatization by efficient solvent have been considered as a key factor for large-scale industrial applications of cellulose. However, cellulose dissolution and derivatization often requires harsh reaction conditions, high energy consumption, and complex solubilizing, resulting in environmental impacts and low practical value. Here we address these limitations by using a low-temperature oxalic acid/sulfuric acid solvent to enable cellulose dissolution and derivatization for high-performance cellulose films . The dissolution and derivatization mechanism of the mixed acid is studied, demonstrating that cellulose is firstly socked by oxalic acid , then more hydrogen bonds ionized by sulfuric acid break cellulose chain, and finally the esterification reaction between oxalic acid and cellulose is catalyzed by sulfuric acid. Solutions containing 8 %–10 % cellulose are obtained and can be stored for a long time at −18 °C without significant degradation. Moreover, the cellulose film exhibits a higher tensile strength of up to 66.1 MPa, thermal stability, and degree of polymerization compared to that fabricated by sulfuric acid. These unique advantages provide new paths to utilize renewable resources for alternative food packaging materials at an industrial scale.
研究领域:
材料科学
·
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Biomass Conversion and Biorefinery
·
2025
·
IF 4.1
Jia Yu,Liang Xuanyu,Tao Hongge,Chen Binglin,He Chao,Jiao Youzhou,Xu Guizhuan
5-Hydroxymethylfurfural (HMF) is an important platform compound that can be used to synthesize drugs, fine chemicals, fuels, and biodegradable plastics. Synthesis of HMF from cellulose is a key step in the production of high-value-added chemicals and fuels from renewable cellulosic biomass. Herein, a cheap way to produce HMF from cellulose was found in this study. Combination of inexpensive metal salts and inorganic acids shows exciting catalytic efficiency in tetrahydrofuran (THF)/H 2 O system. In this article, the effects of key factors such as water/organic solvent ratio, metal salt type, and concentration on the synthesis of HMF from cellulose were investigated. A maximum HMF yield of 46.5% was obtained with high substrate loading (50 g/L) when H 2 SO 4 and Al 2 (SO 4 ) 3 was used as mixed acid catalysts. Reaction kinetics experiments revealed that combination of H 2 SO 4 and Al 2 (SO 4 ) 3 could effectively reduce the activation energy of cellulose hydrolysis, glucose isomerization, and fructose dehydration compared to the single H 2 SO 4 and single Al 2 (SO 4 ) 3 system. Fortunately, the purity of HMF after separation and purification was up to 98.3%, and both the solvent and the extractant can be recycled. A promising strategy is provided for HMF production from cellulose over simple catalysts.
研究领域:
生物化学
·
可再生资源化工
✓ 已验证
产品关联
DOI
高影响因子
Chemical Engineering and Processing-Process Intensification
·
2022
·
IF 4.264
Shuai Guo,Jian-yang Cao,Mei-qi Liu,Le-wu Zhan,Bin-dong Li
Microreactors are becoming an important tool for rapid exothermic chemical reaction process intensification and continuous flow chemistry. This work focuses on the process intensification and kinetics of the trifluoromethylbenzen nitration in microreactors. The reaction of trifluoromethylbenzene with mixed acid is a typical liquid-liquid heterogeneous reaction, so the mass transfer is the rate-determining step. Two strategies of microreaction systems were established to enhance mass transfer, respectively. Firstly, a scheme for intensifying the nitration reaction process in a capillary microreactor was proposed. The results showed that the conversion was low and could not achieve the expected results. Finally, a Heart-type micromixer with barriers was used to improve the mixing and mass transfer performance. The effects of molar ratio, temperature, sulfuric acid concentration, flow rate, and residence time on the conversion were investigated. The results showed that the residence time was significantly reduced from 4 hours in the batch reactor to 30 s in the Heart-type micromixer. The volume mass transfer coefficient and space-time yield were up to 0.031 s −1 and 16053.55 g·cm −3 ·h −1 , respectively. Meanwhile, to better understand and control the nitration reaction process, the kinetics of the nitration of trifluoromethylbenzene was reported for the first time in a capillary microreactor, and all kinetic data were obtained.
研究领域:
化学工程
·
反应工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY
·
2020
·Vol. 35
·期 7
·1405-1411
·
IF 3.498
Wen Zeng,Jing Hu,Hanjiao Chen,Zhirong Zou,Xiandeng Hou,Xiaoming Jiang
A method of cobalt ion assisted enhancement of photochemical vapor generation-atomic fluorescence spectrometry (PVG-AFS) was proposed for sensitive determination of ultratrace tellurium(IV). With a mixture of 5% (v/v) formic acid and 20% (v/v) acetic acid as the reaction medium, more than 13-fold improvement in AFS intensity for Te(IV) was achieved simply by adding 1 mg L−1 Co2+ as a homogeneous catalyst. A possible reaction mechanism was proposed with the characterization results of GC-MS and electron paramagnetic resonance (EPR). Under optimal conditions, the limit of detection (LOD) for Te(IV) was 0.06 μg L−1, with a relative standard deviation (RSD) of 1.3% (10 μg L−1 Te, 7 times). The accuracy and utility of this methodology were validated by analysis of real water samples, with satisfactory recoveries of 91–108%.
研究领域:
分析化学
·
环境科学
✓ 已验证
DOI
高影响因子
KOREAN JOURNAL OF CHEMICAL ENGINEERING
·
2022
·Vol. 39
·期 12
·3323-3333
·
IF 3.146
Liu Dong-yan,Lou Wen-bo,Sun Shi-neng,Zhang Yang,Zhang Ying,Zheng Shi-li
The recovery of iron phosphate involves the addition of oxidizer to oxidize Fe 2+ in the spent LiFePO 4 (LFP) material to Fe 3+ and the agent commonly used is hydrogen peroxide (H 2 O 2 ). Nevertheless, H 2 O 2 has disadvantages of high price, easy decomposition and low utilization efficiency. In this manuscript, a facile method is proposed for efficient synergistic oxidation of Fe 2+ in spent LFP leachate with a mixture of oxygen and ozone. Specifically, we found by thermodynamic computations that the dominant oxidation groups of ozone during oxidation varied with acidity. The oxidation would produce a large number of iron-phosphate complex groups (Fe 3 H 6 (PO 4 )
3+ 4
, FeH 8 (PO 4 )
− 4
and Fe 2 HPO
4+ 4
) in the phosphorus-sulfur mixed acid system, leading to a paradoxical pH drop. The optimized conditions for H 2 O 2 oxidation were explored. It was determined experimentally that oxidation by gas mixture and O 2 belonged to the firstorder and second-order reactions with activation energies of 28.68 kJ/mol and 34.61 kJ/mol, respectively, which were both controlled by a mixture of chemical reaction and diffusion. The optimized oxidation method was finally determined by evaluating the cost and oxidation rate of the oxidizers. The results in this study offer a promising method for new low-cost and efficient Fe 2+ oxidation for industrial production.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2023
·Vol. 13
·期 24
·16536-16548
·
IF 3.9
Hai-Yang Zhu,Ying-Hui Liu,Hai-Yun Sun,Dan-Dan Cao,Yu-Chuan Li,Si-Ping Pang
The development of environment-friendly and non-toxic green energetic materials and their safe, environmentally friendly, and economical production is very important to the national economy and national security. As an innovative, efficient, and environmentally friendly energetic material, the preferred preparation method of ammonium dinitramide (ADN) is the nitro-sulfur mixed acid method, which has the advantages of high yield, simple method, and easy access to raw materials. However, the large number of inorganic salt ions introduced by this method limits the large-scale production of ADN. Nanofiltration (NF) has been widely used in various industrial processes as a separation method with high separation efficiency and simple operation. In this study, NF was used for the desalination and purification of ADN synthesized by the mixed acid method. The effects of NF types, operation process (pressure, temperature, and feed solution concentration) on desalination efficiency, and membrane flux during purification were examined. The results showed that 600D NF could achieve the efficient desalination and purification of ADN. It was verified that the highest desalination and purification efficiency was achieved at 2 MPa pressure, 25 °C, and 1 time dilution of the feed solution, and the membrane flux of the desalination and purification process was stable. Under the optimized process conditions, the removal rate of inorganic salts and other impurities reached 99% (which can be recycled), the purity of ADN reached 99.8%, and the recovery rate reached 99%. This process has the potential for the large-scale production of ADN and provides a new process for the safe, efficient, and cheap preparation of energetic materials.
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 Composites Science
·
2023
·Vol. 7
·期 6
·231
·
IF 3.3
Yongbo Wang,Hui Li,Bowen Cui,Xiaodan Xu,Yanxiang Wang
Flexible supercapacitors are demanded for energy storage of wearable electronics. In this paper, a simple strategy for preparing flexible carbon fibers (CFs) with good energy storage capacity using a mixed acid treatment process is reported. When the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1, the carbon fiber electrodes have the best electrochemical performance with a high capacitance of 27.83 F g−1at 15 mA g−1and extremely high capacitance retention of 79.9% after 500 cycles at 100 mA g−1. Furthermore, their energy density can reach 3.86 Wh kg−1with a power density of 7.5 W kg−1. Such an excellent electrochemical performance of carbon fiber electrodes is attributed to their surface rich oxygen-containing functional groups, rough surface, and a certain number of graphene quantum dots (GQDs). Importantly, the all-solid-state flexible supercapacitor performs excellent bending stability performance with a capacitance retention of almost 100% after 500 times of bending at 180°, showing good prospects and applications in the field of flexible energy storage devices.Keywords:carbon fibers;mixed acid treatment;oxygen-containing functional groups;electrochemical test;flexible supercapacitor
研究领域:
材料科学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE
·
2021
·Vol. 102
·期 7
·2826-2834
·
IF 3.639
Sibo Zhao,Xuezheng Huang,Zhenli Yan,Chun Chang,Guizhuan Xu,Chaojun Du,Youzhou Jiao,Zhiyong Chen
BACKGROUND Environmental concerns and the diminishing availability of unrenewable resources have spurred research into the use of agricultural waste as a feedstock for industrial applications. Efficient conversion of wheat straw into biobased chemicals is an important way to realize the potential value of renewable agricultural biomass. This study investigated one-pot conversion of wheat straw into two notable platform chemicals, levulinic acid (LA) and methyl levulinate (ML). RESULTS A mixed acid catalyst system, including 1% H 2 SO 4 and 0.015 mol L –1 Al 2 (SO 4 ) 3 , was an efficient catalyst for the conversion of wheat straw due to the combination of Brønsted acid and Lewis acid. A ratio of wheat straw to methanol of 5 g/50 mL was identified as the preferred solid/liquid ratio, and a methanol/H 2 O medium with 25% water content aided the simultaneous production of LA and ML from wheat straw. Under optimum conditions, the maximum total yield of LA and ML reached 23.01% at 220 °C and 3 h. The kinetics of biobased chemical formation and the reaction pathways in methanol/water were investigated. CONCLUSION The presence of water in the methanol/H 2 O medium affected the distribution of products and promoted hydrolysis reactions. The methanol/H 2 O medium not only inhibited the side reactions but also promoted the degradation of wheat straw and increased the total yield of LA and ML. This study provides a feasible method for the conversion of wheat straw to prepare biobased chemicals. © 2021 Society of Chemical Industry.
研究领域:
生物化学
·
可再生资源工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）