Oswaldo Curty da Motta Lima

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.

Analysis of Drying Kinetics and Moisture Distribution in Convective Textile Fabric Drying

ABSTRACT The drying process of crude cotton fabric is analyzed under two main aspects: analysis of moisture distribution inside the textile sheet, and analysis of certain operational convective drying process variables. Experimental apparatus consisted of a drying chamber in which samples of pure cotton textile were suspended inside the drying chamber and exposed to a convective hot air flow. The influence of the operational variables on the drying process behavior was studied by two different ways with generalized drying curves. The behavior of moisture distribution profiles was compared to average moisture content of the textile fabric verifying whether average values were able to represent the textile moisture content during the drying process.

Sorption isotherm of agricultural residue of orange bagasse

Wet bagasse can be used as an adsorbent in effluent treatment process. However, before its use a previous drying is necessary. The water activity is an important parameter that affects the fermentation process, and thus its determination becomes most important in order to store this adsorbent. Thus, the objective of this work is to determine the sorption isotherms of orange bagasse at 25, 35 and 50 °C temperatures in order to correlate the moisture with a water activity. The equilibrium moisture content was determined by the static method using salts solution for a 10-80% relative humidity range. The following models were fitted to the experimental data: Henderson, Chung-Pfost, Modified Henderson, Halsey, Luikov and Motta Lima. All models results followed a sigmodal-type function. The equilibrium data for the orange bagasse were better represented by the Luikov and Halsey models.

Moisture Equilibrium Isotherms for a Commercial Liquid Package Paper

Abstract Moisture equilibrium isotherms are very important in drying and storage processes analysis. So, the DEQ/UEM process separation group is building a data bank for cellulose, paper, and textile isotherms and their fit with available literature equations. In this context, the experimental isotherms of a brazilian specific commercial paper, the KLABIN-PR KLAPAK commercial liquid package paper were obtained. The experimental equilibrium data were obtained by exposing the material to different ambient conditions of temperature and relative humidity controlled by the use of saline solutions. The samples were placed in glass flasks left inside an oven to provide a better adjust of temperature conditions, being periodically weighed until constant weight. KLAPAK moisture equilibrium isotherms were built from the obtained experimental results and temperature effects on its behavior were analyzed. Then, these results were fitted with the help of some models and equations available from literature.

The Removal of Fe(III) Ions by Adsorption onto Zeolite Columns

The uptake capacity of Fe(III) ions by NaY zeolite was investigated in this work. Column experiments were undertaken on continuous systems at 30°C, pH = 3.5, employing a flow rate of 2 ml/min and an average particle size of 0.180 mm. The dynamic system exhibited a distinct ion-exchange mechanism which generated a favourable isotherm with an Fe(III) ion uptake of 2.16 mequiv/g. A mathematical model was also applied to represent the dynamics of the sorption process. The dynamic isotherm was successfully modelled by the Langmuir equation while the mathematical model gave a good description of the experimental dynamic data for feed concentrations ranging from 0.2 mequiv/l to 3.5 mequiv/l. The ion-exchange kinetics for Fe(III) ions were studied using the first-, second-order and Langmuir kinetic models.