Optimization of experimental conditions using central composite design for rifampicin removal

This research aims to optimize the impact of parametric conditions on the adsorption process of rifampicin, a drug used in tuberculosis treatment. The study specifically focuses on activated carbon derived from waste generated by a food processing facility, namely cacao shells (CS). Referred to as ACAFW (Activated Carbon Alimentary Factory Waste), the study utilizes a three-factor central composite design (CCD) experimental approach. The investigation is further connected to a parametric study aimed at verifying the effectiveness of the CCD model. Optimal treatment conditions were identified, including a pH of 6, an adsorbent dose of 0.3 g, and an antituberculosis concentration of 10 mg/L. These conditions demonstrated a close alignment between the obtained results (pH of 5.96, ACAFW dose of 0.328 g, and rifampicin concentration of 11.64 mg/L). The study employs a combination of the density functional theory (DFT) approach and infrared (IR) analysis to unravel the structure of rifampicin. Additionally, differential thermal analysis/thermogravimetry (DTA/TG) and Brunauer–Emmett–Teller (BET) analyses were conducted on the material. ACAFW showcased surface areas exceeding 1394 m2/g, and a microporous volume of 0.400 cm³/g. The results from the kinetic study imply that the adsorption process is influenced by competition between internal and external diffusion.