Utilization of sugar industry by-products, the bagasse pith for manufacture of furfural

Abstract

Most of Indian chemical industries have concentrated so far on their production of chemicals mainly on the petroleum based refinery, while other alternatives like those offered by sugar cane have received little attention over the decades. Time is now ripen to pay more attention to explore the possibilities of manufacturing both low volume valued added chemicals and high volume low cost energy from sugarcane economically through both chemical and biochemical routes in most economic ways. Sugarcane offers number of wastes, besides deteriorated sucrose and cane juice, cane leaves and tops, molasses, filter mud, fusel, starch, molasses, bagasse along with pith and bagacillo. The pith, mainly composed of parenchyma cells, has low fiber content which needs lower activation energy compared to any other pentosan bearing materials. This pith is detrimental, not only for production of paper but also it creates health and fire hazardous problems. In this present study, utilization of pith is first reviewed both from research and industrial production point of view for manufacture of furfural and bioethanol in India. It is evident that while the production of the former is in matured state in the industry, the later is in preliminary stage, confined only in the research laboratory. Presently it is recommended by many global industries that furfural and methyl -tetrahydrofuran-based biorefinery. A biorefinery that focuses on converting biomass pentosans to furfural, as a precursor to liquid fuels, appears in many ways to be superior to the ethanol-based concept. Furfural itself is widely used as a solvent in the petroleum refinery, for purification of lubricating oils, plastics and resins, for manufacture of furane resins, for making nylon 6 and nylon 66 (used in the manufacture of parachutes), pharmaceuticals and many others. It is also an important industrial chemical intermediate and can produce wide range of products. Furfural and its derivatives can be manufactured by acid hydrolysis from various raw materials containing cellulose like woods, saw/wood dust, paper dusts, agricultural residues like bagasse, bagasse pith, bagacillo, rice straw, wheat straw, jute stick etc. Even agricultural resources like corn cobs, rice husk, peanut husk, etc. can also been employed. Most of the reported processes use lignocellulosic materials like bagasse, rice straw, barley stalks, zea maize stem pith, rice hull, menthe wastes, oat hulls, cotton seed hull bran, corn stalks, chhestnut etc. However, majority of Indian plants employ either bagasse, or rice husk as raw materials. The process involves hydrolyzing the pentosans of the agricultural resources by digesting them under pressure using mineral acids like sulphuric, hydrochloric, phosphoric and formic acids in presence of metal salts as catalysts such as aluminium, calcium and zinc chloride, besides, pyridine in a fixed or fluidized bed batch reactors and the product is steam distilled. This is then concentrated by fractional distillation. An attempt has been made in the present investigations to explore the possibility of getting furfural using bagasse pith as raw material which needs low thermal energy, low reaction time and operates at comparatively low pressure. The present study has been undertaken to investigate the possibilities of predicting the reactions at low temperature and at atmospheric pressure under the presence of non-polluting catalyst (calcium Acetate) with low heat-input to utilize waste and to produce furfural having no impact on environment. Experiments were conducted in the laboratory starting from isolation of pith, pith characteristics and production of pentosan and furfural. The effects of raw material ratios, temperature, concentration of reactants, reaction time, catalyst type and concentration were optimized for maximum yield. An attempt is also made to compute activation energy which helps to develop an appropriate kinetic model.