Thiabendazole (TBZ) is an ionizable anthelmintic agent that belongs to the class of benzimidazoles. It is widely used in veterinary medicine and as a fungicide in agriculture. Sorption and desorption are important processes influencing transport, transformation, and bioavailability of xenobiotic compounds in soils; data related to sorption capacity are therefore needed for environmental risk assessments. The aim of this work was to assess the sorption potential of TBZ in four Brazilians soils (sandy, sandy-clay, and clay soils), using batch equilibrium experiments at three pH ranges (2.3-3.0, 3.8-4.2, and 5.5-5.7). The Freundlich sorption coefficient (K ) ranged from 9.0 to 58 μg (mL) g, with higher values generally observed at the lower pH ranges (2.3-3.0 and 3.8-4.2) and for clay soils. The highest organic carbon-normalized sorption coefficients (K) obtained at pH 3.8-5.7 (around the natural pH range of 4.1-5.0) for both clay soils and sandy-clay soil were 3255 and 2015 mL g, respectively. The highest correlations K vs SOM (r = 0.70) and K vs clay content (r = 0.91) were observed at pH 3.8-4.2. Our results suggest that TBZ sorption/desorption is strongly pH dependent and that its mobility could be higher in the studied soils than previously reported in soils from temperate regions.
Experiments in saturated soil columns were performed to investigate the transport and retention of 25 nm and 75 nm silver nanoparticles stabilized with polyvinylpyrrolidone (PVP-AgNPs) in two Brazilian soils (sandy and sandy-clay). The normalized concentration of the PVP-AgNPs was obtained through a flow injection analysis method based on the surface plasmon ressonance effect of the metallic nanoparticles. The use of the ultraviolet-visible spectroscopy (UV-Vis) allows a rapid and low-cost analysis. The obtained breakthrough curves (BCs) were modeled with a deterministic model of solute transport in steady conditions of water flow and considering two regions of non-physical equilibrium; this model allowed the determination of the hydrodynamic parameters. It was found that the process occurs in condition of non-equilibrium, with a low mass transfer for larger NP, and that the process is predominantly advective and affected by the pore size of the soil packed in the columns. The BCs for PVP-AgNPs obtained by UV-Vis spectroscopy were compared with the BCs obtained by ICP-MS and with BCs of the bromide anion, confirming that the nanoparticles have a low retention and few modifications when transported through the soil column. These PVP-AgNPs are highly mobile and can be transported through the studied tropical soils, representing a potential environmental problem, due to the possibility of these materials reaching groundwater. On the contrary, the conservative behavior of PVP-AgNPs in the studied tropical soils, indicates its potential use as tracers, substituting the bromide anion which has been demonstrated to be not a good tracer in the same conditions.
Experimentos em colunas com solo saturados foram feitos para investigar o transporte e retenção de nanopartículas de prata estabilizadas com uma capa de polivinilpirrolidona (PVP-AgNP). A concentração normalizada do traçador brometo foi obtida por meio de um método de análise em fluxo baseado no efeito catalítico do brometo na decomposição do azul de metileno usando espectrofotometria ultravioleta-visível (UV-Vis), permitindo uma análise rápida de baixo custo. As curvas de ruptura obtidas foram modeladas com um modelo determinístico de transporte de solutos em condições de régime permanente de fluxo, considerando-se duas regiões de não equilíbrio físico, permitindo encontrar desta forma os parâmetros hidrodinâmicos do transporte. Destas curvas de ruptura foi possível concluir que o brometo apresenta um carácter não conservativo o que indica uma forte interação com a matriz sólida do solo. Já as curvas para as PVP-AgNP obtidas por espectroscopia UV-Vis e ICP-MS mostram que as partículas apresentam baixa retenção e pouca modificação ao longo da coluna de solo. A agregação das PVP-AgNP foi estudada por meio de um planejamento experimental 2 8-4 (16 soluções em água artificial de solo), a resposta do planejamento foi relacionada com a velocidade de modificação da banda do plasmon característica das PVP-AgNP. Os parâmetros que apresentaram efeito significativo foram o tamanho e concentração das AgNP, a presença de matéria orgânica e dois parâmetros de interação: entre o pH e o tipo de eletrólito (mono ou divalente) e a concentração de íon cloreto.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.