[email protected] was prepared using white open cell polyurethane foam with polyether type which supply from an Egyptian company for foam production. A 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 then washed it with water. A 30 ml concentrated HCl was added to 5 g PUF-NH2 cubes until the mixture was warmed.
A 60 ml of saturated solution of ammonium thiocyanate (30 g in 60 ml water) was added slowly to the mixture until got turbid solution. The SVT-PUF was poured into cold water, washed 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. SVT-PUF (yellow foam) was refluxed with ZnONPs for 6 h to get [email protected] composite then filtered and washed with ethanol, finally dried at air.A 0.1 g 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 dissolved in 100 ml distilled water.