Jorge Cuellar

Magnetic cation-exchange resins usually consist of small polymeric particles with a magnetic material dispersed within their structure. Because the mass-transfer kinetics through these solid particles depends on their size, very small diameter particles are desirable. Nevertheless, ...

Abstract A theoretical model for the process of magnetic filtration of paramagnetic particles suspended in water and a method for determining the kinetic parameters of the model is proposed. To validate the theory, 10 experimental runs were conducted on a cylindrical ...

Abstract A theoretical model for the process of magnetic filtration of paramagnetic particles suspended in water and a method for determining the kinetic parameters of the model is proposed. To validate the theory, 10 experimental runs were conducted on a cylindrical ...

Microbeads consisting of a stainless steel nucleus covered with a layer of poly(styrene-co-divinylbenzene ) have been synthesized. To determine the influence of several operation variables in the characteristics of the final product, a 2 IV 8-3 fractional factorial design of experiments was conducted. ...

Magnetic cation-exchange resins usually consist of small polymeric particles with a magnetic material dispersed within their structure. Because the mass-transfer kinetics through these solid particles depends on their size, very small diameter particles are desirable. Nevertheless, ...

La polimerización en suspensión es una de las técnicas de polimerización más ampliamente usada en la industria química para la producción de micropartículas poliméricas.El objetivo de este trabajo es, después de recopilar información de numerosas fuentes y obtener ...

The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have r...

ABSTRACT The esterification of oleic acid with methanol by homogeneous acid catalysis was investigated, using 4-dodecylbenzenesulfonic acid as catalyst. First, the catalytic activity of 4-dodecylbenzenesulfonic acid in this reaction was compared with that of p-toluenesulfonic and sulfuric acid, and it was found that the reaction rate clearly increased with increasing hydrophobicity of the catalyst. Second, the effects of the catalyst/acid molar ratio, the methanol/oleic acid molar ratio, the water content, temperature, the stirring speed and the presence of triglycerides on the kinetics and the equilibrium of this esterification were studied. The main observations were that temperature and the proportion of catalyst had a positive effect on the kinetics, i.e., an increase in any of these factors led to an increase in the reaction rate. Methanol had an almost negligible effect. By contrast, water had a negative effect due to the formation of an aqueous phase, which removed part of the catalyst, thus reducing its concentration in the organic phase and hence the reaction rate. Third, the kinetics of esterification was studied in a wide range of operating conditions and a reversible second-order model was obtained that included the effect of the separation of the aqueous phase from the reaction mixture and hence the progressive decrease in the concentration of catalyst, methanol and the volume of the reaction mixture. This kinetic model adequately predicts the experimental data within the range of operation conditions investigated. The activation energy for the forward reaction was 58.5 kJ/mol, and 63.4 kJ/mol for the reverse reaction.

ABSTRACT The synthesis of biodiesel from triglycerides and methanol using 4-dodecylbenzenesulfonic acid as catalyst was studied. The use of acid catalysts in the production of biodiesel has the advantage that in addition to accelerating the transesterification of triglycerides, they also catalyze the esterification of free fatty acids and, moreover, they do not form soaps or emulsions. Regarding the 4-dodecylbenzenesulfonic acid catalyst used in this work, it has a further advantage in that it has a hydrophobic moiety in its molecular structure, which permits a much higher transesterification rate than that of other acid catalysts and, hence, conversions higher than 95% can be attained under mild reaction conditions in less than 3 h.

A new kind of gel-type magnetic cation-exchange resin based on stainless steel microspheres coated with sulfonated polystyrene-co-divinylbenzene has been synthesized in a two-step process. First, magnetic polymeric beads were prepared by radical suspension ...

The adsorption properties of macroporous polymeric microparticles are dependent on their porous structure, which, in turn, is dependent on the synthesis conditions of the adsorbent material. In the present work, we have investigated whether it is feasible to find a quantitative ...

Macroporous poly(styrene-co-divinylbenzene) microparticles from reactive mixtures with various divinylbenzene and diluent contents have been synthesized. n-Heptane, which is a poor solvent for the copolymer, was used as diluent of the organic phase during the polymerization to ...