Sustainable activated carbon obtained as a by-product of the sugar and alcohol industry for removal of amoxicillin from aqueous solution

The alcohol and sugar industry in Brazil uses a feedstock for sucrose extraction, resulting in waste production, one of them being the sugarcane bagasse. A possible relocation for the use of this residue, produced in millions of tons annually, would be its use in the production of carbonaceous materials, such as activated carbon (AC). The purpose of this study was the production of activated carbon using a faster, simpler and more efficient process with low energy requirements and chemical reagents to obtain a material with a high surface area. The AC samples were prepared by chemical activation with ZnCl2 and carbonization at 600 °C in an oxygen-limiting atmosphere. The average specific surface area of the samples, estimated by the BET method, was 1544 m2 g−1 and the average pore size was 2.6 nm. The surface morphologies of the ACs were characterized using SEM analysis, which showed that the surfaces were irregular, with cracks, pores. The solids were also characterized by FTIR, presenting mainly stretching bands corresponding to O–H, C–O, and C=C groups. EPR analysis showed a resonance line characteristic of an organic free radical with g ~ 2.0031, which is typical of free radicals centered on carbon atoms. The material efficiency for removal of aromatic organic pollutants was evaluated in continuous-flow adsorption tests with the antibiotic amoxicillin. The method provided very satisfactory results, reducing the concentration of the antibiotic from an initial value of 1.37 × 10−3 mol L−1 to about 3.5 × 10−8 mol L−1. The concentration of the antibiotic in water, after adsorption, was therefore reduced by four to five orders of magnitude, confirming the potential application of the materials prepared in this work for the removal of antibiotics residues from the environment.