JOURNAL OF MEMBRANE SCIENCE
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2015
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IF 5.056
Xueqin Li,Zhongyi Jiang,Yingzhen Wu,Haiyang Zhang,Youdong Cheng,Ruili Guo,Hong Wu
Composite membranes were fabricated by incorporating carboxylic acid nanogels (CANs) into a Pebax MH 1657 matrix for potential applications in CO 2 /CH 4 (or N 2 ) separation. CANs were synthesized by precipitation polymerization of N-isopropylacrylamide (NIPAM), acrylic acid (AA) monomer and N,N′-methylenebisacrylamide (BIS) crosslinker. The incorporation of CANs simultaneously tailored favorable water environment and increased CO 2 transport sites within the membranes. With increasing CANs loading, the homogeneously dispersed CANs in the Pebax matrix offered more favorable water environment and the additional carboxyl group sites for efficient CO 2 transport, thus constructing interconnected preferential CO 2 transport passageways. The Pebax-CANs-30 composite membrane exhibited the highest gas separation performance, with the CO 2 /CH 4 and CO 2 /N 2 selectivities of 33 and 85 respectively, and a CO 2 permeability of 2026 Barrer (1 Barrer=10 −10 cm 3 (STP) cm/(cm 2 s cmHg), well surpassing the Robeson's upper bound limit reported in 2008. This effort will give rise to a new option to tailor water environment and increase CO 2 transport sites for fabricating high-performance CO 2 separation membranes .
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JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
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2014
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IF 2.063
Yan Cao,Yunxia Zhao,Zijian Lv,Fujiao Song,Qin Zhong
New composites of UiO-66 and graphene oxide (GO) were synthesized and tested as CO 2 adsorbents at room temperature. The materials and the parent composite components were characterized using X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), nitrogen adsorption–desorption isotherm analysis, scanning electron microscopy (SEM), and FT-IR spectroscopy. The CO 2 isotherms on the UiO-66/GO composites and the UiO-66 were measured by a static volumetric method separately. Experiments of multiple adsorption/desorption cycles were conducted to estimate reversibility of CO 2 on the UiO-66/GO. The results showed that the BET surface area of the composites was higher than that of the parent UiO-66, and the adsorption capacities of CO 2 on the composites were greatly higher than that on the UiO-66 sample. The composite UiO-66/GO-5 exhibited the maximum CO 2 uptake of 3.37 mmol/g at 298 K and 1 bar, which increased by 48% in comparison with that of the UiO-66, and was much higher than those of the conventional activated carbons and the zeolites. The CO 2 adsorption capacity was dependent on the BET surface area and the micropore volume of the composites. Finally, the adsorption/desorption cycle experiment revealed that the adsorption performance of UiO-66/GO-5 was fairly stable, without noticeable degradation in the adsorption capacity of CO 2 after 6 cycles. Therefore, this kind of composites has a potential application on CO 2 capture technologies to mitigate global warming.
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CATALYSIS TODAY
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2015
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IF 3.893
Xiao-Fang Liu,Qing-Wen Song,Shuai Zhang,Liang-Nian He
Carboxyl-containing organocatalysts, e.g. EDTA (ethylenediaminetetraacetic acid) in combination with nucleophilic halide such as n Bu 4 NBr were demonstrated to be efficient catalyst systems for the synthesis of cyclic carbonates from CO 2 and a broad range of epoxides in excellent yield and selectivity. Thanks to synergistic effects of carboxylic groups and bromide anion, the cycloaddition reaction proceeded smoothly at 5 bar CO 2 under mild reaction conditions. Interaction of carboxylic groups in EDTA with the epoxide via hydrogen bonding presumably facilitates the ring-opening of the epoxide by the nucleophile e.g. bromide. In particular, multiple carboxylic groups in one molecule i.e. EDTA could more effectively activate the epoxide and stabilize the alkoxide intermediate through multi-site hydrogen bonding in comparison with monocarboxylic acid. Moreover, the carboxylic acid like EDTA used in this study represents a cheap, commercially available, environmentally benign, metal-free catalyst for CO 2 conversion. Thus, this catalytic protocol could have potential application for catalytic fixation of CO 2 into value-added chemicals.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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2015
·Vol. 17
·期 15
·10080-10085
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IF 4.493
Zhaoming Liu,Yadong Hu,Hongqing Zhao,Yang Wang,Xurong Xu,Haihua Pan,Ruikang Tang
Living organisms such as corals can carry out CO2 looping efficiently via biomineralization under ambient conditions. Inspired by this natural process, we establish a solution system of calcium acetate–ethanol–water (Ca(Ac)2–C2H5OH–H2O) for CO2 chemical looping at constant room temperature. The CO2 capture is achieved by its reaction with Ca(Ac)2 to form calcium carbonate (CaCO3) mineral and HAc in the binary solvent with a high C2H5OH content. However, an increase in the H2O content in the system triggers acetic acid (HAc)-induced CaCO3 dissolution to release CO2. The system can be recovered for CO2 capture readily by the replenishment of C2H5OH. This biomimetic mineralization-based CO2 capture/release is controlled by the ionization states of the electrolytes, and is precisely regulated in the C2H5OH–H2O binary solvent. Our attempt highlights the fundamental principle of solution chemistry in reaction control and provides a bioinspired strategy for CO2 capture/release with very low cost and easy availability.
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POLYMER
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2015
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IF 3.562
Wei Luo,Shoucun Zhang,Peng Li,Ran Xu,Yuexuan Zhang,Liyun Liang,Colin D. Wood,Qunwei Lu,Bien Tan
For tissue engineering, pore structure is an essential element in the development of scaffolds. In this paper, we obtained highly porous cross-linked partially hydrolyzed poly (vinyl alcohol) (PVA) hydrogels by templating concentrated CO 2 -in-water (C/W) emulsions, which avoid the use of traditional organic solvents and additional surfactants . This method is very convenient for the formation of biocompatible PVA hydrogels, because redundant crosslinking agent and catalyst could be easily removed by washing with the absence of organic solvent and surfactants, and would have widespread applications due to the biocompatibility of the resulting materials. These PVA hydrogels were further evaluated for cellular growth and proliferation to demonstrate their applications in tissue engineering.
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Polymer Chemistry
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2015
·Vol. 6
·期 43
·7580-7585
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IF 5.52
Shunjie Liu,Yuyang Miao,Lijun Qiao,Yusheng Qin,Xianhong Wang,Xuesi Chen,Fosong Wang
A CO2-based oligo(carbonate-ether) tetraol was synthesized in a controlled manner by immortal copolymerization of carbon dioxide (CO2) and propylene oxide (PO) in the presence of 1,2,4,5-benzenetetracarboxylic acid (btcH4) catalyzed by using a zinc–cobalt double metal cyanide (Zn–Co–DMC) catalyst. The number average molecular weight (Mn) of the tetraol was in a good linear relationship with the molar ratio of PO and btcH4 (PO/btcH4), and hence can be precisely controlled. Besides, the rapid chain transfer in immortal copolymerization afforded the tetraol with a narrow polydispersity index (PDI) of 1.08 at a Mn of 1400 g mol−1. Notably, the weight fraction of the byproduct propylene carbonate (WPC) was reduced to as low as 4.0 wt%, which is the lowest Wpc ever reported for the synthesis of branched polyols. The structure of the oligo(carbonate-ether) tetraol was confirmed, providing new evidence for the effect of the acidity (pKa1 value) of the chain transfer agent (CTA) on the initial catalytic mechanism. The acid only acts as the CTA directly participating in the copolymerization via the chain transfer reaction when its pKa1 value is higher than that of adipic acid (pKa1 = 4.43). However, when its pKa1 value is lower than that of succinic acid (pKa1 = 4.2), it acts as the initiate-transfer agent, which first initiates PO homopolymerization to an oligo-ether polyol, and then the in situ formed polyol acts as a new CTA for the copolymerization.
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Journal of CO2 Utilization
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2014
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IF 0
Qingzhao Shi,Lishuai Jing,Weihong Qiao
Poor solubility of heavy hydrocarbons in CO 2 has limited the application of CO 2 -EOR (enhanced oil recovery) in modern oil recovery industry to some extent. Therefore, it is crucial to investigate the solubility regularity of different hydrocarbons in supercritical carbon dioxide (scCO 2 ) in the first place. In this paper, our objective is to explore the solubility of n -alkanes (C 6 H 14 –C 18 H 38 ) in scCO 2 . To measure cloud point pressures, the experiment utilizes high-pressure view chamber, and results for accuracy and repeatability of the experimental method and instrument are evidently positive. Then, cloud point pressures for n -alkanes from 318 K to 343 K show a proximately linear and positive correlation with the temperature; they also increase with expanding chain length of n -alkanes. In addition, the result of x (molar fraction of n -alkane at cloud point pressure) indicates that x has a positive correlation with the pressure at identical temperature, and when pressure is constant, temperature increase will reduce x . Finally, relationship studies between density of CO 2 and x reveal that, density of CO 2 has a positive influence on the solubility of n -alkane, and the Chrastil model corrects ln ρ and ln S data. The measured data align with the Chrastil model, with a maximum AARD value of 9.85%.
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ENERGY & FUELS
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2015
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IF 2.79
Hongyan Tang,Yi Zhang,Feng Wang,Huapeng Zhang,Yuhai Guo
Membrane wetting is the main obstacle for carbon dioxide (CO2) capture on long-term operation. In order to understand wetting, polytetrafluoroethylene (PTFE) hollow fiber membranes were fabricated through paste extrusion, stretching, and sintering processes. CO2 capture performance over 180 days was performed. It indicates no obvious deterioration of CO2 flux over 180 days. Subsequently, further investigation was performed through immersion of PTFE hollow fiber membranes in different absorbent solutions. Results of Fourier transform infrared (FTIR) spectroscopy, energy-dispersive spectroscopy (EDS), and variations of membrane weight showed the PTFE polymer kept good stability in the absorbent solutions over 24 weeks. Scanning electron microscopy (SEM) images indicated the pore sizes of the PTFE hollow fiber membranes did not markedly enlarge during immersion, which was proved by pore size distributions. Contact angle measurements indicated no obvious reduction (8° reduction) in the membrane hydrophobicity over 24 weeks. Values of the contact angle relied on the surface tension values of the absorbent solutions. AFM images showed that immersion imposed a negative influence on the roughness values, which was the same order as the contact angle. The results suggested that none of the absorbent molecules entered the interior of the PTFE polymer. PTFE hollow fiber membranes may be a promising alternative for CO2 capture on long-term operation.
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RSC Advances
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2016
·Vol. 6
·期 48
·42693-42700
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IF 3.289
Rui Zhang,Zhenchuan Yu,Yu Cang,Xiaoyan Hou,Zheqi Shen,Jie Deng,Zhiming Zhou,Xuhong Guo,Junwei Wang,Xuedong Zhu
Spherical polyelectrolyte brushes (SPBs), consisting of a poly(styrene) core and poly(acrylic acid) shell densely grafted from the core surface, were synthesized by photoemulsion polymerization. A novel method for highly selective separation of methylene blue (MB) and other dyes is proposed herein, which employs spherical polyelectrolyte brushes as the adsorbent and compressed CO2 as the antisolvent; neither polymer brush nor CO2 on their own can separate the dyes. The SPBs and adsorbed dyes can be precipitated simultaneously from organic solutions by the easy control of CO2 pressure. The effects of several parameters such as CO2 pressure, initial dye concentration and temperature on the removal of MB by PS-PAA have been determined. MB can be selectively adsorbed by PS-PAA from the mixed dye solution with high efficiency, indicating that the binding of MB onto PS-PAA is probably dominated by electrostatic interactions. Due to the Donnan effect of the polymer brush, the adsorbed dyes can be easily eluted by NaCl aqueous solution through ion exchange to obtain the regeneration of the polymer brush, and the recovered PS-PAA retains high adsorption capacity even being regenerated five times. This provides a simple and effective way for the separation of ionic materials, which could be applied in environmental engineering.
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APPLIED SURFACE SCIENCE
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2016
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IF 3.15
Xiancheng Ma,Liqing Li,Shaobin Wang,Mingming Lu,Hailong Li,Weiwu Ma,Tim C. Keener
A porous carbon (ZC) was prepared at 900 °C using zeolitic imidazolate framework-8 (ZIF-8) as a solid template for CO 2 adsorption. The ZC was further treated by ammonia functionalization to improve CO 2 uptake. The textural and surface characteristics of ZC samples were determined by X-ray diffraction (XRD), N 2 adsorption, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It was revealed that ammonia treatment at 600 °C considerably enhanced the specific surface area and N-content of ZC. However, the pyrrolic-N group was decreased, yet the pyridinic-N group was increased with an increased temperature. The pyrrolic-N significantly enhanced CO 2 adsorption. The ammonia treatment, on the one hand, increases the alkalinity of ZC sample and the base–acid interaction between N-containing functional groups with CO 2 . On the other hand, the ammonia treatment increased pyrrolic-N group (NH) into carbon surface facilitating the hydrogen-bonding interactions between proton of pyrrolic-N and CO 2 molecules.
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SENSORS AND ACTUATORS B-CHEMICAL
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2016
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IF 4.758
Wei Lu,Peng Xiao,Jincui Gu,Jiawei Zhang,Youju Huang,Qing Huang,Tao Chen
A polymer-based visible and quantitative fluorometric assay for CO 2 gas is constructed using branched polyethyleneimine (PEI) covalently modified with tetraphenylethylene (TPE). The sensing mechanism relies on the reaction of CO 2 with alkylamines of PEI to induce the “solution-to-precipitation” phase transition of the sensory polymer (TPE–PEI), thus resulting in strong aggregation-induced fluorescent emission of TPE–PEI. It works in a relatively environmental benign ethanol medium and avoids the use of toxic amine compounds with unpleasant odor. More importantly, this system is proved to be highly tolerant to possibly coexisting water, carbon monoxide , acid SO 2 and H 2 S gases as well as many common volatile organic compounds. These characteristics make the presently developed fluorescent chemosensor hold great potential for many real-world applications.
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ACS Applied Materials & Interfaces
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2016
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IF 7.145
Mengya Niu,Huaming Yang,Xiangchao Zhang,Yutang Wang,Aidong Tang
Pristine halloysite nanotubes (HNTs) were pretreated to produce mesoporous silica nanotubes (MSiNTs), which was further impregnated with polyethenimine (PEI) to prepare an emerging nanocomposite MSiNTs/PEI (MP) for CO2 capture. Thermogravimetric analysis (TGA) was employed to analyze the influences of PEI loading amount and adsorption temperature on CO2 adsorption capacity of the nanocomposite. The Brunauer–Emmett–Teller (BET) surface area (SBET) of MSiNTs was six times higher than that of HNTs, and the corresponding pore volume was more than two times higher than that of HNTs. The well dispersion of PEI within the nanotubes of MSiNTs benefits more CO2 gas adsorption, and the adsorption capacity of the nanocomposite could reach 2.75 mmol/g at 85 °C for 2 h. The CO2 adsorption on the nanocomposite was demonstrated to occur via a two-stage process: initially, a sharp linear weight increase at the beginning, and then a relatively slow adsorption step. The adsorption capacity could reach as high as 70% within 2 min. Also, the nanocomposite exhibited good stability on CO2 adsorption/desorption performance, indicating that the as-prepared emerging nanocomposite show an interesting application potential in the field of CO2 capture.
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