| Using the wax characteristics in corn oil, in the process of low temperature dewaxing, the soap adsorbed wax in the state of crystal nucleus, at the same time of crystallization dewaxing, the once soap removal was completed. In the bleaching process, activated clay was added to bleach and the residual traces of soap was further adsorbed by activated clay, so the twice soap removal was completed. The effects of soap content in alkali refined oil, water content in alkali refined oil, crystallization time, and dosage of activated clay on the residual soap content in bleached oil after twice soap removal were investigated. Using single factor experiment and response surface methodology, the optimal process conditions of removing soap from corn oil were obtained as follows: soap content in alkali refined oil 300 mg/kg, water content in alkali refined oil 0.4%, crystallization time 24 h, and dosage of activated clay 0.5%. Under these conditions, the residual soap content in bleached oil was 0.19 mg/kg and the soap removal rate was 99.9%. The new process had a better effect on soap removal, and there was no water washing process and no waste water discharge. It could meet the requirements of energy saving and environmental protection, and the processing craft was simplified. |
