Dual-Functional Graphene-Based Flexible Material for Membrane Filtration and Electrochemical Sensing of Heavy Metal Ions

Abstract

Simultaneous removal and quantification of heavy metal ions are very important since they threaten human health. In this work, a dual-functional, free-standing and flexible reduced graphene oxide (rGO) based paper-like material including zinc oxide nanoparticles (ZnO-NPs) and ethylenediaminetetraaceticacid (EDTA) was produced using successive vacuum-filtration and hydrothermal reduction processes. First, graphene oxide (GO) layers were coated with ZnO-NPs and then EDTA was immobilized by ultrasonic treatment. Prepared GO/ZnO-NPs-EDTA suspension was vacuum-filtrated on a membrane and peeled to obtain GO/ZnO-NPs-EDTA paper. Hydrothermal reduction resulted in rGO/ZnO-NPs-EDTA paper and this material is first-time performed for two applications: Simultaneous removal of heavy metal ions of Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ and their further simultaneous electrochemical detection. Structural, chemical, crystallographic, optical, morphological, and electrochemical characterization of this paper-like material was executed using numerous techniques. Maximum adsorption performance of the rGO/ZnO-NPs-EDTA paper was determined as 2963, 8056, 600, and 1753 mg/g, while electrochemical simultaneous determination revealed linear ranges of 18.5-500, 22.4-700, 8.3-200, 3.3-<inline-formula> <tex-math notation= LaTeX >$300~\\mu \\text{M}$ </tex-math></inline-formula> and detection limit values of 5.6, 6.8, 2.5, <inline-formula> <tex-math notation= LaTeX >$1.0~\\mu \\text{M}$ </tex-math></inline-formula> for Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺, respectively.