An integrated approach for obtaining biodiesel, sterols, gossypol, and raffinose from cottonseed on a biorefinery concept

This study outlined an integrated approach for obtaining several products, such as biodiesel, gossypol, sterols, raffinose, and nontoxic cottonseed meal from cottonseed via modified two-phase extraction (TPE), supercritical methanol transesterification and other technologies. The modified TPE could not only simplify the steps of separating substances, but also improve the quality of cottonseed oil and cottonseed meal. The suitable conditions of modified TPE were as follows: the petroleum ether/methanol volume rate of 1:3, the extraction temperature of 40 °C, and the extraction time of 20 min. The supercritical methanol transesterification had a favorable yield of biodiesel with shorter time. The conversion of cottonseed oil was up to 97.5% with the temperature of 270 °C, the molar ratio of methanol to oil of 40, and a reaction time of 40 min at 10 MPa. Meanwhile, with the suitable conditions, the purity of the obtained gossypol, sterols and raffinose could be got to 92.1%, 89.8% and 94.2%, respectively. This integrated biorefinery could be useful for comprehensive development and utilization of cottonseed with fewer steps and lower cost.