Materials
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2019
·Vol. 12
·期 10
·1663
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IF 2.972
Yuanping Jiang,Cong Yan,Kai Wang,Dawei Shi,Zhengying Liu,Mingbo Yang
Polylactic acid (PLA) holds enormous potential as an alternative to the ubiquitous petroleum-based plastics to be used in packaging film and agricultural film. However, the poor viscoelastic behavior and its extremely low melt strength means it fails to meet the requirements in film blowing processing, which is the most efficient film processing method with the lowest costs. Also, the PLA’s brittleness and insufficient gas barrier properties also seriously limit PLA’s potential application as a common film material. Herein, special stereocomplex (SC) networks were introduced to improve the melt strength and film blowing stability of PLA; polyethylene glycol (PEG) was introduced to improve PLA’s toughness and gas barrier properties. Compared with neat poly(l-lactide) acid (PLLA), modified PLA is stable in the film blowing process and its film elongation at break increases more than 18 times and reaches over 250%, and its O2permeability coefficient decreased by 61%. The resulting film material also has good light transmittance, which has great potential for green packaging applications, such as disposable packaging and agricultural films.Keywords:PLA;biodegradable films;toughness;film blowing
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高影响因子
WATER RESEARCH
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2019
·
IF 7.913
Ming Zhang,Yudong Feng,Daoyong Zhang,Lingfeng Dong,Xiangliang Pan
The hydrophobic polycyclic aromatic hydrocarbons (PAHs) are apt to adhere tightly to the sediments in aquifer and thus pose great threats to the aquatic environment of groundwater and surface water as well as human health. The present study constructed functionalized microbubbles, named colloidal ozone aphrons (COAs), by dissolving ozone-contained air into the nonionic surfactant (Tween-20) solution at the pressure of 300 kPa for the in situ remediation of phenanthrene (PHE)-contaminated sediments. The COA system aimed at improving the PHE elimination in terms of (i) enhancing the migration and transportation ability of the bubble system in the contaminated aquifer matrix, (ii) accurately desorbing the target hydrophobic contaminants from sediments, and (iii) reinforcing the in situ oxidation degradation immediately after or simultaneously when the PAHs are desorbed into the aqueous phase. Experimental results demonstrated that the COAs exhibited similar characteristics as the classical colloidal gas aphrons (CGAs), including the high stability (half-life time > 200 s), typical morphology and average bubble size (114–162 μm); higher air hold-up of COAs was achieved (i. e. > 20%) compared with the air-microbubbles (1–2%) obtained under the same generation conditions. Although the encapsulated ozone could oxidize the surfactant-layers, the properties and behaviors of COAs were not greatly affected. The surfactant multi-layers endowed the COAs with strong hydrophobic attraction with PHE, great migration capacity and enlarged oxidation area in the sediment matrix. Approximately 96.9% of PHE was removed from the sediments and 84.9% of the overall PHE was oxidized at the high ozone concentration of 0.6 mg/L when the initial PHE concentration was 240.0 μg/kg. The COA-involved remediation technology provided the insight of combining the processes of washing and oxidizing through adopting the particularly conceived microbubbles. The in situ and selective removal of hydrophobic organic contaminants from sediments in aquifer was well achieved in this study.
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高影响因子
JOURNAL OF CHROMATOGRAPHY A
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2019
·
IF 3.858
Tao Sun,Liran Qi,Weiwei Li,Yan Li,Xiaomin Shuai,Zhiqiang Cai,Haipeng Chen,Xiaoguang Qiao,Lufang Ma
Efficient separation of aromatic amine isomers is a challenging issue in chemical industry and environmental analysis. Here we report the use of p -amino-tetradecyloxy-calix[4]arene (C4A-NH 2 ) as a novel stationary phase for gas chromatographic (GC) separations. The statically coated C4A-NH 2 capillary column showed a high column efficiency of 4332 plates/m for a 0.25 mm ID column and medium polarity. The C4A-NH 2 stationary phase exhibited an excellent separation performance both for aromatic amine isomers and a complex mixture of aliphatic analytes with a wide ranging polarity, showing distinct advantages over the commercial polysiloxane stationary phases via diversified molecular interactions covering H-bonding, π-π , van der Waals interactions and shape-fitting selectivity. The retention mechanisms of aromatic amine isomers on C4A-NH 2 column were further investigated by quantum chemistry calculations. In addition, the C4A-NH 2 column showed good column repeatability with relative standard deviation (RSD) values of 0.03%-0.07% for run-to-run, 0.10%-0.27% for day-to-day and 2.6%–5.7% for column-to-column, respectively, and thermal stability up to 240℃.
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高影响因子
RENEWABLE ENERGY
·
2019
·
IF 5.439
Shaokai Zhang,Xun Ke,Tong Zeng,Yonghao Ni,Xiaolin Luo,Hui-Chao Hu,Lihui Chen,Liulian Huang
An ammonia-assisted headspace gas chromatography (HS-GC) method was developed to determine the N-methyl morpholine (NMM) concentration in biomass fractionation processes. The use of ammonia gas increased the detection sensitivity of NMM, and minimized the interfering effect of other substances during the analysis. Results showed that, by adding 1.5 mL ammonium hydroxide (28–30%, w/w) and a 0.125 mmol of sodium hydroxide into a 4.0 g of sample solution containing 43.3% N-methylmorpholine N-oxide (NMMO), the gas-liquid equilibration of NMM was obtained within 30 min at 80 °C. The optimum sample size and the NMMO content in the sample solutions were 6.0 g and 43.3%, respectively. The present method was proved to be of high precision (RSD = 4.33%), sensitivity (LOQ = 71.9 mg/kg), and with recovery accuracy of 96.0–102%. The present method was rapid, accurate, which will be a powerful tool to optimize the reaction conditions in NMMO-based biomass pretreatment process for enhancing the cost effectivity.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2019
·
IF 3.375
Hongwei Gao,Yongping Bai,Huihui Liu,Jinmei He
1,6-Hexylenediamine (HMDA) was chosen to replace part of ethylene glycol to develop a novel poly(ethylene terephthalate) structure with amide bonds. Four kinds of poly(ester amide)analogues (p-ETA) with different contents of amide bonds (1–4 mol %) were successfully synthesized via a new simple synthesis procedure. It was proved that the thermal stability and mechanical properties were significantly enhanced because of the introduction of amide bond units. More importantly, adding a small amount (1 mol %) of HMDA could effectively accelerate the orderly arrangement of molecular chains and formation of crystal nuclei proved by differential scanning calorimetry, X-ray diffraction, and polarized optical microscopy test results. It showed that the calendered p-ETA films acted as a good barrier to water and oxygen, expanding its application as packaging materials. Experimental results indicated that the introduction of amide bond units substantially promoted the overall performances of poly(ethylene terephthalate), such as crystallinity (28.4 vs 14.1%), tensile strength (60.9 vs 55.7 MPa), elongation at break (381 vs 226.8%), and so forth.
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JOURNAL OF MEMBRANE SCIENCE
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2019
·
IF 7.015
Mingmin Jia,Xiong-Fei Zhang,Yi Feng,Yichen Zhou,Jianfeng Yao
ZIF-8@cellulose nanofiber (ZIF-8@CNF) composite membranes were prepared via in-situ growing ZIF-8 crystals on cellulose nanofibers (CNFs) and vacuum filtration. Owning to the electrostatic forces between –COO - of CNFs and Zn 2+ of ZIF-8, ZIF-8 crystals were anchored homogenously on CNFs. With ZIF-8 loading increased to sufficiently high, the intrinsic selectivity of ZIF-8 played an important role for gas separation. As a result, the optimum separation performance is achieved over ZIF-8@CNF-70 composite membrane with CO 2 permeability of 550 Barrer and CO 2 /N 2 and CO 2 /CH 4 ideal selectivity of 45.5 and 36.2, respectively.
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SENSORS AND ACTUATORS B-CHEMICAL
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2019
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IF 6.393
Changhao Feng,Zhongwei Jiang,Jingxuan Wu,Bin Chen,Geyu Lu,Chengzhi Huang
In this work, Pt-Cr 2 O 3 -WO 3 composite nanofibers have been designed by using Pt@MIL-101(Cr) and electrospinning. The morphological and microstructural properties of these nanofibers were analyzed by various kinds of techniques. The FESEM and TEM results demonstrate that the size of Pt nanoparticles is ˜ 3 nm, which greatly improved the gas sensing properties of metal oxides. The gas-sensing properties of WO 3 , Cr 2 O 3 -WO 3 and Pt-Cr 2 O 3 -WO 3 composite nanofibers were tested. Compared with pristine WO 3 nanofibers, Pt-Cr 2 O 3 -WO 3 composite nanofibers exhibit superior response toward xylene. At the optimal operating temperature of 325 °C, the response of Pt-Cr 2 O 3 -WO 3 composite nanofibers to 10 ppm xylene is 74.3, the response time is 5 s and the detection limit is 0.5 ppm. The sensing mechanism of the ultrahigh gas sensing properties attributes to the Cr 2 O 3 -WO 3 heterojunction, the catalytic activity of Cr 2 O 3 , porous structure, the electronic and chemical sensitization of Pt nanoparticles.
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JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 53
·期 14
·10469-10478
·
IF 2.993
Fu Shuqing,Yao Jinshui,Yang Zhizhou,Sun Hongqiang,Liu Weiliang
A series of novel silane-based hyper-cross-linked porous polymers was prepared through the Friedel–Crafts alkylation reaction of dimethyldiphenylsilane as the monomer and formaldehyde dimethyl acetal as the external cross-linker. The structures of the polymers were confirmed by FTIR and solid-state cross-polarization magic-angle spinning 13 C NMR. We investigated the porous polymers with different ratios of dimethyldiphenylsilane to formaldehyde dimethyl acetal. Porous properties were determined by nitrogen, carbon dioxide and hydrogen adsorptions. The results revealed that the porous materials possessed surface areas from 742 to 1205 m 2 g −1 with the increasing amount of formaldehyde dimethyl acetal. Moreover, this material exhibited high thermal stabilities, good CO 2 capture, and H 2 storage capacities. The material was also used as adsorbent for organic dyes in aqueous solution and showed an excellent adsorption capacity of 952 mg g −1 for Congo red dye. These results suggest that the silane-based hyper-cross-linked porous polymers are promising materials for CO 2 capture, H 2 storage, and water treatment.
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SENSORS AND ACTUATORS B-CHEMICAL
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2018
·
IF 5.667
Ling Wang,Weiwei Meng,Zhangxing He,Wei Meng,Yuehua Li,Lei Dai
A mixed-potential type sensor using a new sensing electrode (SE) of CeVO 4 is developed for NH 3 detection. Well-dispersed Au nanoparticles are introduced into the CeVO 4 -SE by a simple immersion method to further improve the performances, especially the selectivity of the sensor. The sensor using the CeVO 4 -SE exhibits well response-recovery characteristics to NH 3 at 500–600 °C. Good linear correlations between the response potential difference of sensor and the logarithm of NH 3 concentrations are obtained. The sensor displays the negligible cross-sensitivities to CH 4 and CO 2 except NO 2 present in the gas mixture. After the introduction of the Au nanoparticles into the CeVO 4 -SE, the sensitivities of the sensor reach −78.9, −77.3 and −43.1 mV/decade at 500, 550 and 600 °C, respectively, which are much higher than those using the single CeVO 4 -SE. More importantly, the cross-sensitivity of the sensor with CeVO4/Au-SE to NO 2 is almost eliminated. Introduction of 1000 ppm NO 2 in sample gas containing 300 ppm NH 3 causes a response Δ V from 67.2 (for CeVO 4 -SE) to 4.6 mV (for CeVO 4 /Au-SE). The complex-impedance measurements display that introduction of Au can promote electrochemical oxidation reaction of NH 3 to TPBs. The results of the temperature-programmed desorption indicate that the improvement of the selectivity is attributed to the effective depression of NO 2 adsorption in the sensing electrode by introduction of Au.
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MATERIALS RESEARCH BULLETIN
·
2018
·
IF 2.873
Mingpeng Chen,Dongming Zhang,Jicu Hu,Huapeng Wang,Yumin Zhang,Kejin Li,Qian Rong,Shiqiang Zhou,Jin Zhang,Zhongqi Zhu,Qingju Liu
Highly sensitive and selective detection against toluene gas remains a tremendous challenge in gas sensor applications . In this work, a series of molecular imprinted Ag-LaFeO 3 nanoparticles (IAL NPs) were synthesized in a microwave-assisted colloidal route. Especially, the one prepared with optimal amount of imprint molecules (IAL-2 NPs) have a response of 24.0 to 5 ppm toluene at the optimum working temperature of 215 °C with negligible responses to the other test gases, exhibiting enhanced gas sensing properties for toluene gas at a relatively low working temperature. The improved performance can be attributed to the favorable effect of microwave radiation, the molecular imprinting structure and the sensitization of Ag, which illuminates that IAL-2 NPs is a potential candidate for toluene detection.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2018
·
IF 3.141
Shaobo Cao,Ping Liu,Liangliang Zhang,Baochang Sun,Haikui Zou,Guangwen Chu,Yong Luo,Jianfeng Chen
To ensure steady operation of gas transmission lines and meet the utilization specification of downstream processes, gas dehydration is employed in offshore natural gas production, where urgent demands for space and size exist. In this work, a rotating packed bed (RPB) was used to intensify the triethylene glycol (TEG) dehydration process and the effects of operating variables on the overall volumetric mass transfer coefficient (Kya) and height of mass transfer unit (HTU) were investigated. The value of HTU in a RPB was measured to be 4.3–7.9 mm, which was at least an order of magnitude lower than that in conventional columns, indicating the significant reduction in the size of the dehydration apparatus. The predicted Kya matches well with the experimental data, and the mean relative error (MRE) is only 6.68%.
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FUEL
·
2018
·
IF 4.908
Haifeng Li,Sheng Su,Song Hu,Kai Xu,Long Jiang,Yi Wang,Jun Xu,Jun Xiang
A series of Mn x O y /Al 2 O 3 sorbents with different tissue and chemical structures were prepared by repeated incipient wet impregnation method with different calcination conditions, including calcination temperature from 500 °C to 900 °C and calcination time from 3 h to 9 h. The H 2 S absorption performances of the prepared sorbents were investigated by a model synthesis gas containing 2000 mg/m 3 H 2 S at 850 °C. The chemical and physical structures of the samples were characterized by Brunauer–Emmett–Teller, X-ray diffraction and scanning electron microscopy techniques to obtain fundamental information about the deactivation of Mn x O y /Al 2 O 3 sorbents during desulfurization–regeneration cycles. Results showed that the structural features of the sorbents at high reaction temperature played an important role in the stability of desulfurization performance. The analysis of the characteristics of the sorbents indicated that the sorbents obtained stabilized chemical and physical structures during desulfurization–regeneration cycles when the calcination temperature was 900 °C and the calcination time was above 6 h. The sorbent suffered serious deactivation during five successive desulfurization–regeneration cycles when the calcination temperature of sorbents was below 850 °C. The sulfur capacity decreasing of Mn x O y /Al 2 O 3 sorbents may probably be attributed to a part of Mn x O y covered by Al 2 O 3 , which can un-sulfide during adsorption process. The coverage of active phase Mn x O y may be caused by the shrinking and disappearing of some micropores, and phase transformation of Al 2 O 3 , as well as the transformation of MnAl 2 O 4 lead to a part of Mn x O y on the sorbents being covered by alumina.
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