Design and construction of low-power, portable photocatalytic water treatment unit using light-emitting diode

Limited availability of mobile technology to disinfect drinking water at low cost led to the current research of using titanium dioxide (TiO 2) photocatalysis for drinking water disinfection. New UV light emitting diodes (LEDs) have potential for application in this technology. The research was divided into three parts: immobilization of TiO2, optimization of coating and reactor using methyl orange and investigating disinfection efficiency for Escherichia coli (ATCC 25922). Thin TiO2 films supplemented with Degussa P25, coated on glass beads and calcinated at 500 °C had 9.9 mum maximum and 2 mum average thickness, 0.28 m2/g BET surface area and was dominated by the anatase TiO2 phase. A reactor with LEDs degraded methyl orange with a first order rate constant of 0.39 hr-1 and 3 log 10 E. coli removal was noted in 240 mins. With anticipated drops in LED cost, use of LEDs for TiO2 photocatalysis remains a promising disinfection technology.