ultrasonic-assisted degradation of metformin from pharmaceutical effluent: process optimization via response surface methodology

Introduction: metformin, an extremely prescribed antidiabetic medication, is discharged with minimal or no processing and remains during the usual wastewater treatment procedures. advanced oxidation processes (aop), especially ultrasound-enabled oxidation, are catalyst- and sludge-free reaction pathways for degrading recalcitrant pharmaceuticals. this study aimed to (i) determine the ultrasound-assisted degradation of metformin using hydrogen peroxide, (ii) determine the effect of the main operation parameters, and (iii) optimize the chemical oxygen demand (cod) and total organic carbon (toc) using response surface methodology (rsm).materials and methods: five process parameters were optimized: ph (3-9), ultrasonic power (60-150 w), sonication time (10-60 min), h₂o₂ concentration (0-1.0 ml/l), and initial metformin concentration (5-50 mg/l). dual response variables, including cod and toc removal, were analyzed via quadratic polynomial regression. metformin concentration was quantified using high-performance liquid chromatography at a detection wavelength of 240 nm.results: optimal operating conditions were identified as ph 3.5, ultrasonic power 110 w, sonication time 40 min, and h₂o₂ concentration 0.65 ml/l, achieving 94.5% cod removal, 88.3% toc removal, and 97.2% metformin degradation. both statistical models demonstrated high significance (p < 0.0001) with a coefficient of determination r² > 0.96 and a composite desirability of 0.9845 (98.45%), confirming excellent multi-response optimization.conclusion: metformin significantly reduced the organic load, and the drug was significantly degraded by ultrasonic-assisted oxidation. the optimization method based on rsm offers predictive models that can be used to design the process or the performers.