AICHE JOURNAL
·
2023
·
IF 3.7
Jingwei Zhang,Jianhong Xu,Zhuo Chen
Micro-packed beds have the advantages of excellent heat and mass transfer efficiency and high safety, which have been successfully applied to hydrogenation and oxidation reactions. The dispersion behavior of multiphase flow is closely related to mass transfer and reaction performance. However, the study of dispersion law in micro-packed beds is not sufficient. This work investigated the dispersion behavior of gas–liquid/liquid–liquid two-phase flow in micro-packed beds. The average size and distribution of droplets/bubbles were measured in different systems. Key parameters that affect the dispersion characteristics of the two phases were observed experimentally, including gas/liquid phase flow rate, size of the packing, and physical parameters of the systems. The experimental results showed that gas–liquid and liquid–liquid dispersion processes exhibited different characteristics due to the different physical parameters of liquid and gas as the dispersed phase. The fracture driving force of the gas–liquid process was mainly from the continuous liquid phase, while the fracture driving force of the liquid–liquid process came from both the dispersed phase and the continuous phase.
研究领域:
化学工程
·
传热传质学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2022
·
IF 9.965
Qingwen Dai,Jin Yan,Arman Sadeghi,Wei Huang,Xiaolei Wang,M.M. Khonsari
In this paper, we explore a concept and present the first experimental evidence to show that it is possible to form a stable liquid film and create lifting force at the interface via thermal gradient to minimize interfacial rubbing of surfaces and the associated wear. The approach is based on manipulating the flow behavior via thermocapillary, which describes how a liquid can be made to flow from warm to cold regions purely by inducing a thermal gradient. We show that liquid bridges between two parallel plates can be manipulated and stabilized under a combined effect of the thermocapillary flow and the Couette flow , which describes the motion of a viscous fluid between two parallel plates in a relative sliding motion. The equilibrium stage is confirmed under different experimental conditions of a thermal gradient, interfacial gap, liquid viscosity, and liquid bridge volume. A strategy is proposed to control liquid motion and create lifting force between two plates. A theoretical model is also presented to illustrate the principle of the equilibrium stage. Creating lifting forces at the interface offers a new thermo-hydrodynamic tool for manipulating liquids behavior. This approach has the potential for controlling liquid motion in mechanical components and nature.
研究领域:
机械工程
·
流体力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Nature Communications
·
2020
·Vol. 11
·期 1
·1-9
·
IF 12.121
Dai Qing,Liu Zhiqiang,Huang Ling,Wang Chao,Zhao Yuyue,Fu Qiang,Zheng Anmin,Zhang Huamin,Li Xianfeng
A membrane with both high ion conductivity and selectivity is critical to high power density and low-cost flow batteries, which are of great importance for the wide application of renewable energies. The trade-off between ion selectivity and conductivity is a bottleneck of ion conductive membranes. In this paper, a thin-film composite membrane with ultrathin polyamide selective layer is found to break the trade-off between ion selectivity and conductivity, and dramatically improve the power density of a flow battery. As a result, a vanadium flow battery with a thin-film composite membrane achieves energy efficiency higher than 80% at a current density of 260 mA cm −2 , which is the highest ever reported to the best of our knowledge. Combining experiments and theoretical calculation, we propose that the high performance is attributed to the proton transfer via Grotthuss mechanism and Vehicle mechanism in sub-1 nm pores of the ultrathin polyamide selective layer.
研究领域:
能量存储
·
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2023
·
IF 9.8
Wangjun Lin,Linfeng Peng,Hui Li,Tangfu Xiao,Jianqiao Wang,Nana Wang,Xiangting Zhang,Hanmo Zhang
Fe(II)-induced phase transformations of secondary iron minerals have attracted considerable attention due to their influence on antimony (Sb) mobility. However, Fe(II)-induced natural multicomponent secondary iron mineral (nmSIM) transformations and the corresponding repartitioning of Sb on nmSIM under acidic conditions upon Fe(II) exposure have not been systematically examined. Herein, we investigated the effect of Fe(II) on nmSIM mineralogy and Sb mobility in Sb(V)-bearing nmSIM at pH 3.8 and 5.6 at various Fe(II) concentrations over 15 d. The Sb(V)-bearing nmSIM phase transformation occurred under both strongly and weakly acidic conditions without Fe(II) exposure, while the presence of Fe(II) significantly intensified the transformation, and substantial amounts of intermediary minerals, including jarosite , ferrihydrite , lepidocrocite and fougerite, formed during the initial reaction stage, especially at pH 5.6. X-ray diffraction (XRD) analyses confirmed that goethite and hematite were the primary final-stage transformation products of Sb(V)-bearing nmSIM, regardless of Fe(II) exposure. Throughout the Sb(V)-bearing nmSIM transformation at pH 3.8, Sb release was inversely related to the Fe(II) concentration in the initial stage, and after maximum release was achieved, Sb was gradually repartitioned onto the nmSIM. No Sb repartitioning occurred in the absence of Fe(II) at pH 5.6, but the introduction of Fe(II) suppressed Sb release and improved Sb repartitioning on nmSIM. This transformation was conducive to Sb reimmobilization on Sb(V)-bearing nmSIM due to the structural incorporation of Sb into the highly crystalline goethite and hematite generated by the Sb(V)-bearing nmSIM transformation, and no reduction of Sb(V) occurred. These results imply that Fe(II) can trigger mineralogical changes in Sb(V)-bearing nmSIM and have important impacts on Sb partitioning under acidic conditions. These new insights are essential for assessing the mobility and availability of Sb in acid mine drainage areas.
研究领域:
环境科学
·
矿物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2018
·
IF 4.908
Hongping Quan,Langman Xing
A series of chemical products with characteristic groups in molecular structures were synthesized as novel flow improvers (FIs) for heavy asphaltenic crude oil. The rheological measurement results showed that the FI-5 could behave the better performance in improving fluidity of heavy oil than FI-2 due to the former could form stronger hydrogen bonds with asphaltene in oil, which was confirmed through Fourier transform infrared spectroscopy (FTIR) and energy of simulating studies. Furthermore, X-ray diffraction (XRD) analysis results demonstrated that two products altered asphaltene structure at different degree through hydrogen bonding interaction, and the aggregation-dispersion effect of FIs on asphaltene were respectively obtained through scanning electron microscope (SEM), which beneficially weakened the stable structure of asphaltene in the heavy crude oil system . Hence, the mechanisms were tried to propose that could explain the phenomenon in rheological measurement why FI-2 was not as good as FI-5 in improving fluidity of heavy oil. Results also indicated that the asphaltene content and aggregation structure in oils were vital parameters for its viscosity.
研究领域:
石油化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Cleaner Production
·
2022
·
IF 11.072
Tong An,Yan Qin,Hao Cheng,Jianning Wu,Weihua Su,Guihua Meng,Hongxiao Wei,Chenhui Sun,Zhiyong Liu,Xuhong Guo
Phosphorus (P) is an essential nutrient widely used in crops. Phosphate fertilizers are easily adsorbed on the soil surface, resulting in poor migration to the roots of crops, and a large amount of nutrients cannot be absorbed and utilized, resulting in waste of resources and low bioavailability . To solve the problem of insufficient mobility of phosphate fertilizer, this work uses TiO 2 -WO 3 to catalyze the oxidation and pyrolysis of lignite to synthesize small molecular humic acid , and uses small molecular humic acid to coat commercial phosphate fertilizer (MAP) to obtain a new type of phosphate fertilizer (AMAP) with good fluidity. Water contact angle was determined from initially hydrophobic (132°) to hydrophilic (76°). Humic spectroscopic ratio (E 4 /E 6 ), H/C and molecular weight distributions confirmed the effectiveness of the TiO 2 -WO 3 catalyst and the successful modification of weathered lignite. The migration characteristics of phosphorus in the soil were studied by leaching migration experiments. The results showed that the effective phosphorus content of the new coated phosphate fertilizer (AMAP) in the soil exceeded that of the commercial phosphate fertilizer (MAP) at different vertical migration distances. After 21 d of incubation at the same fertilizer level, new coated phosphate fertilizer (AMAP) of phosphate fertilizer added with different products showed elevated levels of P. Migration data indicated that the migration distance of effective phosphorus approximated the long root distance of early corn, which benefitted crop growth. The pot experiment confirmed improved corn growth and improvement in the utilization rate of phosphorus fertilizer. All in all, activated lignite (AHA) can reduce or inhibit the fixation of phosphorus nutrients in the soil, and has obvious application value for improving the efficiency of phosphate fertilizers.
研究领域:
农业科学
·
土壤学
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2024
·
IF 8.1
Yiwei Zhang,Jiewei Hu,Wenbo Song,Fasheng Zou,Jie Zhang
Polypropylene/elastomer/filler composites are one of the most commonly used materials for spray-free automotive parts to meet the requirements of lightweight. However, its application is serious affected by the flow marks on the surface. Therefore, the reduction or elimination of flow marks defect is important to improve surface quality. In this work, polyolefin elastomer was slightly crosslinked to study its effect on flow marks. The results show that the slightly crosslinking significantly increases the elasticity of elastomer, which makes the melt flow more stable. Meanwhile, the enhanced elasticity is beneficial not only to resist shear deformation of elastomer, but also to recover from deformation during injection molding. As a result, the difference of dispersed phase morphology and surface gloss is reduced, and the flow marks defect is improved. The slightly crosslinked elastomer has little effect on the processability and tensile properties of composites, while the impact properties increase marginally.
研究领域:
材料科学
·
高分子科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2019
·
IF 7.015
Qing Dai,Wenjing Lu,Yuyue Zhao,Huamin Zhang,Xiangxue Zhu,Xianfeng Li
A zeolite composite membrane (ZCM) was designed and fabricated via a simple versatile and scalable method. A thin layer of ZSM-35 flakes with pore size between hydrated protons and vanadium ions was fixed on the poly(ether-sulfone)/sulfonated poly(ether-ether-ketone) (PES/SPEEK) porous substrate by in-situ interfacial polymerization. The ZSM flake layer can perfectly separate hydrated vanadium ions and protons, therefore, show very impressive performance for vanadium flow batteries (VFBs). As a result, a VFB assembled with an optimized ZCM exhibited a columbic efficiency more than 99% and energy efficiency of over 91% at a current density of 80 mA cm -2 , which is among the highest performance ever reported. Furthermore, the energy efficiency can reach 81.6% at a very high current density of 200 mA cm -2 and keep stable for 1000 cycles at a current density of 180 mA cm -2 . This method opened a door toward the large-scale production of highly selective composite membranes for flow batteries.
研究领域:
材料科学
·
能源技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2023
·Vol. 140
·期 10
·e53587
·
IF 3
Mingfu Zheng,Mengdi Chen,Lu Zhang,Wenjun Peng,Xian-Ming Zhang,Wenxing Chen
The melt fluidity of polycarbonate (PC) significantly influences the processing, while the melt viscosity depends on the molecular structure. Specifically, the melt viscosity increases sharply with the increase of polymerization degree. However, the influence mechanism of alkali metal catalysts on the fluidity by affecting the molecular structure remains unclear. Herein, high and low concentrations of NaOH catalysts were used to synthesize PC with different polycondensation degrees. The effect of NaOH catalyst content on the molecular structure and thus melt fluidity of PC were systematically characterized and discussed employing NMR spectroscopy, absolute and relative molecular weight, intrinsic viscosity, melt flow index, and thermal analysis. The results show that a random branched structure of the PC molecular chain caused by excess NaOH improves the melt flowability. However, the residual NaOH promotes the degradation of carbonate bonds during thermal processing, resulting in poor PC stability. Based on the above discussion, empirical fitting equations are proposed to describe the relationship between molecular structure and flow properties, which provides a new way to judge PC performance.
研究领域:
材料科学
·
高分子化学
·
化工工程
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2018
·Vol. 8
·期 6
·249
·
IF 3.465
Nani Zhou,Le Shen,Zhen Dong,Jiahong Shen,Lihua Du,Xiping Luo
The preparation of thioesters through the lipase-catalysed transesterification reaction of thiols with vinyl carboxyl esters is described. The reactions were carried out by Lipase TL IM fromThermomyces lanuginosusas a catalyst and performed under a continuous flow microreactor. We first found that lipase TL IM can be used in the reaction of thioester synthesis with high efficiency. Various reaction parameters were investigated including substrate molar ratio, reaction time, and temperature. Maximum conversion (96%) was obtained under the optimal condition of a substrate molar ratio of 1:2 (4-methylbenzyl mercaptan:vinyl esters) at 50 °C for about 30 min. Compared with other methods, the salient features of this work include mild reaction conditions (50 °C), short reaction times (30 min), high yields, and environment-friendliness.Keywords:enzymatic synthesis;thioester synthesis;flow chemistry;microreactor
研究领域:
生物化学
·
有机化学
✓ 已验证
产品关联
DOI
高影响因子
Particuology
·
2024
·
IF 4.1
Ming Zhou
This work investigates the flow and agglomeration behaviors of battery grade Li 2 CO 3 powder and the influence of stearic acid surface modification. The degree of agglomeration is directly related to the uniformity of Li 2 CO 3 and its powder mixtures. According to the Chinese National Nonferrous Metal Industry Standard, battery grade Li 2 CO 3 powder has D 50 equal to 3–8 μm which belongs to a micron-sized superfine powder. Therefore, with the extension of storage time, the serious agglomeration phenomenon occurs due to the large specific surface area and rough and irregular powder particles. The Hausner ratio (HR) of the unmodified sample increases from 1.14 to 1.41, and the corresponding flowability is classified as good to poor. Instead, among samples with doping stearic acid, the optimum amount of it is 0.10 wt% which exhibits an extremely stable HR value from 1.14 to 1.16. Meanwhile, after 156 days, the repose angle (AR) obtained for samples without surface modification and using 0.10 wt% stearic acid are calculated to be 49° and 28°, respectively. Based on the values of HR and AR, the flowability of the unmodified sample is poor while the sample modified with 0.10 wt% of stearic acid still maintain excellent powder flow property. Moreover, The LiMn 2 O 4 cathode material synthesized from modified Li 2 CO 3 powder with a stearic acid content of 0.10 wt% exhibits good crystallinity and comparable electrochemical performance to that prepared by commercial Li 2 CO 3 . These results indicate that stearic acid has the potential to be an ideal modifier for battery grade Li 2 CO 3 powder that needs to be kept for a long time.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Qiang Chen,Yujun Wang,Guangsheng Luo
Photocatalytic direct decarboxylative carbonylation of ubiquitous carboxylic acids is a promising strategy to obtain highly versatile ketone building blocks, but metal-free and efficient conversions are still lacking. Here, density functional theory calculations are used to guide the experimental screening of catalysts, highlighting the potential influence of frontier molecular orbital energy levels on the catalytic process and revealing an acridine photocatalyst capable of realizing value-added conversion of carboxylic acid at room temperature under visible light with excellent performance. The possible mechanism for this conversion was elucidated in depth by combining study of the excited state behavior of the photosensitizer and the results of detection experiments for radicals. Theoretical calculations and mechanistic studies further disclose the kinetically rate-limiting role of oxygen, including its participation in the formation of superoxide radicals for carbonylation and as an electron trapping agent for catalyst cycling. Based on these findings, a flow microreactor platform was ingeniously built to achieve previously inaccessible photocatalytic decarboxylative carbonylation promoted by acridine in concert with oxygen. Interestingly, the gas–liquid segmented microflow is found to enable a significant acceleration (from 14 to 2 h) and higher yield compared to the batch counterpart, resulting in a high space–time yield of 137.4 g/L d -1 for this transformation, which far exceeds the reported values. This study underscores the feasibility of broadening the competence of acridine photocatalysis through the involvement of kinetically adapted oxygen, thus enabling substitution of metal-dependent photocatalysis and even more efficient and high-yield decarboxylative carbonylation of carboxylic acids.
研究领域:
有机化学
·
催化化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）