Mercury reduction in water by engineered silver nanoparticles (AgNPs): Effects of light irradiation and humic acid coating of AgNPs
Article
Oladoye, PO, Liu, G, Cai, Y. (2026). Mercury reduction in water by engineered silver nanoparticles (AgNPs): Effects of light irradiation and humic acid coating of AgNPs
. SCIENCE OF THE TOTAL ENVIRONMENT, 1041 10.1016/j.scitotenv.2026.181907
Oladoye, PO, Liu, G, Cai, Y. (2026). Mercury reduction in water by engineered silver nanoparticles (AgNPs): Effects of light irradiation and humic acid coating of AgNPs
. SCIENCE OF THE TOTAL ENVIRONMENT, 1041 10.1016/j.scitotenv.2026.181907
Silver nanoparticles (AgNPs), due to their electrochemical capability of reducing mercury (Hg), amalgamation potential with elemental Hg (Hg(0)), and surface plasmon properties under light, may play important roles in Hg redox transformation and cycling when coexisting in the environment. However, the potential effects of AgNPs on the aqueous reduction of Hg(II) are still largely unknown. Herein, we investigated the reduction of 5 mg/L and 250 μg/L Hg(II) by bare AgNPs and humic acid coated-AgNPs (HA-AgNPs) under dark condition and light irradiation for 30 min using acetate buffer as matrix. In addition, we examined the potential role of AgNPs in Hg(II) reduction in wastewater using incubation experiments. We found that coating impacted on the total Hg(0) generated from redox reaction of the nanoparticles with Hg(II), with higher amount in bare AgNPs compared to HA-AgNPs under dark condition. Under light irradiation, coating significantly reduced Hg(0) obtained, suggested to be as a result of photo-production of Hg(0)-oxidants by the humic acid coating. Hg(0) generated was found to amalgamate readily with the solid phase (AgNPs/HA-AgNPs), with little released as purgeable Hg(0). Overall, the concentrations of purgeable Hg(0) obtained from AgNPs and HA-AgNPs suspensions under light irradiation were significantly higher than under dark condition. Results from incubation experiment demonstrated the potential of AgNPs to play key role in Hg(II) reduction in wastewaters under light irradiation than dark condition. This study highlighted the potential roles of AgNPs and HA-AgNPs to act as a sink for Hg(0) (via amalgamation) or a facilitator of reduction (via redox reactions) of Hg(II) in different environmental compartments, thereby playing important roles in the biogeochemical cycling of Hg.
