E.Yu. Kushnir, S.A. Autlov, N.G. Bazarnova
Microwave-Assisted Delignification of Wood with Peracetic Acid
The process of pine (Pinus sylvestris L.) and aspen (Populus tremula L.) delignification with 15% peracetic acid under microwave irradiation at the frequency of 2450 MHz has been studied. Delignification products have been characterized by viscometry, X-ray diffraction and IR spectroscopy methods. It is shown that intensifying effect of microwave radiation allows to reduce wood delignification duration, reducing the depth of oxidation-hydrolytic degradation of cellulose. Optimum duration of pulping was 2–3 times shorter under microwave irradiation as compared to the use of convection heating at 100 °C. On 30 min treatment of wood with peracetic acid pulp samples with 56–58% yield were obtained; polymerization degree was 680– 700, crystallinity index was 0,64 and crystallite transverse size equaled 2,4–2,5 nm. IR spectra of the resulting pulp samples are characterized by the absence of characteristic absorption bands of phenylpropane lignin structures. Absorption in the region of 1730–1740 cm–1 testifies oxidation of hydroxyl groups of cellulose during delignification with peracetic acid under microwave irradiation. Characteristics of the products obtained meet the high yield of pulp with low content of residual lignin.
Key words: pine wood, aspen wood, delignification, peracetic acid, microwave irradiation, high-yield pulp
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