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

• Published in: Applied surface science 2021-02, Vol.540, p.148398, Article 148398
• Main Authors: Roshith, M., Pathak, Abhishek, Nanda Kumar, A.K., Anantharaj, Gopalraman, Saranyan, Vijayaraghavan, Ramasubramanian, S., Satheesh Babu, T.G., Ravi Kumar, Darbha V.
• Format: Article
• Language: English
• Subjects: Continuous flow; Optofluidic reactor; Photocatalyst immobilization; Photocatalytic disinfection; Red phosphorus; Solar water disinfection (SODIS)
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.148398

[Display omitted] •Crystalline red phosphorus (CRP) was immobilized in capillary by solid state method.•Immobilized CRP shown optimum bandgap for the photocatalysis under natural sunlight.•CRP immobilized capillary used as optofluidic reactor for disinfection E. coli.•Excellent disinfection was observed in shorter residence times.•The promising results show the feasibility of scale up of disinfection process. 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.