Sorption and dissolution of bare and coated silver nanoparticles in soil suspensions-Influence of soil and particle characteristics

Sammanfattning

The increasing use of silver nanoparticles (AgNPs) in consumer products triggers the need for investigations that improve the understanding of their chemical transformations upon environmental entry. Such knowledge provides crucial information for toxicological studies and risk assessments. Interactions with the soil compartment need to be explored as there are evident risks of the dispersion of both AgNPs and of released Ag ions/complexes present in wastewater-treated sludge that is distributed onto agricultural land. The dissolution and fractionation in solution of bare (AgNP-bare, noncoated) and coated AgNPs (AgNP-coat, stabilized with two nonionic surfactants, polyoxyethylene glycerol trioleate and Tween 20) were investigated after 4 and 48h in suspensions of one sandy and one clayey soil of different pHs (3.3, 5.2). Parallel experiments were performed with soil suspensions spiked with easily soluble AgNO3. Silver in the water phase was separated in a dissolved fraction (mainly Ag ions/complexes) and a particle fraction (mainly AgNP/agglomerates/Ag adsorbed on organic matter) by means of ultracentrifugation. Bare AgNPs were nonstable and dissolved to a significantly larger extent in the sandy soil mixture compared to coated AgNPs. The concentration of dissolved Ag (ions/complexes) in the water phase was similar in the case of bare AgNPs and AgNO3 (at pH 3 and 5.2) after 24h in sandy soil, which implies a high degree of dissolution of bare AgNPs (50-100%). In contrast, approximately 50% of the coated AgNPs remained in the water phase after 48h of equilibration in the sandy soil at pH 5.2. The clayey soil had a significantly higher sorption capacity of Ag compared with the sandy soil, as Ag in the case of coated AgNPs was only detected in the water phase of pH 5.2 (<1 % of added Ag). Ultracentrifugation was proven more efficient compared with microfiltration to separate the dissolved Ag fraction (ions/complexes) and the particle fraction (AgNPs/agglomerates) of the water phase. This fractionation is not a measure of any potential toxicity.

Nyckelord

microfiltration; dissolution; soil; silver nanoparticles; Absorption spectroscopy; ultracentrifugation; sorption

Publicerad i

Journal of Environmental Science and Health, Part A
2015, volym: 50, nummer: 9, sidor: 891-900
Utgivare: TAYLOR & FRANCIS INC

SLU författare

• Geranmayeh Oromieh, Aidin

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    

• Berggren Kleja, Dan

  • Institutionen för mark och miljö, Sveriges lantbruksuniversitet
    
  • Statens geotekniska institut (SGI)

UKÄ forskningsämne

Markvetenskap
Miljöteknik och miljöledning
Miljövetenskap

Publikationens identifierare

• DOI: https://doi.org/10.1080/10934529.2015.1030271

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/71918