Preparation of long-flame coal flotation collector from waste cooking oil

There is currently a need to develop efficient and environmentally friendly (green) collectors to improve the poor flotation performance of long-flame coal (LFC) due to its vast porosity and high oxidation degree. Herewith, this study introduces ozone (O3) and ultraviolet (UV) oxidation methods to modify waste cooking oil collector (WCOC) and analyzes their effects on the LFC flotation performance. Furthermore, the separation efficiency (SE) of WCOC, O3-WCOC, UV-WCOC and common collectors (diesel, kerosene, DEP) were compared. Fourier Transform Infrared Spectroscopy (FTIR) and Gas chromatography-mass spectrometry (GC-MS) were used to observe the effects of O3 and UV oxidation on WCOC functional groups and chemical composition. The functional groups and wettability changes of LFC treated via common collectors, including WCOC, O3-WCOC and UV-WCOC adsorption were analyzed. Results revealed that a shorter O3 oxidation time resulted in better flotation performance and higher SE compared to UV oxidation. After O3 (5 min) and UV (9 h) oxidations, C-H bonds in WCOC were oxidized and the content of oxygen-containing functional groups (particularly -OH) increased to 4.25% and 4.93% from 0.79%, respectively. Compared to common collectors, O3-WCOC and UV-WCOC demonstrated better reactions with oxygen-containing functional groups (especially O = C-O and C-O) on the LFC surface. This phenomenon led to a substantial increase in contact angle. This novel oxidation method could potentially be applied in wastewater treatment, mineral processing, and other fields.