Desorption of bisphenol-A (BPA) and regeneration of BPA-spent granular activated carbon using ultrasonic irradiation and organic solvent extraction

Abstract: Desorption of bisphenol-A (BPA) from granular activated carbon (GAC) by ultrapure water and regeneration of BPA-spent GAC using ultrasonic irradiation and organic solvent extraction are investigated in this paper. The results showed that the pseudo-second-order kinetic model more appropriately described the BPA desorption pattern, and BPA desorption well followed the classical Arrhenius equation at a temperature range of 288–308 K with an activation energy of −56.47 kJ mol⁻¹. Desorption rates of BPA were significantly favored by increasing acoustic intensity within a range of 17–100 W at 20 kHz frequency. Certain fraction of methanol or ethanol, particularly methanol, in the extraction solution enhanced the BPA desorption from the spent GAC. The optimal volumetric fraction of methanol in the extraction solution was 75% at which 80% of BPA on the spent GAC was desorbed within 400 min. A synergetic enhancement could be observed when ultrasonic irradiation was coupled with methanol for the GAC regeneration, and the regeneration efficiency was improved with the increasing irradiation intensity. Results demonstrate that the proposed ultrasonic irradiation and organic solvent extraction technology is a promising alternative to regenerate the spent GAC with BPA.