Preparation And Mechanism Study Of Kenaf Fiber Based On Steam Explosion And Fenton Oxidation

With the development of society and economy,more and more green and ecological textile products are needed.The development and utilization of natural cellulose fibers have become more and more important in the textile industry.Because of its excellent moisture permeability and unique style,hemp products are favored by people.However,hemp fiber is difficult in degumming.Steam explosion pretreatment method has the advantages of high efficiency,low energy consumption and low pollution.The degumming effect can be greatly improved by combining with chemical reagent presoak.Fenton oxidation combined with alkali boiling degumming can effectively remove the lignin of complex structure in hemp fiber.For the development of new type of hemp fiber and modifying hemp fiber degumming process,the pretreatment of kenaf fiber of presoak-steam explosion method,combined with Fenton oxidation and alkali boiling treatment were used in this article.It discussed how the parameters among presoak steam explosion-Fenton oxidation and alkali cooking process including presoak reagent,alkaline presoak concentration,pressure holding time,the concentration of hydrogen concentration and alkali concentration,effect on the physical and chemical properties of kenaf;Also,we studied the changes of microstructure of kenaf during the whole process by SEM,XRD,FTIR,FTIR-images,GPC,NMR and TG.The results of the research were as follows:1.The effect of chemical reagent pretreatment on the morphology,chemical composition,crystallinity and the adsorption properties of the kenaf fiber was studied.The results show that the chemical reagent and steam explosion together can effectively remove the hemicellulose,lignin,pectin and other non cellulose material of kenaf fiber,make the fiber disperse,promote fiber’s adsorption on iron or ferrous ion,which is conducive to the subsequent oxidative degumming.Among them,sulfuric acid at high temperature mode is easy to damage the cellulose,which is unfavorable for textile application;hydrogen peroxide presoak-steam explosion is not effective on fiber dispersion and gum removing,and the fiber has poor adsorption of iron;the most effective in dispersing is alkali pretreatment,which is good for the subsequent oxydic degumming,and it is recommended for steam explosion of kenaf fiber.2.The effect of alkali presoaking concentration and holding time on fiber morphology,chemical composition and the effect of adsorption of iron,and the effect of concentration of hydrogen peroxide and alkali on kenaf fibers’ morphology,lignin content and cellulose viscosity were studied.The results show that the alkaline steam explosion can effectively remove hemicellulose,but the lignin removal effect is not obvious.The presoak concentration of 1%,the holding time of 3 min was the most suitable parameter,too high presoak concentration or the too long holding time is not conducive to the subsequent degumming process.Fenton oxidation and alkali boiling degumming can effectively remove lignin.When the concentration of hydrogen peroxide is 2%,alkali cooking concentration is below 1%,the effect is appropriate.Bigger concentration damages the cellulose too much,which is unfavorable for textile application.3.The mechanism of the alkaline steam explosion-Fenton oxidation and alkali boiling treatment on the microstructure influence of kenaf fiber was studied.The results showed that the pretreatment of alkaline steam explosion could effectively remove most of the hemicellulose from kenaf fiber,and the Fenton oxidation and alkali cooking could effectively remove the lignin in the fiber.After treatment,hemicellulose,pectin,lignin and other amorphous materials as well as disordered areas in cellulose were gradually removed.With the aggravation of the treatment,the non-cellulosic material was removed,the cellulose was exposed gradually,and because of the inhomogeneity of the degumming process,the cellulose was gradually damaged,resulting in the decrease of the degree of polymerization.But the whole process does not change the chemical structure of cellulose.The structure of lignin changed with the treatment,which is helpful for removing.In addition,due to the increase of the crystalline part,the thermal stability of kenaf fiber is getting better and better,which is advantageous for textile usage.4.Comparison of the alkaline steam explosion and Fenton oxidation-alkali boiling degumming and traditional chemical method were studied.The results show that the alkaline steam explosion and Fenton oxidation-alkali boiling degumming fiber is better on dispersion and average fineness than the traditional chemical degumming fiber.Although the length and breaking strength are not as good as the traditional chemical degumming fiber,it still fits to the standard of spinning.