Miguel Ángel Hernández Rivera

Crosslinking and Reinforcement of PET/TiO2/Clay Composites for Pavement Applications

This project studies the alternative chemical recycling of disposable bottles as raw material for the manufacture of a product known as polymeric concrete, which has several applications in the construction industry. Crosslinked materials from polyethylene terephthalate (PET), glycerol and clay were obtained. First recycled PET bottles were washed, cut and dried; after bis-hydroxyethyl terephthalate monomer was obtained from depolimerization reaction of PET. The monomer, glycerol and titanium dioxide reacts to synthesize a polymeric concrete. Materials with concentrations of clay from 1, 10, 20, 30, 40 and 50%w/w were obtained. Differential scanning calorimeter (DSC), Soxhlet extraction, colorimetry and Shore D hardness were used to characterize the materials. The results indicated a degree of crosslinking in the synthesized material when the amount of clay was increased. A melting point around 265 °C was not observed by DSC analysis; this suggests that a crosslinked material was formed. By TGA analysis temperature degradation was observed at 394°C, which it was increasing from 408 to 416°C according to the addition of clay content. A bad dispersion of particles in the crosslinked polymer decreased the thermal stability of PET when the clay content was increased.

Factors Affecting Microbial Enhanced Oil Recovery (MEOR)

Oil and natural gas are the primary sources of energy used by humanity, as renewable energy is not yet available to the entire population. After an oil field is abandoned, or its production declines significantly, an estimated two-thirds of the oil originally onsite remains in the subsoil, which is difficult and expensive to extract by conventional methods. Enhanced oil recovery techniques are used to increase the recovery of oil from these sites, but they are expensive and often harmful to the environment. A technically and economically viable alternative is the use of microorganisms, which are generally obtained from the oil reservoirs themselves. These microbes are resistant to oil reservoir conditions, including high pressures, temperatures above 85 °C, high salt concentrations, and extreme pH values. During microbial growth, when supplied with appropriate nutrients, these microbes generate biosurfactants, solvents, gases, and organic acids, and in some cases, biopolymers. In addition, such microbes are capable of breaking up long chains of paraffins and asphaltenes, modifying the wettability of the storage rock, decreasing the viscosity and density of the oil, and increasing the pressure within the pore network of the rock. The successful use of microbial enhanced oil recovery has been reported in which the growth of native bacteria from a reservoir was stimulated by supplying nutrients, with most treated reservoirs having shown positive results.

Structural and Optical Properties of InSnO3 Sol-Gel Coatings to Use in Windows Glass Buildings

Indium stannate (InSnO3) films doping with small amounts of copper are made highly useful as architectural window coatings. Indium-tin-oxide (ITO) has attracted intense interest due to some of its unique characteristics; it has high optical transmittance in the visible region, low electric resistivity, and chemical stability. Therefore, ITO thin films have been found to play an important role in opto-electronic applications. In this work, uniform and transparent ITO films were deposited onto glass substrates using a sol-gel process. The initial sols were prepared by mixing solutions of indium chloride prepared in anhydrous ethanol with tin chloride and mechanically stirring and refluxed 2 hours and aged 2 week, the resultant mixture until a clear and sticky coating sol was obtained. The glass substrates were spin-coated and annealed at 500 °C. Because annealing conditions affect the microstructures, the properties of the resultant ITO films can be controlled. The optical transmittance of 200 nm thick ITO film was more than 80% in the visible region. The surface morphology examined by SEM appears to be uniform over large surface areas. The structural, microstructural and optical properties of the coatings and powders made from the sols were extensively characterized by using XRD, AFM and spectrophotometer techniques

New Denatonium Benzoate/tin Heterogeneous Catalyst to Obtain Biodiesel via Low Temperature Transesterification Process(LTTP)

Biodiesel was synthesized using waste chicken oil and ethyl alcohol as reactives as well as denatonium benzoate and tin particles as catalysts in 500 mL three neck flask. The reaction mixtures were mechanically stirred at 200 rpm during 15 minutes at 30, 40, 50, y 60 º C, after that the products were filtered trough a 400 m mesh an then casted in a separating funnel in order to obtain two layers corresponding to glycerol and Biodiesel. The tin catalyst particles were observed by optical microscopy. The biodiesel and glycerol were characterized using refractive index, pH, Fourier transformer infrared spectrometry (FTIR), while the viscosity was determined in a Brookfield viscosimeter and density using a picnometer. The results suggest that at a low concentration of denatonuim benzoate (7 ppm) the reaction will occur only if tin is present at all test temperatures. The pH of biodiesel obtained was 6, similar to petrodiesel used commonly in diesel motors.