Jeferson Steffanello Piccin

Adsorption Isotherms in Liquid Phase: Experimental, Modeling, and Interpretations

Adsorption is a fundamental unit operation used for several purposes in the academy and industry. Particularly, adsorption in liquid phase is used to remove recalcitrant compounds from effluents (dyes, heavy metals, phenols, pharmaceuticals, and others), to recover valuable metals from leachates (gold, silver, cobalt, and others), and to purify products during the industrial processing (fuels, juices, liquors, wines, and others). For all these applications, the obtainment, modeling, and interpretation of the equilibrium isotherms are a key and fundamental study. Based on the abovementioned, this chapter presents the particularities of adsorption equilibrium isotherms in liquid phase from scientific and technological viewpoints. From the scientific viewpoint, the importance of adsorption isotherms will be addressed. For example, the equilibrium isotherms provide parameters for decision-making of the researcher in relation to the adsorption capacity of a particular adsorbent, give an idea how the interaction of adsorbent–adsorbate occurs, and provide means to find thermodynamic parameters, among others. From technological viewpoint, the adsorption capacity of the material is a basic parameter for the project. Thus, in this chapter the following points are highlighted: experimental procedures to obtain equilibrium curves, isotherm analysis, models used to correlate the equilibrium data and interpretation of its parameters, regression methods (comparison between linear and nonlinear regression methods), error analysis, adsorption thermodynamics, and the use of these data for equipment design.

Biossorção passiva de cromo (VI) através da microalga Spirulina platensis

Effluents containing toxic metals are dangerous and more economical, efficient and environmentally friendly treatments must be studied, with the biosorption process with microbial biomass constituting an efficient solution. Thus, the ability of Spirulina platensis biomass for removing chromium (VI) using passive and active biosorption was evaluated. Inactive microalgae biomass and synthetic solution containing chromium (VI) were used to evaluate important factors in the process and biomass biosorption ability. Results of the experiments showed that microalgae have potential for biosorption of chromium (VI), attaining removal of 100.39 mg g-1, and that pH was the variable with the greatest influence on the process.

Chromium (VI) biosorption by Saccharomyces cerevisiae subjected to chemical and thermal treatments

The potential of chemically and thermally treated Saccharomyces cerevisiae as biosorbents for chromium (VI) was investigated in this work. The presence of this toxic metal in industrial effluents is harmful to the environment, so, it is important to develop environmental friendly methods for Cr(VI) removal from these effluents. Biosorption using microorganisms such as S. cerevisiae is a viable treatment option because this biomass is easily available as a residue of fermentation industries. In this study, the affecting variables on Cr(VI) biosorption were studied by constructing biosorption isotherms, using lyophilized yeast subjected to chemical and thermal treatments. S. cerevisiae was able to remove 99.66% of Cr(VI) from effluents by biosorption. The significant variables affecting biosorption were pH, initial Cr(VI) concentration, and contact time. The biosorption isotherms were represented by the Freundlich model for the untreated biomass, BET model for the chemically treated biomass, and Langmuir model for the heat-treated biomass. Thermal treatment increased the biosorption affinity of the biomass for chromium, while the chemical treatment facilitated the formation of a multilayer.

Adsorption Kinetics in Liquid Phase: Modeling for Discontinuous and Continuous Systems

Adsorption is one of the most widely applied unit operations to separate molecules that are present in a fluid phase using a solid surface. Adsorption kinetic aspects should be evaluated in order to know more details about its mechanisms, characteristics, and possibilities of application. These data can determine the residence time to reach the required concentration of the adsorbate, making possible the design and operation of an adsorption equipment and defining the performance in batch and continuous systems. This chapter presents the particularities of adsorption kinetics in liquid phase. Batch and fixed-bed systems are considered. For discontinuous batch systems, diffusional mass transfer models and adsorption reaction models are discussed. For fixed-bed systems, the shape of breakthrough curves is studied on the basis of mass balance equations and empirical models. Furthermore, the design and scale up of fixed-bed columns are detailed according to the length of unused bed (LUB) and bed depth service time (BDST) concepts. Several numerical methods are presented in order to solve the required models for batch and fixed-bed systems. Some parameter estimation techniques are discussed in order to obtain the fundamental parameters for adsorption purposes, like mass transfer coefficients and empirical parameters.

Multilayer Adsorption of Purple NR5 Industrial Dye by Aristeus antennautus Shell in Aqueous Solution

In this work, chitin-based material has been proposed for removing the purple NR5 dye in aqueous solution. The material chosen is from shrimp shell: Aristeus antennautus. This biomaterial is used as a raw form. The adsorption isotherms obtained showed a behavior of L3a indicating the passage of monolayer to multilayer adsorption. The results are well correlated with the BET model, (R²>0.99). And the maximum monolayer adsorption capacity was found to be 667.33 mg/g. The kinetic data were evaluated using pseudo first order, pseudo second order and the intraparticle diffusion models. The chemical nature of the biomaterial is confirmed by Fourier Transform infrared spectroscopy (FTIR).

Mass transfer models for the adsorption of Acid Red 357 and Acid Black 210 by tannery solid wastes

Diffusional mass transfer models with and without external resistance were applied to represent the adsorption of Acid Red 357 (AR357) and Acid Black 210 (AB210) by tannery solid wastes. The mass transfer parameters, such as, external mass transfer coefficient (k f ), surface diffusion coefficient (D s ), and Biot number (B i ) were estimated and interpreted. It was found that the two models agreed with the experimental data and, very similar values of the parameters were obtained. This indicated that the external mass transfer mechanism can be neglected. Then, the model without external resistance, which is simpler, can be used. The D s values ranged from 5.01 × 10−13 to 1.30 × 10−12 m2 s−1 for AR357 and from 3.19 × 10−14 to 5.38 × 10−14 m2 s−1 for AB210. The high values of the B i number confirmed that the adsorption of AR357 and AB210 on tannery solid wastes was controlled by surface diffusion.

Otimização de sistema de autoaspiração de ar tipo Venturi para tratamento de água ferruginosa

In this study the response surface methodology was used to optimize the effect of Reynolds number, flocculation time and sodium hypochlorite concentration on the iron oxidation/flocculation present in groundwaters in an aeration system with air auto-aspiration. This system was composed of a recipient type Venturi coupled to a mixture tube to promote the oxygenation of the water through the suction of the atmospheric air. The hydrodynamic mapping allowed the verification of the operation conditions in which the system presented the best air suction efficiency and energy consumption, and the comparison of the best field conditions. The observed results demonstrated that it was possible to remove 98.7% of present iron (residual iron of 0.06 mg L-1) when the system operated with Reynolds number of 5.39 x 104, sodium hypochlorite concentrations of 38.4 mg L-1 and flocculation time of 30 min. The response surface methodology was satisfactory and allowed for the optimization of the mentioned operational variables.