Characterization and application of activated carbon regenerated by the combination of sulfuric acid pretreatment and thermal regeneration

Spent powdered activated carbon (SPAC) with pigments and impurities was regenerated via sulfuric acid pretreatment combined with thermal regeneration. The main purpose of this study was to restore and improve the adsorption performance of SPAC by exploring the effects of different regeneration conditions on regeneration. The results showed that at a sulfuric acid concentration of 1 mol/L, a solid-liquid ratio of SPAC to sulfuric acid of 50 g/L, a regeneration temperature of 500 degrees C, and a regeneration time of 150 min, SPAC achieved the best regeneration effect. The iodine value and specific surface area (iodine value of 1,037 mg/g and Brunauer-Emmett-Teller (BET) surface area of 1,314 m(2)/g) of the samples obtained under the optimal regeneration conditions were higher than those of virgin PAC (iodine value of 872 mg/g and BET surface area of 1,013 m(2)/g). The regenerated samples were characterized by thermogravimetry, BET, scanning electron microscopy and Raman spectroscopy. Also, the Langmuir adsorption isotherm model showed better correlation for the adsorption of methylene blue (MB) on SA(1/50)S/500/150, indicating that monolayer adsorption occurs on the surface of activated carbon during adsorption. The kinetic experiments revealed that the mechanism of MB adsorption on SA(1/50) S/500/150 followed a pseudo second-order model.