The final carbonation mud resulted from sugar beet clarification process has been and still represents the most common waste problem in sugar industry. It contains mainly calcium carbonate beside other minor constituents. In this study, a novel technique was developed, which involves combination of Limex method and sol–gel method for the preparation of calcium oxide nanoparticles (CON) from the carbonation mud waste. The synthesized nanoparticles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy and X-ray diffraction. The SEM and TEM images showed that the CON particles are semi-hexagonal in morphology with particles size 60–275 nm. A high surface area 747.62 m²/g was also determined. Minerals analysis of CON showed high content of calcium oxide (92.81%) and significant reduction in the percentage of …