Nanoplastics adsorption and removal efficiency by granular activated carbon used in drinking water treatment process.

Autor: Ramirez Arenas L; Group of Environmental Physical Chemistry, Department F.-A. Forel for Environmental and Aquatic Sciences, University of Geneva, Uni Carl Vogt, 66, boulevard Carl-Vogt, CH-1211 Geneva 4, Switzerland. Electronic address: Lina.RamirezArenas@unige.ch., Ramseier Gentile S; SIG, Industrial Boards of Geneva, Ch. du Château-Bloch, Le Lignon, 1211 Genève 2, Switzerland., Zimmermann S; SIG, Industrial Boards of Geneva, Ch. du Château-Bloch, Le Lignon, 1211 Genève 2, Switzerland., Stoll S; Group of Environmental Physical Chemistry, Department F.-A. Forel for Environmental and Aquatic Sciences, University of Geneva, Uni Carl Vogt, 66, boulevard Carl-Vogt, CH-1211 Geneva 4, Switzerland. Electronic address: Serge.Stoll@unige.ch.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2021 Oct 15; Vol. 791, pp. 148175. Date of Electronic Publication: 2021 Jun 01.
DOI: 10.1016/j.scitotenv.2021.148175
Abstrakt: In this study Granular Activated Carbon (GAC) used in drinking water treatment processes is evaluated for its capacity to adsorb and remove polystyrene (PS) nanoplastics. Batch experiments are conducted in ultrapure and surface water from Lake Geneva, currently used as drinking water resources. Equilibrium and kinetic studies are conducted to understand adsorption mechanisms and limiting factors. Our results show that in ultrapure water the adsorption and removal of PS nanoplastics are mainly due to electrostatic interactions between the positively charged nanoplastics and negatively charged GAC. It is found that the adsorption capacity increases with nanoplastic concentration with a maximum adsorption capacity of 2.20 mg/g. The adsorption kinetics follows a pseudo-second-order model and indicates that the intra-particle diffusion is not the only rate-controlling step. The Langmuir isotherm indicates that nanoplastics are adsorbed as a homogeneous monolayer onto the GAC surface with a maximum monolayer adsorption capacity of 2.15 mg/g in agreement with the experimental value. In Lake Geneva water the adsorption capacity and removal efficiency of PS nanoplastics are found three times higher than in ultrapure water and increase significantly with increasing PS nanoplastics concentration with a maximum adsorption capacity of 6.33 mg/g. This improvement in adsorption capacity is due to the presence of Dissolved Organic Matter (DOM), resulting in PS surface charge modification, presence of divalent ions making possible the adsorption of PS-DOM complexes, and, aggregation of PS nanoplastics. The kinetic pseudo-second-order and intra-particle diffusion provide a good correlation with the experimental data. In contrast, neither Langmuir nor Freundlich isotherms describe in a satisfactory way the adsorption of nanoplastics by GAC. This study reveals that GAC produced from renewable sources can be considered as a moderate adsorbent for the removal of PS nanoplastics in water treatment plants and that the presence of DOM and cationic species play a major role.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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