Enhanced desorption performance of aniline-saturated powdered activated carbon using ultrasound assisted with ethanol

The adsorption characteristics of dissolved aniline onto powdered activated carbon (PAC) and the subsequent desorption by ultrasound treatment were studied. The results indicated that the adsorption followed the pseudo-second-order model and the Langmuir model. Acidic conditions were not conducive to the adsorption of aniline. The desorption efficiency of saturated PAC radiated by ultrasound reached a maximum of 24.35% with a sonication power of 180 W at a frequency of 40 kHz, and a pH of 3 within 180 min of sonication time. The addition of ethanol produced a synergistic effect with ultrasound, effectively improved the desorption efficiency to 83.88%. Intermediates of aniline that were formed during the ultrasound irradiation were analyzed by gas chromatography-mass spectrometry and this identified azobenzene as the main by-product. Analysis of the specific surface area, pore structure, and FTIR spectra of PAC indicated that more cavitation occurred in ethanol than in water, and high-speed microjets and high-pressure microstreams enlarged the mesopore of PAC. In general, the physical attack of microjets and microstreams played an active role in the desorption of aniline.