▎ 摘　　要

Microplastic has become one of the ubiquitous pollutants due to its vast growing number in the environment. This is the first study that utilised Design Expert software to interpret the interaction between pH, temperature and catalyst dosage on the microplastic mass loss. In this study, the applicability of photocatalysis in degrading in low density polyethylene (LDPE) microplastic was investigated by using graphene oxide/zinc oxide (GO-ZnO) photocatalyst under UV light irradiation. The photocatalysts were analysed with a scanning electron mi-croscope with energy dispersive X-ray analysis (SEM-EDX) to identify the surface mor-phology and particle size. The average crystallite size of ZnO on GO was 16.43 nm. Fourier transform infrared spectroscopy (FTIR) was used to determine the polymer type used as the microplastic model and to confirm the fabrication of GO-ZnO. From the preliminary study, the microplastic mass loss was the highest at 1000 ppm of GO-ZnO dosage. The photo -degradation efficiency was found to be the highest at pH 7 solution compared to acidic and alkali condition. In addition, the mass loss of microplastic increased with operating tem-perature. The reduced quadratic model was developed to predict the microplastic mass loss under the photodegradation of GO-ZnO. The interaction of pH, temperature and catalyst loading was analysed with Box-Behnken Design via Design Expert 12. From the results ob-tained, the individual impacts of the catalyst dosage as well as the interaction between pH and temperature were significant in affecting the microplastic degradation. The relative importance of the affecting parameters are arranged: photocatalyst dosage > pH and tem-perature > temperature and photocatalyst dosage > temperature > pH. The optimum con-dition where the highest microplastic mass loss was reported (microplastic mass loss of 39.47%) were found to be at pH 9.66, 30 celcius, 1500 ppm within 2 h of photodegradation. Furthermore, the reusability of the GO-ZnO was also reported.(c) 2023 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.