Continuous flow solar photocatalytic disinfection of E. coli using red phosphorus immobilized capillaries as optofluidic reactors

Abstract

An elemental, non-metallic red phosphorus-based photocatalyst for potential continuous flow disinfection of water is reported. The crystalline red phosphorus is immobilized by a solid state method on the inner walls of a quartz capillary tube and a continuous flow photocatalytic disinfection of E. coli solution under direct sunlight is demonstrated using the set-up as an optofluidic reactor. Structural and microstructural analyses employing electron diffraction confirms the fibrous phase of the immobilized red phosphorus. The reactor with the immobilized photocatalyst when tested under direct sunlight resulted in a 6.7 log reduction (>99.9999% reduction) in the concentration of E. coli bacteria within 14 min. The sample aliquot collected at 28 min residence time did not yield any visible colonies indicating the high efficiency of the process. The demonstrated efficiency suggests great potential for commercial scale-up.