Alírio E. Rodrigues

Adsorption of basic dyes on granular acivated carbon and natural zeolite

The adsorption of basic dyes from aqueous solution onto granular activated carbon and natural zeolite has been studied using an agitated batch adsorber. The influence of agitation, initial dye concentration and adsorbent mass has been studied. The parameters of Langmuir and Freundlich adsorption isotherms have been determined using the adsorption data. Homogeneous diffusion model (solid diffusion) combined with external mass transfer resistance is proposed for the kinetic investigation. The dependence of solid diffusion coefficient on initial concentration and mass adsorbent is represented by the simple empirical equations.

Adsorption of carbon dioxide at high temperature—a review

In this review, the adsorption of carbon dioxide on adsorbent materials at high temperature is examined critically. Adsorbent materials including carbon-based adsorbents, metal oxide sorbents, zeolites and hydrotalcite-like compounds (HTlcs) for carbon dioxide at high temperature are discussed. Research areas, which may make a significant impact in future are put forward.

Adsorption, science and technology

I. Characterization of Adsorbents and Tthermodynamics of Adsorption.- Characterization of adsorbents.- Theories of adsorption in micropores.- The statistical thermodynamic approach to the correlation of equilibrium data.- A two-patch heterogeneous model with surface phase transition for benzene adsorption on silicalite.- Interpretation of low temperature gas adsorption and desorption using stochastic pore networks.- Adsorption of n-hexane and 3-methylpentane on zeolites Y and ZSM 20.- II. Kinetics of Adsorption and Fixed-Bed Processes.- Adsorption kinetics.- Dynamics of fixed-bed adsorbers. Isothermal adsorption of single components.- Asymptotic fixed-bed behavior: proportionate and constant patterns.- Pore scale hydrodynamics.- Separation processes based on electrosorption phenomena.- Adsorptive reactors.- Design aspects of fixed-bed adsorption processes.- Numerical methods for the solution of adsorption models.- III. Cyclic Processes and Simulated Moving Beds.- Gas separation by pressure swing adsorption using carbon molecular sieves.- Pressure swing adsorption technology.- Modeling and simulation of rate induced PSA separations.- Thermal swing adsorption.- On countercurrent adsorption separation processes.- Sorbex: continuing innovation in liquid phase adsorption.- IV. Applications in Biotechnology and Environmental Engineering.- The use of granular activated carbon for potable water treatment as an example of liquid phase applications of activated carbon.- Breakthrough time of organic vapours in activated carbon filters as a function of the air flow pattern.- Continuous adsorption in biotechnology.- Continuous chromatographic processes.- Biochemical reaction and separation in chromatographic columns.- Some factors involved in scale-up of industrial biotechnological adsorption processes.- Development of physical and mathematical modelling for scale-up of batch stirred tank and packed-bed column adsorption and chromatographic units.- Optimisation of adsorption techniques for the purification of biomolecules.- Gel filtration chromatography.- Adsorption chromatography for protein purification.- List of Lecturers and Participants.

Ethyl lactate as a solvent: Properties, applications and production processes – a review

Ethyl lactate is an environmentally benign solvent with effectiveness comparable to petroleum-based solvents. The worldwide solvent market is about 30 million pounds per year, where ethyl lactate can have an important share. It is considered a chemical commodity and has attracted much attention in recent years, since it is formed by the esterification reaction of ethanol and lactic acid, which can be generated from biomass raw materials through fermentation. In this work, an overview regarding the main properties and applications of ethyl lactate, as well as its synthesis and production processes, with a particular emphasis on reactive/separation processes, is presented.

Hydrotalcite-like compounds as adsorbents for carbon dioxide

This paper summarizes recent progress in study of the adsorption of carbon dioxide on hydrotalcite-like compounds (HTlcs). Details of their effect factors on the adsorption capacity of carbon dioxide are discussed. Research areas that may make a significant impact on development of the materials in the future are put forward.

Phenol biodegradation by Pseudomonas putida DSM 548 in a batch reactor

Phenol biodegradation in a batch reactor using a pure culture of Pseudomonas putida DSM 548 was studied. The purpose of the experiments was to determine the kinetics of biodegradation by measuring biomass growth rates and phenol concentration as a function of time in a batch reactor. The Haldane equation µ=µ(m)S/((K(s)+S+S(2))/K(i)) adequately describes cell growth with kinetic constants µ(m)=0.436h(-1), K(s)=6.19mgl(-1), K(i)=54.1mgl(-1). These values are in the range of those published in literature for pure or mixed cultures degrading phenol.

Sorption-enhanced reaction process with reactive regeneration

Abstract Sorption-enhanced reaction process with reactive regeneration of adsorbent was proposed where the purge step is performed at a low temperature of 400°C (compared with the reaction temperature of 450°C) with 10% H 2 in nitrogen under atmospheric pressure. Hydrogen-enriched stream with traces of CO 2 and CO can be produced by steam–methane reforming. A mathematical model taking into account multicomponent (six species) mass balances, overall mass balance, Ergun relation for the pressure drop, energy balance for the bed-volume element including the heat transfer to the column wall, and nonlinear adsorption equilibrium isotherm coupled with three main reactions was derived to describe this new cyclic process. The feasibility and effectiveness of this cyclic process is analyzed by numerical simulation. The results show that using either a 4 m or a 6 m long adsorptive reactor (depending on the operation time of the first step), a product gas with above 88% hydrogen purity and traces of CO 2 and CO (CO less than 30 ppm ) can be continuously produced and directly used in the fuel cell applications. The validity of the model prediction was checked by comparing the simulated results with experimental data from the literature where the regeneration of adsorbent is carried out by steam purge at subatmospheric pressure. The model results qualitatively agree with experimental data. The package is needed to improve the design and analysis of sorption-enhanced reaction process.

Adsorption of Carbon Dioxide on Chemically Modified High Surface Area Carbon-Based Adsorbents at High Temperature

The adsorption capacity of carbon dioxide on high surface area carbon-based adsorbents before and after chemical modification at 28°C and 300°C have been studied. The high adsorption capacity adsorbents for carbon dioxide at high temperature have been developed by introducing MgO and S–CaO–MgO on carbon-based adsorbents. Their adsorption capacities for carbon dioxide were 0.28 and 0.22 m mol/g at 300°C, 1 Bar, respectively.

Residence time distribution of inert and linearly adsorbed species in a fixed bed containing “large-pore” supports: applications in separation engineering

Abstract Large-pore materials are used in various chemical engineering applications as catalysts, HPLC packings, ceramic membranes. In such supports, mass transfer due to intraparticle convection has to be taken into account. This paper shows how intraparticle convection affects residence time distribution of inert and linearly adsorbed species in fixed-bed processes. The concept is further illustrated with examples from gas—solid systems and liquid—solid systems (HPLC) showing how the column efficiency (measured by HETP in separation engineering) is improved by the use of large-pore supports.

Importance of intraparticle convection in the performance of chromatographic processes

Abstract Large-pore materials are used in separation engineering as high-performance liquid chromatographic packings and adsorbents; however, they find also many applications in reaction engineering as catalyst supports and ceramic membrane reactors and in biotechnology as supports for mammalian cell cultures or biomass growth. In these large-pore materials, mass transport by intraparticle forced convection should be considered in process analysis. A brief historical survey of research work concerned with intraparticle forced convection is given, showing that the concept to be retained is that of effective diffusivity augmented by convection. The behaviour of the height equivalent to a theoretical plate as a function of bed superficial velocity is explained on the basis of the above concept. Analogies between slab and spherical particle geometries are discussed.