Functionalized Graphene-Based Materials as Innovative Adsorbents of Organic Pollutants: A Concise Overview

Abstract

The functionalization of graphene nanosheets is the cutting edge of materials sciences nowadays. Such research promotes the development of innovative, low cost and highly capable sorbents. This review article aims to assemble the available information on functionalized graphene used for the adsorption of organic pollutants and establishes a critical comparison between the data reported in the literature. Various optimal experimental conditions (pH, temperature, contact time, adsorbent dosage) and adsorbent characterization methods (FTIR, Raman, XPS spectra, XRD, TEM and AFM) have been listed to enlighten adsorption mechanisms, capacity and limiting aspects. Moreover, adsorption isotherms, kinetics and thermodynamic data of different functionalized graphene-based materials towards a wide range of organic pollutants were analyzed and tabulated. In each evaluation topic, environmental and human health protection is subject for discussion, as well as the scientific breakthrough works available in high impact journals in the field.

An Overview and Evaluation of Highly Porous Adsorbent Materials for Polycyclic Aromatic Hydrocarbons and Phenols Removal from Wastewater

“…Apart from that, graphene chemical mobility, which allow for its modification to form other functionalized advanced carbon materials. Graphene oxides (GOs) and reduced graphene oxide (rGO) are among the most advanced graphene-based engineering materials (Figure 4) [132,133] They are regarded as the fascinating forms of graphene materials and thus have versatile applications in various fields such as biomedicines, sensors, metrology, electronic devices, as well as environmental pollutant's remediation in environmental waters [134]. In adsorption studies, their unique chemical properties and high specific surface area has been emphasized.…”

Recent advances in the catalytic applications of GO/rGO for green organic synthesis

“…Owing to their high thermal and chemical stability, low volatility, very high ability to dissolve a wide variety of compounds and more significantly, their environmentally friendly behavior [153], surface functionalization of G and GO using ionic liquids is gaining particular importance recently. The ionic liquid-functionalized graphene (G-IL/GO-IL) has been extensively used in pollutant decontamination, enhancement of styrenebutadiene rubber nanocomposites, high-temperature proton exchange membrane fuel cell, sensing and biosensing, lubrication, catalysis and carbon dioxide capturing and hydrogen production [154][155][156][157][158][159]. Moreover, ionic liquids interact strongly with the sp 2 -hydridized G and GO sheet carbon networks because of their high dipolar nature and make them more dispersible compared to their native networks [153].…”

“…Moreover, ionic liquids interact strongly with the sp 2 -hydridized G and GO sheet carbon networks because of their high dipolar nature and make them more dispersible compared to their native networks [153]. It is established that acylation, isocyanate formation, esterification, amide formation, nucleophilic ring opening, diazotization and cycloaddition reactions generally facilitate the covalent functionalization of G and GO [33,160]. In one such investigation, Nakhate and Yadav [161] synthesized GOsupported functionalized ionic liquid (PTS-Im-3@GO) by anchoring 1-(4-sulfobutyl)-3-(3-propyltriethoxysilyl) imidazolium hydrogen sulfate onto GO via covalent bonds and used it for styrene oxide ring opening reaction with isopropyl alcohol, giving 95% conversion and 100% regioselectivity toward 2-isopropoxy-2-phenylethan-1-ol at 50°C.…”

Organic Functionalized Graphene Oxide Behavior in Water

“…With the protonation of carboxyl groups (at the edge of GO), GO becomes more stable (hydrophilic) at higher pH conditions [ 5 ]. NOM, ubiquitous in the natural system in the range from 0.1 to 20 mg/L [ 12 ], has been observed to sorb on the basal plane of GO by strong π–π interactions or hydrophobic interactions [ 13 ]. Abundant carboxyl and hydroxyl groups from adsorbed NOM provide excellent colloidal stability of GO via EDL repulsion [ 8 , 9 ].…”