Effect of High-Temperature Hydrothermal Treatment on the Cellulose Derived from the Buxus Plant

Abstract

Cellulose has attracted considerable attention as the most promising potential candidate raw material for the production of bio-based polymeric materials. In the last decade, significant progress has been made in the production of biopolymers based on different cellulose forms. In this study, cellulose was obtained in an innovative and environmentally friendly way, using boxwood powder. Crude cellulose was obtained by treating Buxus powder with an ethanol–acetic acid–water mixture. Refined cellulose was then obtained by treatment with an acidic sodium hypochlorite solution and alkaline hydrogen peroxide solution. The novel chemistry of cellulose prepared by this method promises to be not only green, but also highly desirable, because of its lower emissions and low cost. It is crucial for the future of the global polymer industry. The refined cellulose was subjected to a high-temperature hydrothermal treatment under two temperatures and time conditions, with temperature gradients of 120, 140, and 160 °C, and time gradients of 1, 2, and 3 h. The samples were subjected to infrared and thermogravimetric analyses. The cellulose undergoes dehydration and thermal degradation reactions during the heat treatment process, and the thermal stability of the residual is enhanced, compared with that of virgin cellulose. Between 120 and 140 °C, the hydroxyl and hypomethyl groups on the surface of cellulose are shed. Groups in the amorphous region of the polymer are the first to be shed. The dehydration reaction reduces the number of free hydroxyl groups on the surface of the cellulose molecules. The dehydration reaction was accelerated by an increase in temperature. Between 140 and 160 °C, the β-(1,4)-glycosidic bond begins to slowly break and some furans are generated. The structure of cellulose undergoes reorganization during thermal treatment. The thermal stability of the modified material is greater than that of untreated cellulose.