Photopolymerization synthesis of polyacrylic acid dispersant with methoxysilicon end groups and its application in a nano‐SiO2 aqueous system

In order to improve the dispersity and stability of the nano‐SiO₂ aqueous system with high solid content, a kind of polyacrylic acid dispersant with methoxysilicon end groups (KH590‐PAA) was synthesized by photopolymerization of acrylic acid (AA) initiated with (3‐mercaptopropyl)trimethoxysilane (KH590). After adding KH590‐PAA into the nano‐SiO₂ aqueous dispersion system (20 wt% solid content), the viscosity and the curing time of the system were measured with a rotational viscometer and the inverted bottle method. Moreover, the dispersion mechanism of KH590‐PAA for the nano‐SiO₂ aqueous system was researched by measuring the adsorption capacity, the particle size and the zeta potential of the nanoparticles with a conductivity meter, dynamic light scattering, SEM and TEM, respectively. The results showed that the methoxysilicon groups in KH590‐PAA could react with hydroxyl groups on the surface of nano‐SiO₂ in the process of stirring, which enhanced the adsorption capacity of the dispersant and then increased the surface charge of the particles. Therefore, electrostatic repulsion and steric hindrance effects between the SiO₂ nanoparticles could be further enhanced by adding the KH590‐PAA dispersant, and then the nano‐SiO₂ aqueous system exhibited better dispersity and stability. Besides, the dispersion properties of SiO₂ nanoparticles in water were closely related to the addition amount and the molecular weight of the KH590‐PAA dispersant. © 2018 Society of Chemical Industry     

Benzotriazole as inhibitor for copper with and without corrosion products in aqueous polyethylene glycol

Electrochemical methods, including polarization experiments and impedance spectroscopy, were used to evaluate the effectiveness of benzotriazole (BTA) in an aqueous solution of polyethylene glycol (PEG) in protecting polished archaeological copper or archaeological copper covered with corrosion products. The adsorption of PEG on the polished copper significantly limited the corrosion current. The presence of benzotriazole enhanced the protection of the polished copper, giving maximum protection at a concentration of 10^–2moll^–1 of BTA in 20 vol% PEG 400 solution. On the other hand, PEG solutions caused degradation of the corrosion products of the copper. This degradation increased with time. When BTA was added, the corrosion products were preserved and, the higher the BTA concentration, the more the corrosion current decreased. In PEG 400 solution protection of the corrosion products of the copper by BTA improved over time.     

无水氨基酸类离子液体-聚乙二醇混合溶剂吸收CO2的动力学

以聚乙二醇400（PEG400）为溶剂,氨基酸类离子液体（AAILs）作为化学吸收剂的混合体系具有蒸汽压极低、热稳定性好、黏度和再生能耗低、CO₂吸收量和选择性高等优点,适用于燃烧前CO₂捕集过程的高温高压吸收条件。本文采用压降法,测定了以四正丁基膦（[P₄₄₄₄]⁺）为阳离子,甘氨酸（Gly）、丙氨酸（Ala）和脯氨酸（Pro）作为阴离子的3种氨基酸类离子液体的混合溶剂体系对CO₂的吸收速率,并建立了该无水体系的CO₂吸收动力学模型。对于反应速率而言,在333.15K时,[P₄₄₄₄][Gly]-PEG400 > [P₄₄₄₄][Pro]-PEG400 > [P₄₄₄₄][Ala]-PEG400,温度升高至373.15K时,[P₄₄₄₄][Pro]-PEG400 > [P4444][Gly]-PEG400 > [P₄₄₄₄][Ala]-PEG400;根据相关吸收动力学参数,推测出CO₂在AAILs-PEG400中的反应均为快反应。通过研究其吸收动力学,获得了关键的吸收动力学数据,为后续的工业开发设计提供基础数据和设计依据。     

The effects of pH on the partitioning of aromatic acids in a polyethylene glycol/dextran aqueous biphasic system

Distribution ratios of acidic, neutral, and basic compounds were determined in polyethylene glycol (PEG)-6000/Dextran-75000 aqueous biphasic systems (ABSs) at incremental pH values. The nature of the solute species present at each pH was identified using speciation diagrams, and it was determined that the distribution ratios were related to their charge, with maximum distribution to the upper PEG-rich phase when the neutral species were dominant. The results suggest that this ABS is tunable with simple modifications of pH leading to increasing selectivity for specific target solutes.     

Dialdehyde polyethylene glycol cross-linked poly(vinyl alcohol) membranes with enhanced CO2/N2 separation performance

The development of carbon dioxide (CO₂) separation technology is crucial for mitigating global climate change and promoting sustainable development. In this study, we successfully synthesized an array of cross-linked poly(vinyl alcohol) (PVA) membranes, xALD-PEG-ALD-c-PVA, with enhanced CO₂/N₂ separation performance by employing dialdehyde polyethylene glycol (ALD-PEG-ALD) as a cross-linker. The formation of the cross-linked network structure not only inhibits the crystallization of PVA but also disrupts hydrogen bonding and thus increases fractional free volume of PVA chains. Under the synergistic effect of these multiple factors, the cross-linked PVA membranes exhibit a significantly improved CO₂ permeability. Moreover, they maintain high CO₂/N₂ selectivity, attributing to the CO₂-philic characteristic of ethylene oxide groups in the cross-linked structure. At the ALD-PEG-ALD content of 1.6 mmol g⁻¹, the xALD-PEG-ALD-c-PVA membrane demonstrates a CO₂ permeability of 41.4 barrer and a CO₂/N₂ selectivity of 57.4 at 2 bar and 25°C. Furthermore, compared with the pristine PVA membrane, xALD-PEG-ALD-c-PVA membranes manifest superior mechanical properties and outstanding separation performance for a CO₂/N₂ (15/85, vol%) gas mixture. The excellent combination of permeability and selectivity makes xALD-PEG-ALD-c-PVA membranes highly promising for various CO₂ separation applications.     

近-超临界水中Ni/ZrO2催化气化聚乙二醇水溶液的产氢特性

在连续流超临界水反应器中,以Ni/ZrO₂为催化剂,以聚乙二醇（polyethylene glycol,PEG）水溶液作为研究对象,考察了近-超临界状态下的有机质气化产氢特性。实验结果显示,PEG的气化产物主要成分为H₂、CO、CH₄和CO₂;其中,当加入90 g 15% Ni/ZrO₂时,在430℃、压力24 MPa、停留时间300 s的条件下,可以生成70.14 mmol H_2^·（g PEG）^-1,为不加入催化剂时的5.1倍,为加入90 g ZrO₂时的2.6倍,相应的TOC去除率、碳气化率和氢气化率分别达到88.84%、88.50%和169.40%;增大活性组分Ni的质量分数可以提高气化效果,在410℃、压力24 MPa、停留时间180 s的条件下,Ni质量分数从5%提高到15%时,TOC去除率、碳气化率和氢气化率分别从45.31%、44.55%和78.25%提高到58.66%、58.16%和112.49%;反应温度的上升和停留时间的延长对气化效果有正影响,明显提高H₂的摩尔产率;PEG浓度的上升可抑制水气转换反应并促进甲烷化反应的进行而导致其气化效率下降,其中,H₂产量急剧下降,CO₂产量先上升后下降,而CH₄产量随PEG浓度上升而上升。研究结果证明了所研制的Ni/ZrO₂催化剂在近-超临界水中对PEG的催化气化特别是产H₂表现出高活性,在达到相同反应效率前提条件下使反应温度降低约80℃。     

草酸二甲酯加氢合成乙二醇Cu/SiO_2催化剂的稳定性试验研究

合成气经草酸二甲酯加氢制乙二醇技术在工业应用过程中存在一些技术难题,其中草酸二甲酯加氢制乙二醇催化剂的稳定性是制约该技术发展的瓶颈。以Cu/SiO_2草酸二甲酯加氢催化剂A为研究对象,通过2 600 h的稳定性实验研究,考察反应温度对草酸二甲酯转化率、乙二醇选择性以及产物中乙醇酸甲酯含量的影响,为合成气经草酸二甲酯制乙二醇技术的工业应用优化提供重要的技术支持。结果表明,当反应压力2.8 MPa、空速(0.3~0.5)h-1、氢酯物质的量比120~140和反应温度216℃时,草酸二甲酯转化率近100%,乙二醇选择性大于95.0%,产物中乙醇酸甲酯质量分数小于0.5%,Cu/SiO_2催化剂A稳定性较好。     

Modification of polycarbonate membrane by polyethylene glycol for CO2/CH4 separation

In this study, permeation of carbon dioxide (CO₂) and methane (CH₄) through the polycarbonate/polyethylene glycol (PC/PEG) blend membrane was investigated. The effect of PEG content (0–5 wt%) on the permeability and selectivity was studied. Permeability measurements were carried out at pressures of 1–7 bar and at room temperature. The membranes were characterized by Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and density measurement. The results revealed that the PC/PEG blends are miscible/partially miscible without considerable micro-phase separation. The effect of PEG content and gas pressure on the diffusion and solubility of coefficients were also investigated and analyzed. It was concluded that the most influential parameter for the permeation is the diffusion coefficient of the gases. The permeability and selectivity decrease as the operating pressure and PEG content are increased. Furthermore, the results showed that the addition of 5 wt% of PEG into PC increases the CO₂/CH₄ selectivity from 26.6 ± 0.99 to 40.9 ± 2.14 (more than 53%) at 1 bar.     

Thickening of butyl acrylate/styrene/2-hydroxyethyl methacrylate/acrylic acid lattices with dispersion of crosslinked ethyl acrylate/methacrylic acid copolymer

Thickening of lattices of styrene–acrylic copolymers containing a small amount of acrylic acid and various amounts of 2-hydroxyethyl methacrylate (HEMA) with alkali-swellable dispersion of crosslinked ethyl acrylate/methacrylic acid copolymer has been studied using capillary viscometry and dynamic and steady shear measurements. The higher the amount of HEMA incorporated into the latex copolymers, the stronger the thickening effect is. A comparison of flow behavior of thickened systems with those of neat lattices confirmed a significant influence of the effective volume fraction of alkalinized swollen latex particles on the thickening process. Under these conditions, to obtain the same rheological properties, the necessary amount of thickener was lower for the latex copolymers with higher amounts of HEMA because a part of the thickener volume fraction was replaced by an increased volume fraction of swollen latex particles. These findings indicate weakly interacting dispersion systems without strong compression of particle domains.     

Methoxy poly(ethylene glycol)‐block‐poly(D,L‐lactic acid) copolymer nanoparticles as carriers for transdermal drug delivery

This work evaluates the transdermal drug delivery properties of amphiphilic copolymer self‐assembled nanoparticles by skin penetration experiments in vitro. Paclitaxel‐loaded methoxy poly(ethylene glycol)‐block‐poly(D ,L ‐lactic acid) diblock copolymer nanoparticles (PNPs) were prepared by a solid dispersion technique and were applied to the surface of excised full‐thickness rat skin in Franz diffusion cells. HPLC, transmission electron microscopy, Fourier transform infrared spectroscopy and ¹H NMR were used to assay the receptor fluid. The results show that the amphiphilic copolymer nanoparticles with the entrapped paclitaxel are able to penetrate rat skin. Ethanol can improve the delivery of PNPs and increase the cumulative amount of paclitaxel in the receptor fluid by 3 times. Fluorescence microscopy measurements indicate that the PNPs can penetrate the skin not only via appendage routes including sweat ducts and hair follicles but also via epidermal routes. Copyright © 2007 Society of Chemical Industry     

Pd nanoparticles supported on carbon-modified rutile TiO2 as a highly efficient catalyst for formic acid electrooxidation

In this article, Pd nanoparticles supported on carbon-modified rutile TiO₂ (CMRT) as a highly efficient catalyst for formic acid electrooxidation were investigated. Pd/CMRT catalyst was synthesized by using liquid phase reduction method in which Pd nanoparticles was loaded on the surface of CMRT obtained through a chemical vapor deposition (CVD) process. Pd/CMRT shows three times the catalytic activity of Pd/C, as well as better catalytic stability towards formic acid electrooxidation. The enhanced catalytic property of Pd/CMRT mainly arises from the improved electronic conductivity of carbon-modified rutile TiO₂, the dilated lattice constant of Pd nanoparticles, an increasing of surface steps and kinks in the microstructure of Pd nanoparticles and slightly better tolerance to the adsorption of poisonous intermediates.     

Fischer–Tropsch synthesis with promoted iron catalyst: Reaction pathways for acetic acid, glycol, 2-ethoxyethanol and 1,2-diethoxyethane

Reaction pathways for oxygenates, acetic acid, ethylene glycol (EG), 2-ethoxyethanol (2-EE) and 1,2-diethoxyethane (1,2-DEE) added during Fischer–Tropsch synthesis (FTS) over a doubly promoted fused iron catalysts were studied. The addition of acetic acid, EG and 2-EE affected only slightly the CO conversion but resulted in a significant reduction in H₂ conversion while addition of 1,2-DEE results in slight increase in both H₂ and CO conversion. Addition of these oxygenates caused a large decrease in the alkene ratio for C₂ hydrocarbons as compared to an increase for the C₃ and C₄ hydrocarbons suggesting a direct formation pathway of ethane from added oxygenate molecules. The 1-alkene/2-alkene fraction was found to increase significantly when these oxygenates were added and then return to the original value once the addition is terminated, indicating inhibition of secondary reactions of 1-alkene by added oxygenates. Added acetic acid reversibly increased the CO₂ production rate while EG, 2-EE and 1,2-DEE reversibly decreased the CO₂ selectivity. Addition of these oxygenates reduced the production rate of methane. Addition of acetic acid and 1,2-DEE decreased methanol selectivity significantly while added EG results in a significant increase in methanol production. In the case of 2-EE addition, methanol selectivity was nearly constant. Reaction of acetic acid during FTS was found to produce products such as ethyl butanoate, ethylene glycol and its ether, 1,2-diethoxyethane, which are not generally observed in the normal FTS product spectrum. Addition of EG results in a significant increase in the production rate of 1,2-DEE only and no measurable amount of 2-EE was found. While addition of 2-EE caused a significant increase in the production rate of glycol, the addition of 1,2-DEE indicated a significant increase in 2-EE production rate without any measurable change in EG selectivity. The results suggest that acetic acid undergoes some CC bond rupture while 2-EE and 1,2-DEE undergoes cleavage of the ether linkage (COC bond). On the contrary, EG undergoes fast and equally probable COC chain growth in both terminal positions. The results indicate that neither of these oxygenates is a significant intermediate in FTS with an iron catalyst. Product distribution in most of the oxygenate compounds are consistent with hydrogenation of the added oxygenate to acetaldehyde and/or ethanol as primary products followed by secondary reaction of these two primary oxygenate products.     

Micro/nanostructured Bi2Mn4O10 with hierarchical spindle morphology as a highly efficient anode material for lithium-ion batteries

Mullite-type compound Bi₂Mn₄O₁₀ has shown the feasibility as anodes of next lithium-ion batteries (LIBs). Herein micro/nano-Bi₂Mn₄O₁₀ with hierarchical spindle-like architectures has been successfully synthesized using a one-step hydrothermal method without any no surfactant or template. A time-dependent experiment is carried out to observe the morphology evolution, suggesting a nucleation–aggregation/growth–dissolution–recrystallization process. As anode of LIBs, the as-prepared spindle-shaped micro/nano Bi₂Mn₄O₁₀ harvests a significantly high initial discharge capacity of 1022 mA h g⁻¹ at 1 C, an excellent cyclability performance (563.8 mA h g⁻¹ after 400 cycles), a better high-rate capability (100 mA h g⁻¹ at 10 C), quick diffusion kinetics (1.8 × 10⁻¹² cm² s⁻¹), and low active energy (19.5 kJ mol⁻¹), which are significantly superior to that of its bulk counterparts and the previous reports. The encouraging lithium storage performance largely stems from the synergistic effect of the unique spindle-shaped micro/nanostructure.