Search

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. Resumo O semiárido pernambucano é uma região que apresenta grande déficit hídrico, levando a população a explorar os recursos hídricos subterrâneos como os aquíferos aluvionares. O estado de Pernambuco também se destaca por conter o segundo maior polo de confecções têxteis do Brasil. No entanto, o lançamento direto de efluentes têxteis provenientes das indústrias da região tem intensificado os impactos negativos na conservação da água e dos solos aluvionares. O objetivo deste trabalho consiste na caracterização da sorção do corante Direct Black 22 (DB22) em solos de duas camadas de um aluvião na bacia do Capibaribe-PE. Os ensaios de Bacth (cinética e isotermas de sorção) permitiram avaliar o potencial de retenção e mobilidade desse composto nesse ambiente. A cinética de sorção foi verificada com os tempos de agitação de 0,25; 0,5; 1; 2; 4; 6; 8; 10; 12; 24; 48 e 72 horas e os dados experimentais foram ajustados aos modelos cinéticos de primeira e segunda. A isoterma ocorreu com concentrações de 1; 5; 10; 15; 20; 32,5 e 40 mg.L-1, e os dados experimentais foram ajustados ao modelo linear, de Freundlich e de Langmuir. A cinética de sorção do DB22 foi melhor descrita pelo modelo de segunda ordem e as isotermas de sorção para Camadas 1 e 2 ajustaram-se adequadamente aos modelos de Freundlich e Linear. Os teores de matéria orgânica e a capacidade de troca catiônica das camadas de solo foram propriedades que influenciaram na sorção do corante. A camada superficial privilegia fenômenos de retenção do corante enquanto que a camada subsuperficial privilegia fenômenos de mobilidade do corante.

The evaluation of the interaction of pollutants in the vadose zone is fundamental for determining the degree of vulnerability of groundwater when transporting contaminants in the soil. The present work presents the interaction of an antibiotic of the type Sulfaziadina in urban soil in the city of Recife. The kinetics and sorption isotherm of Sulfadiazine (SDZ) were determined in a sandy-loam soil of the urban area of the city of Recife. Sorption kinetics and sorption isotherms were performed in for layers of an urban soil profile. Sulfadiazine concentration was determined by high performance liquid chromatography (HPLC). The kinetics studies showed that the sorption was rapid in the first ten hours of the contact period between the soil and the SDZ solution. The equilibrium was reached with 24 hours if interaction in 04 layers. For this soil, SDZ sorption kinetics were reasonably described by a first order model.The second order kinect model presented the best adjustments of sorption kinetics at all depths with R2 values between 0.94 and 0.98. The model that best fit the representation of sorption isotherms was the Linear model. The low KD values (1.3 to 1.9 L.kg-1) indicate high mobility and high risk of groundwater contamination by this compound.