Dayanne Chianca de Moura

Decontamination of produced water containing petroleum hydrocarbons by electrochemical methods: a minireview

Produced water (PW) is the largest waste stream generated in oil and gas industries. The drilling and extraction operations that are aimed to maximize the production of oil may be counterbalanced by the huge production of contaminated water (called PW) with pollutants, such as heavy metals, dissolved/suspended solids, and organic compounds. PW is conventionally treated through different physical, chemical, and biological methods. In offshore platforms, because of space constraints, compact physical and chemical systems are used. However, major research efforts are being developed with innovative technologies for treating PW in order to comply with reuse and discharge limits. Among them, electrochemical technologies have been proposed as a promising alternative for the treatment of this kind of wastewaters. Then, this paper presents a minireview of efficient electrochemical technologies used until now for treating PW generated by petrochemical industry.

Large disk electrodes of Ti/TiO2-nanotubes/PbO2 for environmental applications

Large disk electrodes of Ti/TiO2-nanotubes/PbO2 (65 cm2 of geometrical area) were successfully synthesized by anodization and electrodeposition procedures. Characterization of anodes was performed by SEM, EDS, AFM and electrochemical measurements, aiming towards environmental applications. PbO2, an electrocatalytic material, promotes the production of strong oxidising species (hydroxyl radicals) that can be used for decontamination. Electrochemical treatment of synthetic dye effluent (2 L) containing 250 mg L−1 of Acid Blue 113 dye (AB 113) was performed using a disk Ti/TiO2-nanotubes/PbO2 anode and an electrochemical flow cell. More than 85% of organic matter was removed by applying current densities of 20, 40 and 60 mA cm−2. Moreover, colour decay achieved values of 60%, 90% and 100%, depending on the applied current density. Alternatively, this study allows us to understand how nanomaterials have prevented the corrosion phenomena on the anode surface (Pb2+ pollution) due to the homogeneous migration of PbO2 within the TiO2 nanotubes previously formed on the Ti support.

Evidence for the electrochemical production of persulfate at TiO2 nanotubes decorated with PbO2

It is well known that PbO2-based electrodes are considered to be non-active anodes, producing higher concentrations of hydroxyl radicals in aqueous solutions, and consequently, favouring the electrochemical degradation of organic pollutants. However, no evidence has been reported on the production of persulfates using this kind of electrode in sulphate aqueous solutions. For this reason, the aim of this work is to prepare (by an electrochemical procedure (anodization and electrodeposition)) and characterize (by X-ray diffraction, scanning electron microscopy, and potentiodynamic measurements) Ti/TiO2-nanotubes/PbO2 disk electrodes (with a geometrical area of 65 cm2) in order to evaluate the electrochemical production of persulfate using Na2SO4 solution as the support electrolyte and applying current densities of 7.5 and 60 mA cm−2, as well as the influence of the electrosynthesis of hydroxyl radicals, in concomitance. The results clearly showed that significant production of hydroxyl radicals and persulfate is achieved at the Ti/TiO2-nanotubes/PbO2 surface, but this depends on the current density. The production of ˙OH at the Ti/TiO2-nanotubes/PbO2 surface in Na2SO4 solution was confirmed by a RNO spin trapping reaction. The results were compared with those of a Ti/Pt electrode in order to understand the effect when a lower amount of ˙OH is produced at the active anode surface. Based on the results, the Ti/TiO2-nanotubes/PbO2 anode could exhibit good electrocatalytic properties for environmental applications involving persulfate oxidants.

The treatment of gummy smile: integrative review of literature

The use of periodontal surgery to treat the condition of gummy smile is an essentially aesthetic approach and plays an important role in raising the self-esteem of patients. Effective treatment requires identification of the best technique for the correction, and the long-term predictability of the procedure. Objective: The aim of this study was to conduct an integrative review of scientific evidence relating to the periodontal surgery techniques used to treat gummy smile. Method and Materials: According to the inclusion and exclusion criteria A total of five (05) articles from the PubMed, Scopus and Web of Science databases were analyzed. The majority of cases found featured women, and the average age was 26 years. In most cases, the predominant surgical technique was based on the use of gingivectomy with osteotomy, with a follow-up period of around 6 months. Conclusion: This review revealed a serious lack of controlled and randomized clinical studies into the use of periodontal surgery to treat gummy smiles and highlighted a need for longitudinal clinical studies, with greater evidence, about the best type of periodontal surgery for this purpose.