Carvão ativado de resíduo de Baru para adsorção de fármacos

Abstract

The present work describes the preparation of activated charcoal from Baru waste (CARB) obtained via pyrolysis in an adapted domestic microwave oven and chemical activation withH3PO4. The obtained CARB was characterized through Elemental Analysis (CHN), Scanning Electron Microscopy (SEM), N2 Adsorption/desorption isotherms using BET, BJH, and DFT methods, Fourier Transform Infrared Vibrational Spectroscopy(FTIR), X-ray Diffractometry, (XRD), Raman Spectroscopy, Boehm Titration Method and Zero Point Charge (pHPCZ). After characterization, CARB was employed for the adsorption removal of caffeine (Caf) and paracetamol (Par) from water. Adsorption assays were conducted using the batch procedure at 25.0°C. Adsorption parameters were investigated, such as the amount of adsorbent mass, pH solution, contac ttime between adsorbent and adsorbate, and initial concentration of adsorbate. The maximum adsorption capacity for Caf and Par was obtained at pH 6- 8. The minimum amount of adsorbent mass necessary to get the maximum adsorption capacities for both drugs was 100.0 mg of CARB in 20.0 mL of the adsorbate. The adsorption kinetics was investigated using the Pseudo-first-order, Pseudo-second orderand Avrami kinetic models. The Avrami model best described the adsorption kinetics for both molecules showing the closest values to the R2adj unit and the lowest values for standard deviation. The equilibrium condition was reached with a stirring time of 60 minutes for both drugs. The Langmuir, Freundlich, and Liu nonlinear equilibrium models were used to describe the adsorbent-adsorbate interaction mechanism. Liu model is the best fit for the experimental data. Based on Liu model, the maximum adsorption capacity (Qmax) was 279.5 mg.g -1 for Caf and 163.9 mg.g -1 for Par. The feasibility of applying CARB in removing Caf and Par from the aqueous environmental matrix was investigated. The results of these studies show that CARB can be used as an efficient adsorbent for the remediation of Caf and Par in water.