J.E. Castanheiro

Hydration of α-pinene over zeolites and activated carbons dispersed in polymeric membranes

Abstract The acid catalysed hydration of α-pinene yields a complex mixture of monoterpenes, alcohols and hydrocarbons. By controlling the reaction variables is possible to make it selective to the terpenic alcohols, namely α-terpineol. In this paper the results of the hydration reaction of α-pinene catalysed by polydimethylsiloxane (PDMS) membranes filled with zeolite USY, zeolite beta or a surface modified activated carbon, are reported. The reaction is carried out at 50°C, using aqueous acetone as solvent. The activity and selectivity towards α-terpineol of the composite membranes are compared with those of the free catalysts.

The acid-catalysed reaction of α-pinene over molybdophosphoric acid immobilised in dense polymeric membranes

Abstract The α-pinene hydration to α-terpineol was studied using as catalysts polymeric catalytic membranes consisting of HPMo entrapped in polyvinyl alcohol (PVA) cross-linked with 10, 20 and 30% of succinic acid, and HPMo encaged in USY zeolites dispersed in a polydimethylsiloxane (PDMS) matrix. In the case of HPMo/PVA membranes it was observed that membrane activity increases with the polymer cross-linking, due to the increase in membrane hydrophobicity, up to the limit of the increasingly restrictions to the molecules mobility. The HPMo-USY/PDMS membrane shows a significantly higher activity for pinene hydration, which is even higher than that observed with USY encaged HPMo alone. However, selectivity to α-terpineol (65% at 80% conversion) is slightly lower than that obtained for the HPMo/PVA cross-linked with 20 or 30% of succinic acid (70–75% at 90% conversion). For both catalytic membranes, HPMo/PVA or HPMo-USY/PDMS, the stability is reasonable good and catalyst activity increases in the subsequent uses of the same membrane, probably due to the interaction between retained α-terpineol and the polymer matrix.

The effect of α-terpineol on the hydration of α-pinene over zeolites dispersed in polymeric membranes

Abstract The hydration of α-pinene over catalytic PDMS membranes loaded with a USY zeolite is studied. The concentration profiles of reagent and products exhibited a pronounced initial induction period followed by a rapid increase of the reaction rate, suggesting an autocatalytic behaviour. The effects of the main reaction product, α-terpineol, on the membrane transport properties are investigated. A simple diffusion-kinetic model which fits experimental concentration data quite well has been developed.

Hydrolysis of sucrose using sulfonated poly(vinyl alcohol) as catalyst.

The hydrolysis of sucrose was carried out over poly(vinyl alcohol) (PVA) with sulfonic acid groups, at 80 degrees C. The products of sucrose hydrolysis were glucose and fructose. A series of PVA with different crosslinking degree were prepared. It was observed that the catalytic activity of PVA matrix increases with the crosslinking degree, due to the increases of the amount of sulfonic acid groups on PVA. Further, the influence of various reaction parameters, such as, catalyst loading, initial concentration of sucrose and temperature, on the hydrolysis of sucrose over PVA_40 was studied. It was found that at 80 degrees C, with 0.511 g of catalyst loading and with an initial concentration of sucrose of 0.6M, a sucrose conversion of about 90%, after 3h, could be obtained. The PVA_40 catalyst was recycled and reused with negligible loss in the activity. A simple kinetic model was developed assuming that the sucrose hydrolysis is an irreversible reaction and the first order with respect to the sucrose concentration. Since the concentration profiles of the reactant and the products do not exhibit any pronounced initial inductive period, the external and internal diffusion of the reactant and products on the catalyst were not considered. It was observed that the kinetic model fits experimental concentration data quite well.

Pharmaceuticals sorption behaviour in granulated cork for the selection of a support matrix for a constructed wetlands system

Biosorbents have been recently gaining importance, with an increasing number of publications on their environmental applications, especially for removal of organic pollutants from aqueous media. The aim of this work was to evaluate the sorption capacity of a biosorbent, namely granulated cork, to remove mixtures of ibuprofen (IB), carbamazepine (CB) and clofibric acid (CA) from water and wastewater. High removal efficiencies were attained for IB and CB while a less satisfactory performance was observed for CA. Simultaneous removal of the three compounds mixed in the same aqueous solution showed no significant differences in comparison to the removal of the isolated compounds in separate solutions, which indicates that no competitive sorption effects occurred at the highest concentrations tested. On the other hand, in wastewater medium the mixture of pharmaceuticals underwent a decrease in the sorbed amounts of all the three substances, probably due to the presence of dissolved organic matter which increases their solubilities. These compounds were removed in the following order of efficiencies in all the tested conditions: IBu2009>u2009CBu2009>u2009CA. The sorption kinetics were characterised by an initial fast step within the first 6u2009h, during which most of the removed pharmaceuticals amounts were sorbed. After the first 6u2009h, CA attained equilibrium concentrations whereas the sorption kinetics for IB and CB were characterised by two pseudo-second order stages, the first one up to 48u2009h and a slower one beyond 48u2009h. Shorter equilibration times and larger removed amounts of pharmaceuticals per unit weight of sorbent were observed in this study for granulated cork in comparison with a previously studied clay material (LECA). The results of this study showed the sorptive qualities of granulated cork but are only a first step in the evaluation of this material for use as support matrix in constructed wetlands designed for removal of pharmaceuticals from wastewaters.

Mesoporous silica containing sulfonic acid groups as catalysts for the alpha-pinene methoxylation

Abstract The methoxylation of a-pinene was studied over sulfonic acid-functionalized mesoporous silica (MCM-41, PMO) at 60°C. The support functionalization was achieved by the introduction of 3-(mercaptopropyl)trimethoxysilane onto the surface of these materials either by grafting or by co-condensation. The thiol groups were oxidized to SO3H by treatment with H2O2. All the catalysts were active in the studied reaction being the PMO-SO3H-g the best one. Good values of selectivity to α-terpinyl methyl ether were obtained with these catalysts. Catalytic stability of the PMO-SO3H-g was evaluated by performing consecutive batch runs with the same catalyst sample. After the third batch it was observed a stabilisation of the activity.

Valorization of Waste Cooking Oil into Biodiesel over an Anionic Resin as Catalyst

Waste cooking oil was converted with methanol into biodiesel over a basic resin (Amberlite IRA96) as catalyst, at 60°C. In order to optimize the reaction conditions, different parameters, such as catalyst loading, temperature, nature of alcohol, molar ratio of waste cooking oil to methanol, and amount of initial free fatty acid, were studied. The catalyst was reused and recycled with negligible loss in the activity. A simple kinetic model can be established based on the assumptions that the triglycerides are consumed according to the consecutive reaction network. It was observed that the kinetic model fits experimental concentration data quite well.

Biodiesel production from waste cooking oil over sulfonated catalysts

ABSTRACT Biodiesel production from waste cooking oil with methanol was carried out in the presence of poly(vinyl alcohol) with sulfonic acid groups (PVA-SO3H) and polystyrene with sulfonic acid groups (PS-SO3H), at 60°C. The PVA-SO3H catalyst showed higher catalytic activity than the PS-SO3H one. In order to optimize the reaction conditions, different parameters were studied. An increase of waste cooking oil conversion into fatty acid methyl esters with the amount of PVA-SO3H was observed. When the transesterification and esterification of WCO was carried out with ethanol over PVA-SO3H, at 60°C, a decrease of biodiesel production was also observed. The WCO conversion into fatty acid ethyl ester increased when the temperature was increased from 60 to 80°C. When different amounts of free fatty acids were added to the reaction mixture, a slight increase on the conversion was observed. The PVA-SO3H catalyst was reused and recycled with negligible loss in the activity.

Fly Ash and Lime-Stabilized Biosolid Mixtures in Mine Spoil Reclamation

Abstract Large areas of land worldwide are estimated to be disturbed by mining activities, thereby contributing to severe environmental consequences. Mining represents one of the greatest transformations of the landscape caused by human activity and high concentrations of heavy metals in mine spoil can adversely impact microbial activity and plant establishment and subsequent revegetation success. Moreover, fly ash (FA), generated during the combustion of coal for energy production, is an industrial by-product, which is recognized as an environmental pollutant. However, several studies proposed that FA can be used as a soil additive that may improve physical, chemical, and biological properties of degraded soils and can act as a source of plant micro- and macronutrients. Furthermore, practical value of FA as an eco-friendly and economic soil amendment for the reclamation of acid mine spoils may be enhanced by coapplication with biosolids. Indeed, addition of biosolids could improve the success of reclamation/revegetation efforts.

Alkoxylation of Terpenes over Tungstophosphoric Acid Immobilised on Silica Support

The alkoxylation of α-pinene, β-pinene and limonene with Cl–C4 alcohols (methanol, ethanol, 1-propanol and 1-butanol) to α-terpinyl alkyl ether was carried out in the presence of silica-occluded tungstophosphoric acid (PW/S) in liquid phase. Different linear and branched alcohols (C1–C4 alcohols) are compared in relation to their activity for the heterogeneously catalysed alkoxylation of alpha-pinene.