Edson Antonio da Silva

A comparative study for the ion exchange of Fe(III) and Zn(II) on zeolite NaY

The uptake capacity of Fe(III) and Zn(II) ions in NaY zeolite was investigated. Experiments were carried out in a fixed bed column at 30 degrees C, pH 3.5 and 4.5 for Fe(III) and Zn(II), respectively, and an average particle size of 0.180 mm. In order to minimize the diffusional resistances the influence of flow rate on the breakthrough curves at feed concentrations of 1.56 meq/L for Fe(III) and 0.844 meq/L for Zn(II) was investigated. Flow rate of the minimal resistance in the bed according to mass transfer parameter were 2.0 mL/min for iron and 8.0 mL/min for zinc ions. Freundlich and Langmuir isotherm models have been used to represent the column equilibrium data. The iron dynamic isotherm was successfully modeled by the Langmuir equation and this mathematical model described well the experimental breakthrough curves for feed concentrations from 0.1 up to 3.5 meq/L. The zinc dynamic isotherm was successfully modeled by the Freundlich equation. This equilibrium model was applied to mathematical model. Experimental breakthrough curves could be predicted. Experiments were also carried out in a batch reactor to investigate the kinetics adsorption of the ions Fe(III) and Zn(II). Langmuir kinetic model fit well both experimental data.

Application of Aqai Stalks as Biosorbents for the Removal of the Dye Procion Blue MX-R from Aqueous Solution

The aqai palm stalk (Euterpe oleracea) is a food residue used in its natural form (AS) and also protonated (AAS) as biosorbents for the removal of the textile dye Procion Blue MX-R from aqueous solutions. This biosorbent was characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption-desorption curves. The effects of pH, biosorbent dosages, and shaking time on the biosorption capacities were studied. In the acidic pH region (pH 2.0) the biosorption of the dye was favorable. The minimum contact time to obtain the equilibrium was 8 hours for AS and AAS biosorbents. The general order kinetic model provided the best fit to the experimental data compared with the pseudo-first order and pseudo-second order kinetic adsorption models. The equilibrium data were fitted to the Langmuir, Freundlich, and Sips isotherm models. For both dyes the equilibrium data were best fitted to the Sips isotherm model. The enthalpy and entropy of adsorption of PB were obtained from adsorption equilibrium experiments ranging from 298 to 323 K. Simulated dyehouse effluent was used to check the applicability of the proposed adsorbents for effluent treatment.

Enzymatic catalyzed palm oil hydrolysis under ultrasound irradiation: diacylglycerol synthesis.

Diacylglycerol (DAG) rich oils have an organoleptic property like that of regular edible oils, but these oils do not tend to be accumulated as fat. Palm oil ranks first in the world in terms of edible oil production owing to its low cost. The aim of this study was to propose a new methodology to produce diacylglycerol by hydrolysis of palm oil using Lipozyme RM IM commercial lipase as a catalyst under ultrasound irradiation. The reactions were carried out at 55 °C with two different methods. First, the reaction system was exposed to ultrasonic waves for the whole reaction time, which led to enzymatic inactivation and water evaporation. Ultrasound was then used to promote emulsification of the water/oil system before the hydrolysis reaction, avoiding contact between the probe and the enzymes. An experimental design was used to optimize the ultrasound-related parameters and maximize the hydrolysis rate, and in these conditions, with a change in equilibrium, DAG production was evaluated. Better reaction conditions were achieved for the second method: 11.20 wt.% (water+oil mass) water content, 1.36 wt.% (water+oil mass) enzyme load, 12 h of reaction time, 1.2 min and 200 W of exposure to ultrasound. In these conditions diacylglycerol yield was 34.17 wt.%.

Adsorption of Reactive Blue 5G Dye by Activated Carbon and Pyrolyzed Shale Oil Residue

This work was aimed at the study of the adsorption mechanism of Reactive Blue 5G dye on activated carbon derived from babassu shells and pyrolyzed oil shale residue. Experiments were undertaken employing a fixed bed reactor at 30°C using continuous systems. To minimize diffusional resistances, the influence of the flow rate was investigated via breakthrough curves at a feed concentration of 35 mg/l. Breakthrough curves for flows in the range 2–10 ml/min were carried out using bed height of 15.5 cm for activated carbon and 9.5 cm for pyrolyzed oil shale residue, with an inlet diameter of 1.01 cm. From the calculated mass-transfer parameters, it was shown that the minimum resistance to flow occurred at 4 ml/min for activated carbon and at 2 ml/min for pyrolyzed oil shale residue. It was concluded that the sizes of the pores in the adsorbents play an important role in the adsorption mechanism.

Continuous Catalyst-Free Esterification of Oleic Acid in Compressed Ethanol

The esterification of oleic acid in a continuous catalyst-free process using compressed ethanol was investigated in the present study. Experiments were performed in a tubular reactor and variables investigated were temperature, pressure, and oleic acid to ethanol molar ratio for different residence time. Results demonstrated that temperature, in the range of 473 K to 573 K, and pressure had a positive effect on fatty acid ethyl esters (FAEE) production. In the experimental range investigated, high conversions can be obtained at low ethanol concentrations in the reaction medium and it was observed that oleic acid to ethanol molar ratios greater than 1 : 6 show no significant increase in conversion. Nonnegligible reaction conversions (>90%) were achieved at 573 K, 20 MPa, oleic acid to ethanol molar ratio of 1 : 6, and 20 minutes of residence time.

Joint Iterative Carrier Synchronization and Signal Detection Employing Expectation Maximization

In this paper, joint estimation of carrier frequency, phase, signal means and noise variance, in a maximum likelihood sense, is performed iteratively by employing expectation maximization. The parameter estimation is soft decision driven and allows joint carrier synchronization and data detection. The algorithm is tested in a mixed line rate optical transmission scenario employing dual polarization 448 Gb/s 16-QAM signal surrounded by eight on-off keying channels in a 50 GHz grid. It is shown that joint carrier synchronization and data detection are more robust towards optical transmitter impairments and nonlinear phase noise, compared to digital phase-locked loop (PLL) followed by hard decisions. Additionally, soft decision driven joint carrier synchronization and detection offers an improvement of 0.5 dB in terms of input power compared to hard decision digital PLL based carrier synchronization and demodulation.

Avaliação da eficiência de diferentes agentes coagulantes na remoção de cor e turbidez em efluente de galvanoplastia

In this work it was evaluated the efficiency of different coagulants agents in the process of coagulation/flocculation in the treatment of effluent from an electroplating industry. The following coagulants were evaluated: inorganic (ferric chloride and aluminum sulfate) and organic (chitosan and seeds of moringa, Tanfloc SG and Acquapol C1). The parameters evaluated were color and turbidity. The experiments were carried out in Jar-Test using a speed of 120 rpm and a time of 1.5 min for fast mixture and 20 rpm and 15 min for the slow mixture. The chitosan coagulant agent presented as more promising for the removal of color and turbidity in effluents from electroplating, removing 97.76% to 98.06% of color and turbidity, respectively for the concentration of 7 ppm and the sedimentation time of 20 min.

Biosorption of Chromium(III) and Copper(II) Ions onto Marine Alga Sargassum sp. in a Fixed-bed Column

The simultaneous biosorption of chromium(III) and copper(II) ions onto Sargassum sp. alga in a fixed-bed column reactor was investigated. Experiments were undertaken to determine the effect of the feed concentration (1, 2, 3 and 6 mequiv/ℓ) and the composition of the metal ion solution [0.25, 0.50 and 0.75 Cu(II)/Cr(III) ratio] on the behaviour of the breakthrough curves. A mathematical model was applied to describe the biosorption in a fixed-bed column. Equilibrium was described in this model in terms of a binary Langmuir-type adsorption process, together with mass transfer in the biosorbent based on the Linear Driving Force (LDF) model. The partial differential equations for the system were solved numerically by the finite volume method. The proposed mathematical model for the biosorption process provided a satisfactory description of the dynamics of metal ion removal in the column relative to the experimental data obtained. The adsorptive capacity of the biomass for Cr(III) ions in the binary system was greater than that for Cu(II) ions. The developed model could provide a useful tool for the optimization of Cr(III) and Cu(II) ion removal processes by Sargassum sp. biomass and the design of the corresponding fixed-bed columns.

Competing Ion Exchange of Zn2+ and Fe3+ in NaY Zeolite

This study was aimed at investigating the equilibrium and interactive effects of binary solutions containing Zn+2 and Fe+3 ions in fixed-bed columns of NaY zeolite. To calculate the dynamic equilibrium through isotherms, experiments were carried out in a fixed-bed column. Reagent-grade ZnCl2 and FeCl3·6H2O solutions were mixed with deionized water to prepare the feed solutions with total ion concentrations in the range of 0.5–5.0 meq/ℓ. Experiments were then carried out using Fe3+ and Zn2+ ions in the following concentration ratios: 0.75:0.25, 0.50:0.50 and 0.25:0.75. The experimental equilibrium data were then described using Langmuir-type models (binary Langmuir model, Langmuir-type model, Jain and Snoeyink model, and noncompetitive Langmuir model) as well as ion exchange model. Results of our analysis revealed that NaY zeolite has a higher affinity for Zn2+ than Fe3+ ions. The equilibrium data were best fit to the Langmuir-type model. Zn2+ ions are removed through an ion-exchange process while the Fe3+ ions may be preferentially adsorbed onto the already exchanged zeolitic sites. This equilibrium model was then applied to a dynamic mathematical model. We describe the equilibrium in this model by assuming the binary Langmuir-type model and mass transfer in the zeolite based on the linear driving force model.

Modeling the water uptake by chicken carcasses during cooling by immersion

In this study, water uptake by poultry carcasses during cooling by water immersion was modeled using artificial neural networks. Data from twenty-five independent variables and the final mass of the carcass were collected in an industrial plant to train and validate the model. Different network structures with one hidden layer were tested, and the Downhill Simplex method was used to optimize the synaptic weights. In order to accelerate the optimization calculus, Principal Component Analysis (PCA) was used to preprocess the input data. The obtained results were: i) PCA reduced the number of input variables from twenty-five to ten; ii) the neural network structure 4-6-1 was the one with the best result; iii) PCA gave the following order of importance: parameters of mass transfer, heat transfer, and initial characteristics of the carcass. The main contributions of this work were to provide an accurate model for predicting the final content of water in the carcasses and a better understanding of the variables involved.