RESUMO
Metal corrosion is becoming increasingly serious in oil and gas production, and one way to solve this problem is to modify the metal surface. Thus, a corrosion inhibition coating on the N80 steel was constructed via the self-polymerization and assembling of the dopamine. The optimum reaction condition of polydopamine films was determined by the corrosion rate assessment of the films coated N80 steel, which was the reaction at 60 °C and 5 g/L dopamine in the Tris-HCl buffer solution (pH = 8.5) for 1 h. The spectral results confirmed the existence of the polydopamine coating on the surface of N80 steel, and high stability of the coating in the oil well produced water was observed. The anti-corrosion performance of the polydopamine-coated N80 steel confirmed that high temperature accelerated the anti-corrosion effect of the coating, and the corrosion rate of N80 plate in 90 °C oil well produced water was 0.0591 mm·a-1, lower than the standard value. The corrosion rates of the polydopamine coated N80, A3 and J55 plates at 90 °C were 0.0541 mm·a-1, 0.0498 mm·a-1 and 0.0455 mm·a-1, respectively. No significant effects of the categories of corrosive medium and steel plate on the performance of the coating were observed.
RESUMO
The novel composite, Fe3O4@SiO2@mSiO2-PW12/Ag, was successfully prepared by in situ loading Ag nanoparticles (Ag NPs) on the surface of grafted phosphotungstate (denoted as PW12) Fe3O4@SiO2@mSiO2via a photoreduction deposition method. PW12 not only acts as a reducing agent and stabilizer for Ag NPs but also as a bridge to link Ag NPs and the SiO2 shell in the loading process. Its activity toward the photodegradation of methyl orange (MO) and photoreduction of Cr2O72- anions was evaluated. Experimental results showed that Fe3O4@SiO2@mSiO2-PW12/Ag with 5.3 wt% Ag loading and 18.65 wt% of PW12 exhibits the highest photocatalytic efficacy, and complete degradation of MO and 91.2% photoreduction of Cr(vi) were realized under simulated sunlight for 75 min, respectively. The enhanced catalytic activities of the composite are due to its high specific surface area, the synergistic effect among the components and the formation of a heterojunction of PW12/Ag. The possible enhanced photocatalytic mechanism is proposed. The catalyst is durable and can be easily recovered using a magnet for recycling without a significant loss of catalytic activity.
