Graphene-based materials are gaining heightened attention as novel materials for environmental applications The unique physicochemical properties of graphene, notably its exceptionally high surface area, electron mobility, thermal conductivity, and mechanical strength, can lead to novel or improved technologies to address the pressing global environmental challenges This critical review assesses the recent developments in the use of graphene-based materials as sorbent or photocatalytic materials for environmental decontamination, as building blocks for next generation water treatment and desalination membranes, and as electrode materials for contaminant monitoring or removal The most promising areas of research are highlighted, with a discussion of the main challenges that we need to overcome in order to fully realize the exceptional properties of graphene in environmental applications

Environmental applications of graphene-based nanomaterials.

A review of functionalized carbon nanotubes and graphene for heavy metal adsorption from water: Preparation, application, and mechanism.

A high efficiency and eco-friendly porous cellulose-based bioadsorbent was synthesized by grafting acrylic acid and acrylamide to remove anionic dye acid blue 93 (AB93) and cationic dye methylene blue (MB) from single and binary dye solutions. The effects of initial dye concentration, bioadsorbent dosage, contact time, solution pH value, temperature, ionic strength and surfactant content on the adsorption capacity of the bioadsorbent were investigated. The maximum adsorption capacities of the bioadsorbent for both AB93 and MB were 1372 mg g–1 at an initial concentration of 2500 mg L–1. The conditions-dependent adsorption characteristics of the bioadsorbent indicated a high efficiency of dyes removal. The appropriate isotherm model for the equilibrium process was the Freundlich, and the kinetic studies revealed that the adsorption of AB93 and MB followed the pseudo-second-order kinetic models. The adsorbent behaviors were dominated by the electrostatic interactions between the bioadsorbents and the dye mol...

Adsorption Removal of Dyes from Single and Binary Solutions Using a Cellulose-based Bioadsorbent

Recent advances in cellulose and chitosan based membranes for water purification: A concise review.

Competitive adsorption of Pb(II), Cd(II) and Cu(II) onto chitosan-pyromellitic dianhydride modified biochar.

Effects of the oxidation degree of graphene oxide on the adsorption of methylene blue.

Efficient adsorption of both methyl orange and chromium from their aqueous mixtures using a quaternary ammonium salt modified chitosan magnetic composite adsorbent

In this work, graphene oxide (GO) has been employed as an efficient adsorbent for the removal of three aromatic organic compounds (AOCs), namely, aniline, nitrobenzene, and chlorobenzene, from water under various initial AOC concentrations and pH levels. Based on the characteristics of surface structures of GO, a simple semiquantitative model has been provided to describe the intrinsic adsorption behavior of GO to AOCs. Accordingly, the adsorption mechanism has been discussed in detail at molecular levels. The contribution coefficients derived from the proposed model indicate that the most preferential interactions between GO and AOCs are hydrophobic interactions (π–π stacking and hydrophobic effect) that occur on graphitic zones of GO (unoxidized region). In the oxidized region, there also exist the hydrophobic interactions on sp2 clusters, although they may be hindered by surrounding sp3 zones which are the most unfavorable and are only accessible to AOCs through hydrogen bonding or electrostatic effect...

Influence of the surface structure of graphene oxide on the adsorption of aromatic organic compounds from water

A novel magnetic composite microsphere based on polyacrylamide (PAM)-grafted chitosan and silica-coated Fe3O4 nanoparticles (CS-PAM-MCM) was successfully synthesized by a simple method. The molecular structure, surface morphology, and magnetic characteristics of the composite microsphere were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating-sample magnetometer (VSM), and scanning electron microscopy (SEM). The prepared CS-PAM-MCM was applied as an efficient adsorbent for the removal of copper(II), lead(II), and mercury(II) ions from aqueous solutions in respective single, binary, and ternary metal systems. Compared with chitosan magnetic composite microsphere (CS-MCM) without modification, CS-PAM-MCM showed improved adsorption capacity for each metal ion and highly selective adsorption for Hg from Pb and Cu. This improvement is attributed to the formation of stronger interactions between Hg and the amide groups of PAM branches for chelating effects. The adsorption isotherms of Hg/Cu and Hg/Pb binary metal systems onto CS-PAM-MCM are both well-described by extended and modified Langmuir models, indicating that the removal of the three aforementioned metal ions may follow a similar adsorption manner; that is, through a homogeneous monolayer chemisorption process. Furthermore, these magnetic adsorbents could be easily regenerated in EDTA aqueous solution and reused virtually without any adsorption capacity loss.

Preparation of chitosan-graft-polyacrylamide magnetic composite microspheres for enhanced selective removal of mercury ions from water

A novel two-dimensional carbon-based magnetic nanomaterial, magnetic graphene oxide (MGO), was prepared and then used as an efficient adsorbent. MGO showed rapid and complete removal of iron(II) (Fe) and manganese(II) (Mn) from micropolluted water bodies over a wide pH range. After saturated adsorption, MGO could be rapidly separated from water under an external magnetic field. Results of the adsorption equilibrium study indicated that the adsorption of Fe and Mn by MGO took place via monolayer heterogeneous and spontaneous processes resulting from the heterogeneity of the MGO surface as well as from the electrostatic interactions between surface acidic groups of MGO and metal ions. In addition, both the Fe and Mn uptake of MGO was very slightly affected by NaCl, although it decreased with increased humic acid in solutions. In an Fe/Mn binary aqueous system, both metal ions can be efficiently removed at low concentrations, but MGO showed preferential adsorption of Fe in a concentrated aqueous mixture. The adsorption behavior in the binary system was due to different affinities of surface oxygen-containing functional groups on MGO to Fe and Mn. Finally, unlike traditional approaches in recycling and reusing an adsorbent, the Fe- and Mn-loaded MGO can be directly applied as a new adsorbent to achieve the efficient removal of fluoride from aqueous solutions.

Kun Li

Papers

Effects of the oxidation degree of graphene oxide on the adsorption of methylene blue.

Efficient adsorption of both methyl orange and chromium from their aqueous mixtures using a quaternary ammonium salt modified chitosan magnetic composite adsorbent

Influence of the surface structure of graphene oxide on the adsorption of aromatic organic compounds from water

Preparation of chitosan-graft-polyacrylamide magnetic composite microspheres for enhanced selective removal of mercury ions from water

Rapid removal and separation of iron(II) and manganese(II) from micropolluted water using magnetic graphene oxide.