Production of activated carbon from organic by-products from the alcoholic beverage industry: Surface area and hardness optimization by using the response surface methodology

The ability of activated carbon to remove pollutants from water in packed column systems is dependent on granular material with mechanical strength sufficient to avoid attrition caused by stream flow. Therefore, an appropriate balance between surface area and hardness is essential when using activated carbon in real systems. The purpose of this research is to determine the optimal production conditions that generate activated carbon with adequate physical properties to be used in packed systems from agave bagasse, a waste product from the mezcal industries in Mexico. Activated carbons were produced by chemical activation (ZnCl₂ or H₃PO₄). Response surface methodology (RSM) was used to evaluate the effect of the activation temperature (250-550 °C), activation time (0-50 min), and the concentration of activating agent (0.2-1.4; g activating agent/g bagasse) on both surface area and hardness. The production conditions that generated optimal characteristics in the activated carbon were 392 °C, 1.02 g activating agent/g bagasse and 23.8 min for H₃PO₄ activated samples and 456 °C, 1.08 g activating agent/g bagasse and 23.8 min for ZnCl₂ activated samples. The surface area and hardness of the activated carbon produced from bagasse under these conditions were similar to activated commercial carbons (surface area > 800 m²/g and hardness > 85%).