Study On Comprehensive And Value-added Utilization Of Rice Husks And Straws

This study proposed hydrothermal sulfonation as component separation method for rice husks and rice straws,the reaction was optimized.Meanwhile,low temperature acetylation and dry-wet combined slurrying were processed to explore the value-added utilization of the products after separation:(1)The optimal conditions for rice straws hydrothermal sulfonation were as follows:reaction temperature at 160?,the ratio of liquid to solid was 5,the dosage of Na₂SO₃ was 10 wt%,the heating time was 80 min and the holding time was 50 min,the yield rate and lignin removal rate of delignificated products were 58.0%and 90.5%respectively;The optimal conditions for rice husks hydrothermal sulfonation were as follows:reaction temperature at 160?,the ratio of liquid to solid was 2.5,the dosage of Na₂SO₃was 20 wt%,the heating time was 50 min and the holding time was 60 min,yield rate and lignin removal rate of rice husks delignificated products were 69.0%and 80.4%respectively;(2)Paper pulp was preparaed with rice straw delignificated products through ball milling and the yield rate was 58.0%;(3)Cellulose acetate was preparaed with rice husks delignificated products through low temperature acetylation.The prepared cellulose acetate with DS=2.40?2.90 and DS>195 were characterized by FT-IR,XRD,¹H NMR,TG and membrane casting test to confirm the structures and properities.The results showed comparable properties to commercial cellulose acetate;(4)The spent liquor from the delignification of rice straws and rice husks were used as dispersant of coal water slurry and coal water slurry with concentration was62.30 wt%,apparent viscosity was 810 m Pa·s and good mobility was preparaed with lignitous coal through dry-wet combined slurrying,this shows the spent liquor from the delignification of rice straws and rice husks have comparable dispersion ability to polycondensation of naphthalene sulfonate formaldehyde,a commercial dispersant.The feasible slurry prepare conditions were:the ratio of coal powder to spent liquor was 7:3(weight ratio),and the optimal powder grade ratio of milled 1 h coal powder to milled 5 h coal powder was 1:1,the slurrying time was 2 h.This paper integrated component separation method of lignocellulose and high value-added utilization of lignin and cellulose,exploited fresh approach for the utilization of rice husks and rice straws,and the rate of comprehensive utilization was nearly 100%.This study provides experimental suggestions for resourceful utilization of agricultural waste and is significant to economy and environment.