Water pollution due to industrial waste, particularly methylene blue (MB), remains a major environmental challenge. In this study, a composite catalyst composed of activated carbon from coffee bean husks, CaO from eggshells and natural clay (AC/CaO: Clay) was synthesized via a solid-state reaction for MB degradation. The photocatalytic performance was evaluated under real environmental conditions without UV lamps or mechanical stirring and MB degradation was monitored using an Internet of Things (IoT) system. The results show that under optimal conditions (pH 9, 25.6 °C and a photocatalyst dose of 0.5 g), the AC/CaO: Clay composite can degrade up to 80% of MB (500 mg/L) over a 24-h photocatalytic process. The structural and optical properties that influenced these results include a high BET surface area (112.5 m2/g), small crystallite size (33.71 nm), consistent Formula: see text narrowing (882 cm⁻¹) and a suitable Formula: see text (3.57 eV). These findings confirm the composite's applicability for sustainable wastewater treatment.
Heryanto et al. (Tue,) studied this question.