- Biodiesel production by novel techniques such as ultrasonication, continuous-microwave, radio frequency and microbial process
- Value-added utilization of crude glycerol by catalytic steam reforming, high temperature and pressure and microbial techniques
- Catalytic steam reforming of butanol over mixed oxide catalysts
- Catalysts for pressurized pyrolysis of cassava to produce possible fuels and chemical feedstocks
Microwave pyrolysis (MP) is a relatively new technique that provides many advantages over conventional processes. As the energy can be transferred directly to materials, microwave heating is an extremely efficient method for selective heating. This results in less energy consumption, process time saving and more environmental friendly. Microwave pyrolysis has a great potential to be applied for many raw materials to increase their values, especially for by-products from industrial processes such as mixed-hydrocarbons, crude glycerol, etc.
For hydrocarbons conversion, the use of microwave pyrolysis may lead to new hydrocarbon products. In addition, it helps reducing unwanted side reactions that usually occur in conventional conversion processes. In case of glycerol, the microwave pyrolysis technique may be used to transform low-value and abundant crude glycerol to hydrogen gas, or to synthesis gas for further processing. Our current research is preliminarily exploring the potential of microwave pyrolysis technique for upgrading by-products and wastes from industrial processes. Effect of important operating parameters such as temperature, reaction time, type of catalyst/receptor, and power of microwave reactor on product quality and yield will be investigated. Preliminary results showed that a good deal of benzene and toluene can be produced from hydrocarbons feed. In case of glycerol feed, a large amount of hydrogen can be produced directly from crude glycerol.
Petroleum-based fuel plays an important role in the energy sector mainly as fuel for vehicles and engines in the transportation. However, it is not sustainable energy and its prices also tend to increase continuously. Thus, alternative fuels especially renewable and non-toxic energy are becoming significantly important. The well-known alternative is biodiesel which is derived from transesterification of vegetable oils and animal fats with alcohol in the presence of catalyst. The major factors that affect to the biodiesel production such as reaction temperature, reaction time, catalyst amount, methanol to oil molar ratio and raw material have been studied in many research works. In conventional transesterification process, the temperature and reaction time are 55-65ºC and 30-120 min, respectively. Theoretical methanol to oil molar ratio is 3:1 but the higher molar ratio in the range of 6:1-9:1 is used in order to force the reaction in forward direction for completion. Typically, the use of biomass which is non-edible and low cost feedstock has been widely investigated, for example, palm stearin which is a by-product of the palm olein vegetable oil industry.
Several techniques for biodiesel synthesis include conventional heating, lipase catalyst method, ultrasonic method and microwave irradiation. In comparison, the conventional heating method requires longer reaction times with higher energy inputs and losses to surrounding. Microwave irradiation, on the other hand, is an energy-efficient and quick process because it delivers energy directly to the reactants. Furthermore, the influence of agitation intensity on the reaction rate is most significant during the initial slow rate region of the reaction. A higher conversion of the oil in a shorter reaction time was reached at higher agitation speeds of 300 and 600 rpm. The biodiesel yield and purity from this process meet the biodiesel standard of 96% and 96.5%, respectively.
By microbial techniques
Plastics are the most popular material and widely used in many applications. Plastics (petrochemical products) are derived from petroleum; therefore, they are not naturally degradable. This contributes to the growing waste around the world, especially, burning plastic can release toxic fumes to the atmosphere. These issues have led researchers to search for alternative sources of plastic that are biodegradable and do not consume the limited resource of petroleum. These biodegradable plastics can be in the form of polylactic acid (PLA) and polyhydroxyalkanoates (PHAs) for the environmental safety standard. In addition, there is a growing market for packaging due to the environmental friendly.
Ralstonia eutropha ATCC 17699 produces polyhydroxybutyrate-valerate (PHBV) which can accumulate in the cell as the energy source. PHBV has recognized as an alternative substitute for the non-biodegradable petrochemical polymers. Crude glycerols derived from the biodiesel industry were used as a sole carbon source. Batch fermentations were carried out under aerobic condition near ambient temperature to produce PHBV. However, the fermentation time is very long for a low yield.
Electrical technology can be used as a non-thermal food preservation processing technology that is currently being investigated to inactivate microbial cells or microorganisms. To prolong the shelf life of food, it is mostly pasteurized. Heating is the most commonly used for short-time pasteurization method (similarly to UHT process) but it leads to worsening of the taste and appearance of the food, texture and aroma, while it is an energy intensive method. Non-thermal process, such as High Electric Field Pulsed (HEFP) or Pulsed Electric Field (PEF) treatment would be the alternative process and it is a potential technology to replace or partially substitute thermal processes due to the promising results have been obtained on the inactivation of microbial cells in liquid juices such as orange juice, lemon juice, apple juice, milk and beaten eggs. Microorganisms in liquid foods can be inactivated with pulsed electric fields at ambient or refrigerated temperatures for a short treatment time of less than a second. The fresh-like quality of food is preserved without the use of traditional preservatives. For food quality attributes, HEFP or PEF technology may be superior to traditional heat treatment of foods.
Coconut juice is a tropical fruit gaining popularity as a sport drink beverage because of tremendous nutritional values such as protein, carbohydrates, fats, vitamin and minerals. HEFP treatment chamber was constructed and used to treat coconut juice under the microbial contaminated with three pathogenic bacteria , Escherichia coli , Salmonella typhimurium and Saccharomyces cerevisiae. Coconut juice was treated with HEFP varying electrical voltage and number of pulses and were significantly sterilized the coconut juice under the minimum nutritional losses. Bacterial death kinetics were analyzed. The destruction of morphological structure before and after exposed electrical field was confirmed by a scanning electron microscopy.
Numerical simulations aim at modeling various aspects of the physics of materials to solve a number of practical problems related to the treatment of material in the industry and explore the effect of many parameters in a system that are simply not accessible to experimentation. Most physical materials and systems are discontinuous at some level. The continuum assumption is valid if the microstructure has a length scale much smaller than that of the interest objects. Finite element, boundary element, and Lagrangian finite difference methods are based on the continuum mechanics approach to solve scientific engineering problems. These methods formulate the problems as mathematical boundary value problems (BVP). Also, they assume that the material properties can be scaled from small laboratory samples to large material masses using constitutive relations, not based on physics.
By modeling continuum materials as discontinuum, not only are these limitations lifted, but new knowledge on macroscopic behavior can be gained when their microscopic mechanisms are well understood. The Discrete Element Method (DEM) allows particle penetration that results in energy dissipation and this method has been used in a wide range of engineering problems, including simulation of granular media, modeling of particle flows, rock mechanics analysis, process engineering modeling, simulation of ice mechanics problems, etc. The colloidal system had been previously investigated with different computer simulation methods such as Molecular Dynamics (MD) and Finite Element Method (FEM). However, this system has not been widely studied with the use of DEM.
Two-dimensional colloidal aggregates of polystyrene microspheres were formed on the air-liquid interface and characterized by digital video microscopy. Since, this two-dimensional colloidal aggregates can be treated as the granular material or discontinuum materials, the dynamics behavior can be monitored and investigated with the used of DEM computer simulation and the static assemblies can be further study in a statistical mechanical analysis of contact forces and stress. In addition, compressive behaviors of clusters and rearrangement mechanisms of the aggregates can be investigated along with the experimental work.
The mission of the biomass conversion research laboratory at TGGS is to develop cost effective and environmentally attractive means of generating fuels, chemical, food, and feeds from renewable plant biomass. By extracting simple fermentable sugars from plant biomass and producing biofuels from them, the potential of the most energy-efficient and environmentally sustainable fuels can be realized. To promote commercialization of biofuels research, we focused on two divisions: biomass deconstruction, and fuel synthesis. The knowledge gained through R&D is transferred: into industrial applications and into the education of researchers.
- Biomass Deconstruction
The complex polysaccharide sugars in plant cell walls are locked within a tough material called lignin. Deconstruction Division are developing new and improved ways to release these polysaccharides and reduce them to fermentable sugars that can be synthesized into fuels. The deconstruction process normally requires two steps: pretreatment and enzymatic hydrolysis. One focus of the Deconstruction Division is on the development of means of biomass pretreatment using microwave and ionic liquid. Another focus of Deconstruction Division researchers is exploring known ecosystems, such as Thai rain forest floors and composts, for new microbial enzymes that are capable of efficiently deconstructing both the sugar and lignin components of plant cell walls. Genetic engineering and bioinformatics are applied to produce enzyme cocktails optimized for rapidly hydrolyzing the polysaccharides present after pretreatment into fermentable sugars. The characterized enzymes can also be utilized by animal food production to enhance digestivity of cattle.
- Fuel Synthesis
Simple and advanced biofuels made from the cellulosic biomass of non-food crops and agricultural waste are renewable. However, whereas the sugars derived from food-crops are simple and readily fermented into ethanol by yeast, sugars derived from cellulosic biomass are complex and contain chemicals that in the past have prevented them from being fermented by yeast. We are engineering new strains of bacteria that can quickly and efficiently ferment these complex sugars into advanced biofuels. To do this, we are using the advanced tools of biotechnology, including synthetic biology, an emerging scientific field in which novel biological devices, such as proteins, genetic circuits or metabolic pathways, are designed and constructed, or existing biological systems, such as microbes, are re-designed and engineered. The goal is to produce fuels and other valuable chemical products from simple, inexpensive and renewable starting materials in a sustainable manner.