Photocatalytic Degradation of Some Charges Aqueous Phase Pollutants using Nafion and Silica Modified TiO2

The present study investigated the use of modified titanium dioxide (TiO2) based photocatalytic degradation (PCD) process for the removal of some critical charged aqueous phase pollutants. First of all, the use of Nafion TiO2 (Nf-TiO2) and silica TiO2 (Si-TiO2) for the removal of aqueous phase ammonia (NH4+/NH3) species employing near UV lamp as energy source was studied. The use of Nf-TiO2 enhanced NH4+/NH3 PCD with optimum removal noted for 1 mL of Nafion solution coating per g of TiO2 and respective overall NH4+/NH3 removal was about 1.7 times higher compared to plain TiO2 at 6 h reaction time. Similarly the 0.5 mL silica solution coating per g TiO2 sample, also enhanced NH4+/NH3 removal with optimum efficiency similar to Nf-TiO2. The results from effect of ammonia concentration on to its PCD using Nf-TiO2 indicated that overall mass based NH4+/NH3 removal was higher at greater NH4+/NH3 amounts indicating high efficiency of Nf-TiO2. Similar trends were noted for Si-TiO2 as well. Furthermore, the results from modified TiO2 and mixed NH4+/NH3 and cyanide (CN-) systems indicated successful removal of co-pollutant CN-along with simultaneous degradation of NH4+/NH3 species at rates that were still higher than plain TiO2. Nevertheless application of Nf-TiO2 for the treatment of cationic dye methylene blue (MB) indicated slower MB removal compared to plain TiO2 though significant MB degradation using Nf-TiO2 could still be achieved at pH3. Additionally the results from solar radiation energized PCD process indicated positive role of solar radiation for the removal of NH4+/NH3 species under a varying set of conditions.