Nanoparticle CdS-Sensitized TiO2 Catalyst for Photo-Degradation of Water Organic Contaminants: Feasibility Assessment and Natural-Dye Alternatives

The photocatalytic degradation of organic contaminants (like dyes, insecticide, pesticide, … etc) in water, using TiO2 under UV are commonly used procedures. Modifying TiO2 with CdS also a common technique used for water purification under visible light. In this work both commercially and prepared TiO2 were used for photo-degradation of both contaminates models ( Methyl Orange MO and Phenazpyridine PhPy), TiCl3 was used as a starting rote for preparation of rutile structure TiO2 by hydrolysis. In order to sensitization of TiO2 to photoexcited under visible light, A chemical path deposition method (CBD) was used to precipitate a nonsocial particles of CdS on TiO2 particles surface. Sand was used as a supporting surface for the prepared catalyst. UV-visible scanning, photoluminescence measurements, XRD characterization, and SEM imaging were run for the prepared catalyst systems. The particles size of prepared CdS particle was found to be 20 nm. The influence of the catalyst concentration, initial contaminant concentration and pH on photo-degradation rate were studied. Turnover number and Quantum yield were also calculated for comparison study. There is no observable increases in photo-degradation rate with increasing contaminants and catalyst concentration, but a decrease in the rate was observed, no effect to the temperature on the rate, also a higher photo-degradation rate for (MO & PhPy) was observed at higher pH degrees. Voltametric analysis shows almost complete CdS decomposition during the photo-degradation process. Due to hazardous and toxicity of decomposed Cd2+ in the treated water, an alternative of natural nontoxic dyes (Anthocyanin) was used for the first time as a sensitizer for the rutile TiO2. AC was also used as a supporting substrate. Electronic absorption spectra, FT-IR spectra, and TGA analysis were applied on the prepared TiO2/Anthocyanine catalyst systems.A screen study was done to test the efficiency of the prepared sensitized catalyst, the catalyst was applied to photodegradate MO and PhPY. An observable efficiency was noted specially when using AC/TiO2/Anthocyanin at low pH in photo-degradation of MO.