Adsorption of organic contaminants by graphene nanosheets: A review

石墨烯纳米片在有机污染物吸附中的应用综述

Water Research, Volume 126, 1 December 2017, Pages 385-398

Gamze Ersan, Onur G. Apul, Francois Perreault, Tanju Karanfil

Abstract:Graphene nanosheets (GNS) such as graphenes and graphene oxides (GOs) have been widely investigated as next-generation adsorbents in both water and wastewater treatment processes due to their unique physicochemical properties and their affinity towards different classes of organic contaminants (OCs). In the last five years, more than 40 articles investigating adsorption of different classes of OCs by graphene and GO were published in peer-reviewed journals. Adsorption mechanisms were controlled by molecular properties of OCs (e.g., aromatic vs aliphatic, molecular size and hydrophobicity), characteristics of adsorbents (e.g., surface area, pore size distribution, and surface functional groups), and background solution properties (e.g., pH, ionic strength, surfactants, NOM, and temperature). This literature survey includes: (i) a summary of adsorption of OCs by GNS, (ii) a comprehensive discussion of the mechanisms and factors controlling the adsorption of OCs by GNS and a comparison of their adsorption behaviors with those of CNT. This literature survey also identifies future research needs and challenges on the adsorption of OCs by GNS.

Graphene composites as dye adsorbents: Review

基于石墨烯复合材料的染料吸附剂综述

Chemical Engineering Research and Design, In press, accepted manuscript, Available online 11 November 2017

George Z. Kyzas, Eleni A. Deliyanni, Dimitrios N. Bikiaris, Athanasios C. Mitropoulos

Abstract：One of the most important decontamination techniques is considered to be adsorption. It is fast, simple, low-cost with many opportunities to modify the initial materials after appropriate synthesis routes etc. Numerous adsorbent materials are prepared the last years having as ultimate scope to remove some toxic pollutants especially from contaminated waters (effluents originated from industries). But the composition of each type of effluents is varying. Dyes are some major components of industrial wastewaters. In the last years, graphene attracted many researchers employing with adsorption technique, because of its excellent properties and two-dimensional structure. Researchers started to synthesize more effective graphene adsorbents making some additions to initial structure, preparing many graphene composites. This review summarizes the important contribution of graphene composites to adsorption technique. Many preparation routes of graphene composites are given along with the respective characterization techniques, properties of the materials, and of course detailed adsorption evaluation of graphene composites. The latter is based on some adsorption parameters as maximum adsorption capacity, kinetic behavior, thermodynamics, and possible reuse ability. The data clearly demonstrate that the adsorption capacity of graphene composites is very high (up to 1300 mg/g depending on the dye molecule). The majority of works has been successfully fitted to Langmuir isotherm model and pseudo-second order kinetic equation. To highlight the superiority of graphene composites, comparison with other adsorbents is mandatory. This work summarizes the very recently published works of the last years.

Graphene-based devices for measuring pH

石墨烯基pH检测仪器

Sensors and Actuators B: Chemical, In press, corrected proof, Available online 12 October 2017

P. Salvo, B. Melai, N. Calisi, C. Paoletti, F. Di Francesco

Abstract:pH measuring and monitoring is fundamental to understand or control many chemical processes in biological, industrial or environmental fields. Potentiometric measurements by a glass electrode is the most common method to measure pH, although single-use paper strips are also widely used. Other methods include the use of hydrogen, quinhydron, and antimony electrodes, the imaging using pH-sensitive indicators such as dyes or proteins, and the use of ion-selective field effect transistor (ISFET). Due to the chemical reactivity of both sides of its 2D structure, nanometer thickness, high electron mobility, high reactivity to oxygen groups such as OH−, and ultrafast optical response, graphene has the potential to be used for the fabrication of nanoscale, wide-range, high-sensitivity and flexible pH sensors. This review describes how graphene, graphene oxide and reduced graphene oxide can be used to fabricate pH-sensitive devices (e.g. solution-gated FETs, solid-gate FETs, electrochemical sensors, and pH-sensitive quantum dots). The various configurations are reported along with the advantages and current limitations.