Coagulation of TiO₂, CeO₂ nanoparticles, and polystyrene nanoplastics in bottled mineral and surface waters. Effect of water properties, coagulant type, and dosage

Abstract

Intensive use of engineered nanoparticles (NPs) results in their release into aquatic systems and consequently into drinking water resources. Therefore, it is important to evaluate how NPs can be effectively removed through water treatment processes, such as coagulation, to control environmental and health risks associated with NP exposure. This work investigates the effect of two conventional coagulants, polyaluminum chloride (PACl) and iron chloride (FeCl3), on NPs. Three bottled mineral and Lake Geneva waters, currently used as drinking water resources, were considered to get an insight into coagulation efficiency. TiO2, CeO2 NPs, and polystyrene (PS) nanoplastics were selected, owing to their large number of applications and contrasting surface charge and aggregation behavior at environmental pH. Our findings indicate that PACl is more efficient compared with FeCl3 since lower dosages are required to coagulate all nanoparticles. On the other hand, nanoplastic coagulation is found less efficient compared with TiO2 and CeO2 NPs. This is an important outcome indicating that nanoplastic stability and dispersion state will be more pronounced and therefore more challenging to eliminate. Results highlight the key role of NP and PS nanoplastic surface charge, as well as water properties, coagulant type, and dosage on nanoparticle elimination from aquatic systems. Practitioner Points pH, water hardness, and NOM are playing roles in final coagulant dosage concentration. PACl is more efficient than FeCl3 in most conditions. Positively charged nanoplastics are more difficult to eliminate by coagulation. NP surface properties in bottled mineral and surface waters are controlled by pH, divalent cations, and NOM. NP surface charge and coagulation efficiency depend on water properties.

Polystyrene Nanoplastic Behavior and Toxicity on Crustacean Daphnia magna: Media Composition, Size, and Surface Charge Effects

“…Z-average diameter variations (Figure 2B) are found to be in good agreement with ζ-potential values, i.e., decreasing the ζ-potential value results in an increase in the zaverage size and consequently the formation of NPL aggregates. The above results are found to be in good agreement with a previous study considering PS positively charged in bottled mineral and surface waters, in which the role of NOM and ionic composition was considered [35].…”

“…Z-average diameter variations (Figure 2B) are found to be in good agreement with ζpotential values, i.e., decreasing the ζ-potential value results in an increase in the z-average size and consequently the formation of NPL aggregates. The above results are found to be in good agreement with a previous study considering PS positively charged in bottled mineral and surface waters, in which the role of NOM and ionic composition was considered [35]. Z-average diameter variations (Figure 2B) are found to be in good agreement with ζ-potential values, i.e., decreasing the ζ-potential value results in an increase in the zaverage size and consequently the formation of NPL aggregates.…”

U–Pb geochronology of Variscan granitoids from the Moroccan Meseta (Northwest Africa): Tectonic implications

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Removal of nanoparticles (both inorganic nanoparticles and nanoplastics) in drinking water treatment – coagulation/flocculation/sedimentation, and sand/granular activated carbon filtration

“…The removal of nanoparticles by means of CSF has been described in literature, [32][33][34][35][36][37][38] but studies on sand or GAC (granular activated carbon) filtration are limited. Ramirez Arenas et al [39][40][41] studied the effect of coagulation and filtration over sand or GAC filters on the removal of polystyrene nanoparticles (90 ± 7 nm). The efficiency of the CSF process strongly depends on parameters, such as the type of nanoparticles, composition and concentration of NOM, ions, pH, and type and dosing of the coagulant.…”