Aqueous removal of inorganic and organic contaminants by graphene-based nanoadsorbents: A review

Abstract

Various graphene-based nanoadsorbents, including graphenes, graphene oxides, reduced graphene oxides, and their nanocomposites, have been widely studied as potential adsorbents due to their unique physicochemical properties, such as structural variability, chemical strength, low density, and the possibility of large scale fabrication. Adsorption mechanisms are governed largely by the physicochemical properties of contaminants, the characteristics of nanoadsorbents, and background water quality conditions. This review summarizes recent comprehensive studies on the removal of various inorganic (mainly heavy metals) and organic contaminants by graphene-based nanoadsorbents, and also discusses valuable information for applications of these nanoadsorbents in water and wastewater treatment. In particular, the aqueous removal of various contaminants was reviewed to (i) summarize the general adsorption capacities of various graphene-based nanoadsorbents for the removal of different inorganic and organic contaminants, (ii) evaluate the effects of key water quality parameters such as pH, temperature, background major ions/ionic strength, and natural organic matter on adsorption, (iii) provide a comprehensive discussion of the mechanisms that influence adsorption on these nanoadsorbents, and (iv) discuss the potential regeneration and reusability of nanoadsorbents. In addition, current challenges and future research needs for the removal of contaminants by graphene-based nanoadsorbents in water treatment processes are discussed briefly.

Tartrazine Removal from Aqueous Solution by HDTMA-Br-Modified Colombian Bentonite

“…Organic pollutants commonly found in the aquatic environment are dyes, biocides compounds, phenols, surfactants, pesticides, and pharmaceuticals, among others [1, 2]. As coloring agents, some dyes are resistant to degradation and their presence in water might be harmful to human beings and hazardous to aquatic organisms [3].…”

Graphene-Based Nanosystems: Versatile Nanotools for Theranostics and Bioremediation

“…With regard to the chemical versatility of GBNs, this material is certainly advantageous in comparison with other adsorbents [15,19,20]. For example, GO has oxygen-functionalized groups (e.g., COOH) which are deprotonated at a broad range of pH values (≈ pH > 4.5) and therefore negatively charged groups establish electrostatic interactions with cationic pollutants [19].…”

“…Numerous investigations have demonstrated potential in the use of GO and other GBNs for the adsorption of PAHs, phenolic compounds, pesticides, and pharmaceutical drugs [20,21,25,29,135,138]. In general, there are five potential interactions, including hydrophobic effects, π-π stacking, hydrogen bonds, and covalent and electrostatic interactions, which are assumed to be responsible for the adsorption of organic compounds on the GBNs' surface [15,19,20,25] (Figure 3). In the case of GO and other GBNs, the majority of investigations have shown that ππ association plays an important role in the adsorption of aromatic organic contaminants [25].…”

“…Graphene and GBNs can therefore be found in numerous applications in the areas of electronics, physics, and material science [5][6][7]. In recent times, considering an emerging opinion on the eco-friendly characteristics of graphene and its derivatives, researchers have agreed to use these nanomaterials in other fields of science, for example in medical [8][9][10][11][12][13] and environmental applications in bioremediation [14][15][16][17][18][19][20][21].…”

Polypyrrole modified magnetic reduced graphene oxide composites: synthesis, characterization and application for selective lead adsorption

“…13,14 Graphene oxide (GO) has a large surface area and a large number of functional groups such as hydroxyl groups, carboxyl groups, and epoxy groups, which provide abundant active adsorption sites for various contaminants and functionalized attachment sites in aqueous solutions. 15 In addition, GO is more environmentally friendly and has better biocompatibility than other carbonaceous nanomaterials. 16 Therefore, it is considered an ideal sorbent for water purication.…”