Lignin degradation is an effective means of achieving the high-value application of lignin, but degradation usually requires the use of high temperatures and harsh reaction-conditions. This study describes a green, mild approach for the degradation of lignin, in which chlorine dioxide (ClO2) was used for the oxidative degradation of lignin (IL) in an acidic aqueous suspension at room temperature. The optimal process conditions were: 30 mL of ClO2 solution (2.5 mg·L-1), pH 4.5 and 3 h. The FT-IR, NMR (1H NMR, 2D-HSQC and 31P NMR), XPS and GPC analyses indicated that lignin could be degraded by ClO2 relatively well at room temperature, to form quinones and muconic acids. Additionally, DIL was reduced to substances with a high phenolic-hydroxyl (OH) content (RDIL) under the presence of NaBH4, which further confirmed the composition of DIL and which can be applied to the development of lignin-based phenolic resins, providing a reference for the further modification as well as the utilization of DIL.
Abstract— The plasticized poly(vinyl alcohol) (PVA) films were prepared by the casting method using glycerin as the plasticizer. The interaction between PVA and glycerin was analyzed by Fourier transform infrared(FTIR) spectroscopy, Thermogravimetric analysis(TGA) and Differential scanning calorimetry(DSC). Thermal properties, water resistance and mechanical properties of PVA and plasticized PVA were studied respectively. It was found that the glass transition temperature and thermal decomposition temperature of modified PVA were lower than PVA. The plasticized PVA had lower strength and higher elongation at break, lower degree of swelling and higher solubility than PVA.
The GC-MS technique was applied to analyze the essential oil extracted by hydrodistillation from Pinus massoniana Lamb.,P.sylvestris var.mongolica Litvin.and Abies nephrolepis(Trautv.)Maxim needles.The results showed that the essential oil yields of P.massoniana,P.sylvestris and A.nephrolepis were 0.50 %,0.43 %,0.48 % respectively.Forty-six components in the essential oil from P.massoniana needles were identified,representing 99.24 % of the TIC peak area.The main componentsare α-pinene(16.30 %),β-caryophyllene(14.65 %),β-pinene(9.38 %),etc.Thirty-seven components in the essential oil from P.sylvestris needles were identified,representing 99.08 % of the TIC peak area.The main components are δ-cadinene(18.55 %),α-cadinol(10.23 %),τ-muurolol(9.84 %),etc.Forty-eight components in the essential oil from A.nephrolepis needles were identified,representing 99.73 % of the TIC peak area.The main components are bornyl acetate(19.16 %),α-limonene(14.93 %),alcanfor(10.73 %),etc.The contents of monoterpenes in the essential oil from P.massoniana are 43.80 %,sesquiterpenes are 50.21 %,and diterpenes are 4.63 %.The contents of monoterpenes in the essential oil from P.sylvestris are 12.72 %,sesquiterpenes are 84.73 %,and diterpenes are 0.25 %.The contents of monoterpenes in the essential oil from A.nephrolepis are 75.59 %,sesquiterpenes are 20.46 %,and diterpenes are 1.72 %.The essential oil yeilds of the 3 spcies were similar but their chemical components and contents differed greatly,which might be resulted from the factors of species,age and growth environment.
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