INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2022
·
IF 4.326
Kejian Yang,Qi Guo,Yanlin Liu,Jinping Ni,Zhaobin Tang,Xudong Chen
The long-ignored discoloration behavior of polyamide during polymerization has a significant impact on its properties and applications. Here, we innovatively analyzed the discoloration behavior of pentamethylenediamine-derived bio-based copolyamide (PA5T/56) and proposed a possible discoloration mechanism. Pentamethylenediamine performed cyclization reactions at high temperature to generate piperidine, which was then combined with terephthalic acid to form dipiperidine terephthalate. After being oxidized, dipiperidine terephthalate was converted to terephthalic acid bis(2-carbonyl substituted piperidine), which was believed to be responsible for the discoloration of polyamide during polymerization. Moreover, it was demonstrated that the discoloration behavior led to poor spinnability and dyeability of ultrafine polyamide fibers. This work will help to optimize the polymerization process of pentamethylenediamine-derived polyamide and expand its applications in high-performance fibers and other fields.
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JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
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2022
·
IF 4.383
Xiao-qi Chen,Zhi Huang,Yan-ying Liu,Qian Zhang,Jun-ming Hong
Conventional metal–organic frameworks (MOFs) used for electrocatalytic applications have the drawbacks of poor conductivity and instability. Herein, a Cu–1,2,3,4,5,6-benzenehexamine (Cu-HAB)/graphene oxide (GO) composite was prepared for the electrocatalytic degradation of tetracycline hydrochloride (TCH). Our characterization results show that Cu-HAB/GO has more active sites ( I D / I G = 1.0030), larger surface area (S BET = 395.3441 m 2 /g), and faster electron transport (Rct = 20.69) than Cu-HAB. Simultaneously, the improvement in the number of active sites, surface area and electron transport leads to a superior TCH electrocatalytic degradation efficiency. The reaction rate constant (0.70575 min −1 ) of the composite was higher with a 51.81% improvement observed when compared to Cu-HAB under the optimum conditions of 1 g/L NaCl, 20 mA, and 20 °C. In addition, 100% of the degradation efficiency was maintained after five cycles. A detailed study of the mechanism revealed that 1 O 2 and active chlorine were the critical active species for the degradation of TCH via quenching and electron paramagnetic resonance (EPR) studies. The possible TCH degradation pathway has been proposed. This study provides a novel and feasible method for the preparation of MOF-based electrocatalysts to expand their application to environmental fields.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2023
·
IF 8.6
Miaomiao Ye,Ningyao Tao,Xiaojiao Zhou,Xingyuan Wang,Wen Jin,Tuqiao Zhang,Xiaowei Liu
Salt accumulation and volatile organic compounds (VOCs) entering condensed freshwater are two main drawbacks in the new approach of solar-driven seawater desalination. In this work, a super-hydrophilic honeycomb activated carbon (SHHAC) evaporator was fabricated for simultaneous salt rejection and VOCs removal. The optimal water evaporation rate of the SHHAC evaporator was as high as 1.50 kg·m −2 ·h −1 under one sun illumination with the corresponding photothermal conversion efficiency of 99.4 %. Due to the super-hydrophilic properties, high water absorption capacity, fast water absorption rate and unique honeycomb structure of SHHAC, the salt-rejection property of the SHHAC evaporator was achieved by flowing back the concentrated brine to the underneath seawater. Simultaneously, the distillation concentration ratio (R D ) of phenol was reduced from 75 % to 0 % by the SHHAC evaporator resulting in zero phenol entering condensed freshwater. Finally, the potential application of the SHHAC evaporator was demonstrated by an expanded outdoor experiment using the real seawater as the feedwater.
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Polymer Chemistry
·
2023
·Vol. 14
·期 6
·754-762
·
IF 4.6
Lei Zhang,Yujie Liang,Jiazhu Xu,Hong Zheng,Wenjie Sun,Yonghong Cheng
1,3-Benzoxazine has long been considered as a unique polymerizable benzoxazine species to prepare high performance polymers. Herein, polymerization of 2H,4H-3,1-benzoxazine is observed for the first time and the thermal properties of the obtained material are studied. A phenolic hydroxyl-containing mono-functional 3,1-benzoxazine monomer has been synthesized. With additional phenol substitution, 3,1-benzoxazine is able to undergo ring-opening polymerization. The reaction kinetics and variation in the molecular structure during polymerization were systematically investigated. Besides, quantum chemistry simulation showed that the C–O and C–N bond strength reduction in the 3,1-oxazine ring induced by adjacent phenol substitution is the critical factor that endows the monomer with polymerization ability. A polymerization mechanism of 3,1-benzoxazine has been proposed. The reported 3,1-benzoxazine monomer has good evaporation resistance even at 200 °C for 2 hours. More importantly, the cured material shows attractive thermal performance, with a glass transition temperature of 217 °C and a decomposition temperature above 400 °C together with a char yield of 54%. This study offers a new way to develop polymerizable benzoxazines with high performance for numerous emerging applications.
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Food Chemistry-X
·
2023
·
IF 6.1
Shi-Kang Chen,Hai-Feng Lin,Xin Wang,Yi Yuan,Jun-Yi Yin,Xiao-Xiao Song
In this study, ten pea ( Pisum sativum L.) varieties were compared in their nutrient composition, phenolic compounds, antioxidant properties and their diversity were deciphered by multivariate analysis of correlation analysis and principal component analysis (PCA). The ten pea cultivars are rich in nutrients with different contents in lipid (0.57 to 3.52%), dietary fiber (11.34 to 16.13%), soluble sugar (17.53 to 23.99%), protein (19.75 to 26.48%) and starch (32.56 to 48.57%). Through the UPLC-QTOF-MS and HPLC-QQQ-MS/MS analysis, the ethanol extracts of ten peas mainly included 12 kinds of phenolic substances and showed good antioxidant activities on the 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). The phenolic content and protocatechuic acid showed a positive correlation with antioxidant capacity. All results provide theoretical basis for the development and rational application of different varieties of peas and their related products.
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CHEMOSPHERE
·
2023
·
IF 8.8
Bo Cao,Jianhua Qu,Yingyu Chu,Yujiao Zhu,Yuxin Jiang,Xiubo Zhang,Mingze Sun,Zhao Jiang,Shouyi Ma,Ying Zhang
Persulfate (PS) activation by nanoscale zerovalent iron (nZVI) is promising for water purification , while is limited due to its easy agglomeration and oxidation. Herein, nZVI encapsuled in carbon matrix shell was synthesized via one-step carbothermal reduction. The core-shell structure effectively inhibited oxidation and agglomeration of nZVI core, and graphitized porous structures facilitated phenol binding with maximal adsorption capacity of 117.10 mg/g achieved by nZVI 0.6 -BC 800 . Both reactive oxygen species ( S O 4 • − , O • H , O 2 • − and 1 O 2 ) and electron transfer process resulted in phenol decomposition. Owing to diversified active sites, the nZVI 0.6 -BC 800 /PS system could completely degrade phenol degradation within short time, and exhibited great adaptation to extensive pH range (3.0–9.0) and coexisting substances. Additionally, the nZVI 0.6 -BC 800 /PS system could maintain over 85% removal of phenol after three recycles or 50 days of storage, and was highly-efficient to different water environments, thus proposing rational design of iron-carbon catalyst with potential in water treatment.
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MACROMOLECULAR RESEARCH
·
2023
·Vol. 31
·期 1
·45-52
·
IF 2.4
Zhao Wenqian,Yang Richie,Yang Shengfu,Zhang Kan
We observed an unusual low polymerization temperature for the ortho -amide benzoxazine in comparison with its para -isomer. Density functional theory (DFT) calculations suggested that the intramolecular hydrogen bond between the oxazine ring and the adjacent amide softens the C–O bond, resulting in a reduced activation energy and thus a low ring-opening polymerization temperature. In addition, the polymerization kinetics of both para - and ortho -amide functional benzoxazines were investigated using the Starink method, which confirmed a relatively lower activation energy for the ortho -amide functional benzoxazine compared with its para -isomer. Our work suggests that softening chemical bonds by intramolecular hydrogen bonding may become a new strategy for the design of high-performance polybenzoxazine thermosets with low processing temperatures. Graphical abstract
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Catalysis Science & Technology
·
2023
·Vol. 13
·期 6
·1748-1754
·
IF 5
Shaoyuan Guo,Xinli Tong,Lingwu Meng,Guobao Yang
Selective oxidative C–C and C–O bond cleavage is of significance to the efficient utilization of biomass and biomass-derived platform compounds. In this work, the selective oxidative cleavage of C–C and C–O bonds has been developed with an iron-based catalyst (Fe–N–C) in the presence of molecular oxygen. Specifically, the β-O-4 lignin model compound was successfully converted to phenol and methyl benzoate in a methanol solvent, where the substrate conversion was 95.0% and the yields of phenol and methyl benzoate were 94.9% and 63.7%, respectively, when the reaction was performed with the Fe–N–C-850 catalyst at 120 °C for 4 h. Also, the oxidative transformations of other lignin models to phenols and methyl benzoates were achieved. Further investigations showed that the existence of the Fe3C phase in the catalyst plays an important role in the aerobic oxidative cleavage of C–C and C–O bonds in the β-O-4 lignin model.
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2022
·Vol. 140
·期 7
·e53497
·
IF 3.057
Jilei Xu,Ping Chen,Shuaijiang Ma,Guohao Zhu
In this work, three bismaleimides containing cardo and ortho -oxazine structures, with dual advantages of bismaleimide and benzoxazine resins, were synthesized. Their chemical structures were characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The polymerization behaviors of bismaleimides were investigated using non-isothermal differential scanning calorimetry and in situ Fourier transform infrared spectroscopy. Results showed that the inclusion of both, bismaleimide and benzoxazine, provided a new structure with better thermal stability and solubility, as compared to the same type and commercial bismaleimides. The ortho-oxazine functionalized bismaleimide resin exhibited excellent thermal stability up to 440°C, whereas the carbon residue rate reached 73% at 800°C. Additionally, further thermal rearrangement of the internal structure of the polymer at high temperature provided a benzoxazole structure that had better thermal stability. The rearrangement due to the thermal changes was confirmed by in situ FTIR and solid-state 13 C-NMR spectroscopy. Based on the micro calorimetry characterization, it is found that both the bismaleimide and the benzoxazole resins formed after thermal rearrangement have excellent flame-retardant properties.
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ANALYTICA CHIMICA ACTA
·
2022
·
IF 6.911
Wen-Bo Xie,Hao Li,Lei Zeng,Li-Juan Jiang,Wen Li,Lu Xia,Fu-Hou Lei
A column prepared using a unique three-membered phenanthrene skeleton of rosin has complementary selectivity to a C18 column for some separation tasks. In this study, propylene pimaric acid (16-hydroxyethyl acrylate-34-n-butyl) ester (BRB) and propylene pimaric acid (16-hydroxyethyl acrylate-34-dodecyl) ester (BRLA) were used as functional ligands to prepare two novel stationary phases, namely BRB@SiO 2 and BRLA@SiO 2 , through a “thiol-ene” click chemistry reaction. The characterization results of Fourier transform infrared spectroscopy , thermogravimetric analysis , nitrogen adsorption-desorption measurements, and contact angle tests showed that the BRB@SiO 2 and BRLA@SiO 2 stationary phases were successfully prepared. In addition, the performance of the columns was evaluated using the Tanaka test and hydrophobic subtraction model, which showed that the stationary phases exhibited typical reversed-phase chromatography performance and good hydrophobicity , hydrophobic selectivity , and steric selectivity. The changes in the retention of Panax notoginseng saponins on a column under different chromatographic conditions (acetonitrile content, flow rate , and column temperature) were investigated. The separation effect of BRB@SiO 2 and BRLA@SiO 2 columns on P. notoginseng saponins was better than that of the C18 column and the BRLA@SiO 2 column could replace the C18 column for the detection of P. notoginseng saponins.
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Polymers
·
2022
·Vol. 14
·期 22
·4895
·
IF 4.967
Xuedong Lv,Haitao Lin,Zhengxiang Wang,Ruixue Niu,Yi Liu,Yen Wei,Liuchun Zheng
Novel poly(butylene succinate-butylene furandicarboxylate/polyethylene glycol succinate) (PBSF-PEG) was synthesized using two-step transesterification and polycondensation in the melt. There are characterized by intrinsic viscosity, GPC,1H NMR, DSC, TGA, tensile, water absorption tests, and water degradation at different pH. GPC analysis showed that PBSF-PEG had high molecular weight with average molecular weight (Mw) up to 13.68 × 104g/mol. Tensile tests showed that these polymers possessed good mechanical properties with a tensile strength as high as 30 MPa and elongation at break reaching 1500%. It should be noted that the increase of PEG units improved the toughness of the polyester material. In addition, the introduction of PEG promoted the water degradation properties of PBSF, and the copolymer showed a significantly faster water degradation rate when the PEG unit content was 20%. This suggests that the amount of PEG introduced could be applied to regulate the water degradation rate of the copolymers. Hence, these new polymers have great potential for application as environmentally friendly and sustainable plastic packaging materials.Keywords:biodegradable polyester;poly(butylene succinate);hydrolysis degradation;poly(ethylene glycol)
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Food Bioscience
·
2022
·
IF 5.318
Yaling Huang,Junwen Wan,Min Sun,Tao Feng,Qian Liu,Shiqing Song,Xiaoming Zhang,Chi-Tang Ho
The sensomics approach was applied to elucidate the flavor profile of Chinese steamed breads (CSBs) fermented by different fresh and dry yeast, respectively. The quantitative descriptive analysis (QDA) led to the establishment of seven sensory attributes. Results noted that fresh yeast CSBs were characterized by milk, bouquet, sweet, and sour attributes, while the corresponding dry yeast CSBs exhibited wheat and yeast attributes. According to OAVs ≥1, 34 aroma-active chemicals were shown to be significant odorants. Isoamyl alcohol, 2,3-butanediol, benzoic acid , acetoin, hexanal, and indole had a significant contribution to the different aroma profiles of dry and fresh yeast CSBs. The result of correlation analysis showed that 2,3-butanediol and benzoic acid were correlated with sweet, milk, and sour attributes, hexanal and indole were related to bouquet attribute, and acetoin was associated with flour. Further aroma recombination confirmed the contribution of these key components in flavor discrimination of CSBs. These results will provide guidance for the yeast-CSBs flavor evaluation, improvement, and quality control.
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