Design and optimization of biodiesel production from rice bran oil by transesterification method using lipase enzyme.

Dissertation for M.A.

"Biotechnology trend"

Abstract

Today, due to the reduction of fossil fuel resources and the destructive effects of these types of fuels on the environment, researchers are thinking of alternatives. They are doing it. In recent years, biodiesel fuel is considered the most suitable alternative to diesel fuel due to its renewable nature and less pollution. The primary sources of biodiesel production include wood waste, residues of agricultural products, sugarcane, algae, and vegetable and animal oils. Rice bran oil is a vegetable oil that is available in large quantities in rice-growing countries. The purpose of this study is to design and optimize the production of biodiesel from rice bran oil by transesterification method using lipase enzyme. In this laboratory study, enzyme solutions were first prepared from free lipase enzyme and lipase Novozyme 435 stabilized on nanochitosan and the activity was determined by two methods, including the method of using paranitrophenyl palmitate (pNPP) substrate, and the specific activity of the enzyme was determined by measuring the total protein in the enzyme solution using the Bradford method. 

Then free and stabilized lipase enzymes were used as catalysts in the transesterification reaction. For the production of biodiesel, first the optimal conditions of the transesterification reaction were investigated and finally, the reaction mixture containing rice bran oil 9% by weight, free or stabilized enzyme at a molar ratio of 3:1 with methanol and a ratio of 2:1 by volume of tert-butanol solvent at a temperature of Co40 for 72 hours at 300 rpm was determined as the optimal condition.  After the completion of the reaction, confirmation of the production of methyl ester (biodiesel) was first qualitatively performed by thin layer chromatography (TLC) method, and then the final and quantitative analysis of biodiesel samples was performed using a gas chromatography (GC) device. The use of Sigma free lipase showed a yield of 12%. The higher yield of Novozyme 435 lipase compared to free Sigma lipase can be due to the greater stability of the enzyme and the preservation of higher enzyme activity due to stabilization operations.

Key words: biodiesel, transesterification, rice bran oil, free and stabilized lipase, fuel. rtl;">1-1-Biomass

Increasing environmental awareness and reducing fossil resource reserves lead the industry to expand the production of other viable fuels from renewable sources that are more environmentally acceptable. Biofuel 1 is a type of fuel that is obtained from biomass sources. Biomass is the translation of the word Biomass and refers to all the materials obtained from living organisms and their wastes.

Fossil fuels, which are exploited today, are the source of that biomass, but they were formed in very distant years. 

Today, due to the reduction of fossil fuel sources, on the one hand, the destructive effect of the use of these types of fuels on the environment, has led researchers to think about replacing these sources. Biofuel [1] is a type of fuel that is obtained from biomass sources. Biomass is the translation of the word Biomass and refers to all the materials obtained from living organisms or their wastes and excreta.

Fossil fuels that are exploited today are also the source of that biomass, but they were formed in very distant years]1 [.

1-2- Sources of biomass

Forests and forest wastes

Wood, wood chips and sawdust are considered as biomass forest resources. This source of energy has been used for domestic and industrial purposes for centuries. About one hundred and fifty years ago, 75% of the energy needed by humans was supplied from biomass (mainly from forests and forest waste). At present, more than 1.2 gigatons of wood are consumed annually in the world for energy production.. Many industries in developing countries, such as bread baking industries, processing products such as sugar, tea, coffee, coconut, cocoa, and brick and lime factories, use these wastes as fuel. Sugarcane, all kinds of fruits, oil plants and their wastes such as rice bran, straw and corn. Relatively speaking, 25% of the weight of any agricultural product is waste, 25% of the weight of rice is its bran. About 45% of peanuts are sprouts. Studies show that, theoretically, the domestic fuel needs of rural areas can be provided through waste.

Alcohol and biodiesel are two important energy products that are obtained from agricultural products and waste.

Industrial wastewater waste

In the wastewater of some factories such as textile industries, alcohol There is a large amount of biomass that can be used to produce energy and animal feed from manufacturing, wood and paper, and food industry wastes such as cheese making and fruit juice production. About 20% of the weight of the fruit is pulp (depending on the type of fruit, this amount varies between 9% and 25%). Another food industry whose wastewater causes severe pollution in the environment is the cheese industry. Whey is a liquid obtained after the removal of milk fat and casein during the cheese making process. Whey can be used for both animal feed and alcohol production. In the animal feed industry, by cultivating microscopic living organisms that can collect a lot of protein and grow very well on whey, they prepare a very rich and nutritious biomass, which after drying and grinding the resulting material, it is used as animal feed. In many countries of the world, whey is used to produce alcohol.

Solid waste, urban sewage and livestock waste

Urban solid waste can be divided into two categories:

Ordinary garbage: such as household waste, urinals, stores and restaurants (food waste, paper, Carton) bulky household waste (wooden furniture such as cupboards, tables, etc.) waste from gardens and greenhouses (branches and leaves).

Special waste: such as industrial waste, construction waste, worn tires, radioactive materials and contaminated hospital waste.

1-3- The function of biomass

A large part of the share of biomass energy in supplying the world's primary energy consumption is dedicated to thermal applications and direct combustion, especially in developing countries. The main use of biomass resources is in providing heat and cooking [1].

More than 25 million small and medium-sized digesters have been installed in the world, which use animal and human waste and in this way, gas is produced. India and China are leaders in this field. Among the hot topics that are discussed today in the field of biomass is the production of car fuel in this way, which produced 50 billion liters of fuel from this source in 2006. Biofuels (biofuels) including bioethanol, biomethanol and biodiesel have attracted attention in many countries and Brazil has replaced most of its gasoline consumption with renewable fuels [1]. on the environment, researchers are thinking about replacing it. In recent years, because of renewable and less polluting properties of biodiesel, diesel fuel is considered the most suitable alternative. The primary source of biodiesel production includes wood waste, agricultural waste, sugar cane, algae and vegetable and animal oils. Rice bran oil is a vegetable oil that is present in large amounts in the countries that grow rice.