Studi Komposisi dan Ketebalan Polyvinyl Acetate - Graphene Oxide sebagai Bahan Sensor untuk Aroma Kopi Robusta

Abstract

The current development of gas sensors focuses on PVAc/GO composites as sensor receptors. GO synthesized by Hummers-Offeman method use graphite and characterized by UV-Vis and FTIR spectrophotometers. Composites made using PVAc and GO blending methods with various compositions, and their thickness through the coating process on the electrode surface. PVAc/GO sensor was then tested and evaluated for performance using coffee samples from three different plantations Sidomulyo, Gumitir, and Garahan. The successful synthesis of PVAc/GO composites shown by presence of PVAc and GO spectra combination. Results characterization using UV-Vis spectrophotometer showed two peaks at a wavelength of 220 nm reflecting GO compounds and 260 nm indicating PVAc compounds. Likewise, results of FTIR characterization show CH2 stretching vibrations in the GO area 2927,37 cm-1, the peak 1224,44 cm-1 showing C-O-C from PVAc, of wavelength 1726,55 cm-1 indicated carbonyl groups from PVAc and GO, and at a wavelength 3255,01 cm-1 indicates the COOH groups of GO. Optimization composition carried out by varying the mass ratio and obtained ratio of 0,4 g GO and 0,6 g PVAc giving the highest response of 1,344 x 10-7 S. Likewise, effect thickness and highest PVAc/GO sensor response obtained thickness of 0,13 mm with conductance value of 1,731 x 10-7 S. Consistency PVAc/GO sensor preparation very good with repeatability of 3,46% and reproducibility of three sensors tested using three coffees from different plantations had values range of 2,45% - 4,24%. PVAc/GO sensor is able to distinguish three aromas of coffee from different plantations and has fairly high sensitivity indicated by a slope value of 0,7142 in detecting the aroma of Sidomulyo coffee. In addition, PVAc/GO gas sensors also have a long lifetime, with %RSD values ranging from 4,25% - 4,30%, for six weeks.