Anais da 43ª Reunião Anual Virtual da SBQ

An extensive sugarcane planting is necessary due to the high demand for alcohol production, which after processing to obtain the dense broth, millions of tons of bagasse are generated. Many papers have been done to show that porous materials, such as activated carbon, produced from agroindustrial residues, have high adsorptive capacity in aqueous solutions. The aim here was to produce activated carbon from sugarcane bagasse to evaluate its adsorptive capacity in atrazine (ATZ) and methylene blue (MB) solutions. Sugarcane bagasse was collected at the Cambui Industry in Goias state, was dried at 100 ºC and submit to carbonization (thermal activation), for 3 and 5 hours at 200 ºC (CA3 and CA5, respectively). Samples CA3 and CA5 were characterized: (1) Fourier Transform Infrared Spectroscopy (FTIR) to analyze the changes in the functional groups of the compounds present in the material during carbonization; (2) Scanning Electron Microscopy (SEM) where the micrographs showed that the quantity of particles decrease and the porous increase with carbonization time and (3) thermogravimetry (TG), which shows a mass loss at 350 ºC related to 80 % cellulose/hemicellulose composition. To the ATZ adsorption analyses, 10 mL (5 – 50 mg L -1 ) was added to 10 mg of CA3 and CA5 sample and stirred at 150 rpm for 24 hours. For MB, 50 mL (5 – 40 mg L -1 ) was added to 50 mg of CA3 and CA5 sample and stirred at 150 rpm for 24 hours. The solutions were filtered through a 0.45 µm pore size syringe filter and analyzed by UV-Vis spectrophotometer (λATZ = 222 nm; λMB = 664 nm). For residual concentration calcule was done by standard curve equation (R2 ATZ = 0,999; R2 MB = 0,999). The isotherms (Figure 1) and qe values (Table 1) show that CA3 has the best performance on adsorption to the MB (qe = 33,08 mg g - 1 ). The carbonization effect was observed on the ATZ adsorption, when the qe value increase from 22,62 to 31,87 mg g -1 , which are associated to increase of carbonization time, creating a number of available sites for molecular adsorption1 , and decreasing on particle size raising the specific surface area2 . The Langmuir isotherm can adequately represent the data obtained, which demonstrate the high correlation coefficients3 .