This study aims to investigate the production of hydroxymethylfurfural (HMF) and furfural from cassava waste using a sulfonated carbon-based catalyst and to determine the suitable conditions for the reaction. With the use of the catalyst, the appropriate reaction medium for the production of HMF and furfural was a mixture of acetone/DMSO (70/30% w/w) and water at a ratio of 10/90% w/w. The reaction temperature and time were 250◦C and 1 min, respectively, and the corresponding weight ratio of the catalyst to cassava waste was 0.05:1. Furthermore, the carbon-based catalyst was found to be highly stable and thus can potentially replace the conventional homogeneous acid catalysts such as sulfuric acid for biomass conversion to liquid alkane. Particularly, the catalyst plays an important role in enhancing hydrolysis of cellulose and hemicelluloses and promoting the dehydration of xylose and glucose to form HMF and furfural.

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Abstract.Marigold is a rich source of a Xanthophyll called lutein, which shows antioxidant and anti-cancer activities and is beneficial to eye health. This has led to various extraction and purification studies to obtain the high purity free lutein suitable for human applications. Liquid chromatography is extensively used to purify high value natural compounds because the process results in high purity products. The suitable mobile phase and stationary phase are the key factors to achieve high purity. In this work, chromatographic separation of lutein extracted from marigold flowers was investigated, using silica gel and mixture of hexane:ethyl acetate as a stationary and a mobile phase, respectively. Initially, the suitable composition of hexane:ethyl acetate was determined using a thin layer chromatography. Hexane:ethyl acetate mixture at 70:30 volume ratio was found to be an appropriate mobile phase for a normal phase chromatographic separation of free lutein. Preliminary experiments on a semi-preparative and a preparative column carried out at the mobile phase flow rate of 10 ml/min suggested that as high as 97.1 % purity free lutien could be obtained with a 60 % approximate yield. Moreover, since the separation by chromatography arises from the adsorption of free lutein onto silica gel, thus to better understand the process, a batch adsorption study was carried out to obtain the equilibrium adsorption data. The isotherm plotted from these data was found to be reasonably described by Langmuir adsorption model.

This study presents a synergistic catalytic system using the combination of Brønsted hydrothermal carbon-based acid (HTCG-SO3H) and Lewis acid catalysts for one-pot conversion of cellulose to levulinic acid (LA). Chromium chloride (CrCl3), among a number of other Lewis acidic metal chlorides, was found to give the highest LA yields, and was therefore used in combination with the HTCG-SO3H, for cellulose conversion to LA. With the appropriate amount of HTCG-SO3H, the formation of side products could be reduced, resulting in improved selectivity of LA. Compared with that obtained by CrCl3 alone, at 5 wt % HTCG-SO3H, 0.015 M CrCl3, 200 °C and 5 min reaction time, the LA yield was considerably enhanced from 30 wt % to 40 wt %. Since HTCG-SO3H is a heterogeneous catalyst that can be easily prepared from biomass at moderate temperature, its use in such combined catalyst system offers economic and environmental benefits, thus making large-scale implementation of such process potentially feasible.