Spectroscopic and Microscopic Study of Peroxyformic Pulping of Agave Waste

Abstract

The peroxyformic process is based on the action of a carboxylic acid (mainly formic acid) and the corresponding peroxyacid. The influences of processing time (60-180 min), formic acid concentration (80-95%), temperature (60-80°C), and hydrogen peroxide concentration (2-4%) on peroxyformic pulping of agave leaves were studied by surface response methodology using a face-centered factorial design. Empirical models were obtained for the prediction of yield, κ number (KN) and pulp viscosity as functions of the aforementioned variables. Mathematical optimization enabled us to select a set of operational variables that produced the best fractionation of the material with the following results: pulp yield (26.9%), KN (3.6), and pulp viscosity (777 mL/g). Furthermore, this work allowed the description and evaluation of changes to the agave fibers during the fractionation process using different microscopic and spectroscopic techniques, and provided a comprehensive and qualitative view of the phenomena occurring in the delignification of agave fibers. The use of confocal and scanning electron microscopy provided a detailed understanding of the microstructural changes to the lignin and cellulose in the fibers throughout the process, whereas Raman spectroscopy and X-ray diffraction analysis indicated that cellulose in the pulp after treatment was mainly of type I.

Determination of Biosorption Mechanism in Biomass of Agave, Using Spectroscopic and Microscopic Techniques for the Purification of Contaminated Water

“…The bands in 1629-1612 cm −1 , 1319 cm −1 ,1313 cm −1 , 1141 cm −1 , 1231 cm −1 , 768 cm −1 , 669 cm −1 can be ascribed to the vibration by the presence of Lignin. Those peaks can be attributed to the vibration of C=C bonds present in lignin and C=O of carbonyl groups and the presence of N-H bonds and C = S.The identified adsorption bands in the spectra are similar to agave bagasse (Hernandez-Hernandez et al, 2016;Cruz-Olivares et al, 2010;Velazquez-Jimenez et al, 2013;Flores-Alamo et al, 2015;Romero-Cano et al, 2016). Fig.…”

“…Also, in this case the disappearance of Mg is observed. The molecules responsible for the biosorption can be lignin, chlorophyll, cellulose, and hemicellulose, which have groups and metals that can participate in the biosorption process, mainly the carboxyl, hydroxyl and metals groups of the porphyrin ring of chlorophyll (Hernandez-Hernandez et al, 2016;Velazquez-Jimenez et al, 2013).…”

Agave By-Products: An Overview of Their Nutraceutical Value, Current Applications, and Processing Methods

“…In this step, fibers are extracted by hydrolysis of the lignin and hemicellulose. Acid hydrolysis depolymerizes the lignocellulosic material, increasing the amorphous cellulose, which favors the release of sugars and improves their digestibility and fermentability [19,76,94]. Diluted acid is the most effective way to achieve high efficiency in hemicellulose depolymerization, but also to degrade the amorphous regions and to obtain cellulose nanocrystals [39].…”

Assessment of Mechanical Property Variation of As-Processed Bast Fibers

“…Coletta et al utilized this confocal microscopy to investigate the effect of alkali and acid pretreatments on the delignification of sugarcane bagasse [45]. Other non-bast natural fibers, such as agave plant fibers and wood tracheids, have also been investigated through fluorescence confocal microscopy [44,46,47]. The methods utilized by Hilda et al were replicated in this study and applied to bast fibers in order to characterize the lignin content in commercially available fibers and investigate its relationship to material properties and their variation [46].…”