Fabrication of AuNPs into alginate biopolymer and functionalized by thiourea as a film shape probe for palladium(II) sensing

Abstract

• Au nanoparticles (AuNPs) were in situ synthesized into alginate polysaccharide biopolymer. • The AuNPs entrapped in the alginate networks were functionalized by thiourea and shaped as a film. • Functionalized thiourea AuNPs-alginate biopolymer film was used for palladium(II) detection. • The characteristics of thiourea/AuNPs alginate film was performed by TEM, DLS, EDAX and UV–vis spectrophotometry. A simple process was developed for the fabrication of alginate biopolymer film embedded by thiourea-functionalized AuNPs (thiourea/AuNPs) for palladium(II) detection. A mixture of sodium alginate and HAuCl 4 was prepared as the main matrix and the AuNPs were in situ synthesized in alkali media provided by borax. The AuNPs entrapped in the alginate network were functionalized by thiourea and fabricated as a transparent film. The characteristics of thiourea/AuNPs alginate biopolymer film were investigated by Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDX) and UV–vis spectrophotometry. The UV–vis absorption spectrum showed the maximum wavelength of thiourea/AuNPs was at 530 nm. The effect of various parameters such as pH and thiourea concentration on the sensing of palladium(II) ions was investigated. The prepared alginate biopolymer film showed good stability over the time. The calibration graph was linear in the range of 0.05−2.10 μg mL −1 with a detection limit of 0.038 μg mL −1 . The relative standard deviation (n = 10) for 0.6 and 1.2 μg mL −1 of palladium(II) was 4.6% and 3.5%, respectively. The sensing system was successfully applied for the determination of palladium in walnut leaves, wastewater, dental amalgam, and ceramic capacitor samples.