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In this study, decolorization and degradation of aqueous nickel phthalocyanine reactive dye solutions was comparatively studied by electrochemical methods, such as electrocoagulation, electrooxidation and electro-Fenton processes. In the electrocoagulation process with aluminum electrodes the colored aqueous solutions containing 100 mg/L nickel phthalocyanine and 6 g/L NaCl were treated at initial pH 7.5 and applied current densities of 5, 10 and 20 mA/cm 2 , where fast and 100% decolorization was achieved in 10, 5 and less than 2.5 minutes of electroprocessing respectively. The electrooxidation process was conducted in acidic electrolyte solutions containing 100 mg/L nickel phthalocyanine and 6 g/L Na 2 SO 4 with Ti/Pt and graphite plate electrodes at the applied current density of 5 mA/cm 2 . Even after 60 minutes of electrolysis time the dye remained undegradable by 17 and 40%, respectively. Substituting Na 2 SO 4 with the same concentration of NaCl, complete degradation of the dye was achieved in 30 and 20 minutes with Ti/Pt and graphite electrodes respectively. In the electroFenton process with Fe electrodes and added amounts of H 2 O 2 at pH 3 and an applied current density of 5 mA/cm 2 complete degradation of nickel phthalocyanine occurred in 20 minutes.

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The unique properties of graphene oxide (GO) have attracted the attention of the research community and cost-effective routes for its production are studied. The type and percentage of the oxygen groups that decorate a GO sheet are dependent on the synthesis path, and this path specifies the carbon content of the sheet. The chemical reduction of GO results in reduced graphene oxide (rGO) while the removal of the oxygen groups is also achievable with thermal processes (tpGO). This review article introduces the reader to the carbon allotropes, provides information about graphene which is the backbone of GO and focuses on GO synthesis and properties. The last part covers some characterization techniques of GO (XRD, FTIR, AFM, SEM-EDS, N2 porosimetry and UV-Vis) with a view to the fundamental principles of each technique. Some critical aspects arise for GO synthesized and characterized from our group.

Surface sediment samples from Strymonikos and Ierissos Gulfs were analyzed for Cu, Pb, Zn, Cr and Ni. The results showed that the sediment of Ierissos Gulf is more polluted with Cu, Pb, and Zn as compared to that of Strymonikos Gulf. The benthal area located off the load-out facility of the mining operations in the town of Stratoni, in Ierissos Gulf is established as the most polluted region. The distribution of Cr and Ni in both gulfs indicates the natural origin of these metals with the weathering of Strymon River and of other smaller rivers rocks being responsible for their enrichment.