PMMA-titania floating macrospheres for the photocatalytic remediation of agro-pharmaceutical wastewater.

Antibiotics such as tetracycline are used on a large scale in agriculture, and can become concentrated in wastewater lagoons that are used in conjunction with confined animal feeding operations. Solar-illuminated titanium dioxide can be used to photocatalytically degrade aqueous tetracycline, but its application in a lagoon environment requires that the photocatalyst be supported on a macroscopic support material to prevent loss of the nanoscale photocatalyst into the environment. In this work, titanium dioxide was deposited within a porous poly(methyl methacrylate) film on the surface of floating 7.0 cm diameter acrylic spheres. Six of these floating spheres removed over 96% of the tetracycline in 3.5 L of 60 mg/L tetracycline in natural pond water during 24 hours of solar illumination. The durability of these spheres under long-term solar exposure was also investigated along with the amount of photocatalyst lost from the sphere surface during use. These macroscale floating composite spheres provide a new method for removing tetracycline from wastewater lagoons with minimal risk of being displaced in the environment due to the large size of the spheres.