Recent advances in the use of graphene-family nanoadsorbents for removal of toxic pollutants from wastewater

Abstract

Adsorption technology is widely considered as the most promising and robust method of purifying water at low cost and with high-efficiency. Carbon-based materials have been extensively explored for adsorption applications because of their good chemical stability, structural diversity, low density, and suitability for large scale production. Graphene--a single atomic layer of graphite--is the newest member in the family of carbon allotropes and has emerged as the "celeb" material of the 21st century. Since its discovery in 2004 by Novoselov, Geim and co-workers, graphene has attracted increased attention in a wide range of applications due to its unprecedented electrical, mechanical, thermal, optical and transport properties. Graphene's infinitely high surface-to-volume ratio has resulted in a large number of investigations to study its application as a potential adsorbent for water purification. More recently, other graphene related materials such as graphene oxide, reduced graphene oxide, and few-layered graphene oxide sheets, as well as nanocomposites of graphene materials have also emerged as a promising group of adsorbent for the removal of various environmental pollutants from waste effluents. In this review article, we present a synthesis of the current knowledge available on this broad and versatile family of graphene nanomaterials for removal of dyes, potentially toxic elements, phenolic compounds and other organic chemicals from aquatic systems. The challenges involved in the development of these novel nanoadsorbents for decontamination of wastewaters have also been examined to help identify future directions for this emerging field to continue to grow.

Keywords: AFM; ATR-IR; Adsorption; Atomic force microscopy; Attenuated total reflection infrared spectroscopy; BET; BJH; Barrett–Joyner–Halenda pore size and volume analysis; Brunauer–Emmett–Teller surface area analysis; DRIFTS; Diffuse reflectance infrared Fourier transform spectroscopy; EA; EDAX; EDS/EDX; EM; Elemental analysis; Elemental mapping; Energy dispersive X-ray analysis; Energy dispersive X-ray spectroscopy; Environmental remediation; FESEM; FS; FTIR; Field emission scanning electron microscopy; Fluorescence spectroscopy; Fourier transform infrared spectroscopy; Graphene materials; HRTEM; High resolution transmission electron microscopy; MS; Micro-Fourier transform infrared spectroscopy; Mossbauer spectroscopy; NMR; Nuclear magnetic resonance spectroscopy; PSD; PZCM; Particle size distribution analysis; Point of zero charge measurement; Pollutants; RS; Raman spectroscopy; SAED; SEM; SEM/EDAX; SQUIDM; STEM; STEM-EELS; STEM-HAADF; Scanning electron microscopy; Scanning electron microscopy/Energy dispersive X-ray analysis; Scanning transmission electron microscopy; Scanning transmission electron microscopy-Electron energy loss spectroscopy; Scanning transmission electron microscopy-High angle annular dark field imaging; Selective area electron diffraction; Superconducting quantum interference device magnetometry; TEM; TGA; Thermogravimetric analysis; Transmission electron microscopy; UV–vis; UV–vis absorption spectroscopy; VSM; Vibrating sample magnetometry; WAXD; Wastewater reclamation; Water treatment; Wide angle X-ray diffraction analysis; X-ray diffraction analysis; X-ray photoelectron spectroscopy; XPS; XRD; ZPM; Zeta potential measurements; μ-FTIR.