Regeneration of Spent Activated Carbon by Yeast and Chemical Method

In this study, spent activated carbon (AC) saturated with caramel was regenerated by using yeast and NaOH. The efficiency of regeneration was evaluated under parameters such as amount, treatment time, temperature, pH value, stirring temperature of yeast and NaOH concentration. The optimum condition for AC regeneration was 8 h for yeast treatment time, 35°C for 0.075% yeast culture temperature, a pH value of 6 for the yeast dealing with the spent AC, 90°C for NaOH stirring temperature of AC and 6% NaOH for washing after the spent AC was treated by yeast. Under these conditions, methylene blue (MB) adsorption was 213 mg·g−1 in comparison with 60 mg·g−1 of spent AC. The micro structure and surface area of the regenerated AC were characterized by scanning electron microscope (SEM) and N2 sorption, respectively. The pore size distributions of virgin and regenerated AC were analyzed by means of H-K equation, resulting in a mean pore diameter of 1.28 nm and a pore volume of 1.13 cm3·g−1. This study provides data for theoretical support of the AC regeneration technology.