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Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content on

《化学科学与工程前沿（英文）》 2023年 第17卷 第10期   页码 1484-1502 doi: 10.1007/s11705-023-2331-y

摘要： Various hydrophilic poly(ethylene-co-vinyl alcohol) (EVOH) were used herein to precisely control the structure and hydrodynamic properties of polysulfone (PSF) membranes. Particularly, to prepare pristine PSF and PSF/EVOH blends with increasing vinyl alcohol (VOH: 73%, 68%, 56%), the non-solvent-induced phase separation (NIPS) technique was used. Polyethylene glycol was used as a compatibilizer and as a porogen in N,N-dimethylacetamide. Rheological and ultrasonic separation kinetic measurements were also carried out to develop an ultrafiltration membrane mechanism. The extracted membrane properties and filtration capabilities were systematically compared to the proposed mechanism. Accordingly, the addition of EVOH led to an increase in the rheology of the dopes. The resulting membranes exhibited a microporous structure, while the finger-like structures became more evident with increasing VOH content. The PSF/EVOH behavior was changed from immediate to delayed segregation due to a change in the hydrodynamic kinetics. Interestingly, the PSF/EVOH32 membranes showed high hydrophilicity and achieved a pure water permeability of 264 L·m–2·h–1·bar–1, which was higher than that of pure PSF membranes (171 L·m–2·h–1·bar–1). In addition, PSF/EVOH32 rejected bovine serum albumin at a high rate (> 90%) and achieved a significant restoration of permeability. Finally, from the thermodynamic and hydrodynamic results, valuable insights into the selection of hydrophilic copolymers were provided to tailor the membrane structure while improving both the permeability and antifouling performance.

关键词： polysulfone     blend modification     ultrafiltration membrane     formation hydrodynamics     poly(ethylene-co-vinyl alcohol) copolymer    

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Influence of accelerated curing on the compressive strength of polymer-modified concrete

Izhar AHMAD; Kashif Ali KHAN; Tahir AHMAD; Muhammad ALAM; Muhammad Tariq BASHIR

《结构与土木工程前沿（英文）》 2022年 第16卷 第5期   页码 589-599 doi: 10.1007/s11709-022-0789-1

摘要： In recent building practice, rapid construction is one of the principal requisites. Furthermore, in designing concrete structures, compressive strength is the most significant of all parameters. While 3-d and 7-d compressive strength reflects the strengths at early phases, the ultimate strength is paramount. An effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate (EVA) at the later phases. Kolmogorov-Smirnov (KS) goodness-of-fit test was used to examine distribution of the data. The compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28, 56, 90, 120, 210, and 365 d. An accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression fit. Based on the results of KS goodness-of-fit test, it was concluded that KS test statistics value (D) in each case was lower than the critical value 0.521 for a significance level of 0.05, which demonstrated that the data was normally distributed. Based on the results of compressive strength test, it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16% concentration. Furthermore, it was concluded that predicted compressive strength values lies within a 6% difference from the actual strength values for all the mixes, which indicates the practicability of the regression equations. This research work may help in understanding the role of EVA as a viable material in polymer-based cement composites.

关键词： compressive strength prediction     polymer-modified concrete     linear regression fit     early age strength     ethylene vinyl acetate    

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Insight of chemical environmental risk and its management from the vinyl chloride accident

《环境科学与工程前沿（英文）》 2023年 第17卷 第4期 doi: 10.1007/s11783-023-1652-x

摘要： The combustion of vinyl chloride (VC) after the train derailment accident in Ohio, USA in February, 2023 has caused widespread concern around the world. This paper tried to analyze several issues concerning the accident, including the appropriateness of the VC combustion in the emergency response in this accident, the meanings of so-called “controlled combustion”, the potential environmental risks caused by VC and combustion by-products, and follow-up work. In our view, this accident had surely caused environmental and health risks to some extent. Hence, a comprehensive environmental risk assessment is necessary, and then the site with risk should be comprehensively remediated, hazardous waste should be harmlessly treated as soon as possible. Finally, this accident suggests that further efforts should be taken to bridge the gap between chemical safety management and their environmental risk management.

关键词： Vinyl chloride     Combustion     Chemical safety management     Environmental risk     Emerging contaminants    

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Molecular diffusion in ternary poly(vinyl alcohol) solutions

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 1003-1016 doi: 10.1007/s11705-021-2121-3

摘要： The diffusion kinetics of a molecular probe—rhodamine B—in ternary aqueous solutions containing poly(vinyl alcohol), glycerol, and surfactants was investigated using fluorescence correlation spectroscopy and dynamic light scattering. We show that the diffusion characteristics of rhodamine B in such complex systems is determined by a synergistic effect of molecular crowding and intermolecular interactions between chemical species. The presence of glycerol has no noticeable impact on rhodamine B diffusion at low concentration, but significantly slows down the diffusion of rhodamine B above 3.9% (w/v) due to a dominating steric inhibition effect. Furthermore, introducing surfactants (cationic/nonionic/anionic) to the system results in a decreased diffusion coefficient of the molecular probe. In solutions containing nonionic surfactant, this can be explained by an increased crowding effect. For ternary poly(vinyl alcohol) solutions containing cationic or anionic surfactant, surfactant–polymer and surfactant–rhodamine B interactions alongside the crowding effect of the molecules slow down the overall diffusivity of rhodamine B. The results advance our insight of molecular migration in a broad range of industrial complex formulations that incorporate multiple compounds, and highlight the importance of selecting the appropriate additives and surfactants in formulated products.

关键词： fluorescence correlation spectroscopy     poly(vinyl alcohol)     anomalous diffusion     crowding effects     dynamic light scattering     binding effects     rhodamine B    

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Catalysis of semihydrogenation of acetylene to ethylene: current trends, challenges, and outlook

《化学科学与工程前沿（英文）》 2022年 第16卷 第7期   页码 1031-1059 doi: 10.1007/s11705-021-2113-3

摘要： Ethylene is an important feedstock for various industrial processes, particularly in the polymer industry. Unfortunately, during naphtha cracking to produce ethylene, there are instances of acetylene presence in the product stream, which poisons the Ziegler–Natta polymerization catalysts. Thus, appropriate process modification, optimization, and in particular, catalyst design are essential to ensure the production of highly pure ethylene that is suitable as a feedstock in polymerization reactions. Accordingly, carefully selected process parameters and the application of various catalyst systems have been optimized for this purpose. This review provides a holistic view of the recent reports on the selective hydrogenation of acetylene. Previously published reviews were limited to Pd catalysts. However, effective new metal and non-metal catalysts have been explored for selective acetylene hydrogenation. Updates on this recent progress and more comprehensive computational studies that are now available for the reaction are described herein. In addition to the favored Pd catalysts, other catalyst systems including mono, bimetallic, trimetallic, and ionic catalysts are presented. The specific role(s) that each process parameter plays to achieve high acetylene conversion and ethylene selectivity is discussed. Attempts have been made to elucidate the possible catalyst deactivation mechanisms involved in the reaction. Extensive reports suggest that acetylene adsorption occurs through an active single-site mechanism rather than via dual active sites. An increase in the reaction temperature affords high acetylene conversion and ethylene selectivity to obtain reactant streams free of ethylene. Conflicting findings to this trend have reported the presence of ethylene in the feed stream. This review will serve as a useful resource of condensed information for researchers in the field of acetylene-selective hydrogenation.

关键词： selectivity     hydrogenation     acetylene     ethylene     palladium    

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Electricity-driven ammonia oxidation and acetate production in microbial electrosynthesis systems

《环境科学与工程前沿（英文）》 2022年 第16卷 第4期 doi: 10.1007/s11783-021-1476-5

摘要：

• MES was constructed for simultaneous ammonia removal and acetate production.

关键词： Biocathode     Carbon dioxide     Electrochemical oxidation     Graphite anode     Boron-doped diamond    

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Durable and recyclable BiOBr/silk fibroin-cellulose acetate composite film for efficient photodegradation

《化学科学与工程前沿（英文）》 2023年 第17卷 第11期   页码 1765-1775 doi: 10.1007/s11705-023-2323-y

摘要： A stable and recyclable of BiOBr/silk fibroin-cellulose acetate composite film was prepared by blending-wet phase transformation and in situ precipitate technology. The cellulose acetate film modified by silk fibroin formed a finger-shaped porous structure, which provided a large space for the uniform growth of BiOBr nanosheets and facilitated the shuttle flow of dyes in film. The morphology, phase structure, and optical properties of the composite films were characterized using various techniques, and their photocatalytic performance for dye wastewater was evaluated under visible light irradiation. Results showed that the BiOBr/SF-CA composite film exhibited efficient photocatalytic activity with 99.9% of rhodamine B degradation rate. Moreover, the composite film maintained high catalytic stability because Bi as the active species deposited on the film showed almost no loss. Finally, the possible photocatalytic mechanisms in the BiOBr/SF-CA composite film were speculated through radical-trapping experiments and electron spin resonance testing.

关键词： BiOBr nanosheet     cellulose acetate     silk fibroin     photocatalytic degradation     dye wastewater    

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Gas phase ethylene polymerization over SiO

Liuzhong LI, Aiyou HAO, Ruihua CHENG, Boping LIU

《化学科学与工程前沿（英文）》 2011年 第5卷 第1期   页码 89-95 doi: 10.1007/s11705-010-0558-x

摘要： Although an important industrial catalyst for producing high density polyethylene, the SiO -supported organosilyl chromate UCC S-2 catalyst has not been fully investigated compared with the SiO -supported oxo chromium Phillips catalyst. In this work, gas phase ethylene polymerization by S-2 catalysts (Cat-1, Cat-2, and Cat-3) was carried out in a high-speed stirred-autoclave reactor. The effects of temperature, time, and pressure on kinetics, activity, and product properties were studied. All kinetics were typical built-up types with slow decay. Compared to the simple physical mixtures of Cat-1 and Cat-2, Cat-3 showed higher activity and its product had a broader molecular weight distribution, indicating new active species induced during blending of Cat-1 and Cat-2 in -hexane. The innovation by a simple catalyst technology created a new application to meet market demands.

关键词： UCC S-2 catalyst     Al-alkyl co-catalyst     gas-phase ethylene polymerization     high density polyethylene    

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Progress on cleaner production of vinyl chloride monomers over non-mercury catalysts

Jinli ZHANG, Nan LIU, Wei LI, Bin DAI

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 514-520 doi: 10.1007/s11705-011-1114-z

摘要： Polyvinyl chloride (PVC) has become the third most used plastic after polyethylene and polypropylene and the worldwide demand continues to increase. Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM), which is manufactured industrially via the dehydrochlorination of dichloroethane or the hydrochlorination of acetylene. Currently PVC production through the acetylene hydrochlorination method accounts for about 70% of the total PVC production capacity in China. However, the industrial production of VCM utilizes a mercuric chloride catalyst to promote the reaction of acetylene and hydrogen chloride. During the hydrochlorination, the highly toxic mercuric chloride tends to sublime, resulting in the deactivation of the catalyst and also in severe environmental pollution problems. Hence, for China, it is necessary to explore environmental friendly non-mercury catalysts for acetylene hydrochlorination as well as high efficiency novel reactors, with the aim of sustainable PVC production via the acetylene-based method. This paper presents a review of non-mercury heterogeneous and homogeneous catalysts as well as reactor designs, and recommends future work for developing cleaner processes to produce VCM over non-mercury catalysts with high activity and long stability.

关键词： polyvinyl chloride     vinyl chloride monomer     acetylene hydrochlorination     non-mercury catalysts     green chemical process    

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Toughening of vinyl ester resins by two-dimensional MXene nanosheets

《化学科学与工程前沿（英文）》   页码 1651-1658 doi: 10.1007/s11705-022-2208-5

摘要： Two-dimensional nanosheets are highly effective tougheners for vinyl ester resins. The toughening effect is related to the high specific surface area and unique two-dimensional planar structure of the nanosheets. In this study, a coupling agent γ-(2,3-epoxypropoxy) propytrimethoxysilane (Kh-560) was used to modify MXene nanosheets (M-MXene) for use in toughening vinyl ester resin. The mechanical properties, including the tensile strength, flexural strength, Young’s modulus and elongation, of neat vinyl ester resin and vinyl ester resin modified with MXene and M-MXene were investigated. The results showed that modification significantly improved the mechanical properties of the vinyl ester resin. The tensile and flexural strengths of the MXene-nanosheet-modified vinyl ester resin were 27.20% and 25.32% higher, respectively, than those of the neat vinyl ester resin. The coupling agent improved the interfacial compatibility between the MXene nanosheets and vinyl ester resin, which resulted in the tensile and flexural strengths of the M-MXene-nanosheet-modified vinyl ester resin being 52.57% and 54.60% higher, respectively, than those of the neat vinyl ester resin for a loading quantity of nanosheets of only 0.04 wt %, which is economically viable. The main mechanisms by which the nanosheets toughen the resin are crack deflection and crack pinning.

关键词： MXene nanosheets     2D material     vinyl ester resin     modification     coupling agent    

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Methyl acetate–methanol mixture separation by extractive distillation: Economic aspects

Elena Graczová, Branislav Šulgan, Samuel Barabas, Pavol Steltenpohl

《化学科学与工程前沿（英文）》 2018年 第12卷 第4期   页码 670-682 doi: 10.1007/s11705-018-1769-9

摘要：

Methyl acetate is considered low toxicity volatile solvent produced either as a by-product during methanol carbonylation or via acetic acid esterification with methanol. In both cases, pure methyl acetate has to be isolated from the reaction mixture. Simulation of methyl acetate separation from its mixture with methanol by extraction distillation was carried out in ASPEN+ software. In total three case studies were assumed using two different extraction solvents and two solvent regeneration strategies. In case A, novel extraction solvent 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid, was considered. Raw material separation was achieved in an extraction distillation column while the solvent regeneration was accomplished in a second distillation column in this case. In case study B, the same extraction solvent was used; however, its regeneration was carried out in a single-effect evaporator. Dimethyl sulfoxide was the second extraction solvent selected. Its use in methyl acetate-methanol separation is presented in case study C. As high purity of dimethyl sulfoxide was required for the methyl acetate-methanol azeotrope breaking, its regeneration was carried out in the second distillation column only. To simulate the ternary methyl acetate–methanol–extraction solvent mixtures separation, vapor–liquid equilibrium was predicted based on the NRTL equation. Further, unknown properties of the considered ionic liquid and variation of these properties with temperature were predicted and introduced into the ASPEN+ components properties database. Based on these data, optimum operation parameters of the respective separation equipment were established. In all case studies, the same condition had to be fulfilled, namely minimum methyl acetate content in the distillate from the extraction distillation column of 99.5mol-%. Results of simulations using the respective optimum operation parameters were employed in the economic evaluation of the three separation unit designs studied. It was found that the least energy-demanding design corresponds to the case study B in terms of both capital as well as operation expenses.

关键词： methyl acetate     1-ethyl-3-methylimidazolium trifluoromethanesulfonate     extraction distillation     dimethyl sulfoxide     economic evaluation    

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聚乙烯吡咯烷酮/聚(乙烯-乙烯醇)共混膜的制备及其油水分离性能

白云翔,吴国梁,张春芳,顾瑾,孙余凭

《中国工程科学》 2014年 第16卷 第7期   页码 79-83

摘要：

将聚乙烯吡咯烷酮（PVP）与聚(乙烯-乙烯醇)（EVAL）共混，采用浸没沉淀法制备了PVP/EVAL共混膜，并用于油水乳液分离过程。通过全反射红外光谱、扫描电子显微镜、拉伸试验、接触角测试等对膜的组成、结构形态、机械性能、亲水性进行了表征，并研究了PVP添加量对共混膜油水分离性能的影响。结果表明：添加PVP能较显著地改变EVAL膜的结构，且共混膜的机械强度和亲水性得到明显改善，当PVP添加量为10 wt%（PVP在铸膜液中的质量分数）时，其拉伸强度和断裂伸长率分别为纯EVAL膜的1.88 倍和1.34 倍。当PVP 添加量为4 wt%时，油水分离稳定通量为纯EVAL 膜的1.81 倍，截留率为92.2 %，比纯EVAL 膜略高。PVP 添加量为10 wt%的PVP/EVAL 共混膜清洗后通量恢复率由纯EVAL 膜的51 %增至77.98 %。

关键词： 聚乙烯吡咯烷酮     聚(乙烯-乙烯醇)     共混膜     油水分离     浸没沉淀    

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Optimization and simultaneous heat integration design of a coal-based ethylene glycol refining process

《化学科学与工程前沿（英文）》 2023年 第17卷 第9期   页码 1280-1288 doi: 10.1007/s11705-023-2301-4

摘要： Coal to ethylene glycol still lacks algorithm optimization achievements for distillation sequencing due to high-dimension and strong nonconvexity characteristics, although there are numerous reports on horizontal comparisons and process revamping. This scenario triggers the navigation in this paper into the simultaneous optimization of parameters and heat integration of the coal to ethylene glycol distillation scheme and double-effect superstructure by the self-adapting dynamic differential evolution algorithm. To mitigate the influence of the strong nonconvexity, a redistribution strategy is adopted that forcibly expands the population search domain by exerting external influence and then shrinks it again to judge the global optimal solution. After two redistributive operations under the parallel framework, the total annual cost and CO2 emissions are 0.61%/1.85% better for the optimized process and 3.74%/14.84% better for the superstructure than the sequential optimization. However, the thermodynamic efficiency of sequential optimization is 11.63% and 10.34% higher than that of simultaneous optimization. This study discloses the unexpected great energy-saving potential for the coal to ethylene glycol process that has long been unknown, as well as the strong ability of the self-adapting dynamic differential evolution algorithm to optimize processes described by the high-dimensional mathematical model.

关键词： ethylene glycol     redistribution     heat integration     optimization     parallel framework    

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Thermodynamic analysis of ethanol synthesis from hydration of ethylene coupled with a sequential reaction

Jie Gao, Zhikai Li, Mei Dong, Weibin Fan, Jianguo Wang

《化学科学与工程前沿（英文）》 2020年 第14卷 第5期   页码 847-856 doi: 10.1007/s11705-019-1848-6

摘要： Coal-based ethanol production by hydration of ethylene is limited by the low equilibrium ethylene conversion at elevated temperature. To improve ethylene conversion, coupling hydration of ethylene with a potential ethanol consumption reaction was analyzed thermodynamically. Five reactions have been attempted and compared: (1) dehydration of ethanol to ethyl ether ( ), (2) dehydrogenation of ethanol to acetaldehyde ( ), (3) esterification of acetic acid with ethanol ( ), (4) dehydrogenation of ethanol to ethyl acetate ( ), and (5) oxidative dehydrogenation of ethanol to ethyl acetate ( ). The equilibrium constants and equilibrium distributions of the coupled reactions were calculated and the effects of feed composition, temperature and pressure upon the ethylene equilibrium conversion were examined. The results show that dehydrogenation of ethanol to acetaldehyde has little effect on ethylene conversion, whereas for dehydrogenation of ethanol to acetaldehyde and ethyl acetate, ethylene conversion can be improved from 8% to 12.8% and 18.5%, respectively, under conditions of H O/C H = 2, 10 atm and 300°C. The esterification of acetic acid with ethanol can greatly enhance the ethylene conversion to 22.5%; in particular, ethylene can be actually completely converted to ethyl acetate by coupling oxidative dehydrogenation of ethanol.

关键词： ethylene     ethanol     thermodynamics     coupling    

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Catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over the

Zhidan Fu, Lisha Liu, Yong Song, Qing Ye, Shuiyuan Cheng, Tianfang Kang, Hongxing Dai

《化学科学与工程前沿（英文）》 2017年 第11卷 第2期   页码 185-196 doi: 10.1007/s11705-017-1631-5

摘要： The Pd catalyst supported on cryptomelane-type manganese oxide octahedral molecular sieve (OMS-2) were prepared. The effect of Pd loading on the catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over Pd/OMS-2 has been investigated. The results show that the Pd loading plays an important role on the physicochemical properties of the Pd/OMS-2 catalysts which outperform the Pd-free counterpart with the 0.5Pd/OMS-2 catalyst being the best. The temperature for 50% conversion was 25, 240 and 160 °C, and the temperature for 90% conversion was 55, 285 and 200 °C for oxidation of CO, toluene, and ethyl acetate, respectively. The low-temperature reducibility and high oxygen mobility of Pd/OMS-2 are the factors contributable to the excellent catalytic performance of 0.5Pd/OMS-2.

关键词： cryptomelane-type manganese oxide octahedral molecular sieve     oxygen mobility     reducibility     carbon monoxide oxidation     volatile organic compound combustion    

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标题 作者 时间 类型 操作

Uncovering the effect of poly(ethylene-co-vinyl alcohol) molecular weight and vinyl alcohol content on

期刊论文

Influence of accelerated curing on the compressive strength of polymer-modified concrete

Izhar AHMAD; Kashif Ali KHAN; Tahir AHMAD; Muhammad ALAM; Muhammad Tariq BASHIR

期刊论文

Insight of chemical environmental risk and its management from the vinyl chloride accident

期刊论文

Molecular diffusion in ternary poly(vinyl alcohol) solutions

期刊论文

Catalysis of semihydrogenation of acetylene to ethylene: current trends, challenges, and outlook

期刊论文

Electricity-driven ammonia oxidation and acetate production in microbial electrosynthesis systems

期刊论文

Durable and recyclable BiOBr/silk fibroin-cellulose acetate composite film for efficient photodegradation

期刊论文

Gas phase ethylene polymerization over SiO

Liuzhong LI, Aiyou HAO, Ruihua CHENG, Boping LIU

期刊论文

Progress on cleaner production of vinyl chloride monomers over non-mercury catalysts

Jinli ZHANG, Nan LIU, Wei LI, Bin DAI

期刊论文

Toughening of vinyl ester resins by two-dimensional MXene nanosheets

期刊论文

Methyl acetate–methanol mixture separation by extractive distillation: Economic aspects

Elena Graczová, Branislav Šulgan, Samuel Barabas, Pavol Steltenpohl

期刊论文

聚乙烯吡咯烷酮/聚(乙烯-乙烯醇)共混膜的制备及其油水分离性能

白云翔,吴国梁,张春芳,顾瑾,孙余凭

期刊论文

Optimization and simultaneous heat integration design of a coal-based ethylene glycol refining process

期刊论文

Thermodynamic analysis of ethanol synthesis from hydration of ethylene coupled with a sequential reaction

Jie Gao, Zhikai Li, Mei Dong, Weibin Fan, Jianguo Wang

期刊论文

Catalytic oxidation of carbon monoxide, toluene, and ethyl acetate over the

Zhidan Fu, Lisha Liu, Yong Song, Qing Ye, Shuiyuan Cheng, Tianfang Kang, Hongxing Dai

期刊论文