Optimization of carbofuran degradation in microwave-granular activated carbon system using response surface methodology

Present study revealed tremendous improvement in carbofuran degradation in a Microwave - Granular Activated carbon (MW-GAC) system compared to natural hydrolysis process and the degradation half-life was 12 and 0.189 min at a pH of 6 and 10 respectively at a reaction temperature of 80 °C. In addition, the effect of several operating parameters such as carbofuran concentration, MW output power and reaction time was modelled using Central composite design (CCD) and response surface methodology (RSM) with 17 experimental runs. Carbofuran degradation/mineralization process was described in terms of carbofuran concentration, MW output power and reaction time. The experimental outcomes from CCD indicated improved degradation and mineralization of carbofuran with the increase in reaction time. On the other hand, lower MW output power resulted in poor degradation and mineralization of carbofuran. RSM showed highest correlation coefficient for carbofuran removal per MW output power, Rw (0.92) and COD removal efficiency, ηCOD (0.82). Therefore, quadratic models were developed using regression analysis to predict Rw and ηCOD. Good correlation between the observed values and predicted values by the developed models indicated that the developed models can be used to design required Rw and ηCOD within the experimental conditions.