Removal of As(V) by iron-based nanoparticles synthesized via the complexation of biomolecules in green tea extracts and an iron salt

• Published in: The Science of the total environment Vol. 764; p. 142883
• Main Authors: Wu, Zhicheng, Su, Xiaobao, Lin, Zhang, Khan, Nasreen Islam, Owens, Gary, Chen, Zuliang
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10-04-2021
• Subjects: Adsorption; As(V); Green synthesis; Green tea extract; Iron; Iron-based nanoparticles; Nanoparticles; Plant Extracts; Removal; Tea; Water Pollutants, Chemical; Removal; As(V); Green tea extract; Green synthesis; Iron-based nanoparticles
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.142883

While iron-based nanoparticles (nFe) prepared using green tea extracts have been successfully used to degrade many organic contaminants, their application to remove As(V) remains limited. Thus, in this work, nFe (GT-1) prepared using a green tea extract was used to removal As(V). The maximum adsorption capacity of GT-1 for As(V) was 19.9 mg g−1 at 298 K. The formation of GT-1 and the removal mechanism of As(V) by GT-1, was examined using XRD, TEM and SEM, which showed that GT-1 was composed of amorphous particulates sized between 50 and 100 nm. GC–MS and LC-MS analysis also showed that biomolecules presented in the green tea extract, including polyphenols and L-theanine, participated in the formation of GT-1. Mössbauer spectral analysis confirmed that an organo-Fe(III) complex was formed due to the reaction between biomolecules and Fe(III). FTIR and XPS showed that the adsorption of As(V) by GT-1 occurred both via complexation with Fe(III) in GT-1 and via coordination of As(V) with free hydroxyl groups on the surface of GT-1. Batch experiments showed that adsorption was spontaneous and conformed to the pseudo-second order kinetic model. Finally, mechanisms for the formation of GT-1 and the removal of As (V) by GT-1 were proposed.
Green synthesis of GT-1 iron nanoparticles from green tea extract for removal of As(V). [Display omitted]
•Polyphenols and L-theanine participated in the formation of GT-1.•During GT-1 synthesis caffeine in plant extracts acted as a capping agent.•Mössbauer spectroscopy confirmed that an organo-Fe(III) complex was formed.•The maximum adsorption capacity of GT-1 for As(V) was 19.9 mg g−1.•A mechanism of nFe formation and As(V) removal was proposed.