Schiff’s base vanillin thiourea polyurethane foam (PUF) was prepared using open cell flexible polyurethane foam polyether type which supply from an Egyptian company for foam production. 5 g of PUF cubes was soaked in 1 mol/L HCl leaving it whole night soaked then squeezed it very well to get over all HCl remain and then washed it with distilled water. A 25 ml concentrated HCl was added to 5 g PUF-NH2 cubes until this mixture was warmed. A 60 ml of saturated solution of ammonium thiocyanate (1:2) was added slowly to PUF-NH2 cubes and the solution was warmed until the solution got turbid. The turbid mixture was poured into cold water, filtered and dried at room temperature (Mathapati et el., 2012).
The next step is adding vanillin to PUF (1:1) to reflux with 200 ml ethanol for 2h .The [email protected] composite was prepared by refluxing the SVT-PUF with ZnONPs at 6 h then filtered, washed with ethanol and air dried. Stock solutions of brilliant green (Br.G; C27H34N2O4S, 482.65 g/mol), toluidine blue (To.B; C15H16ClN3S, 305.83g/mol) and trypan blue (Tr.B; C34H24N6O14S4Na4, 960.81 g/mol) were prepared by dissolving 0.1 g of each dye in 100 ml distilled water.