Functional graphene nanocomposite as an electrode for the capacitive removal of FeCl3 from water

Abstract

Capacitive deionization (CDI) is a promising desalination technology which has attracted enormous interest in recent years due to its economic advantages over traditional technologies. In this paper, the facilely synthesized graphene and resol (RGO-RF) nanocomposite was proposed as a CDI electrode for the removal of ferric ions. The addition of resol led to less aggregation of the graphite oxide, while after calcination the structure collapsed and the pore size distribution widened. This was confirmed by Brunauer-Emmett-Teller (BET) techniques. The electrode's performances, involving the adsorption isotherm and kinetics, were investigated through batch mode experiment. It was found that the electrosorptive capacity of the RGO-RF electrode was 3.47 mg g À1 with an electrical voltage of 2.0 V and initial solution concentration of 40 mg L À1 . This is higher than the corresponding activated carbon and graphene electrode due to the presence of resol which is beneficial in restricting the aggregation of graphene, resulting in a high specific surface area and therefore a high electrosorption capacity. Further, the electrosorption of ferric ions onto RGO-RF follows the Langmuir isotherm, implying monolayer adsorption. Meanwhile, regardless of the electrical voltage, the kinetic analysis illustrated that the pseudo-first-order model can describe the electrosorption behaviour of the RGO-RF electrode very well.

Synthesis of graphene–NiFe2O4 nanocomposites and their electrochemical capacitive behavior

“…Besides, all the values calculated by the galvanostatic charge-discharge tests are higher than the previously reported RGO synthesized by us. 42 The increase may be caused by the combination of electric double-layer capacitance of RGO and the peeling of graphene sheets with the addition NiFe 2 O 4 nanoparticles. With increasing current density, the capacitance of the electrode is decreased from 345 F g À1 to 101.8 F g…”

Energy Consumption and Recovery in Capacitive Deionization Using Nanoporous Activated Carbon Electrodes

“…Therefore, the electrosorption capacity is determined by the volume (porosity) of the micropores and the energy barrier. The microporosity-based electrosorption theory is critical in analyzing energy consumption during CDI.z E-mail: kkarthikeyan@wisc.edu Although significant progress has been made recently in the development of diverse electrode materials, 13,[19][20][21][22][23][24][25][26][27] theoretical models, [16][17][18] water treatment and desalination devices, 28-30 only very few studies address the issue of energy consumption during CDI. The role of electrode materials in electrosorption and energy consumption is not completely understood and, more importantly, the impact of operational conditions on energy consumption has not been rigorously evaluated when nanoscale porous electrode is applied.…”

Zinc Imidazolate Metal–Organic Frameworks (ZIF‐8) for Electrochemical Reduction of CO2 to CO

“…It is known that anion incorporation into an MOF is strongly related to the size of the anions when the charge is the same; anions with smaller hydratedr adius can therefore easily absorb into or desorbf rom the MOF pores. [31] Under the electrolysis conditions, the Zn node changesb etween the high and low oxidation states, thus requiringf acile anion exchange for chargeb alance. The Cl À anion with small hydrated radius, compared to ClO 4 À and HCO 3 À , probably allows more mobility and thusb alances the chargem ore efficiently during the electrocatalysis, leading to enhanced electrochemical reduction of CO 2 .T his may also explain that ZIF-8 SO4 holds relativelyh igh CO 2 selectivity due to lessi nteraction between the SO 4 2À anion and Zn nodes and thus better diffusion for SO 4…”