Optimization of Removal Efficiency and Minimum Contact Time for Cadmium and Zinc Removal onto Iron-modified Zeolite in a Two-stage Batch Sorption Reactor

In highly congested industrial sites where significant volumes of effluents have to be treated in the minimum contact time, the application of a multi-stage batch reactor is suggested. To achieve better balance between capacity utilization and cost efficiency in design optimization, a two-stage batch reactor is usually the optimal solution. Thus, in this paper, a two-stage batch sorption design approach was applied to the experimental data of cadmium and zinc uptake onto iron-modified zeolite. The optimization approach involves the application of the Vermeulen’s approximation model and mass balance equation to kinetic data. A design analysis method was developed to optimize the removal efficiency and minimum total contact time by combining the time required in the two-stages, in order to achieve the maximum percentage of cadmium and zinc removal using a fixed mass of zeolite. The benefits and limitations of the two-stage design approach have been investigated and discussed. This work is licensed under a Creative Commons Attribution 4.0 International License

Design of Fixed Bed Column for Lead Removal on Natural Zeolite Based on Batch Studies

This paper presents the prediction of breakthrough curves for the fixed bed column based on batch studies. Batch equilibrium studies of lead removal on natural zeolite clinoptilolite have been performed. The obtained experimental data have been tested according to the Langmuir and the Freundlich isotherm, and their parameters have been calculated. These parameters and the Mass Transfer Model have been used to predict theoretical breakthrough curves. Theoretical breakthrough curves have been compared with the experimental ones and good agreement has been observed. This indicates that the Mass Transfer Model is applicable for prediction of breakthrough curves from batch studies. The overall mass transfer coefficient has been calculated from column experiments. This value allows for calculation of the height of the mass transfer zone as a very important parameter necessary for column design

Removal of lead from aqueous solutions by using the natural and Fe(III)-modified zeolite

In the present study, the sorption of lead by the natural and Fe(III)-modified zeolite (clinoptilolite) is described. The characterization of the natural zeolite-rich rock and the Fe(III)-modified form was performed by chemical analysis, point of the zero charge (pHpzc), X-ray powder diffraction, applying the Rietveld/RIR method for the quantitative phase analysis, and scanning electron microscopy. The effects of sorbents dose and the initial lead concentrations on its sorption by two sorbents were investigated. For both sorbents, it was determined that at lower initial concentrations of lead, ion exchange of inorganic cations in zeolites with lead, together with uptake of hydrogen dominated, while at higher initial lead concentrations beside these processes, chemisorption of lead occurred. Significantly higher sorption of lead was achieved with Fe(III)-modified zeolite. From sorption isotherms, maximum sorbed amounts of lead, under the applied experimental conditions, were 66 mg/g for the natural and 133 mg/g for Fe(III)modified zeolite. The best fit of experimental data was achieved with the Freundlich model (R-2 >= 0.94)