C. A. M. Abreu

Evaluation of BTEX and phenol removal from aqueous solution by multi-solute adsorption onto smectite organoclay.

The removal process of BTEX and phenol was evaluated. The smectite organoclay for single-solute system reached removal was evaluated by adsorption on smectite organoclay adsorbent by kinetic and equilibrium efficiencies between 55 and 90% while was reached between 30 and 90% for multi-solute system at 297 K and pH 9. The Langmuir-Freundlich model was used to fit the experimental data with correlation coefficient between 0.98 and 0.99 providing kinetic and equilibrium parameter values. Phenol and ethylbenzene presented high maximum adsorbed amount, 8.28 and 6.67 mg/g, respectively, compared to the other compounds for single-solute. Toluene and p-xylene presented high values of adsorption constant which indicates a high adsorption affinity of compounds to organoclay surface and high binding energy of adsorption. Phenol presented low kinetic adsorption constant value indicating slow rate of adsorption.

Catalytic wet-air oxidation of lignin in a three-phase reactor with aromatic aldehyde production

In the present work a process of catalytic wet air oxidation of lignin obtained from sugar-cane bagasse is developed with the objective of producing vanillin, syringaldehyde and p-hydroxybenzaldehyde in a continuous regime. Palladium supported on g-alumina was used as the catalyst. The reactions in the lignin degradation and aldehyde production were described by a kinetic model as a system of complex parallel and series reactions, in which pseudo-first-order steps are found. For the purpose of producing aromatic aldehydes in continuous regime, a three-phase fluidized reactor was built, and it was operated using atmospheric air as the oxidizer. The best yield in aromatic aldehydes was of 12%. The experimental results were compatible with those values obtained by the pseudo-heterogeneous axial dispersion model (PHADM) applied to the liquid phase.

Sucrose hydrolysis catalyzed by auto-immobilized invertase into intact cells of Cladosporium cladosporioides

The enzyme known as invertase ( E.C. 3.2.1.26 - β-D-fructofuranosidase ) catalyzes the sucrose hydrolysis producing an equimolar mixture of glucose and fructose named inverted sugar. The fungus Cladosporium cladosporioides has invertase as its constituent. Hence, its use as a natural immobilized support for the invertase produces interesting results for the enzyme. The present work has the objective of determining the optimum operational conditions of auto-immobilized invertase, as well as its kinetic parameters (K M and V max ). A complete 2 3 factorial planning was done for the evaluation of such parameters. Temperature, pH and agitation level were the studied variables. The hydrolysis percentage was the monitored result. Batch tests in optimum conditions were done to determine the kinetic parameters. Temperature of 70oC, pH 6 and agitation of 170 rpm were the established conditions for the hydrolysis process. The auto-immobilized invertase presented a K M of 447 mM and V max of 2,805 mmol/min.

Kinetic evaluation of hydrogenation of sucrose over ruthenium containing Y zeolites

Hydrogenation of sucrose over Ru/NaY, Ru/USY and Ru/CaY catalysts was carried out in a slurry reactor at 135°C and 12 atm. The catalysts were prepared by ion exchange followed by calcination and reduction. These were characterised as AA, TPR, DTA/TGA, H2/Chemisorption, CO-FTIR, XRD and t-plot. To describe kinetic product distribution, the 4th order Runge-Kutta method was used for determining the kinetic parameters.

Kinetic evaluation of polyol production by three-phase catalytic hydrogenation of saccharides

Kinetic evaluations were accomplished in a discontinuous three-phase reactor for saccharose, glucose and fructose hydrogenations at 373, 393 and 413 K, and 24 atm. Selectivities attained values in the order of 99.05%. Langmuir-Hinshelwood models based on heterogeneous mechanisms were proposed and the optimization and kinetic quantification of the process were performed.

Experimental dynamic evaluation of three-phase reactors

The hydrodynamic parameters were determined for two different three-phase systems (fluidized-bed and trickle-bed) through the experimental evaluation of the dynamic residence time distribution in the gas or liquid phase. For different fluid phase flow rates the fluidized-bed system was operated with a tracer in the gas phase and in the trickle-bed with a tracer in the liquid phase. The analysis of the processes was achieved through the application of different models representing the dynamic behavior of tracers present in the gas and liquid phases with a simulation of experimental operations of the three-phase reactors. The transfer functions developed for the two systems made it possible to estimate the hydrodynamic parameters providing the gas holdup (2.22 x 10-2 to 8.42 x 10-2) and the gas phase Peclet number (54.18 to 41.20) for the fluidized-bed and the liquid holdup (0.16 to 0.25), the liquid phase Peclet number (20.37 to 4.52) and wetting efficiency (0.34 to 0.56) for the trickle-bed.

Experimental analysis and evaluation of the mass transfer process in a trickle-bed reactor

A transient experimental analysis of a three-phase descendent-cocurrent trickle-bed H2O/CH4-Ar/g -Al2O3 system was made using the stimulus-response technique, with the gas phase as a reference. Methane was used as a tracer and injected into the argon feed and the concentration vs time profiles were obtained at the entrance and exit of the bed, which were maintained at 298K and 1.013 105 Pa. A mathematical model for the tracer was developed to estimate the axial dispersion overall gas-liquid mass transfer and liquid-solid mass transfer coefficients. Experimental and theoretical results were compared and shown to be in good agreement. The model was validated by two additional experiments, and the values of the coefficients obtained above were confirmed.

Removal of Effluent from Petrochemical Wastewater by Adsorption Using Organoclay

Water contaminated with petroleum derivates is produced in large volumes in many stages of refining oil. This mixture should be treated to separate these derivates from water before it can return to the environment. However, treatment with conventional processes is very often not economically feasible, or do not have the appropriate efficiency with regard to separation, or produce large amounts of mud that also need treatment (Almeida Neto et al., 2006).

Applying Combined Langmuir-Freundlich Model to the Multi-Component Adsorption of BTEX and Phenol on Smectite Clay

Adsorption using clay is increasingly being applied in the secondary treatment of effluents contaminated with organic compounds discharged from oil industries. This study was aimed at applying a combined Langmuir–Freundlich model to describe the multi-component adsorption of organic compounds such as benzene, toluene, ethylbenzene, xylenes and phenol using smectite clay. The results of the study well fitted with the model developed. In addition, the model parameters suggest that maximum adsorption capacities (qm) can be achieved between 2.45 (toluene) and 22.40 mg g−1 (phenol). The equilibrium points for the compounds were achieved in approximately 20–30 minutes.

Preparação e utilização de uma argila esmectítica organofílica como adsorvente de fenol

The main goal of this research was the preparation and use of a organophilic smectitic clay able to promoting the adsorption of phenol. In this work was used a natural clay called Chocolate, from Campina Grande - PB (Brazil). The natural clay was treated with a solution of sodium carbonate. After this the sodium clay was treated with quaternary ammonium salt. The adsorptive study was conducted by different values of pH and temperature. The results showed a better performance in adsorptive at pH 7 and temperature 30 oC, with removal of more than 80% of phenol.