Synthesis of Bio-lubricant base stock's (Turning the waste into wealth):
Lubricant is a "substance which induces the relative motion between two moving surfaces to reduce the friction between them, improving the efficiency (lifespan), and reducing wear (stress)". Conventional lubricant base stocks are originated from the fossil resources, which are non-renewable, ecologically unfit, higher cost and lower biodegradability. Due to the aforementioned negative causes, many technocrats are looking forward for the potential alternate renewable raw materials, which can replace the conventional resources. In this regard, non-edible plant seed oils along with waste (used) cooking oils gained much attention to replace the conventional base stocks. Since, the year of 2010, our research group started work on preparation of castor, waste cooking oil and its methyl esters bio-lubricant base stocks.
In choosing the lubricant basestocks its thermo-oxidative stability and cold flow properties plays a major role. Therefore, we determined the aforesaid properties (Borugadda V B and Goud V V., Journal of Renewable and Sustainable Energy, 5, 063104, 2013 and Thermochimica Acta, 577, 33-40, 2014,) and found that properties needs to be improved in ordered to use it as base stock. Further, aforementioned oils and esters were used to prepare bio-lubricant base stock via epoxidation and addition of commercially available high molecular weight alcohols and acids. In every reaction, process parameters were optimized by response surface methodology to obtain maximum product and its significant base stock properties. At the end of each reaction, significant physico-chemical properties were determined for the end product and compared with the conventional lubricant base stock. Currently one of our research groups is extending their thoughts on the formulation of eco-friendly Bio-lubricant base stocks for various applications.
Sub critical water pre-treatment of lignocellulosic biomass:
The conversion of biomass to fuels is advancing on two fronts: first, to enhance the usability of biomass and second, to generate the biofuels. Lignocellulosic-containing plants are those types of biomass that include wood, agricultural and forest residues. Lignocellulose is composed of the biopolymers cellulose, hemicellulose and lignin. Cellulose, a polymer of glucose, is the component in lignocellulose that has potential for the production of fuel-grade ethanol by direct fermentation of the glucose. Lignin generally presents a barrier to biomass utilization and it hinders enzymatic hydrolysis of lignocellulose and raw cellulose into glucose. Since the rate of and extent of hydrolysis of natural cellulose is very slow, it need to be pretreated for its effective hydrolysis to sugars by enzymes. Pretreatment is the most significant determinant of success of cellulosic bioethanol technology because it defines the extent to and the cost at which the cellulose and hemicellulose can be converted to bioethanol. Cost effective pre-treatment of cellulosic biomass is a major challenge of cellulose bioethanol technology and there is a huge scope in lowering the cost of pre-treatment process through extensive research and development approaches. Currently work on subcritical water pre-treatment of locally available lignocellulosic biomass such as bagasse, bamboo, miscanthus etc is in progress. The key objective of this work is to maximize the total reducing sugar content with minimum degraded products 5-HMF etc (Shown in scheme below). This concept was granted and funded by DST for a period of three years
Super Critical Fluid Extraction of Natural Antioxidants for Food Preservation from Spices and Non Conventional Fruits Endemic in North Eastern Region:
Phytochemicals in the strictest sense are chemicals produced by plants having different biological activities, but are not essential nutrients means these are not essentially require for the basic process of growth and development. Plants produce these chemicals to protect themselves from biotic (insects, pests, pathogens, predators etc.) and abiotic stress (drought, heat, cold, submergence etc.) and phytochemicals can also improve humans health and protect against diseases. Phytochemicals are extensively used in food, pharmaceuticals, and cosmetic industries as antioxidants, food additives, flavoring agents, sweeteners, sugar substitutes, coloring substances, drugs and antimicrobial agents etc.
Antioxidants play a major role in preventing or delaying autoxidation and have attracted much attention as food stabilizers, dietary supplements and natural health products. The oxidative deterioration of fats and oils in food is responsible for rancid odors and flavors, with a consequent decrease in nutritional quality and safety caused by the formation of secondary, potentially toxic compounds. The addition of antioxidant is required to preserve flavor, color and to avoid nutrients degradation. Currently, the food process industries are using synthetic antioxidants like butylated hydroxyl anisole (BHA), butylated hydroxyl toluene (BHT) propyl gallate (PG) and tertiary-butyl hydroquinone (TBHQ) to prolong the storage stability of food product. Some reports have indicated that certain synthetic antioxidants such as BHA and BHT may possess carcinogenic effect and have other health hazards in animals. In addition, use of synthetic antioxidants like TBHQ is restricted in many countries. Therefore, it is proposed to develop process to isolate natural antioxidants like ascorbic acid, tocopherols, catechin, lecithin, quercetin, ?-oryzanol, sesamol, etc. from whole spices, herbs, vegetables, or leaves, stems, roots, fruits, seeds, grains and other parts of different plants which are abundant in NE India Region (3 PhD students are working in this area). Super critical fluid extraction process delivers a superior extract which has incredible purity and is highly concentrated. This extraction leaves no harmful residues and the process use natural carbon dioxide unlike solvent extraction with industrial solvents like hexane and acetone where harmful residues of such chemicals may remain in the extract. The microencapsulated Supercritical Fluid Extracted product will be used as a replacement to synthetic antioxidants for food preservation. The natural antioxidants have anti-ageing, anti-carcinogenic, anti-mutagenic, immune protective and many other beneficial effects and therefore can also be used in preventive and therapeutic medicine as well as neutraceuticals in India and abroad. Other products of the process, beside antioxidants, can be used for various purposes. e.g. Essential oil and fixed oils have a wide range of applications in many industries like food processing, pharmaceuticals, soft drink, confectionary and cosmetic industries. Moreover this will fulfill the consumer's demand of safer and natural products. Consequently, the market will increase for such naturally preserved food products which will earn remunerative prices in domestic and export market. This work is carried out in collaboration with Prof. L Sahoo (Dept. of Biotechnology, IIT Guwahati).
Though microalgae stand behind plants in the hierarchy, their unicellular nature, growth characteristics and high lipid accumulation make them more attractive for the biodiesel production than the first and second generation plant derived feedstocks. Photosynthetic behaviour, carbon dioxide sequestration and high lipid productivity per unit area are the advantages of microalgae as a biodiesel feedstock. The drawbacks in biodiesel production from microalgae are the surplus water requirement and downstream processing mainly harvesting. Taking the advantage of biofilm forming capability of microorganisms, both the problems can be overcome. When the microalgae is allowed to form biofilm on a specific substratum or surface instead of cultivating them in raceway ponds or photo bioreactors, the harvesting will become favourable and by recycling the medium, the water requirement can be reduced. M.S. student Ms. Pushpita Das is working on identifying the best microalgae species for this work. Recently this concept was granted and funded by DBT for a period of one year.