(544fz) Decolouration of Dye Solutions By Oxidation with H2O2 in the Presence of Modified Natural Zeolites

Combination of silver modified natural zeolites with H₂O₂ was studied as colour removal catalyst. For this purpose three different zeolite samples in respect to their surface functionalization were synthesized and characterised. Raw zeolites show a low level of affinity to azo-dyes therefore non-catalytic reaction is neglectable. Also, due to low surface area of natural zeolites the contribution of adsorption low. Silver modified zeolite catalyses the decomposition of H₂O₂ into highly reactive hydroxyl radical. Based on the experiments with different silver modified zeolites it is proven that the form of silver deposited on the surface plays a key role with the samples with silver nanoparticles being the most active. The effect of different reaction conditions and silver forms on the surface of natural zeolite were evaluated. For dyes under investigation the physical adsorption and non-catalytic peroxide oxidation were found ineffective. Therefore the significant synergic effect was gained when the oxidation was carried in the presence of modified natural zeolites.