Regina Sandra Veiga Nascimento

TG characterization of organically modified montmorillonite

Montmorillonite was modified with octadecyltrimethylammonium chloride, under different reaction conditions, as evidenced by TG and XRD. TG curves presented two degradation peaks (295 and 395°C). At low salt concentrations, only the 395°C-degradation appeared, which increased with reaction time to the limit of 9 g of salt/100 g of clay. The second peak presented a limit at 17/100 m/m of salt/clay ratio. XRD analysis confirmed clay organic modification as the basal distance increased, showing greater reaction time effect than the salt mass effect, and with only one d-spacing. This suggested that an intercalation complex was formed but also that octadecyltrimethylammonium was adsorbed on the external surfaces of clay particles.

Effect of clays on the fire-retardant properties of a polyethylenic copolymer containing intumescent formulation

Abstract Organophilic clay particles were added to a standard intumescent formulation and, since the role of clay expansion or intercalation is still a matter of much controversy, several clays with varying degrees of interlayer distances were evaluated. The composites were obtained by blending the nanostructured clay and the intumescent system with a polyethylenic copolymer. The flame-retardant properties of the materials were evaluated by the limiting oxygen index (LOI), the UL-94 rating and thermogravimetric analysis (TGA). The results showed that the addition of highly expanded clays to the ammonium polyphosphate and pentaerythritol formulation does not significantly increase the flame retardancy of the mixture, when measured by the LOI and UL-94. However, when clays with smaller basal distances were added to the intumescent formulation, a synergistic effect was observed. In contrast, the simple addition of clays to the copolymer, without the intumescent formulation, did not increase the fire retardance of the materials.

Development of Polyurethane Antimicrobial Composites Using Waste Oil Refinery Catalyst

Waste oil refinery catalyst from the FCC unit was tested as a possible additive for the production of polymeric composites with antimicrobial properties. The effect of the silver ion on the growth inhibition of bacteria (E. coli and S. aureus), mold (A. niger), and yeasts (C. tropicalis and Cr. humicolus) was studied. The catalyst was ion exchanged with silver nitrate and incorporated into thermoplastic polyurethanes with different hardness ratings. The materials produced were submitted to microbial testing both in solid and liquid media, and the effect of the polymeric matrix on the rate of silver ion release from these materials was also investigated. The results obtained show that polyurethane composite containing the silver-ion-exchanged waste catalyst successfully inhibited the growth of all microorganisms under study.

Spent refinery catalyst as a flame retardancy enhancer in an intumescent polymeric system

Spent oil refinery catalyst from the FCC unit has been evaluated as an additive in intumescent flame retardant formulations containing ammonium polyphosphate (APP) and pentaerythritol (PER) in an ethylene– butyl acrylate–maleic anhydride terpolymer matrix. UL-94, LOI and cone calorimetry analyses were carried out and the results show that the addition of small amounts of the catalyst to the additive system greatly enhances flame retardancy performance of the intumescent formulations. All materials containing intumescent formulations were V0 rated according to the UL-94 standard. A ten unit increase in LOI values was observed by the addition of 5 wt.% of catalyst to the APP/PER formulations, and significant lowering in the rate of heat release, total heat evolved, smoke, CO and CO2 emission were detected by cone calorimetry.

Acetalization of hexanal with 2-ethyl hexanol catalyzed by solid acids

The catalyst activity of solid acids such as niobium phosphate and Amberlyst 35, an ion exchange resin, was evaluated in the acetalization of hexanal with 2-ethyl-hexanol. The catalyst loading and the reaction temperature were evaluated in the hexanal conversions. The possibility of recycling niobium phosphate was also studied, showing that it was possible to reuse this catalyst without significant loss in its catalytic activity. The yield in acetal was above 90% under mild conditions.

BIODIESEL PRODUCTION FROM FATTY ACIDS OF REFINED VEGETABLE OILS BY HETEROGENEOUS ACID CATALYSIS AND MICROWAVE IRRADIATION

This work presents the biofuel production results of the esterification of fatty acids (C12-C18) and high-acid-content waste vegetable oils from different soap stocks (soybean, palm, and coconut) with methanol, ethanol, and butanol by acid catalysis. We used Amberlyst-35 (A35) sulfonic resin as a heterogeneous acid catalyst and p-toluenesulfonic acid as a homogeneous catalyst for comparison. Both the heterogeneous (A35) and homogeneous (p-toluenesulfonic acid) reactions were performed with 5% w/w of catalyst. The final products were analyzed by proton nuclear magnetic resonance (1H NMR). The homogeneous catalyzed esterification of fatty acids with methanol, ethanol, and butanol produced esters with yields higher than 90%. In the reaction with fatty acids and methanol catalyzed by A35, the best results were achieved with lauric acid and methanol, with a yield of 97%. An increase in the hydrocarbon chain decreased the rate of conversion and yield for stearic acid with methanol, which was 90%. Maximum biodiesel production was achieved from coconut and soybean soap stocks and methanol (96%-98%), which showed conversions very close to those obtained from their respective fatty acids. Microwave irradiation reduced the reaction time from 6 to 1 h in the esterification reaction of fatty acids with butanol.

New Applications for Soybean Biodiesel Glycerol

Glycerol (Fig. 1.1) is a viscous and polar substance that has long been known for its useful properties. As long ago as 1779, the Swedish scientist Karl Wilhelm Scheelle obtained glycerol from olive oil. In 1813, Michael E. Chevreul showed that glycerol was involved in the triglyceride structure, and called it glycerin, from the greek word that means sweet. The elucidation of its structure as a trihydroxylated alcohol was due to Wurtz in 1855. The name glycerin was changed to glycerol to indicate its alcohol nature. It is now common to refer to the pure chemical product as glycerol and refer to the commercial grades with varying glycerol content as glycerin (or glycerine). The first example of a chemical industrial application of glycerol is nitroglycerin which was synthesized by Ascanio Sobrero. In 1860 it was transformed into a safer and more convenient form of use by Alfred Nobel [Jerome et al, 2008; Shreve & Brink, 1977; Kirk & Otmer, 1951].

Powdered microporous glasses: changing porosity through aging

Recently, we have reported the production of a microporous high purity silica powder from the acid leaching of glasses with average pore size around 2.5nm and specific surface area of 420m2/g (BET). The employed glasses derived from the melting of two types of waste from the industrial processing of Brazilian oil shale (retorted oil shale and the top fraction of the intermediate layer of Irati Formation). Depending on the proportion of the two wastes employed in the formulation of the glasses, either a silica gel or a powdered one is obtained, after leaching. The acid leaching of those glasses with hydrochloric acid, at 90 °C, was used to produce powdered microporous silica. In the present work it is studied the effect of aging time and temperature on the morphology and structure of the obtained powdered silica. Aging studies were performed in two different media, an acidic (hydrochloric acid) and a basic one (ammonium hydroxide) for different periods of time and temperatures. XRD, SEM/EDX, TEM, specific surface area measurements and DTA/TGA were used to characterize these materials. The results have shown a decrease of specific surface area with increasing time and temperature. Apparently, this behavior may be associated with dissolution and re-precipitation mechanisms.