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排序方式: 共有109条查询结果,搜索用时 171 毫秒
61.
《Arabian Journal of Chemistry》2022,15(11):104293
This study aimed to get an insight into the adsorption of three synthetic dyes onto chitin using experimental and computational approaches. The successful preparation of α-chitin was confirmed using the Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD). In addition, the presence of porous and fiber on the surface of the extracted chitin was revealed by the Scanning Electron Microscopy (SEM) analysis. The extracted α-chitin was then used as an adsorbent to remove synthetic dyes, namely Malachite green, Basic red 18, and Alizarin yellow R. The kinetic study showed that the adsorption of dyes was well-described using a pseudo-second-order model, whereas the isotherm adsorption obeyed the Freundlich model. The Frontier Molecular Orbital (FMO) revealed several locations of dyes and chitin molecules that are potentially active sites for adsorption. The adsorption trend could be related to the Highest Occupied Molecular Orbital (HOMO) – Lowest Unoccupied Molecular Orbital (LUMO) energy gap and electrophilicity index of the dyes. The Conductor-like Model for Real Solvent (COSMO-RS) model demonstrated, for the first time, that several interactions occurred during the adsorption of dyes onto α-chitin. For the Malachite green and Basic Red 18, the Van der Waals forces of the dyes controlled its adsorption behavior. In contrast, the hydrogen bonding interaction governed the adsorption behavior of Alizarin yellow R dye onto α-chitin. The gathered insight from this work might guide us better to understand the molecular level of dyes–chitin interactions and, ultimately, to design adsorbents to remove synthetic dyes from wastewater. 相似文献
62.
Mahmoud Mehranian Reza Farshbaf Pourabad Nemat Sokhandan Bashir Soheila Taieban 《高分子科学杂志,A辑:纯化学与应用化学》2017,54(10):720-726
Moth chitin was extracted from adult of the Mediterranean flour moth by alkali-acid treatment and its characteristics were investigated and compared with shrimp chitin because the specific applications of chitin is directly associated with its physicochemical properties. The results revealed that the moth contained significant amounts of chitin but lower amounts of minerals. Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), scanning electron microscopy (SEM) and energy dispersive x-ray diffraction (EDX) were used to investigate physicochemical characteristics of chitin samples. FT-IR spectra revealed that the moth chitin had α-chitin form (anti-parallel chains) with respect to the different orientations of its microfibrils. The degree of acetylation of chitin from moth and shrimp calculated using the FT-IR stretching bands were 70.82% and 71.42%, respectively. The SEM observation exhibited the presence of fibrillar material and porous structures in surface of the chitin samples. EDX analysis revealed that the main elements present in the moth chitin (beyond C, O and N) were Br (10.5%) and Si (9.7%). Our study of enzymatic activity toward colloidal chitin as substrate showed that the extracted chitin from E. kuehniella had high chemical purity as well as commercial chitin. 相似文献
63.
碳酸钙在水溶性甲壳素溶液中的结晶行为 总被引:1,自引:1,他引:0
依据生物矿化基本原理,以甲壳素作为有机基质,探讨了在不同浓度甲壳素溶液中CaCO3晶体的生长情况;同时研究了生长体系的pH值和温度对生成CaCO3晶体的影响。通过傅里叶红外光谱、扫描电子显微镜进行表征的结果表明,甲壳素溶液中形成的CaCO3晶体完全不同于纯水中形成的晶体;而且甲壳素溶液的浓度不同,形成的CaCO3晶体的晶型也有较大差别。在CaCO3结晶过程中,CaCO3对甲壳素也有影响,即晶体与甲壳素之间存在相互作用。 相似文献
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In order to evaluate the effect of ultrasound to chitinase from a molecular level, atomic force microscopy (AFM) was employed to investigate the interaction force of chitinase binding onto chitin surface. In the measurement of force-distance curve, a series of pull-off events were discovered using the immobilized AFM tips with chitinase either treated by ultrasound or not, whereas no interaction peak was observed by the AFM tips without chitinase, indicating that the obtained adhesion forces were coming from the binding functions between chitinase and chitin. Through the analysis of these force curves, at the loading velocity of 0.3 μm/s, the maximum binding force of the chitinase treated by ultrasound for 20 min onto chitin was measured to be 105.33 ± 23.51 pN, while the untreated onto chitin was 71.05 ± 12.73 pN, suggesting the stronger binding force between ultrasonic treated chitinase and chitin substrate. Therefore, AFM has provided a useful method to directly and quantitatively characterize the interactions between chitinase and chitin, and successfully proved that ultrasound could activate chitinase by enhancing the binding ability of chitinase onto chitin. 相似文献
66.
Aiming at the combination of the biological properties of chitin and the mechanical and thermal characteristics of polyurethane, the two polymers were combined in two macromolecular configurations. In the first, the polymers were mixed forming blends and in the second tridimensional networks were built. The potential application of the two systems as biomedical materials was studied, showing that both blends and networks presented high stability with low mass loss in media simulating living tissue. No toxic products were released and the adhesion to Vero cells was low. These preliminary results in vitro indicated that the materials are potentially biocompatible, with potential bio medical applications. 相似文献
67.
Willian Garcia Birolli Jorge Augusto de Moura DelezukSérgio Paulo Campana-Filho 《Applied Acoustics》2016
This paper discusses the production of chitosan by applying high intensity ultrasound irradiation to alpha-chitin suspended in 40% aqueous sodium hydroxide. The average degree of acetylation (DA) of chitosan was determined by 1H NMR spectroscopy and titrimetry while its viscosity average molecular weight (Mv) was calculated from the intrinsic viscosity as determined by capillary viscometry. The results show that fully acid-soluble chitosans (DA < 32%; 100,000 g/mol ? Mv ? 200,000 g/mol) are produced at very high yield (>95%) by applying non-isothermal ultrasound-assisted N-deacetylation process to alpha-chitin suspension (44 mg/mL). It is also shown that such a process is more efficient than thermochemical N-deacetylation, even being carried out at a lower temperature due to the effects of high intensity ultrasound irradiation. 相似文献
68.
The objective of this study is to explore the effect and mechanism of ultrasound on chitin extraction from shrimp shells powder (SSP) by the co-fermentation of Bacillus subtilis and Acetobacter pasteurianus. After pre-treating the SSP with high-intensity ultrasound (HIU) at 800 W, the protease activity in the fermentation solution reached 96.9 U/mL on day 3, which was significantly higher than for SSP that had not been pre-treated with ultrasound (81.8 U/mL). The fermentation time of the chitin extraction process was 5.0 d without ultrasound pre-treatment, while it was shortened to 4.5 d when using ultrasound at 800 W to treat SSP. However, there were no obvious differences when we applied ultrasound at low power (200 W, 400 W). Furthermore, chitin purified from shrimp shells pre-treated with HIU at 800 W exhibited lower molecular weight (11.2 kDa), higher chitin purity (89.8%), and a higher degree of deacetylation (21.1%) compared to SSP with no ultrasound pre-treatment (13.5 kDa, 86.6%, 18.5%). Results indicate that HIU peels off the protein/CaCO3 matrix that covers the SSP surface. About 9.1% of protein and 4.7% of Ca2+ were released from SSP pre-treated with HIU at 800 W. These figures were both higher than with no ultrasound pre-treatment (4.5%, 3.2%). Additionally, the amount of soluble protein extracted from SSP through HIU at 800 W was 50% higher than for the control sample. SDS-PAGE analysis indicated that the soluble protein was degraded to the micromolecule. It also revealed that HIU (600, 800 W) induced the secondary and tertiary structure destruction of protein extracted from SSP. In conclusion, HIU-induced degradation and structural damage of protein enhances the protein/CaCO3 matrix to be peeled off from SSP. Also, in the co-fermentation process, an increase of protease activity further accelerates deproteinization. 相似文献
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