Enhanced solar light photoreduction of innovative TiO2 nanospherical shell by reduced graphene oxide for removal silver ions from aqueous media

Abstract

TiO2 nanospherical shell incorporated reduced graphene oxide (RGO) as photoreduction adsorbent catalyst was successfully synthesized via a one-step ecofriendly hydrothermal colloidal suspension solution technique to remove the risk of Ag+ from potable water samples under solar light irradiation. The fabricated photoreduction adsorbent catalyst exhibited an excellent, efficient result by reducing the silver ions to nanoparticles, which can facilely adsorb on its surface under optimum conditions. Several factors were investigated in details, such as solution pH, kinetic isotherm models, competing foreign ions, reduced graphene oxide ratio (rGO) and elution/reuses. The prepared photoreduction adsorbent catalyst effectively utilized in the acidic pH region of 6.5. The results shown that remarkable photoreduction of Ag+ onto TiO2 nanospherical shell surface enhanced by the rGO which has a superior photogenerated carrier recombination as well as high specific surface area obtaining a maximum adsorption capacity of 34.8 mg/g. Moreover, the data confirmed that the foreign competing ions have no affected on the photoreduction adsorption capacity in aqueous media. The used of photoreduction adsorbent catalyst was eluted with 0.5 M thiourea/0.1 M HNO3 to its original form without significant loss in its performance although several cycles after extraction/elution processes were conducted. This photoreduction ecofriendly adsorbent nanocomposite has a potential application in large scale heavy metal ion wastewater treatment process.