Aggregation behaviour of black carbon in aquatic solution: Effect of ionic strength and coexisting metals

Kiran Dhangar; Manish Kumar; Marwan Aouad; Jurgen Mahlknecht; Nirav P Raval

doi:10.1016/j.chemosphere.2022.137088

Aggregation behaviour of black carbon in aquatic solution: Effect of ionic strength and coexisting metals

Chemosphere. 2023 Jan;311(Pt 2):137088. doi: 10.1016/j.chemosphere.2022.137088. Epub 2022 Nov 1.

Authors

Kiran Dhangar¹, Manish Kumar², Marwan Aouad³, Jurgen Mahlknecht⁴, Nirav P Raval⁵

Affiliations

¹ Discipline of Earth Science, Indian Institute of Technology Gandhinagar, Gujarat, 382-355, India.
² Discipline of Earth Science, Indian Institute of Technology Gandhinagar, Gujarat, 382-355, India; Sustainability Cluster, School of Engineering, University of Petroleum & Energy Studies, Dehradun, Uttarakhand, 248007, India; Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Monterrey, Eugenio Garza Sada 2501 Sur, Monterrey, 64849, Mexico. Electronic address: manish.env@gmail.com.
³ College of Engineering, Applied Science University, Bahrain.
⁴ Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Monterrey, Eugenio Garza Sada 2501 Sur, Monterrey, 64849, Mexico.
⁵ Laboratoire Environnement Dynamiques Territoires Montagnes, Université Savoie Mont Blanc, Campus Scientifique - Savoie Technolac, Le Bourget-du-Lac, 73376, Cedex, France.

PMID: 36332736
DOI: 10.1016/j.chemosphere.2022.137088

Abstract

Black Carbon (BC) is an important constituent of both aquatic and terrestrial environment, but also has several adverse effects on human health, aquatic life, and contributes to the global climate change. Thus, to understand the fate and transport of BC nanoparticles (NPs) in the environment, it's important to understand the colloidal stability or aggregation behaviour and factors affecting it, under various environmental conditions, including both aquatic and atmospheric. This study investigated the individual influence of ionic strengths, valence (Na⁺, Ca²⁺ and Mg²⁺), metals (Zn²⁺, Cu²⁺, Ni²⁺ and Cd²⁺), and organic substances (PO₄^3- and Humic Acid: HA) on the effective diameter or hydrodynamic diameter and zeta potential of BC-NPs in aquatic systems. A dynamic light scattering (DLS) principle-based 90 Plus Particle Size Analyzer was used for measurements of BC particle size and zeta potential at varying ionic chemistry. The results showed that strong ionic strength promotes aggregation of BC-NPs till the repulsion forces become dominant due to more negative zeta potential. The Aggregation of BC-NPs was observed to be significantly dependent on the ionic valence, where divalent ions caused more aggregation than monovalent ions. Metal ions at higher concentration (around 1 mM) promoted the aggregation rate of BC-NPs, and Cu⁺² dominated among all selected metals. Conversely, organic matter (PO₄^3- and HA) tends to promote stabilisation of BC-NPs instead of aggregation. Though this study investigated individual effect of substances, influence of possible environmental combination of substances will help to get more clear idea.

Keywords: Aggregation; Black carbon nanoparticles; Ionic strength; Metals; Organic matter.