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The present paper describes an investigation of the adsorption of lead ions (Pb2+) on graphene-based nanocomposites obtained via exfoliation of hydrolyzed expanded graphite intercalation compound. Three types of these nanocomposites - suspension of graphene nanoplatelets (SGN), paste of multi-layered oxidized graphene (PMOG), and paste of few-layered oxidized graphene (PFOG) - were used to extract Pb2+ from 1,040 mg L-1 aqueous solutions of Pb (NO3)2, and the kinetic of the Pb2+ adsorption was studied. It was found that the kinetic data are best fitted by the pseudo-second-order model. The adsorption equilibrium was achieved within 30 min under normal conditions. The maximum Pb2+ adsorption capacity of SGN, PMOG and PFOG was found to be 457, 103 and 38 mg g-1, respectively. Considering the obtained results, it can be assumed that the phenolic and hydroxyl oxygen-containing functional groups located at the surface of the adsorption materials under study play an important role in the Pb2+ removal process.

The present work aims at implementing heat accumulators in real technological processes and poses a problem of practical importance.Heat accumulators have been the subject of laboratory research for a long time. Several authors have obtained certain results while studying such devices, but only few of them have considered their introduction into the industrial practice. In this regard, the present research provides two directions for applying heat accumulators: thermotherapy and methane tanks.The need to stabilize temperature conditions is common to these processes. To achieve this goal, graphene-modified sodium acetate (thermal conductivity ≈5,000 W/(m K))was used herein as heat accumulator with controlled discharge mode (heat dissipation). The possibility of improving the stability of sodium acetate when introducing graphene thereinto was established. Besides,charge/discharge modes were investigated under the operating conditions of thermotherapy and methane tanks.

In the present research, phenol-formaldehyde resins were used instead of common surfactants for dispersing carbon nanotubes and graphene nanoplatelets in order to develop new composite materials. The use of such resins makes it possible to increase the concentration of nanoparticles in solution by approximately two orders of magnitude. The presence of reactive groups on the surface of the phenol-formaldehyde-resin-modified carbonnanotubes and graphene nanoplatelets promotes synthesis of a variety of composites. According to the experiments performed herein, the modification of the nanomaterials with the phenol-formaldehyde resin significantly improves their compatibility and provides good water-solubility. While dispersing in water, the aggregates of the carbon nanotubes disappear, giving rise to an ordered structure. Besides, they form stable colloidal solutions at slightly alkaline pH values, but coagulate when decreasing the pH. This effect allows for self-assembly of carbon and composite nanostructures from nanoparticles in solution due to pH adjustment. This enables easy synthesis of hybrid composite materials based on carbon nanotubes, graphene nanoplatelets and phenol-formaldehyde resins.

In this study, nanoporous carbon material (NCM) specimens were synthesized from polymer raw materials (a mixture of furfural, hydroquinone, and urotropine). The influence of the conditions and parameters of the synthesis method (temperature, weight ratio of the activating agent to the precursor and contact time) on the NCM structure was examined. The effect of the weight ratio of the initial components on the properties of the resulting NCM was investigated, and the optimal composition of the ternary system of furfural, hydroquinone and urotropine was found. The results of nitrogen adsorption-desorption showed that NCM specimens obtained by varying the activation temperature were microporous but with different micropore volumes and the same pore size distribution. Varying the weight ratio of the activating agent (KOH) to the precursor made it possible to obtain microporous, micromesoporous, and mesoporous NCMs. NCM specimens with different pore hierarchy and different specific surface area were also obtained, including microporous NCMs (SBET: 1546–3030 m3/g; Vmic/Vt: 76.0–100%), micro- mesoporous NCMs (SBET: 3204–3516 m3/g; Vmic/Vt: 41.2–57.4% Vmes/Vt: 42.6–58.8%) and mesoporous NCMs (SBET: 3641–3649 m3/g; Vmes/Vt: 74.0–83.8%). Further, a mechanism for the development of pores during KOH activation of polymeric carbon precursor was proposed. The outcomes of this study signify that the NCM5/750/1 has a high adsorption capacity for CH4and has good prospects for monitoring CH4emissions and reducing greenhouse gas emissions.

The paper presents studies on highly porous graphene-like structures as an electrode material for supercapacitors. The experimental research was performed in inorganic (3 M sulfuric acid) and organic (1 M tetraethylammonium tetrafluoroborate in acetonitrile) electrolytes. It was found that in the inorganic medium the electrodes made on the basis of graphene-like structures possess higher specific capacitance. When increasing the potential scan rate from 5 to 100 mV/s the “electrode-electrolyte” system lost 40-80% of the capacitance. The cyclic current-voltage curves obtained for the organic electrolyte were more strongly distorted when increasing the potential scan rate, which might be related to more severe transport limitations imposed on large organic ions.