COMBUSTION AND FLAME
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2023
·
IF 4.4
Bingjie Chen,Peng Liu,Bingzhi Liu,Zhandong Wang,Xiang Gao,William L. Roberts
As a representative aromatic component of practical fuels, understanding the low temperature chemistry of 1,2,4-trimethylbenzene under the reaction environment of fuel mixtures is necessary to improve the ignition and combustion process . In this work, low temperature oxidation of 1,2,4-trimethylbenzene was examined in a jet stirred reactor with reactants of n-heptane and 1,2,4-trimethybenzene in a fuel mixture (1:1 in mole, 500–800 K, ϕ = 0.5, τ = 2.0 s, p = 1 bar). Chemical species and their mole fraction evolution with reaction temperatures were recorded by the time of flight molecular beam mass spectrometer using synchrotron vacuum ultraviolet radiation as photon ionization source. Molecular structures of 56 species were identified by comparing the species ionization energies and the photonionization efficiency curves. 25 chemical formula of monocyclic oxygenated aromatics and oxygenated polycyclic aromatic hydrocarbons (OPAH) are detected, and 12 of them are identified. Some of the OPAHs are more toxic than the polycyclic aromatic hydrocarbons, indicating the importance of revealing their formation pathways in low temperature oxidation of aromatics. Numerical simulations using the latest kinetic model from Lawrence Livermore National Laboratory well predict the mole fractions of the reactants and most intermediates, but many monocyclic oxygenated aromatics and OPAHs are missing. The detection and identification of key monocyclic oxygenated aromatics (e.g., peroxides, aldehydes, dialdehydes, and ketohydroperoxides of 1,2,4-trimethylbenzene) provide important clues to unravel the low temperature oxidation pathways of alkylated aromatics like 1,2,4-trimethylbenzene. For monocyclic oxygenated aromatics and OPAHs that are missing in the kinetic model, potential formation pathways were proposed based on the molecular structure information, which might be useful for future kinetic model development.
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JOURNAL OF MEMBRANE SCIENCE
·
2023
·
IF 9.5
Zhen Wang,Runnan Zhang,Shiyu Zhang,Wenwen Li,Keda Zhi,Yanlei Su,Zhongyi Jiang
Development of high-performance nanofiltration membranes with extreme-pH stability is an urgent need for treatment of wastewater from metallurgical and paper industries. In this study, we design a kind of oil phase monomer toluene diisocyanate (TDI) and the aqueous phase monomer polyethyleneimine (PEI) to prepare polyurea nanofiltration membranes . The special bonding type and dense crosslinking structure of polyurea were used to resist the attack of extreme pH conditions. The support-free interface polymerization was employed to minimize the membrane thickness. The TDI-PEI 10000 composite membranes achieved rejection of 97.5% for MgCl 2 , with a corresponding pure water permeance of 20.0 L m -2 h -1 bar -1 . After exposure to H 2 SO 4 solution with pH=1 for 440 h or NaOH solution with pH=13 for 200 h, the MgCl 2 rejection remained above 90%. Our study provides a facile approach to constructing extreme pH-stable separation membranes .
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Ruixian Zhang,Xiuxiu Ren,Pingxiong Cai,Lei Zhong,Yanyue Lu,Zeguang Zhou
Efficient separation materials with multifunctional and switchable properties are urgently needed to treat submicron-scale oily droplets. Herein, tannic acid (TA) and polyethylenimine (PEI) were blended with poly(vinylidene fluoride) (PVDF) and used to coat a polydimethylsiloxane (PDMS)-modified non-woven fabric immersed in a CuSO 4 /H 2 O 2 coagulation bath. TA and PEI form a phenolamine hydrophilic network that migrates to the surface and firmly binds to the PVDF substrate. CuSO 4 catalyses the H 2 O 2 oxidation, promoting the self-polymerisation of phenol hydroxyl group for forming a carboxyl group. Furthermore, the remaining Cu 2+ ions complex with TA to form a metal–phenol cross-linked network. A double-cross-linked hydrophilic layer with polyphenols as connection points was formed on the PVDF surface. The hydrophilic contact angle of the membrane reached 0°. A rough structure with PDMS micro-/nanoparticles was constructed on the PVDF underside via surface nanocasting and the hydrophobic contact angle of the membranes reached 165°. In experiments, each side of the obtained Janus membranes demonstrated surface superhydrophilic and superlipophilic properties and a high flux and excellent separation efficiency for various oil–water emulsions. The integrated Janus membranes are suitable for unidirectional liquid collection, oil–water emulsion separation, cationic pigment adsorption and dealing with complex dye–emulsion pollutants. The integrated structure formed by the hydrophilic layer and the membrane enhances the fouling resistance of the membrane and the removal rate of pollutants reached >99 %. This research presents a simple approach to prepare Janus membranes with asymmetric wettability.
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Catalysts
·
2023
·Vol. 13
·期 10
·1383
·
IF 3.9
Zhen Jiang,Liduo Chen,Yanhong Cui,Huijie Gao,Yisi Zhou,Wei Zhang,Yanhua Suo,Yingjun Wang
n-Alkane hydroisomerization over bifunctional catalysts is an effective approach for clean fuel production. However, achieving metal–acid synergy and enhancing the catalytic performance by the preparation of bifunctional catalysts with suitable proximity between the metal sites and Brønsted acid sites are still challenging. In this work, a series of Pt/SAPO-11 catalysts with different Pt loading applied inn-heptane hydroisomerization was synthesized. SAPO-11 was synthesized by the Instant Exactness Synthesis (IES) method, which, with unique morphology and pore structure, was chosen as support for the hydroisomerization catalysts; Pt/SAPO-11 was synthesized with the impregnation method, Pt nanoclusters with trace loading were fabricated over the SAPO-11 support, and the as-synthesized catalysts with different Pt loading were labeled as xPt/SAPO-11 (x = 0.1, 0.3, 0.5, 0.8 and 1.0). Various characterizations, including XRD, nitrogen adsorption–desorption, SEM, TEM, NH3-TPD and XPS, were carried out on catalysts to obtain deep insights into the microstructure and valence states of xPt/SAPO-11. The catalytic performance of xPt/SAPO-11, including catalytic selectivity and conversion, was investigated in then-heptane hydroisomerization in detail. Pt loading affected the catalytic properties of xPt/SAPO-11 in the hydroisomerization ofn-heptane. The selectivity of 0.5Pt/SAPO-11 toward isomers was about 65% with a conversion of 77% at 310 °C, which was obviously higher than other xPt/SAPO-11 catalysts.
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Gels
·
2023
·Vol. 9
·期 11
·902
·
IF 4.6
Jian Li,Yaning Li,Wei Xiao,Jingyan Wang,Boliang Wang
Investigating the structural evolution of particulate gels is a very challenging task due to their vulnerability and true flow characteristics. In this work, deeper insight into the rheological properties of gel fuels filled with fumed silica (FS) and aluminum microparticles (Al MPs) was gained by changing shear procedures. Firstly, the flow curves were found to no longer follow the monotonic power law and exhibited subtle thixotropic responses. As the shear rate increased, the gel structure underwent a transition from local shear to bulk shear in the nonlinear region after yielding. This finding reveals the prevalence of nonideal local shear in industry. Secondly, the time-dependent rheological responses demonstrated that the strength spectrum of gel fuels depends on the applied shear rate, with stress relaxation more easily observed at lower shear rates. Those results involved the structural disruption, recovery, and equilibrium of particulate gels from two scales of shear rate and shear time.Keywords:gel fuels;microstructure;solid–liquid transition;thixotropy;local shear;shear history
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Journal of Industrial Textiles
·
2023
·
IF 3.2
Jiahua Gu,Huiting Wang,Xinxin Dai,Yuqi Zhu,Dongqi Lin,Siyi Liu,Xu Han,Bin Lu,Yinsong Hu,Yinjiang Zhang
The contact layer of traditional medical dressing is easy to adhere to the new wound granulation tissue, which brings the deficiency of secondary wound injury. This work assumed that low-cost and soft mesh spunlace nonwoven was used as medical dressing contact layer. After micro-nano SiO2 modification, polydimethylsiloxane (PDMS)/n-heptane were uniformly sprayed on the surface of materials. PDMS modification was studied by using the three-factor three-level orthogonal experiment. The results showed that when the PDMS concentration was 1%, the heat treatment temperature and time were 120°C and 12 h respectively, material possessed the optimal hydrophobicity and its water contact angle (CA) was 151.0 ± 1.1°. Meanwhile, the hydrophobicity, microstructure, thermogravimetry, composition, tensile mechanics, adhesion resistance and durability of materials with/without treatment were compared. It was proved that PDMS was indeed grafted onto the material and could effectively improve the hydrophobicity in coordination with micro-nano SiO2 without affecting the mesh structure of material. The machine direction (MD) and cross-machine direction (CD) strength of material decreased but the elongation increased slightly. The MD and CD peeling energy was 129.7 ± 33.9 J/m2 and 98.1 ± 38.3 J/m2, respectively. Moreover, the water CA of material modified by micro-nano SiO2/PDMS was still 139.4 ± 1.4° after 10 friction stroke tests, indicating that the modified material possessed the great durability. Overall, this study can provide the research basis for the development of anti-adhesion medical dressing contact layer.
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CHEMICAL ENGINEERING JOURNAL
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2023
·
IF 15.1
Teng Lu,Zhaomin Li,Liping Du
This study explores the combined application of hydrophobic silica aerogels and SDS to enhance CO 2 storage capacity and oil recovery. Experimental data highlighted a marked increase in CO 2 solubility within silica aerogel-SDS nanofluids compared to brine and SDS solutions. Molecular dynamics simulations revealed CO 2 adsorption into nanopores. Silica aerogel nanoparticles extended CO 2 foam half-life by 6 % versus 62 % decline for sole SDS foam from 30 to 140 °C. Adjusting the SDS to nanoparticle ratio affects foam properties, with a ratio of 1.5 yielding optimal results. Core flooding experiments demonstrated a 75 % rise in CO 2 trapping efficiency using the nanofluids over SDS solutions. Two-dimensional tests showed aerogel-SDS foam surpassed SDS foam flooding by 12 % incremental oil recovery in upper layers, attributed to enhanced profile control. The combined agents present an effective approach for geological CO 2 storage and EOR optimization.
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TALANTA
·
2023
·
IF 6.1
Yuanchao Lu,Yingcheng Tang,Ningxiang Yu,Xiaohua Nie,Xianghe Meng
Sensitively, accurately, and rapidly evaluating edible oils’ peroxide value (PV) is significant for safeguarding food quality and safety. However, the conventional detection methods are challenging to meet the above demands due to their complex operation, poor reproducibility, and professional personnel. The colorimetric method is an emerging technique to rapidly and on-site determine the PV of edible oils . CsPbBr 3 NCs, as a novel fluorescent-sensing material, have been applied in the chemical colorimetric analysis . However, the heavy use of high-toxic solvents (toluene, chloroform) in the CsPbBr 3 NCs colorimetric system significant-negatively influences the environment. This study evaluated the performances of CsPbBr 3 NCs in nine low-toxic solvents and investigated the potential response mechanism to PV. The results presented that CsPbBr 3 NCs in ethyl acetate displayed the highest photoluminescent intensity and the most uniform distribution. The results performed that the micro-morphology and crystal structure of CsPbBr 3 NCs in ethyl acetate were similar to that in toluene, demonstrating the potential excellent performance. Under optimum conditions, three methods, including photoluminescence (PL)-decreased, wavelength-shifted, and phone-based colorimetric methods, were established to evaluate PV with the LOD of 0.0034 g/100 g. The PV recovery rates in Soybean oil, Camellia oil, Linseed oil, and Olive oil were from 75.0% to 100.0%, with a relative error below 25%. Furthermore, it was believed that the decreased PL and shifted wavelength originated from the halogen substitution with the crystal-structure destructions and the surface-defect formations. Thus, developing the low-toxic colorimetric CsPbBr 3 NCs system with ethyl acetate could reduce the environmental influence and even enlighten the rise of other green detection methods for PV in edible oils.
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Journal of Water Process Engineering
·
2023
·
IF 7
Junna Yan,Mengyu Ma,Bo Zhao,Feihu Li
Excessive discharge of phosphorus (P) to natural watercourses not only causes eutrophication of water bodies but also results in the loss of P resources. P-containing wastewater is a crucial secondary P resource. Zirconium-based metal-organic frameworks (MOFs), particularly UiO-66 has been shown great promise in efficiently capturing P from water. In this study, a group of UiO-66@sponge composites was prepared by a facile layer-by-layer in-situ growth approach using melamine sponge (MS) as scaffolds. The as-prepared UiO-66@sponge composites exhibit high chemical and dimensional stability when used as adsorbents for reclaiming P from wastewater. Batch adsorption results show that one UiO-66@sponge composite exhibited the highest phosphorus adsorption capacity of 83.55 mg g −1 at pH 6.0, outperforming most other UiO-66 adsorbents under environmentally relevant conditions. The intrinsic mechanical flexibility and chemical stability of these UiO-66@sponge composites enable us to efficiently enrich phosphorus from a dilute solution by a rapid adsorption-desorption operation. This work provides a promising strategy to integrate MOFs with dimensionally stable and flexible sponges for rapid adsorption and recovery of phosphate from wastewater and could be potentially expanded to the recovery of other value-added or technology-critical elements from waste streams.
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JOURNAL OF POLYMER RESEARCH
·
2023
·Vol. 30
·期 9
·1-8
·
IF 2.8
Qiao Xiaoguang,Dong Xin,shi Ge,He Yanjie,Pang Xinchang
The postsynthesis polymeric modifications by grafting from the active sites were the primary focus of the structurally tailored and engineered macromolecular (STEM) gels. Therefore, Reversible-deactivation radical polymerization (RDRP) techniques have been employed to more precisely tailor and tune STEM gels. In contrast to atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer polymerization (RAFT), nitroxide-mediated polymerization (NMP) is known to have the advantages of simple components and pure products. Here we report the preparation of polydimethylsiloxane (PDMS) composite gel networks through oxygen tolerance NMP process, with tert-Butyl acrylate (tBA) and fluorinated monomer 2-(Perfluorooctyl)ethyl methacrylate (FMA) as functional comonomers. Compared with conventional radical polymerization (FRP) method, composite gels prepared through NMP method showed higher swelling rate and elongation at break, which proved that the network structure formed by NMP was more uniform. In addition to better thermal stability and toughness, the dormant polymer chain could be reactivated and lead to the “living” post-modification of PDMS gel matrix.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2023
·
IF 8.2
Danmin Yang,Qun Liu,Xu Zeng,Xiaoting Chen,Meng Li,Xialing Wu,Yue Liu,Yanzhen Zheng,Jionghua Xiang,Chunchun Wang,Wuyin Weng,Yucang Zhang
The cellulose nanofibers (CNFs) based pH-sensitive indicator films were developed by mixing guar gum (GG) with bromothymol blue-anchored chitin (BTB-Chitin) as an indicator to monitor shrimp freshness. The BTB-Chitin was prepared by grafting hydroxypropyltriethylamine groups (HPTA) to chitin first, then anchoring bromothymol blue (BTB) to prepare intelligent pH response BTB-Chitin. The 0.08 BTB-Chitin films had a good tensile strength of 11.76 MPa and the water contact angle values were 125°, which displayed obvious color response to pH buffers and acid base volatile gas. Besides, the homogeneous and flexible composite films showed good color stability and reversibility. The released amount of BTB was very low from the BTB-Chitin films in heptane and corn oil. The composite films had been degraded completely in 15 days in soil. The pH and volatile base nitrogen were measured to determine the degree decay of shrimp ( Litopenaeus vannamei ), and the prepared pH-sensitive films changed from yellow (fresh) to cyan (spoiled) with the freshness of shrimp decreased, indicating the BTB-Chitin films could detect the shrimp freshness in real-time and high visibility.
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FOOD RESEARCH INTERNATIONAL
·
2023
·
IF 8.1
Qiaoyu Liu,Menglin Lei,Jianjun Lin,Wenhong Zhao,Xiaofang Zeng,Weidong Bai
The roles of enzymatic (Lipoxygenases, LOX) oxidation and autoxidation in the dry-cured processing of mackerel were investigated by adding exogenous substances in this study. Four groups, namely control, chlorogenic acid (inhibiting LOX activity), EDTA-2Na (inhibiting autoxidation), and exogenous LOX (adding eLOX), were assigned. The results showed that lipid oxidation of mackerel was reduced by inhibiting LOX activity and autoxidation, while adding eLOX promoted lipid oxidation. Inhibition of LOX activity and autoxidation suppressed fatty acid accumulation mainly in the air-drying and curing stage, respectively. The total contents of key flavors in the mackerel during dry-cured processing were decreased by inhibiting LOX activity and autoxidation, and the former inhibitory effect was stronger than autoxidation, while it was corresponding increased through adding eLOX, of particular in the later stage of air-drying. Collectively, LOX could promote the flavor formation of the mackerel in the dry-cured processing, which could be applied in the flavor adjustment of aquatic products or some similar fields.
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