Efficiency of acetic acid and formic acid as a catalyst in catalytical and mechanocatalytical pretreatment of barley straw

In this study, the potential of organic acids (formic acid, acetic acid) in a catalytical and mechanocatalytic conversion of lignocellulosic barley straw to valuable sugars is explored using sulfuric acid as a reference. Acid-catalyzed hydrolysis has been carried out with acid-impregnated samples as well as unmodified barley straw. In the mechanocatalytical approach, pretreatment consists of impregnation with the acid catalyst and mechanical treatment by ball milling following chemical hydrolysis. Straw samples and residues were analyzed by Fourier transform infrared spectrometry (FT-IR) whereas hydrolysate analysis was based on total reducing sugar (TRS) determination following the DNS method and capillary electrophoresis (CE) analysis. The results indicated that acetic acid and formic acid are rather mild acids yielding low TRS levels compared to the reference acid. Mechanocatalytical pretreatment slightly increased TRS yields, but not significantly. Strikingly, sulfuric acid showed an efficient conversion efficiency yielding almost 45% of TRS. Furthermore, this study provided evidence for the acetylation of straw components when acetic acid was used as catalyst. Alkali hydrolysis induced the de-esterification, but revealed no significant increase of TRS yields.     

Dissolution and stability of chitosan in a sodium hydroxide/urea aqueous solution

Medium‐molecular‐weight chitosan (MMWC; 157.5 kDa) and low‐molecular‐weight chitosan (LMWC; 53.4 kDa) samples were dissolved in an NaOH/urea solution by freeze–thaw treatment. The factors affecting dissolution were optimized, and the stability of chitosan in the produced solution was investigated. NaOH and urea concentrations of 2 and 0.67 mol/L, respectively, and a treatment temperature of ?18°C were optimized as the dissolving conditions. MMWC and LMWC could be completely dissolved in the 2 mol/L NaOH/0.67 mol/L urea solution after six and five cycles of freeze–thaw treatments, respectively. Dissolution and storage in the 2 mol/L NaOH/0.67 mol/L urea solution slightly increased the deacetylation degree of chitosan and slightly decreased the molecular weight. The solution stability of LMWC was better than that of MMWC. MMWC tended to form a gel during storage. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39819.     

Synergistic effects of modified TiO2/multifunctionalized graphene oxide nanosheets as functional hybrid nanofiller in enhancing the interface compatibility of PLA/starch nanocomposites

The aim of this study is to investigate the synergistic effects of modified TiO₂/multifunctionalized graphene oxide nanosheets at different ratios on the interface compatibility between starch and poly(lactic acid) (PLA). To this end, silanylated nano-TiO₂ (MTiO₂, 1 and 2%) and alkylated maleic anhydride grafted graphene oxide (f-GO, 0.1, 0.2, and 0.4%) at different combinations are blended with the PLA-starch composites using solution blending technique. Then, the synergistic effects of MTiO₂ and f-GO on PLA/starch matrix are investigated in terms of the morphology, crystallinity, structural characterization, thermal stability, dynamic mechanical, and antiaging properties, and the related mechanisms. The Raman and Fourier transform infrared spectroscopy spectra verify the successful synthesis of the two modified nanofillers (f-GO and MTiO₂) and the formation of strong hydrogen bond within the PLA-starch nanocomposites. Due to the strong interfacial interaction and the synergistic effect from the combination of 1% MTiO₂ and 0.2% f-GO, obvious improvement was observed in PLA-starch versus other nanocomposites in terms of morphology, thermal stability, surface hydrophobicity, storage modulus, ultraviolet-shielding capacity, and aging-resistance. Furthermore, differential scanning calorimeter (DSC), isothermal crystallization kinetic, and X-ray diffraction analysis demonstrate that f-GO and the M-TiO₂ significantly synergize in enhancing the crystallization rate and crystallinity of PLA/starch matrix. These results provide novel insights for constructing high-performance nanocomposites and facilitate their applications in food packaging.     

燕麦β-葡聚糖的凝胶质构性能研究

以我国山西产燕麦为原料,提取并分离纯化燕麦β-葡聚糖,以X-T21型质构仪为主要研究设备,重点研究了β-葡聚糖凝胶性能和相关影响因素。研究结果表明,β-葡聚糖的浓度和分子质量大小会直接影响其凝胶的形成。同时,其凝胶性能受β-葡聚糖浓度、分子质量、pH、溶剂种类和盐等因素的影响。提高β-葡聚糖浓度、分子质量、降低体系pH和添加适量的盐、尿素及硼砂等均有助于其凝胶质构性能的改善;而提高体系pH、增加溶剂种类的极性则会降低其凝胶质构性能。     

茶叶籽淀粉提取工艺研究

以茶叶籽为原料,利用超声波辅助水提法工艺从中提取淀粉。响应面分析得出茶叶籽淀粉的最佳提取条件为：原料粉碎度60～80目,液固比为6．9：1（mL/g）,浸提温度48℃,浸提时间3．7h,兑浆水pH为9,超声时间40min。此条件下,淀粉提取率可达81．93％,粗淀粉中淀粉含量为84．53％。     

Effects of sulfate ions and slightly acidic pH conditions on Cr(VI) adsorption onto silica gelatin composite

The feasibility of utilizing CTAB–silica gelatin composite (C-SGC) to remove hexavalent chromium from aqueous solutions under different conditions was investigated. Removal of chromate was assessed through evaluation of the adsorption kinetics of chromate ions on the composite under equilibrium conditions in the presence of sulfate ions and at a slightly acidic pH condition (pH 5.8). Adsorption competition tests in the presence of sulfate ions showed that Cr(VI) was still effectively adsorbed from aqueous solution regardless of the presence of the competing anions. In fact, the adsorption kinetics performed at different initial chromate concentrations were unaffected by the presence of 100 mg L^?1 sulfate ions (pH 7.5). The equilibrium adsorption data were fitted by Freundlich adsorption isotherms which confirmed that the adsorption efficiency of chromium on the CTAB–silica gelatin composite was unchanged in the presence of sulfate ions. Further, the adsorption process was shown to be pH dependent and more efficient at slightly acidic pH (5.8). These findings demonstrated a high specificity of the CTAB–silica gelatin composite for chromium, and highlight the possibility of using this matrix for efficient removal of chromium from industrial wastewater without the need to eliminate contaminant sulfate ions.     

燕麦的综合开发与利用

分析了燕麦的各组成成分,主要有蛋白质、淀粉、β-葡聚糖、膳食纤维和脂质,介绍了燕麦的生理和营养功能、提取方法及应用,旨在对燕麦进行综合利用,提高其经济效益和社会效益。     

高效液相色谱法测定柑橘中的柠檬苦素类似物

建立了同时测定柑橘中柠檬苦素和诺米林2种苷元的高效液相色谱方法。色谱柱为Phenomenex C18(250mm×4.6mm,5μm),流动相为体积分数45%乙腈,流速为1.0mL/min,柱温为25℃,检测波长在210nm。经考察该方法可行性强,柠檬苦素和诺米林的平均回收率分别99.91%和98.28%,RSD分别为2.55%和2.30%。因此用该法测定了柑橘中的柠檬苦素和诺米林的含量,并取得了理想的结果。     

A new strategy for the preparation of porous zinc ferrite nanorods with subsequently light-driven photocatalytic activity

Porous zinc ferrite (ZnFe₂O₄) nanorods have been synthesized by the thermal decomposition of ZnFe₂(C₂O₄)₃ nanorods precursor, which was prepared by template-, surfactant-free solvothermal method. The morphology and structure of the obtained ZnFe₂(C₂O₄)₃ nanorods precursor and porous ZnFe₂O₄ nanorods were characterized by X-ray powder diffraction, transmission electron microscopy, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicated that the as-synthesized ZnFe₂O₄ retained the precursor morphology of 1D nanorods with diameters of 100–200 nm and lengths of several micrometers and plenty of nanoparticles were interconnected to each other to form porous nanorods. The as-prepared ZnFe₂O₄ nanorods as a kind of subsequently light-driven photocatalyst exhibited good photocatalytic decomposition activity for methylene blue (MB).