5th Joint International Conference on Nanoscience & Nanoengineering x International Conference on Advanced Technology and Multidiscipline

Preliminary Evaluation of a Low-Cost Integrated RGB Sensor for Time-Resolved Monitoring of Ag–SiO₂-Catalyzed Rhodamine B Reduction: Challenges Toward Process-Analytical Deployment

30 Sept 2026, 12:15

15m

Mawar 1&2, Level 3 (Tenera Hotel & Suites)

Nanoengineering Session 1C

Speakers

Mr Juhen Fashikha Wildan (Robotics and Artificial Intelligence Engineering Study Program, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga)Ms Eirene Mayza BR Sitepu (Nanotechnology Engineering Study Program, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga)Ms Sayyida Faradilla Muhta (Nanotechnology Engineering Study Program, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga)Ms Sahda Nabilah Alodia Septiana (Nanotechnology Engineering Study Program, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga)Ms Nailul Fitriani (Nanotechnology Engineering Study Program, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga)Ms Zafirah Aida Adista (Nanotechnology Engineering Study Program, Faculty of Advanced Technology and Multidiscipline, Universitas Airlangga)

Description

Monitoring the removal of synthetic dyes such as Rhodamine B (RhB) during catalytic treatment typically relies on UV–Vis spectrophotometry, an accurate but laboratory-bound and costly technique. This preliminary study develops a low-cost integrated red–green–blue (RGB) sensor (TCS34725/ESP32) operating in transmission mode and evaluates its suitability for time-resolved monitoring of the Ag–SiO₂-catalyzed reduction of RhB by sodium borohydride. Calibration of the sensor against RhB standards was performed using previously synthesized Ag-SiO2 nanocatalyst. Among the light-source and detection-channel combinations examined, a yellow light source paired with the red channel gave the best (most linear and sensitive) response (R² > 0.99); this combination places the illumination on the long-wavelength flank of the RhB absorption band (λmax ≈ 554 nm) while matching the emission to the responsivity of the red channel. A single proof-of-concept run demonstrated that the platform follows the reduction in real time rather than only at its end-point. Critically, the study identifies the practical challenges that currently preclude quantitative kinetic determination — most notably interference from hydrogen bubbles evolved during the reaction, together with the need for replication and the characterization of analytical figures of merit. By mapping these obstacles and proposing mitigation strategies, this work provides a foundation and roadmap toward a validated, low-cost tool for time-resolved and, prospectively, process-analytical monitoring of catalytic dye reduction.
Keywords: Rhodamine B; catalytic reduction; Ag–SiO₂; RGB colorimetry; low-cost sensor; time-resolved monitoring; process analytical technology.