International Graduate Conference on Science, Humanities and Engineering 2011 (IGCSHE2011)

Hikmat S. Hilal's picture
Research Title: 
Water Disinfection by Photo-Degradation of Microorganisms Using Natural Dye- Sensitized ZnO Catalyst
Hikmat S. Hilal
Sondos Ateeq
Ahed Zyoud
Majdi Dweikat
Wed, 2011-05-04
Water Disinfection by Photo-Degradation of Microorganisms Using Natural Dye- Sensitized ZnO Catalyst3.81 MB
Research Abstract: 

Several procedures are commonly used for water purification, such as adding chlorine containing substances,peroxide, bromine, silver-copper, ozone and UV. Photodegradation of microorganisms has also been examined inwater disinfection. TiO2 and ZnO were examined by researchers for inactivation of Escherichia coli andLactobacillus helveticus using photo-degradation techniques.Although ZnO is a wide band gap (3.2 ev) semiconductor, with limited photo-catalytic applications to shorterwavelengths only, and demands UV region for excitation; it has attracted attention as an interesting alternative toTiO2 in dye sensitized solar cells. Both TiO2 and ZnO have similar band gaps (3.2 ev) and similar electron injectionefficiencies from excited dyes. Moreover, ZnO exhibits analogous transport properties as TiO2. ZnO has otheradvantages such as improved performance with cheap organic dyes (it absorbs larger fraction of solar UV light thanTiO2 does).Because only about 4% of the solar spectrum falls in the UV region, ZnO semiconductor is sensitized by dyemolecules. Sensitized ZnO catalysts have been investigated for organic pollutant degradation in a safe and simplemanner.In this work, ZnO semiconductor nano-particles, combined with safe low cost sensitizer (the natural dyeanthocyanin) was used to disinfect water from bacteria by photodegrading it with solar light .The natural dyesensitizes ZnO to the visible light, the dye has lower band gap and absorbs in the visible region.Illumination has been constructed by a solar simulator lamp. A pre-contaminated water sample with e-coli bacteriawas treated with the catalyst (ZnO/anthocyanin) under halogen spot lamp. A noticeable decline in bacteriaconcentration was observed. Contaminated samples treated with naked ZnO, anthocyanin dye, and light source(without any additions) separately in control experiments.Up to 90% degradation was achieved by the ZnO/anthocyanin catalyst system under solar light in 90 minutes.Effect of different parameters on reaction rate and efficiency, such as temperature, pH, concentration and otherswill be presented.