Modification Of Hemicellulose And Its Application In Retention And Drainage System Of Papermaking

The mass utilization of oil and coal resources makes the non-renewable resources lessand brings many environment problems at the same time. So the utilization of renewable andbiodegradable natural biomass has caused wide public concern. The content of hemicellulosein biomass is rich. But most of the hemicellulose becomes waste because its complexchemical structure which limits its application to low utilization rate in industrial production.So the modification of hemicellulose to increase its utilization value has become a researchhotspot.With the strating point of high use value of hemicellulose, this paper mainly study themodifications of hemicellulose with different modifying agents and the applications of themodified products in retention and drainage system of papermaking. In order to make itbecome the new renewable, biodegradable retention and filtration aid in papermaking.This thesis mainly discuss the modifications of hemicellulose respectively with the2,3-epoxypropyltrimethylammonium chloride (EPTA), acrylamide (AM) and the combinationof2,3-epoxypropyltrimethylammonium chloride and acrylamide (EPTA+AM) as modifier.The products are characterized by Fourier transform infrared spectroscopic analysis,thermogravimetric analysis and13C-NMR spectrum analysis. The degree of substitute (DS),Zeta potential and charge density are measured so as to optimize the reaction conditions likethe alkali concentration, reaction time, reaction temperature and dosage of modifier. Then inorder to characterize the application effect on retention and drainage system of papermakingof modified products, the fines rention using the products as the additives are measured by thedynamic filter water meter.Results show that:(1) With EPTA as modifying agent, the substitution degree can reach0.112when the alkali concentration is5%, the reaction time is3h, the reaction temperature is60℃, EPTA/Xylan (mass ratio) is1.5:1, mass ratio of water to Xylan is20:1, alcohol waterratio is4:1. Under these conditions, Zeta potential can reach-5.94mv and it is improved24.56mv compared with the native-30.50mv, Charge density can reach-0.248mmol/g andit is improved0.253mmol/g compared with the native-0.501mmol/g. (2) With AM as modifying agent, the substitution degree can reach0.47when the alkaliconcentration is15%, the reaction time is5h, the reaction temperature is60℃, AM/Xylan(mass ratio) is12:1, mass ratio of water to Xylan is20:1, alcohol water ratio is1:1. Underthese conditions, Zeta potential can reach-21.8mv and it is improved8.7mv compared withthe native-30.50mv, Charge density can reach-0.318mmol/g and it is improved0.183mmol/g compared with the native-0.501mmol/g. The theromal stability decreases but stillsatisfys the requirments of papermaking.(3) With the combination of EPTA and AM (EPTA+AM) as modifying agents, thesubstitution degree can reach0.40when the alkali concentration is9%, the reaction time is4h,the reaction temperature is60℃,(EPTA+AM)/Xylan (mass ratio) is8:1, EPTA/AM (massratio) is1:1, mass ratio of water to Xylan is20:1, alcohol water ratio is1:1. Under theseconditions, Zeta potential can reach+26.7mv and it is improved57.2mv compared with thenative-30.50mv, Charge density can reach+0.604mmol/g and it is improved1.105mmol/gcompared with the native-0.501mmol/g. The theromal stability decreases but still satisfys therequirments of papermaking.(4) Modified products are applied into retention and drainage system of papermaking tostudy the fines retentions, the experimental results show that fines retention is improved.