Kinetic modeling of the adsorption and desorption of metallic ions present in effluents using the biosorbent obtained from Syagrus romanzoffiana.

In this study, the kinetic mechanism of adsorption and desorption, as well as the equilibrium isotherms, of four metallic ions (Cd2+, Cu2+, Ni2+, and Zn2+) mono and multicomponent were investigated. The biosorbent used was produced from Jerivá (Syagrus romanzoffiana-commonly known as queen palm) coconut. A kinetic model that considers macropore diffusion as a control step was solved. The finite volume method was used in the discretization of the equations, and the algorithm was implemented in the Fortran programming language. The equilibrium time for monocomponent adsorption was 5 min; for the multicomponent tests, equilibrium occurred instantly (less than 2 min of adsorption). The pseudo-second-order model presented the lowest mean of the sum of normalized errors (SNE) and represented the experimental data of mono and multicomponent adsorption and desorption. Single and multicomponent Langmuir model represented the adsorption isotherms. The maximum capacity of adsorption of metallic ions, both mono and multicomponent, was higher for copper, and the multicomponent adsorption proved to be antagonistic; the presence of co-ions in the solution reduced the removal of metals due to competition between these contaminants. The capture preference order was justified by the physicochemical properties of the ions, such as electron incompatibility and electronegativity. All these situations justified the maximum adsorption of Cu2+, followed by Zn2+, Cd2+, and Ni2+ in the mixture.

Ibuprofen removal from synthetic effluents using Electrocoagulation-Peroxidation (ECP).

Concerning water resources, several ordinances and legislation determine standards and conditions for the discharge of effluents into water bodies. However, several contaminants are not covered by these guidelines due to little knowledge of their long-term effects and because they are found in low concentrations. These contaminants are called emergent and this category includes drugs, such as anti-inflammatory drugs. The electrocoagulation process associated with advanced oxidation comes up as an alternative to conventional effluent treatment processes, and the objective of this study was to evaluate this process using scrap iron as sacrificial electrodes in the treatment of synthetic effluents containing ibuprofen. High-performance liquid chromatography was used to quantify the drug in synthetic effluents. The Central Rotational Composite Design 24 was used in an experimental design, considering independent variables the concentration of contaminants, applied current, the concentration of the primary oxidizing agent H2O2, and the reaction time. The optimized conditions determined by statistical analysis were drug concentration of 5 mg L-1, H2O2 concentration of 200 mg L-1, current of 5 A, and 150 min. The removals obtained under these conditions were higher than 92% in the aqueous phase, showing that electrocoagulation peroxidation technique has the potential to treat contaminants such as drugs present in effluents and waters.

Enhanced UV Direct Photolysis and UV/H2O2 for Oxidation of Triclosan and Ibuprofen in Synthetic Effluent: an Experimental Study.

This study aimed to evaluate the implementation of an advanced oxidation system based on UV radiation and UV/H2O2 for degradation of TCS and IBU in synthetic effluent. The assays occurred in a 2-L reactor, protected from external light and equipped with a UV lamp (λ = 254 nm). The effect of contaminant concentration, fractions of chemical species present, and mineralization were evaluated. In the UV/ H2O2 system, different concentrations of H2O2 were studied for oxidation of the contaminants. The kinetic experiments took place between 75 and 270 min of UV irradiation. The results showed > 99% oxidation of TCS in the direct photolysis system at pH 9.4 after 12 min. The degradation of IBU in the UV/H2O2 system, when 10 mg L-1 of H2O2 was used, was 97.39% oxidation. We obtained k' values of 0.189 min-1 for TCS when its highest oxidation occurred and k' values of 0.0219 min-1 for IBU. The system was not able to completely mineralize the contaminants, presenting high values of TOC and COD after treatment, thus suggesting the occurrence of phototransformation. Supplementary Information: The online version contains supplementary material available at 10.1007/s11270-022-05583-z.

Electrocoagulation applied for textile wastewater oxidation using iron slag as electrodes.

The indigo blue dye is widely used in the textile industry, specifically in jeans dyeing, the effluents of which, rich in organic pollutants with recalcitrant characteristics, end up causing several environmental impacts, requiring efficient treatments. Several pieces of research have been conducted in search of effective treatment methods, among which is electrocoagulation. This treatment consists of an electrochemical process that generates its own coagulant by applying an electric current on metallic electrodes, bypassing the use of other chemical products. The purpose of this study was to evaluate the potential use of iron slag in the electrocoagulation of a synthetic effluent containing commercial indigo blue dye and the effluent from a textile factory. The quantified parameters were color, turbidity, pH, electrical conductivity, sludge generation, phenol removal, chemical oxygen demand (COD), and total organic carbon (TOC). The electrocoagulation treatment presented a good efficiency in removing the analyzed parameters, obtaining average removal in the synthetic effluent of 85% of color and 100% of phenol after 25 min of electrolysis. For the effluent from the textile factory, average reductions of 80% of color reaching 177.54 mg Pt CoL-1, 91% of turbidity reaching 93.83 NTU (nephelometric turbidity unit), 100% of phenol, 55% of COD with a final concentration of 298.8 mg O2 L-1, and 73% of TOC with a final concentration of 56.21 mg L-1, in 60 min of electrolysis. The reduced time for removal of color and phenolic compounds in synthetic effluent demonstrates the complexity of treating the real effluent since to obtain removals of the same order a 60-min period of electrolysis was necessary. The results obtained demonstrate the potential of using iron slag as an electrode in the electrocoagulation process in order to reuse industrial waste and reduce costs in the treatment and disposal of solid waste. Thus, the slag can be seen as an alternative material to be used in electrocoagulation processes for the treatment of effluents from the textile industry under the experimental conditions presented, its only limitation being the fact that it is a waste and therefore does not have a standardization in the amounts of iron present in the alternative electrodes.

Tratamento numérico e ensaios experimentais da remoção de fenol em reator batelada e coluna de leito fixo utilizando carvão ativado / Numerical treatment and experimental tests of phenol removal in batch and fixed bed column using activated carbon

RESUMO Neste estudo, foram obtidas as cinéticas e isotermas de adsorção do fenol presentes em efluentes sintéticos em reator batelada e coluna de leito fixo, utilizando como adsorvente carvão ativado de casca de coco. O objetivo foi a obtenção dos parâmetros cinéticos e de equilíbrio do processo para simular diferentes condições operacionais em uma coluna de adsorção em leito fixo. Foram avaliadas a influência do pH, a massa de adsorvente, a concentração inicial de fenol e três diferentes temperaturas para os testes em reator batelada. Foi possível trabalhar no pH natural da solução e o aumento da temperatura indicou adsorção exotérmica, favorável e espontânea. Os dois modelos de isoterma (Langmuir e Freundlich) representaram bem os dados experimentais (R2 ≈ 0,9). Valores aproximados de capacidade máxima de adsorção foram encontrados para o reator batelada e para a coluna de leito fixo (qmáx = 41,69 mg.g-1 para o reator batelada e qmáx = 41,98 mg.g-1 para a coluna de leito fixo). O método de Volumes Finitos foi utilizado na discretização das equações matemáticas e um algoritmo computacional foi implementado em linguagem FORTRAN. O código computacional foi validado com dados experimentais deste trabalho (erro médio de 13%), podendo-se assim simular diferentes condições operacionais do sistema de adsorção em coluna de leito fixo com vista a futuras aplicações industriais.

ABSTRACT In this study, the kinetics and adsorption isotherms of phenol present in synthetic effluents were obtained in a batch reactor and fixed bed column, using adsorbent coconut shell activated carbon. The objective was to obtain the kinetic and equilibrium parameters of the process to simulate different operating conditions in a fixed bed adsorption column. The influence of the pH, adsorbent mass, initial phenol concentration, and three different temperatures for the batch reactor tests were evaluated. It was possible to work on the natural pH of the solution and the temperature increase indicated exothermic, favorable, and spontaneous adsorption. Both isotherm models (Langmuir and Freundlich) represented the experimental data (R2 ≈ 0.9). Approximate values of maximum adsorption capacity were found for the batch reactor and for the fixed bed column (qmax = 41.69 mg g-1 for the batch reactor and qmax = 41.98 mg g-1 for the fixed bed column). The Finite Volume method was used in the discretization of the mathematical equations and a computational algorithm was implemented in FORTRAN programming language. The computational code was validated with experimental data of this work (mean error of 13%) and it was possible to simulate different operational conditions of the fixed bed column adsorption system for future industrial applications.