Open AccessRoles of Silver–Chloride Complexations in Sunlight-Driven Formation of Silver Nanoparticles
Author(s) -
Abhishek Singh,
Wen Che Hou,
Tsair Fuh Lin,
Richard G. Zepp
Publication year - 2019
Publication title -
environmental science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.851
H-Index - 397
eISSN - 1520-5851
pISSN - 0013-936X
DOI - 10.1021/acs.est.9b02115
Subject(s) - chemistry , silver nanoparticle , chloride , sunlight , ionic strength , irradiation , photochemistry , ion , silver chloride , ionic bonding , visible spectrum , nanoparticle , nuclear chemistry , inorganic chemistry , nanotechnology , materials science , organic chemistry , aqueous solution , physics , optoelectronics , electrode , astronomy , nuclear physics
In aerobic natural surface water, a silver ion (Ag + ) exists in various Ag + -Cl - complexes because of a strong affinity for a chloride ion (Cl - ); however, little information is available about the role of the Ag + -Cl - complex in the formation of silver nanoparticles (AgNPs). This study demonstrates that soluble AgCl x ( x -1)- species act as a precursor of AgNPs under simulated sunlight irradiation. The AgNP photoproduction increases with Cl - levels up to 0.0025 M ([Ag + ] = 5 × 10 -7 M) and decreases with continued Cl - level increase (0.09 to 0.5 M). At [Cl - ] ≤ 0.0025 M (freshwater systems), photoproduction of AgNP correlates with the formation of AgCl (aq) , suggesting that it is the most photoactive species in those systems. Matching the ionic strength of experiments containing various Cl - levels indicates that the trend in AgNP photoproduction correlates with Cl - concentrations rather than ionic strength-induced effects. The photoproduction of AgNPs is highly pH-dependent, especially at pH > 8.3. The UV and visible light portions of the solar light spectrum are equally important in photoreduction of Ag + . Overall, we show evidence that AgCl x ( x -1)- species irradiated under sunlight conditions contributes to the formation of nanosized silver (Ag) in the environment.