The influence of heavy metals in road dust on the surface runoff quality: Kinetic, isotherm, and sequential extraction investigations.
Ecotoxicol Environ Saf
; 176: 270-278, 2019 Jul 30.
Article
em En
| MEDLINE
| ID: mdl-30947030
ABSTRACT
This study examines the adsorption and desorption characteristics of heavy metals in road dust (RD) for the aspect of integrated stormwater management. The chemical fractionations of Cu, Zn, Ni, and Cd were determined by a three-step sequential extraction protocol. Pseudo-first-order and Pseudo-second-order kinetic models, along with Langmuir, Freundlich, and Temkin isotherms were adopted to simulate the batch experimental data. The proportional shift of metals' chemical fractionations in original RD, adsorption equilibrium, and desorption equilibrium were determined. Results show that RD has a remarkable affinity to adsorb heavy metal within a short time. The adsorption processes were well described by the Pseudo-second-order kinetic model (R2â¯=â¯0.98-0.99) and Freundlich isotherm (R2â¯=â¯0.89-0.98) for most of the given metals indicating that the chemical adsorption was probably the rate-controlling step and the binding energy for each site was not identical. The maximum adsorption capacities for Cu, Cd, Zn, and Ni were 6300â¯mgâ¯kg-1, 5800â¯mgâ¯kg-1, 4000â¯mgâ¯kg-1, and 3200â¯mgâ¯kg-1, respectively. A linear fit to the equilibrium pH and the total amounts of the adsorbed metals indicates a strong pH-dependent adsorption. According to the proportional shift of metals' chemical fractionations during the adsorption and desorption processes, the exchangeable fractions of heavy metals in RD were irreversible. It suggests that a portion of the surface sites of RD would be not exchangeable once it was occupied.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Poluentes Químicos da Água
/
Metais Pesados
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Poeira
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Ecotoxicol Environ Saf
Ano de publicação:
2019
Tipo de documento:
Article
País de publicação:
HOLANDA
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HOLLAND
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NETHERLANDS
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NL
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PAISES BAJOS
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THE NETHERLANDS