title: Arsenate Adsorption by Hydrous Ferric Oxide Nanoparticles Embedded in Cross-linked Anion Exchanger: Effect of the Host Pore Structure.
abstract: Three composite adsorbents were fabricated via confined growth of hydrous ferric oxide (HFO) nanoparticles within cross-linked anion exchangers (NS) of different pore size distributions to investigate the effect of host pore structure on the adsorption of As(V). With the decrease in the average pore size of the NS hosts from 38.7 to 9.2 nm, the mean diameter of the confined HFO nanoparticles was lessened from 31.4 to 11.6 nm as observed by transmission electron microscopy (TEM), while the density of active surface sites was increased due to size-dependent effect proved by potentiometric titration. The adsorption capacity of As(V) yielded by Sips model was elevated from 24.2 to 31.6 mg/g via tailoring the pore size of the NS hosts, and the adsorption kinetics was slightly accelerated with the decrease of pore size in background solution containing 500 mg/L of Cl(-). Furthermore, the enhanced adsorption of As(V) was achieved over a wide pH range from 3 to 10, as well as in the presence of competing anions including Cl(-), SO4(2-), HCO3(-), NO3(-) (up to 800 mg/L), and PO4(3-) (up to 10 mg P/L). In addition, the fixed-bed working capacity increased from 2200 to 2950 bed volumes (BV) owing to the size confinement effect, which did not have adverse effect on the desorption of As(V) as the cumulative desorption efficiency reached 94% with 10 BV of binary solution (5% NaOH + 5% NaCl) for all the three adsorbents. Therefore, this study provided a promising strategy to regulate the reactivity of the nanoparticles via the size confinement effect of the host pore structure.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, China.
authors.forename: Hongchao
authors.initials: H
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Shan
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, China.
authors.forename: Yanyang
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, China.
authors.forename: Jianguo
authors.initials: J
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, China.
authors.forename: Weiming
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, China.
authors.forename: Bingcai
authors.initials: B
authors.lastname: Pan
keywords: composite; ion exchanger; nanoparticle; pore structure; size confinement effect; sorption