Highly Efficient Removal of Silver-Containing Nanoparticles in Waters by Aged Iron Oxide Magnetic Particles

Abstract

Methods for the removal of silver nanoparticles (AgNPs) and their transformation products, silver-containing nanoparticles (AgCNPs), are important, because of their potential risks to the general population and the environment. In this study, aged iron oxide magnetic particles (IOMPs) were synthesized by a simple solvothermal reaction and used for the removal of AgCNPs. The prepared IOMPs exhibit a high adsorption capacity toward AgCNPs in aqueous medium. Kinetic studies indicated that the adsorption of AgCNPs is a pseudo-second-order process. The experimental data for the adsorption of AgCNPs follow the Langmuir isotherm model, and their maximum adsorption capacities were 19.9–62.8 mg/g at pH 6.2 and 298 K. The sorption mean free energy calculated by the Dubinin–Radushkevich isotherm was 4.09–5.17 kJ/mol, indicating the occurrence of physisorption, which was mainly due to the electrostatic interactions. The IOMP adsorbents maintained high removal efficiencies after four cycles of adsorption–desorption, suggesting good reusability of the developed IOMPs. Moreover, good removal efficiencies (63.3%–99.9%) and recoveries (67.1%–99.9%) were obtained from the real samples spiked with AgCNPs at levels of 10 μg/L, showing that the aged IOMPs could be used as efficient and low-cost adsorbents for the removal and recovery of AgCNPs from real waters.

A proposed activated carbon for the removal of silver nanoparticles from water environment

“…A similar finding was also obtained from previous work when several models were used for explaining the behaviors of AgNPs adsorption by following the pseudo-second-order [14]. It is noted that the pseudo-second-order performed well for various data.…”

“…In general, the experimental data can be well described using mixed 1,2-order followed by fractal-like pseudo-first-order, pseudo-first-order, Avrami, fractal-like pseudo-second-order, pseudo-second-order, and Power kinetic models. This is evidence that the pseudo-second-order that is commonly employed for various AgNPs adsorption data with the best performance is inappropriate for this work [14].…”

“…It was found that AgNPs can be removed up to 75% by their proposed adsorbent. Alternatively, the aged iron oxide magnetic particles were also proposed for the removal of AgNPs from aqueous solution [14]. Interestingly, almost 100% AgNPs were removed using the proposed adsorbent.…”

Characterization of resorcinol–formaldehyde hydrogel as adsorbent for cesium ion

“…According to the following Eq. (4), we estimated the mean free energy, E [kJ mol −1 ], which had been employed to evaluate the strength of the interaction between an ionic species and an adsorbent (Zhou et al 2017;James et al 2019):…”

Purification of Aqueous Media by Biochars: Feedstock Type Effect on Silver Nanoparticles Removal

“…Adsorption can serve as an alternative. Some natural and synthetic adsorbents for Ag-NP removal have been investigated, e.g., activated carbon [ 12 ], dolomite limestone [ 13 ], activated sludge [ 14 ], natural clinoptilolite [ 15 ], nanofiber membrane [ 16 ], poly(vinyl alcohol) [ 17 ], and ZnO [ 18 ]. Biochars can be also promising materials in the removal of nano impurities [ 10 , 19 ].…”