This　study　investigated　the　ultrasonic-thermal　regeneration　of　powdered　activated　carbon　(PAC)　spent　using　4-chlorophenol　(4-CP).　Similarly,　a　thermal　regeneration　process　was　also　studied　and　the　reaction　conditions　(i.e.,　regeneration　temperature,　heating　rate,　regeneration　time)　were　tested.　Fourier　transform　infrared　spectroscopy　(FT-IR),　thermogravimetric　analysis　(TGA),　scanning　electron　microscopy　(SEM),　X-ray　photoelectron　spectroscopy　(XPS)　and　X-ray　diffraction　(XRD)　analysis　were　applied　to　characterize　the　regenerated　PACs　under　different　treatments　(thermal,　ultrasonic　and　ultrasonic-thermal)　and　also　compare　them　with　the　fresh　and　exhausted　PACs.　According　to　our　regeneration　observations,　the　ideal　regeneration　parameters　were　determined　to　be　a　40　kHz　frequency,　0.18　W/mL　sonication　power,　0.1　M　NaOH　and　50%　(v/v)　ethyl　alcohol　as　the　regeneration　solution,　and　1　g/L　of　saturated　PAC　mass　with　thermal　regeneration　as　the　second　stage　at　500　?,　desorbed　for　30　min　with　a　heating　rate　of　20　?　min(-1).　Under　these　conditions,　the　RE　value　achieved　90.99%　and　the　?　value　reached　5.6%.　The　results　of　FTIR,　XPS　and　XRD　revealed　that　the　oxygen　functional　group　content　of　ultrasonic-thermal　regenerated　PAC　significantly　increased.　These　oxygenous　groups　exerted　a　positive　effect　on　the　adsorption　process　of　the　regenerated　PAC　and　the　subsequent　adsorption-regeneration　process.