A novel carbon ceramic electrode consisting of CuNPs and MWCNT was developed to treat reactive orange 84(RO84)wastewater using ultrasound-assisted electrochemical degradation.The proposed electrode generated more hydroxyl radicals than non-nanoparticle electrodes did.In addition,a new electrochemical sensor was ap-plied to determine residue RO84 in an aqueous medium during discoloration.This sensor is based on a glassy car-bon electrode modified with gold nanourchins and graphene oxide and can detect RO84 concentration in the range of 1.0-1200 μmol·L-1 with the detection limit of 0.03 μmol·L-1.The degradation effects of the modified electrode on RO84 were evaluated systematically with different initial pH values,time durations,and amounts of CuNPs and MWCNT.The results suggested that the removal efficiency of RO84 was approximately 83％after 120 min of electrolysis in a phosphate buffer with pH 8.0 using a carbon ceramic electrode made with 4.0 wt％CuNPs and 4.0 wt％MWCNT.The possible mechanism of RO84 degradation was monitored by gas chromatogra-phy-mass spectrometry,and degradation pathways were proposed.