Research On The Clean Preparation Of Kenaf Fiber Based On Eutectic Solvent

As the demand for comfortable,healthy and ecological textiles increases,the application of renewable hemp fibers to the textile industry is one of the research and development trends in the textile field.The new high lignin content of hemp fiber has become an important source of natural fiber.As a traditional textile fiber resource,kenaf has not been effectively used in textile production for a long time.The main reason is that there are a series of problems in the preparation of hemp fibers by traditional degumming methods,including long process,long time consumption,and water resource requirements Large,polluting,etc.,it is necessary to develop an efficient and eco-friendly degumming method to produce kenaf bast fiber.The eutectic solvent is a new type of green solvent,which is non-volatile,non-flammable,non-toxic,biodegradable and thermally stable.The eutectic solvent assisted degumming method is expected to achieve green,simple and efficient extraction of hemp fibers.In addition,microwave technology and ultrasonic technology are also cutting-edge technologies for fiber degumming.This subject combines microwave technology and ultrasonic technology to research and develop a new multi-element eutectic solvent degumming method and apply it to the extraction of kenaf fiber.The main research contents are as follows:(1)Compounding and optimization of eutectic solventsIn order to select a suitable kenaf degumming eutectic solvent,this study analyzed the effects of different hydrogen bond donors and different molar ratios between components on the physicochemical properties of the eutectic solvent and the effect of predegumming of kenaf fiber.The results show that the type of hydrogen bond donor and the appropriate molar ratio are very important for the formation of eutectic solvents.At a molar ratio of 1: 2,the Ch-U system can form a uniform,stable,and transparent liquid eutectic solvent at room temperature.At other ratios,the mixture will stand at room temperature as a solid showing one of the reagents' state.Different eutectic solvent systems have different treatment effects on kenaf bast,and lignin removal rate and degumming effect are obviously different.The eutectic solvent of the choline chloride-urea system(Ch-U)has a moderate effect on kenaf bast and can effectively remove part of the lignin(lignin content decreased from 15.7% to 11.4%).(2)Optimization of microwave pretreatment and ultrasonic alkali treatment conditionsIn order to study the best process conditions of eutectic solvent in microwave pretreatment and ultrasonic alkali treatment of kenaf bast,single factor experiments wereconducted with kenaf residual gum rate as indicators.The results show that the optimal microwave eutectic solvent pretreatment process is 130?,the bath ratio is 1:20,and the kenaf bast is 20 minutes.The optimal ultrasonic alkali treatment process is 50?,and the kenaf bast is 1 hour.(3)Preparation of kenaf fiber by eutectic solvent degumming method and characterization of fiber qualityIn order to improve the degumming efficiency,this study designed the eutectic solvent-microwave and eutectic solvent-microwave-alkali ultrasonic how far eutectic solvent degumming method,and applied to the preparation of kenaf fiber.The results show that the ultrasonic alkali treatment of kenaf bast after microwave DES pre-degumming can effectively prepare kenaf fiber,and compared with the traditional two-step alkaline cooking method,the appearance and residual gum rate(9.42%,7.38%)),Cellulose(88.17%,89.45%),hemicellulose(9.27%,7.33%)and lignin(2.57%,2.87%)are similar.In addition,the linear density(4.13 tex)of kenaf fiber prepared by ultrasonic alkali treatment after microwave DES pre-degumming is slightly higher than that of kenaf fiber(3.22 tex)prepared by traditional two-step alkaline cooking method;the elongation at break is similar(2.76%),2.75%)The main body feels harder;the breaking strength(13.65 cN/tex)of kenaf fiber prepared by ultrasonic alkali treatment after microwave DES pre-degumming is lower than that of kenaf fiber prepared by chemical two-step alkaline cooking(18.90 cN/tex).(4)Benefit analysis of eutectic solvent degumming method for clean preparation of kenaf fiberCompared with traditional chemical degumming,the degumming method of ultrasonic alkali treatment after microwave DES pre-degumming is compared with the time,water consumption and the use of chemical reagents.The results show that the microwave DES pre-degumming and ultrasonic alkali treatment degumming method compared with the traditional chemical two-step alkaline cooking method when treating 1kg of kenaf bast with 1.76 kg of chemical reagent,the reaction time is shortened by 2.67 h,resulting in waste water pollution Things have been reduced by 2/3.