To solve the problems of environmental pollution and food safety issues caused by waste cooking oil (WCO) as well as to alleviate energy shortage, WCO-to-BFA (bio-flotation agent) as an innovative process for WCO conversion and application is proposed, and SO42/Zr-SBA-15 materials are synthesized. The SO42/Zr-SBA-15 materials present excellent catalytic activity in the transesterification of WCO with methanol under optimized conditions, and the triglyceride conversion and fatty acid methyl ester yields achieved 98.5% and 95.2%, respectively. More importantly, SO42/Zr-SBA-15 materials display excellent stability and reusability, maintaining about 80% of triglyceride conversion after six reaction runs. BFA products as a coal flotation agent used for coal froth flotation exhibit obvious advantages compared with the advanced flotation agent (Nalco) and the traditional flotation agent diesel, with the dosage of BFA being only about 1/5 and 1/13 of Nalco and diesel, respectively. (C) 2014 Elsevier Ltd. All rights reserved.