Herein, the adsorption performance of sodium-doped graphitic carbon nitride in relation to the removal of methyl blue is investigated. The adsorbent was synthesized via the direct thermal polycondensation of cyanamide in the presence of sodium chloride. The inclusion of sodium in graphitic carbon nitride resulted in a substantial improvement of its adsorption capacity and adsorption kinetics. The maximum capacity for methyl blue was at least 8 times higher in comparison to commercial activated carbon and even 36 times higher than in the case of undoped material. The obtained adsorbents had very low porosity, and the resultant high adsorption capacities, as determined from the experiments, pointed to the extraordinary adsorption. Moreover, the equilibrium of the adsorption process was reached at the contact time less than 5 min. The obtained adsorbent was thoroughly investigated by means of various physical and chemical analyses. Additionally, the regeneration studies of the spent adsorbents were carried out.

The synthesis of graphitic carbon nitride (g-CN) doped with s-block metals is described. The materials were synthesized via thermal polycondensation of cyanamide and the appropriate metal chloride. The inclusion of the metal precursor strongly influenced the surface chemistry features as well as the textural, morphological, and structural properties of the g-CN. The doping of g-CNwith s-block metals markedly enhanced its adsorption performance, which was studied during the removal of two model solutes (methyl blue and copper ions) from aqueous solutions. The maximum adsorption capacity for the organic dye was increased by 680 times after the doping process. The uptake of copper(II) increased ca. 30 times for the doped g-CN. The improvement of the adsorption performance is discussed in terms of the surface chemistry and textural features.

Herein we present a continuous and catalyst free method for the synthesis of graphene sheets from aliphatic alcohols in a radiofrequency thermal plasma jet. Nine aliphatic linear alcohols (ethanol-decanol) were tested as possible precursors for the massive production of graphene sheets. Moreover, additional tests were also carried out with the inclusion of gaseous oxygen in order to promote the formation of graphene and to eliminate the unwanted carbon byproducts. The obtained materials were investigated by electron microscopy, Raman and infrared spectroscopy. The thermal stability of products was also evaluated using thermogravimetry. The surface chemistry features were analyzed using acid-base titration and X-ray photoelectron and IR spectroscopy. Finally, the adsorption performance of graphene sheets was tested in the removal of 4-chlorophenol from aqueous solutions. The highest content of graphene sheets was found in the product obtained from ethanol with the production rate of ca. 1.5 g/h. The plasma processing of higher alcohols yielded a mixture of graphene sheets and spherical carbon nanoparticles.

No abstract

The carbon coating in carbon-encapsulated magnetic nanoparticles is considered as a tight and impermeable barrier which should perfectly protect the magnetic core material from external chemical environment. To study the integrity of the coating, carbon-encapsulated iron nanoparticles were subjected to corrosion tests, in which various corrosion agents were used. Several mineral and organic acids, as well as active gaseous environments with various oxidation potential, were applied. Additionally, the corrosion resistance was studied under the so-called galvanic corrosion, using two metal ions (copper and silver) which have higher redox potential than the zero-valent iron. The release of iron from the core as well as the morphology, structural features, chemical composition, and magnetic properties of carbon-encapsulated iron nanoparticles was systematically monitored at each stage of the corrosion process. The largest release of Fe from the encapsulate core was observed when nitric acid was used as the corrosion agent.