Search results for "sellu"

Efficiency of acetic acid and formic acid as a catalyst in catalytical and mechanocatalytical pretreatment of barley straw

2016

In this study, the potential of organic acids (formic acid, acetic acid) in a catalytical and mechanocatalytic conversion of lignocellulosic barley straw to valuable sugars is explored using sulfuric acid as a reference. Acid-catalyzed hydrolysis has been carried out with acid-impregnated samples as well as unmodified barley straw. In the mechanocatalytical approach, pretreatment consists of impregnation with the acid catalyst and mechanical treatment by ball milling following chemical hydrolysis. Straw samples and residues were analyzed by Fourier transform infrared spectrometry (FT-IR) whereas hydrolysate analysis was based on total reducing sugar (TRS) determination following the DNS met…

Transparent hemicellulose-DWCNT electrode

2015

Carbon nanotubes (CNTs) and graphene have shown promising potential as next-generation transparent conducting materials due to their high electrical and thermal conductance, flexibility and transparency in both visible and infrared spectral regions. In this study transparent and conductive thin films with a novel hemicellulose and double-walled carbon nanotube (HC-DWCNT) hybrid material were produced with spray-coating, droplet casting and vacuum filtration deposition methods. HC-DWCNT material is easily dispersed in water and usable for mass-production. These films showed good conductivity, stability at ambient air, very good transparency in the visible and excellent transparency in the in…

Dynaamisen visuaalisen ja auditiivisen aistiärsykkeen havaitsemiskyvyn yhteys lukutaitoon 9- ja 10-vuotiailla lapsilla

2000

Advanced Biorefinery Concepts Integrated to Chemical Pulping

2017

Selective hemicellulose hydrolysis of Scots pine sawdust

2019

The depletion of fossil resources is driving forward the search for new and alternative renewable feedstocks in the production of renewable chemicals, which could replace the petroleum-based ones. One such feedstock is pine (Pinus sylvestris) sawdust, which is generated enormous amounts in Finnish sawmills yearly. However, prior to the utilization in high-value applications, it needs to be fractionated into its constituents. In this work, the objective was to produce monomeric hemicellulose sugars from pine sawdust without degrading cellulose or lignin simultaneously. The influence of the reaction temperature and time, as well as acid type and concentration, was studied. Based on the result…

Pyrolytic behavior of lignocellulosic-based polysaccharides

2018

The thermochemical behavior of cellulose, glucomannan, and xylan was investigated by pyrolysis–gas chromatographymass spectrometry (Py-GC/MS). In each case, major GC-amenable condensable products were classified into several compound groups, and the formation of these monomer-related fragments from the model substance samples was determined at 500, 600, and 700 C with a residence time of 5 s and 20 s. The results revealed that despite some general formation trends, no compound group was selectively formed at certain temperatures. Of the 11 product groups, the primary ones, including lactone, furan, and cyclopentenone derivatives, accounted for 72–85% (from cellulose), 86–90% (from glucomann…

Structural characterisation of wood pulp fibres and their nanofibrillated materials for biodegradable composite applications

2011

Introduction: The utilization of wood pulp fibres in composite materials has gained major interest during the last years. One of the major motivations has been the potential of wood pulp fibres and their nanofibrillated derivatives for increasing the mechanical properties of some materials. However, in order to exploit the full potential of wood pulp fibres and cellulose nanofibrils as reinforcement in hydrophilic and hydrophobic matrices, several characteristics of fibres and their interactions with a given matrix need to be understood. With the increasing capabilities of novel microscopy techniques and computerized image analysis, structural analysis is moving forward from visual and subj…

Host-related factors affectingisopod (Asellus aquaticus) susceptibility to and interaction with an acanthocephalan (Acanthocephalus lucii) parasite

2013

The Effect of Mechanocatalytic Pretreatment on the Structure and Depolymerization of Willow

2020

In this study, the effect of a mechanocatalytic pretreatment on the structure of willow and sugar release from pretreated willow was explored. In the mechanocatalytic approach, the pretreatment consists of solvent-free impregnation with sulfuric acid and a mechanical treatment with ball milling. Willow sawdust and pretreated samples were analyzed with field emission scanning electron microscope and X-ray diffraction. The products in the sugar solution were determined as the total reducing sugars with the 3,5-dinitrosalicylic acid method and monosaccharides with capillary electrophoresis. According to the results, milling increased the sugar production, depending on the sulfuric acid load. T…

Selluloosajohdannaisten rakenteen ja substituutioasteen tutkiminen

2016

Nykyään ympäristöystävällisille, biohajoaville ja uusiutuvista luonnonvaroista valmistetuille tuotteille on suuri kysyntä. Tämän takia erilaiset selluloosan johdannaiset ovat kiinnostavia. Näistä karboksimetyyliselluloosa on eniten käytetty vesiliukoinen selluloosan eetteri. Tässä pro gradu -tutkielmassa käsiteltiin karboksimetyyliselluloosan selluloosarakenteen ja substituutioasteen tutkimuksessa hyödynnettäviä analyysimenetelmiä. Kromatografiset ja spektroskopiset menetelmät ovat tärkeimpiä selluloosarungon tutkimuksessa. Substituutioaste voidaan määrittää esimerkiksi perinteisillä titrausmenetelmillä. Substituutioastejakaumaa puolestaan voidaan tutkia nestekromatografisesti.