DOI: https://doi.org/10.55373/mjchem.v27i2.104

Keywords: Transparent film; Nata de Sago bacterial cellulose; zinc oxide; purified mangosteen peel extract; hexavalent chromium

Abstract

This article reports the green synthesis of zinc oxide (ZnO) nanostructures using a purified mangosteen peel extract as a plasmonic dopant in Nata de Sago bacterial cellulose transparent films used for the detection of hexavalent chromium (Cr(VI)) in aqueous media by UV-Vis spectroscopy. Purification of the mangosteen extract produced an ethyl acetate-n-hexane fraction and an ethyl acetate-methanol fraction, which act as a reducing agent and capping agent. UV-Vis characterization showed stable ZnO nanostructures with consistent surface plasmon resonance (SPR). FTIR analysis identified -OH, C-H, and Zn-O functional groups, while PSA showed the particle size of ZnO-FEM was smaller (below 100 nm) than ZnO-FEN. SEM and XRD analyses showed that ZnO-FEM had a more dispersed morphology and a smaller crystallite size (8.91–65.92 nm). ZnO-FEM showed superior optical properties with stable fluorescence intensity at an excitation wavelength of 500 nm and a low band gap energy of 1.926 eV. Detection of Cr(VI) by UV-Vis spectrophotometry in the concentration range of 0.01 - 1 ppm using ZnO-FEM 40:50 transparent film showed a good linear relationship (R² = 0.9996), good sensitivity with a slope value of 0.6353, good accuracy (102 % recovery) and precision (0.09 % RSD) with an LOD of 0.0138 ppm and LOQ of 0.0188 ppm. The results indicate that the ZnO-FEM 40:50 transparent film has good potential as an optical sensor for Cr(VI) detection by UV-Vis spectrophotometry.