Parametric optimization and kinetic analysis of cephalexin sequestration from simulated wastewater by KMnO4 modified Milicia excelsa biochar

Abstract

The ineffectiveness of conventional sewage treatment plants in removing pharmaceuticals has resulted in environmental contamination. Consequently, the development of new technologies to address this issue is necessary. To ascertain the optimal circumstances for the elimination of Cephalexin (CPX) from synthetic wastewater, a response surface methodology (RSM) was utilized in this study to optimize the process parameters. The study utilized modified biochar derived from Milicia excelsa sawdust for this purpose. The synthesis of the modified biochar (named KMB) involved pyrolysis followed by impregnation with KMnO4, and its properties were characterized using various techniques including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared (FTIR). Box-Behnken experimental design (BBD) using RSM was used to study and assess the effects of factors like the modified biochar dosage, initial CPX concentration, and reaction time. The predicted optimal CPX removal of 87.35% was obtained under the following conditions; KMB quantity: 0.1 g, initial concentration: 80 mg/L and contact time: 20 min. A high degree of fit was achieved with the quadratic model. The PSO model with R2 value greater than 0.97, is an excellent and appropriate model for assessment and the true mechanism of CPX uptake is chemical adsorption, according to experimental kinetic data fitting to kinetic models. The Langmuir and Freundlich models were shown to be consistent with the isotherm data by adsorption analysis. In summary, KMB, which was made from easily accessible waste biomass, may be employed as a potential biosorbent to eliminate CPX from aquatic environments.