A comprehensive estimate of the aggregation and transport of nSiO2 in static and dynamic aqueous systems

• Published in: Environmental science--processes & impacts 2022-05, Vol.24 (5), p.675-688
• Main Authors: Ghosh, Debayan, Das, Soupam, Gahlot, Vikas Kumar, Pulimi, Mrudula, Anand, Shalini, Chandrasekaran, N, Rai, Pramod Kumar, Mukherjee, Amitava
• Format: Article
• Language: English
• Subjects: Agglomeration; Aggregation behavior; Aquatic ecosystems; Aquatic environment; Aquatic organisms; Aqueous environments; Aqueous solutions; Drinking water; Environmental aspects; Humic acids; Ionic strength; Lakes; Nanoparticles; Parameters; pH effects; Sedimentation; Sedimentation & deposition; Shear forces; Silicon dioxide; Spatial distribution; Stability analysis; Terrestrial environments; Transport phenomena
• ISSN: 2050-7887; 2050-7895
• DOI: 10.1039/d2em00016d

Silicon dioxide nanoparticles (nSiO2) are extensively used in diverse fields and are inevitably released into the natural environment. Their overall aggregation behaviour in the environmental matrix can determine their fate and ecotoxicological effect on terrestrial and aquatic life. The current study systematically evaluates multiple parameters that can influence the stability of colloidal nSiO2 (47 nm) in the natural aquatic environment. At first, the influence of several hydrochemical parameters such as pH (5, 7, and 9), ionic strength (IS) (10, 50, and 100 mM), and humic acid (HA) (0.1, 1, and 10 mg L−1) was examined to understand the overall aggregation process of nSiO2. Furthermore, the synergistic and antagonistic effects of ionic strength and humic acid on the transport of nSiO2 in the aqueous environment were examined. Our experimental findings indicate that pH, ionic strength, and humic acid all had a profound influence on the sedimentation process of nSiO2. The experimental observations were corroborated by calculating the DLVO interaction energy profile, which was shown to be congruent with the transport patterns. The present study also highlights the influence of high and low shear forces on the sedimentation process of nSiO2 in the aqueous medium. The presence of shear force altered the collision efficiency and other interactive forces between the nanoparticles in the colloidal suspension. Under the experimental stirring conditions, a higher abundance of dispersed nSiO2 in the upper layer of the aqueous medium was noted. Additionally, the transport behaviour of nSiO2 was studied in a variety of natural water systems, including rivers, lakes, ground, and tap water. The study significantly contributes to our understanding of the different physical, chemical, and environmental aspects that can critically impact the sedimentation and spatial distribution of nSiO2 in static and dynamic aquatic ecosystems.