Ultrasonic aided sorption of oil from oil-in-water emulsion onto oleophilic natural organic-silver nanocomposite

Abstract

Herein, we reported for the first time the application of silver nanoparticle (AgNP) based sorbent for the sorption of oil from simulated oil-polluted water. An oleophilic natural organic-silver nanocomposite (AgAW) was synthesized in a one-pot system by impregnation of AgNPs on a natural organic sorbent (AW), which was applied for the ultrasonic sorption of oil. The characterizations proved successful synthesis of the nanocomposite containing 18.92 nm average size AgNPs. A shift from the microporous structure (1.184 nm) of AW to the mesoporous structure (2.231 nm) of AgAW was obtained. The impregnated AgNPs enhanced the hydrophobic characteristics of AgAW for the oil phase, with a maximum oil uptake of 2.66 g/g and 6.11 g/g obtained for AW and AgAW respectively. Besides AgAW exhibited higher oil uptake than the pristine AW at variations in pH (2.0–10.0), sonication time (5–60 min), temperature (395–325 K), and oil concentration (200–1000 g/L). The presence of competing Pb(II) and Cd(II) ions in solution did not significantly affect the oil uptake on the sorbents. In addition, successful regeneration of the sorbents using n-pentane and petroleum ether was achieved with over 85.3% oil desorption. In addition, the sorbents were efficiently reused for oil uptake with a slight decrease in oil sorption capacity. The mechanism of oil sorption on AgAW was found to be purely hydrophobic interactions brought about by the impregnated AgNPs. The efficacy of the synthesized AgAW composite for oil spill treatment based on the oleophilic character, high oil uptake as well as the efficient regeneration and reuse was established.