A recent mathematical model describing the pretreatment and alkaline hydrolysis of lignocellulosic biomasses in twin screw extruders (TSEs) is used to study the deconstruction and degradation of blue agave bagasse (BAB), an important waste biomass from the Tequila industry, in a laboratory-scale extruder. This pretreatment process using TSEs is technologically important. Experiments using NaOH for the delignification, extraction, and partial hydrolysis of hemicellulose and cellulose were performed. The effects of using different configurations of the screw elements, temperatures, and operational conditions on biopolymer degradation were assessed. NaOH concentration, residence time, and temperature are found to be determining factors in the extraction of cellulose and hemicelluloses. Partial hydrolysis of the carbohydrates is observed at some of the studied conditions. Reasonably good agreement between experimental data and model predictions is observed, which confirms that the key aspects of the actual process are captured well with the model. This modeling frame may be used in the future for the analysis and study (e.g., scaling up) of industrial processes.
A critical review on the synthesis, characterization, and modeling of polymer grafting is presented. Although the motivation stemmed from grafting synthetic polymers onto lignocellulosic biopolymers, a comprehensive overview is also provided on the chemical grafting, characterization, and processing of grafted materials of different types, including synthetic backbones. Although polymer grafting has been studied for many decades—and so has the modeling of polymer branching and crosslinking for that matter, thereby reaching a good level of understanding in order to describe existing branching/crosslinking systems—polymer grafting has remained behind in modeling efforts. Areas of opportunity for further study are suggested within this review.
The graft polymerization reaction between ethylene carbonate (EC) and scots pine sawdust (SPS) or peat moss (PM) offers a solvent-free approach to the simple and inexpensive aliphatic derivatization of these lignocellulosic fibers. This reaction was studied with liquid or vapor EC phases in three different reactor configurations: batch stirred (BSR), semi-continuous stirred (SSR) and continuous tubular in the gas phase (CVTR). The use of a vapor phase allowed a satisfactory grafting yield and minimal production of non-grafted polyol by-products. The crosslinking agent 4,4'-methylenebis(phenylisocyanate) (MDI) achieved superior characteristics to form shaped tablets resistant to water disaggregation, a high water retention capacity and high compression strength, characteristics that conventional organic supports like PM or PM-polyurethane foam mixtures used in biofiltration of waste gases do not completely possess.
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