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  • The influence of heavy meta...
    Zhang, Jin; Wang, Xun; Zhu, Yu; Huang, Zhenyu; Yu, Zhujing; Bai, Yun; Fan, Gongduan; Wang, Peng; Chen, Hao; Su, Yiming; Trujillo-González, Juan Manuel; Hu, Bill X.; Krebs, Peter; Hua, Pei

    Ecotoxicology and environmental safety, 07/2019, Letnik: 176
    Journal Article

    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 (R2 = 0.98–0.99) and Freundlich isotherm (R2 = 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 6300 mg kg−1, 5800 mg kg−1, 4000 mg kg−1, and 3200 mg 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. Display omitted •Road dust with a finer grain size is an important source of metal ions retention.•A two-stage adsorption kinetic behavior for Cu, Zn, Ni, and Cd was found.•Pseudo-second-order kinetic fitted better to the given metals.•Both of the Langmuir and Freundlich isotherms were fitted well for Zn, Ni, and Cd.•Metals' exchangeable fractions in road dust could be considered as irreversible.