Refining Microbubble Ozonation Processes for Polyester Microplastic Removal: Optimization and Kinetic Analysis

In this study, the degradation of synthetic micropolyester effluent (SMPE) was investigated using the microbubble ozonation technique (MOz). A novel approach for quantifying microplastics based on chemical oxygen demand (COD) was adopted in this study. The degradation efficiency under varying process parameters, like pH, contact time, and initial concentration, was evaluated on the basis of the one factor at a time (OFAT) method. Response surface methodology (RSM) using the Box–Behnken design (BBD) was used to optimize the parameters further. Overall, 86% degradation at an optimum pH of 9, a contact time of 60 min, and an ozone flow rate of 1.42 × 10⁻⁵ m³/s was achieved. Kinetic analysis revealed pseudo-first-order reaction behavior. Fourier transform infrared (FTIR) and GC–MS analyses confirmed the breakdown of complex microplastic additives into smaller, oxidized, and potentially biodegradable compounds. Thus, the MOz process effectively reduced the toxicity of SMPE by transforming persistent compounds into less hazardous by-products, enhancing environmentally safe treated effluent. This study establishes a foundation for employing COD as a reliable parameter for measuring the degradability of microplastic, also highlighting the potential of MOz in microplastic effluent treatment.