Owing to its subtropical or tropical environment and climate, South China is home to unique agricultural crops such as sugar cane, pineapple, banana, cassava, and rice, which generate a large amount of lignocellulosic agricultural wastes during agricultural as well as associated industrial processing. The efficient utilization of these wastes will have a significant impact on the economy and sustainable development of South China. This paper reviews the research investigations conducted both in China and elsewhere on the conversion of wastes from these subtropical or tropical agricultural crops into useful chemicals, energy, and biomaterials. The goal of this paper is to promote and summarize the extensive investigations on these agricultural wastes for the development of biorefinery.

Hydroxypropyl celluloses (HPC) were homogenously synthesized by the reaction of cellulose with propylene oxide in NaOH/urea aqueous solution. Water-soluble HPC with molar degree of substitution (MS_NMR) in the range of 0.52~0.78 was prepared from microcrystalline cellulose, cotton linters, and spruce sulfite pulp. The structure of the HPC samples was characterized by means of FT-IR, NMR, gas chromatography (GC), and size exclusion chromatography (SEC) analyses. Three types of cellulose samples with different molecular weights were found to dissolve well in the NaOH/urea solvent with no obvious differences in reactivity and regioselectivity. The relative reactivity of hydroxyl groups in the glycosyl unit was in the following order: O-6 > O-2 > O-3. In addition, the results of the study indicated that the tandem reaction during hydroxypropylation could be ignored.