Use of brewing industry waste to produce carbon-based adsorbents: Paracetamol adsorption study

Abstract

This work aimed to produce activated carbon (AC) from brewing industry waste (the malt bagasse) to adsorb Paracetamol. Malt bagasse was characterized by moisture and ash contents and thermogravimetric analysis. Three types of AC were prepared: C400 (400 °C) and C500 (500 °C) under oxidizing atmosphere, and CN550 (550 °C) under nitrogen atmosphere. Some of these ACs were characterized by pH, point of zero charge (pH_PZC), infrared spectroscopy, N₂ adsorption-desorption isotherms, scanning electron microscopy, and temperature-programed desorption of CO₂ and NH₃. A pH_PZC value < 7.0 and high density of acid sites were identified for CN550. Specific surface areas were between 192.5 and 364.0 m².g⁻¹. Adsorption kinetic studies were performed in a batch system with 50 mL of Paracetamol solution (100 mg.L⁻¹) under pH 4 and 0.75 g of adsorbent (optimized conditions). The time to reach adsorption equilibrium was 20 min with 98.3% Paracetamol removal for CN550 AC. The pseudo-second order model and the Langmuir isotherm best fitted experimental data. Brewing industry waste can be used as a source of organic matter for AC production, since the percentage of Paracetamol removal in this study showed that CN550 AC presentes high adsorption efficiency and economically viable production.

Keywords:

• Pollution control
• reuse of industrial waste
• adsorption isotherms
• pharmaceuticals

Acknowledgments

The authors would like to thank the LCME-UFSC for technical support during electron microscopy work.