44 research outputs found
Nitrogen-enriched activated carbons prepared by the activation of coniferous tree sawdust and their application in the removal of Nitrogen dioxide
New functionalised polymeric microspheres for multicomponent solid phase extraction of phenolic compounds
Characterisation of Activated Carbons with High Surface Area and Variable Porosity Produced from Agricultural Cotton Waste by Chemical Activation and Co-activation
Preparation and catalytic performance of a carbon-based solid acid catalyst with high specific surface area
Structure and properties of oxidatively stabilized viscose rayon fibers impregnated with boric acid and phosphoric acid prior to carbonization and activation steps
The role of boric acid-phosphoric acid (BA-PA) impregnation and oxidation on the structure and properties of viscose rayon fibers was examined in air at temperatures ranging from 150 to 250 A degrees C. The results obtained from the measurements of fiber thickness, linear density, X-ray diffraction, thermal analysis (DSC and TGA), and infrared spectroscopy demonstrated that oxidation temperature had a significant influence on the structure and properties of oxidized viscose rayon fibers. Physical transformations were characterized by fiber thickness and linear density values together with color variations and improved burning behavior with progressing oxidation temperature. The DSC analysis showed that BA-PA impregnation enhanced thermal stability and prevented the evolution of volatile by-products by blocking the primary hydroxyl groups. TGA thermograms revealed an enhancement in the char yields. X-ray diffraction analysis showed the loss of cellulose II crystalline structure caused by the decrystallization process initiated by the gradual loss of intermolecular hydrogen bonds. Analysis of IR spectra revealed gradual and continuous loss of intramolecular and intermolecular hydrogen bonding as part of the simultaneously occurring dehydrogenation and dehydration reactions. Analysis of IR data also demonstrated the disturbance of the cellulose II crystalline structure with increasing oxidation temperature in agreement with the results obtained from X-ray diffraction measurements. The formation of C=C bonds attributed to the crosslinked ladder-like structure was also confirmed by the IR spectra.The role of boric acid–phosphoric acid (BA–PA) impregnation and oxidation on the structure and properties of viscose rayon fibers was examined in air at temperatures ranging from 150 to 250 C. The results obtained from the measurements of fiber thickness, lineardensity, X-ray diffraction, thermal analysis (DSC and TGA), and infrared spectroscopy demonstrated that oxidation temperature had a significant influence on the structure and properties of oxidized viscose rayon fibers. Physical transformations were characterized by fiber thickness and linear density values together with color variations and improved burning behavior with progressing oxidation temperature. The DSC analysis showed that BA–PA impregnation enhanced thermal stability and prevented the evolution of volatile by-products by blocking the primary hydroxyl groups. TGA thermograms revealed an enhancement in the char yields. X-ray diffraction analysis showed the loss of cellulose II crystalline structure caused by the decrystallization process initiated by the gradual lossof intermolecular hydrogen bonds. Analysis of IR spectra revealed gradual and continuous loss of intramolecular and intermolecular hydrogen bonding as part of the simultaneouslyoccurring dehydrogenation and dehydration reactions.Analysis of IR data also demonstrated the disturbance of the cellulose II crystalline structure with increasing oxidation temperature in agreement with the results obtained from X-ray diffraction measurements. The formation of C=C bonds attributed to the crosslinked ladder-like structure was also confirmed by the IR spectra