High Efficiency Regeneration Performance of Exhausted Activated Carbon by Superheated Steam and Comparison with Conventional Chemical Regeneration Method

Spent activated carbon is a common by-product of pollution treatment with granular activated carbon (GAC) adsorption and therefore spent activated carbon treatment for reuse is critical to maximize cost-effectiveness and sustainability. Superheated steam regeneration is a novel treatment technology that uses water vapor and is more energy- and cost-efficient than other thermal regeneration methods. This work has value in that two modes of operation are compared in a small-scale process, whose experiment is well designed to reflect its large-scale process. Our study evaluated the effects of superheated steam regeneration on phenol-saturated activated carbon using a rapid small-scale column test (RSSCT) and evaluated this approach with the conventional chemical regeneration method. Our findings indicated that superheated steam regeneration achieved optimal performance at 500°C for 60 min, whereas chemical regeneration performance was optimal using 4% NaOH coupled with a low flow rate. Based on these observations, cyclic adsorption/regeneration tests were conducted six times. Additionally, differences on the carbon surface after regeneration were explored via scanning electron microscopy (SEM). The results indicated that superheated steam was more efficient and rendered cleaner carbon surfaces.