Cleaning up oil pollution in the ocean with photocatalytic concrete marine structures

Abstract

Treating petroleum pollution in the ocean by use of photocatalytic techniques has become a hot topic in recent years, but the existing methods that degrade petroleum by photocatalytic techniques are still limited. This paper proposed an approach to clean up oil pollution in the ocean with marine structures constructed of photocatalytic concrete. The photocatalytic concrete was prepared by using a photocatalyst (Na-g-C3N4) and ordinary concrete. The Na-g-C3N4 was created from waste melamine and NaCl and was then combined with the concrete surface. In this way, the surfaces of marine concrete structures would have the capability to degrade petroleum films on the sea surface under sunlight. To test the performance of photocatalytic concrete, we conducted degradation experiments, and seven influencing factors (e.g., irradiation time, irradiation intensity, irradiation angle, time of wave scouring, height of photocatalytic region, pH and seawater temperature) were also considered. The experimental results showed that the degradation rates of petroleum hydrocarbons by photocatalytic concrete could reach approximately 50%. Among the seven influencing factors, the first five factors could influence the degradation process significantly, while the pH and temperature of seawater do not play an important role in photocatalytic degradation. Based on the observations of the trials, it was found that the degradation rate was limited to about 50% due to the thickness of the petroleum film. When the film thickness is not sufficient to support the formation of petroleum film, the photocatalytic degradation process will stop. Our study represents a successful attempt to combine the fields of clean energy, photocatalysis, environmental pollution control and building materials, as well as to provide a new method to clean up petroleum pollution by photocatalytic techniques. We will demonstrate that photocatalytic concrete can effectively degrade oil films on the surface of the ocean in complex marine environments, so it is feasible to use marine photocatalytic concrete structures to eliminate petroleum pollution in the ocean.