| Pulping and papermaking waste is mainly composed of lignin.However, lignin possessesinherently complex structure,ununiform moleculer weight distribution,and lower reactivity.Sofar,the utilization of lignin was less than1%in chemical resources.The objectives of this paperis to design and synthesis a kind of deep eutectic ionic liquid,by this DES and plasma toincrease the activite point of reaction and improve the activity of lignin.We studied the DESdosage, reaction temperature and time on alkali lignin macromolecules fragmentation reactionmechanism.With plasma followed by degradation techniques were using a variety of gasesdielectric barrier discharge plasma treateated with lignin, study the best conditions and the roleof plasma oxidation mechanism of action of lignin degradation.The last,under these optimumconditions will be the plasma treatment for eutectic ionic liquid, handling activated alkalilignin, explore the synergistic effect.According to the study, following coclutions were arrived:(1) Synthesis of ionic liquid eutectic by different raw material ratios, temperature,infrared spectroscopy showed DES compared with a simple mixture of urea and ZnCl2there isa new strong absorption peak, indicating that the system has a new substance formed; thentesting the DES system for physical characterization, the results show the molar fraction of30%ZnCl2DES system has a low Tg (-16.7℃), density, viscosity, surface tension, highconductivity and stability was superior to ZnCl240%mole fraction of Urea/ZnCl2DES.(2) Use the above two kinds of DES to activating lignin, and through ESR, FTIR, ligninphenolic hydroxyl content,1H-NMR to explain the effect of the modified lignincharacterization. Total hydroxyl content as a indexe,the optimum experimental condition was:a molar fraction of30%ZnCl2of DES system, solid-liquid ratio of1:70, the processing timewas1h.After treating,total phenolic hydroxyl content increased from2.231L·g-1·cm-1to6.678L·g-1·cm-1.FTIR showed there was a certain degree of degradation in lignin.1H-NMRfurther proof of the breaking of β-0-4-type bond, methoxy syringyl structural unit is reduced toincrease the hydroxyl content of lignin to improve the activity. XPS analysis was the C1andC2incthesed, C3and C4reduced, demonstrated degradation also. C9empirical formula ofCPL and L1obtained by elemental analysis respectively is C9H10.67O3.2（OCH3）1.7、C9H12.26O3.17（OCH3）1.4, demonstrating the occurrence of degradation in lignin.(3) Adopting the method of single factor experiment, using different plasma gases,processing power, time and gas flow to treat lignin. By contact angle measurements, ATR-FTIR,ESR, SEM studied the effects of plasma on lignin structure and explored its oxidationmechanism. After processing, the surface wettability of the sheet-like industrial alkali lignin becomed better, showed that plasma can improve the number of polar groups on the surface oflignin, ATR-FTIR proved that plasma can make the surface of lignin carbonyl and carboxylcontent increasing,air, oxygen, argon plasma can make lignin chemical bonds break, having acertain degree of degradation effect, in which oxygen plasma oxidation effect was best.Through the ESR analysis, we got that different gas plasma proced different free radicals,determining the optimum processing conditions was: Oxygen atmosphere,60s,150w,1L/mingas flow. XPS instructed that plasma introduced oxygen-containing functional groups to ligninsurface, oxidation reaction occurred. Throgh SEM we can see the plasma made the surface ofthe lignin become rough, showed the plasma had a etching effect on lignin. These results provethat plasma treatment had an oxidative degradation effect on lignin.(4) Comparing CPL、L1、L2、L3，discussion the two methods for the synergistic effect onlignin. ESR showed that combination can significantly increase the quantity of free radicals,which is because after Urea/ZnCl2DES processing, lignin got a certain degree of degradation,increased in the number and activity of free radicals. ATR-FTIR was further evidenced that thealkali lignin happened oxidation reaction through combination. XPS showed the results wasplasma introduced oxygen-containing functional groups to lignin surface, but the effect is lessthan simple plasma treatment, it may be because a series of complex reactions, this pendingfurther study. |
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