Ultrafast regeneration of spent activated carbon and sustainable application

Granular activated carbon (GAC) with large adsorptive capacity and high mechanical strength is the highly favored adsorbent for gold extraction. Once adsorption reaching saturation after prolong used, however, GAC usually needs periodic regeneration, which suffers from energy-intensity, low efficiency, serious carbon loss, and structure degradation. A novel approach for the ultrafast regeneration of spent activated carbon (SAC) after gold extraction is presented through combination of high temperature shock (HTS) and ultrasonic pickling (UP) treatment. This ultrafast regeneration is realized via a well-designed two-step method, in which the transient thermal treatment caused by HTS and chemical cleaning enhanced by ultrasound greatly shorten process duration to improve efficiency, suppress carbon loss and maintain carbon strength. As a result, SAC was regenerated to activated carbon (RAC) only in 150 s with an iodine adsorption value of ∼960.8 mg/g and average crushing strength of ∼43.51 N, respectively, significantly superior to the conventional methods. In addition, damaged fine-grained carbon after regeneration were also repurposed to prepare MoS 2 @AC composites for adsorbing organics (e.g. methylene blue dye), thereby achieving a sustainable application. This work not only provides a solution to the efficient regeneration of SAC, but also facilitate the sustainable recycle application of waste carbon materials.