POLYMER DEGRADATION AND STABILITY
·
2018
·
IF 3.193
Niya Ye,Yixin Xu,Dengji Zhang,Jingshuai Yang,Ronghuan He
We employed four radical inhibitors to investigate their influences on the degradation of poly (4-vinylbenzyl chloride-styrene) based anion exchange membranes (AEMs) in alkaline solutions. It is found that the presence of the radical inhibitors could effectively restrain the nucleophilic attack of hydroxide ions to the AEMs according to the conductivity measurements, especially the one p -ethyl phenol (PEP), which could significantly protect the AEMs against the attack. More evidences including water uptake, swelling ratio as well as FT-IR analysis further proved this phenomenon by comparison those properties of the membranes before and after the stability test in 8 M KOH at 80 °C for 24 h. According to the 1 H NMR spectra, the quaternary ammonium groups of the AEMs were mainly degraded into tertiary amines in the hot alkaline solutions; while in the presence of PEP, this degradation was restrained and the quaternary ammonium groups maintained by reaction with PEP. Fenton test results further indicated that high oxidative stability of the AEMs benefited from the presence of a small amount of PEP, which could reduce the generation of the oxidants. Thus an inhibition reaction mechanism of the radical inhibitors preventing the AEMs from alkaline degradation is proposed.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Li-Yun Guo,Hai-Qin Lu,Darryn Rackemann,Changrong Shi,Wen Li,Kai Li,William O.S. Doherty
Quaternary ammonium-functionalized magnetic chitosan microspheres (QAMCM) were fabricated for the removal of high-molecular-weight invert sugar alkaline degradation products (HISADPs), the main class of colorants in beet juice. The equilibrium adsorption capacity of QAMCM for HISADP was 98.03 mg/g at 0.6 mg/mL QAMCM dosage, 333 K temperature, pH 7, and 60 mg/L initial HISADP concentration, and the corresponding removal rate reached 98.03%. The adsorption kinetics were studied by using a pseudo-first-order and pseudo-second-order (PFO–PSO) combined model. Results revealed that HISADP adsorption by QAMCM is a complex process because of the involvement of both chemisorption and physisorption instead of only one mechanism. However, chemisorption (electrostatic attraction and electron sharing) is the dominant kinetic mechanism. Analysis of the mass transfer mechanisms showed that the dynamic characters of the adsorption capacities of the liquid film around QAMCM and the pores of QAMCM could be well described using a film–pore mass transfer model, which could be used to provide insights into the adsorption mass transfer behaviors of the system. Additionally, HISADPs with smaller sizes were preferentially adsorbed by QAMCM compared with larger ones. Research on the isotherms and thermodynamics showed that HISADP adsorption by QAMCM occurred via an endothermic multi-layer process and was spontaneous. Overall, QAMCM was found to be an efficient, green, and recyclable decolorization adsorbent for beet juice.
研究领域:
食品科学
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环境工程
·
生物材料
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2025
·
IF 8.5
Shiqi Xia,Congli Cui,Dong Li,Li-jun Wang
The composite adsorbent consisting of sodium alginate (SA) and quaternary ammonium-functionalized chitosan (QACS) was prepared using the calcium slow-release method to remove high-molecular-weight invert sugar alkaline degradation products (HISADPs) from the beet juice. The SA/QACS composite adsorbent has a honeycomb porous structure. Comparing the single-component QACS dispersion and SA adsorbent, the incorporation of SA increased the storage/elastic modulus ( G′ ) and loss/viscous modulus ( G′′ ) of the SA/QACS composite hydrogels, while the incorporation of QACS enhanced the adsorption capacity of the SA/QACS composite adsorbents. Specifically, when 5 % QACS and 2 % SA were added, both G' and G" of the SA/QACS adsorbent were approximately 100 times greater than those corresponding to the QACS dispersion. Concurrently, its maximum adsorption capacity attained 164.5 mg/g, which was superior to that of the SA adsorbent. The adsorption isotherms and adsorption kinetics further demonstrated that the Langmuir model and the pseudo-second-order (PSO) model were congruent with the adsorption data of the SA/QACS composite adsorbent concerning HISADPs. Overall, these findings highlight the potential of the SA/QACS adsorbent as an effective adsorbent for the removal of HISADPs from beet juice.
研究领域:
食品科学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL SCIENCE & TECHNOLOGY
·
2021
·
IF 9.028
Qiliang Chen,Xiaolong Lian,Jingjing An,Ningbo Geng,Haijun Zhang,Jonathan K. Challis,Yun Luo,Yaxin Liu,Guanyong Su,Yuwei Xie,Yingwen Li,Zhihao Liu,Yanjun Shen,John P. Giesy,Yufeng Gong
Due to commercial uses and environmental degradation of aryl phosphate esters, diphenyl phosphate (DPhP) is frequently detected in environmental matrices and is thus of growing concern worldwide. However, information on potential adverse effects of chronic exposure to DPhP at environmentally realistic concentrations was lacking. Here, we investigated the effects of life cycle exposure to DPhP on zebrafish at environmentally relevant concentrations of 0.8, 3.9, or 35.6 μg/L and employed a dual-omics approach (metabolomics and transcriptomics) to characterize potential modes of action. Exposure to DPhP at 35.6 μg/L for 120 days resulted in significant reductions in body mass and length of male zebrafish, but did not cause those same effects to females. Predominant toxicological mechanisms, including inhibition of oxidative phosphorylation, down-regulation of fatty acid oxidation, and up-regulation of phosphatidylcholine degradation, were revealed by integrated dual-omics analysis and successfully linked to adverse outcomes. Activity of succinate dehydrogenase and protein content of carnitine O-palmitoyltransferase 1 were significantly decreased in livers of male fish exposed to DPhP, which further confirmed the proposed toxicological mechanisms. This study is the first to demonstrate that chronic, low-level exposure to DPhP can retard growth via inhibiting energy output in male zebrafish.
研究领域:
环境毒理学
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水生生物学
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分子生物学
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生态毒理学
✓ 已验证
DOI
PubMed
高影响因子
MACROMOLECULAR RESEARCH
·
2021
·Vol. 29
·期 7
·462-469
·
IF 2.227
Wang Lei,Yan Shijing,Zhang Lei,Mai Yuliang,Li Weihao,Pang Hao
The degradation and recycling of waste epoxy resin products is an urgent environmental problem. To solve this issue, we use acid-/base-degradable 1,1′,1″-(1,3,5-hexahydro-s-triazine-1,3,5-triyl) tris(3-ethylamino-propan-1-one) (TAHT-EA) as curing agent to introduce the hexahydro-s-triazine (HT) ring structure into the cross-linking network to prepare degradable epoxy resin. Specifically, 1,3,5-triacryloylhexahydro-1,3,5-triazine (TAHT) and ethylamine quickly complete the Aza-Michael addition reaction at the interface of chloroform and water droplets under the catalysis of water. The FTIR spectra, NMR spectrum and mass spectrum show that mono- and bis-addition products of ethylamine coexist in the product in which the content of the primary addition product reaches 97%. TAHT-EA can be decomposed by acid and base solutions. Through NMR analysis of the degradation products, it can be explained that the degradation mechanisms are different. The breaking of amide bonds and HT rings in acid solution and the cracking of amide bonds in base solution are speculated to be the main mechanisms under these two different circumstances, respectively. We tested the mechanical, thermal and degradation properties of the epoxy resin cured by TAHT-EA, and compared it with the epoxy resin cured by 4,4′-diaminodiphenylmethane and triethylenetetramine. TAHT-EA-cured epoxy resin shows comparable mechanical properties with Young’s modulus up to 2.05 GPa and tensile strength up to 70.9 MPa. What is more, it degrades completely by 1 M H + /OH − solution at 60 °C within 36 h. Nevertheless, it exhibited a relatively low crosslinked density (633 mol/m 3 ) and low heat resistance (the initial decomposition temperature is lower than 205 °C). Overall, TAHT-EA cured epoxy resin has the potential to gradually replace traditional thermosetting resin, thereby solving the environmental problems caused by discarded epoxy resin products.
研究领域:
材料科学
·
高分子化学
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环境科学
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可持续材料
✓ 已验证
产品关联
DOI
高影响因子
EUROPEAN POLYMER JOURNAL
·
2020
·
IF 3.862
Pengli Zhang,Yanfang Zhao,Rentong Yu,Jianhe Liao
Six-arm star polycaprolactone with core of cyclotriphosphazene ( s -PCL) was synthesized via ring-opening polymerization and characterized by NMR and GPC . Epoxy thermosets incorporating 10–40 wt % of this copolymer were cured with 4,4′-methylenebis(2-chloroaniline) (MOCA) and 4,4′-diaminodiphenyl sulfone (DDS), respectively. In these thermosets, intermolecular specific interactions had a significant impact on their morphologies. Specifically, no discernable macroscopic phase separation was found in FESEM images of MOCA-cured epoxy resins . However, for the DDS-cured system, s -PCL was partially miscible with the epoxy thermosets, as evidenced with FTIR and DMA. This is may be owning to enriched concentration of hydroxyl groups in the s -PCL favored the miscibility between PCL subchains of carbonyl and the epoxy matrix. Dispersed phase, further confirmed by XRD to be amorphous , with a diameter of 0.34–0.44 μm could be observed ( s -PCL’ content ≤ 20 wt %) in this system. Nevertheless, crystallization of PCL could not be suppressed completely ( s -PCL’ content > 30 wt %). Besides, epoxy thermosets containing crystalline PCL were found to be more resistant to thermal degradation but sensitive to alkaline degradation (10% NaOH aqueous solution) according to TGA and FESEM results. This work presented here is a meaningful report on the presence of alkaline-labile crosslinking points through the whole networks.
研究领域:
高分子科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）