Sorption of the Direct Black 22 dye in alluvial soil

Abstract

<jats:p>The semiarid region of Pernambuco has a large water deficit, leading the population to explore groundwater resources such as alluvial aquifers. The state of Pernambuco also stands out for having the second-largest textile manufacturing center in Brazil. However, the direct discharge of textile effluents from the region's industries has intensified the negative impacts on water conservation and alluvial soils. This work characterized the sorption of Direct Black 22 dye (DB22) in two layers of alluvial soil in the Capibaribe-PE basin. Batch experiments (kinetics and sorption isotherms) allowed the evaluation of the retention potential and mobility of this compound in this environment. Sorption kinetics were verified for stirring times of 0.25; 0.5; 1; 2; 4; 6; 8; 10; 12; 24; 48 and 72 hours and the experimental data was adjusted to the first- and second-order kinetic models. The isotherm occurred with concentrations of 1; 5; 10; 15; 20; 32.5 and 40 mg.L-1 and experimental data was adjusted to the linear, Freundlich and Langmuir models. The sorption kinetics of DB22 was best described by the second-order model, while the Freundlich and Linear models properly fitted sorption isotherms for Layers 1 and 2. The organic matter contents and the cation-exchange capacity of the soil layers influenced the sorption of the dye. The superficial layer privileges dye retention phenomena, while in the subsurface layer dye mobility phenomena prevail.</jats:p>

Removal of Remazol Black B dye using bacterial cellulose as an adsorbent

“…In order to know some characteristics about the adsorption kinetics of RBB in cellulose, the experimental data obtained in the kinetic study were evaluated by three kinetic models, namely: the pseudo-first order, pseudo-second order and intraparticle diffusion models (Morris-Weber) using Linear Equations 5, 6 and 7 [25,28,29].…”

“…The adsorption isotherms represent a balance between the concentration of dye in the liquid phase and the amount of dye present in the adsorbent [28,29]. All equilibrium tests were performed in triplicate, the conditions used were: 0.5 g of adsorbent, 150 rpm for 12 h and pH 3.5, in different concentrations of the dye solution (25, 35, 45, 55 and 65 mg L -1 ) and different temperatures (30, 40, 60 and 100 ± 2 ºC).…”

“…All equilibrium tests were performed in triplicate, the conditions used were: 0.5 g of adsorbent, 150 rpm for 12 h and pH 3.5, in different concentrations of the dye solution (25, 35, 45, 55 and 65 mg L -1 ) and different temperatures (30, 40, 60 and 100 ± 2 ºC). The models used were Langmuir and Freundlich according to linearized Equations 8, 9 and 10 [25, [28][29][30][31].…”

“…The thermodynamic characteristics of the process were expressed at different temperatures and concentrations. Through linearized Equations 11, 12 and 13 it is possible to determine the variations of entropy, enthalpy, Gibbs free energy and activation energy of the adsorptive process [25,28,29,32].…”

Performance of slow sand filters in the after-treatment of effluent from Pernambuco state textile center

“…Soils have good retention capacity for textile contaminants, especially in the case of dyes (Alexandre et al, 2020;Alves et al, 2020), proving that simple techniques also produce satisfactory results. Therefore, slow sand filtration appears as a simple alternative for treating textile effluents.…”