Treatment of Sebacic Acid Industrial Wastewater by Extraction Process Using Castor Oil Acid as Extractant

Wastewater containing high concentrations of phenol and sodium sulfate is generated in sebacic acid (SA) industry. Castor oil acid, a raw material for producing SA, can be used to extract phenol from wastewater in order to reduce the amount of phenol used in the process and discharge of phenol. The results show that the extraction mechanism is that hydroxyl group of phenol is linked to carboxyl group of castor oil acid by hydrogen bond. The extraction process approaches equilibrium in 30 min. Extraction ratio increases with the increase of sodium sulfate and castor oil acid, and decreases as phenol increases. When the oil-water ratio is 1 : 3, the optimal distribution coefficient of 40 is obtained. Phenol saturation concentration in castor oil acid is 1.03 mol·L−1 after extraction for 4 times. The equilibrium constant (Kex) at 25 °C is 8.41 and the endothermic enthalpy (ΔH) is 1.513 kJ·mol−1. The Gibbs free energy (ΔG) is −5.277 kJ·mol−1 and the value of ΔS is calculated to be 22.3 J·mol−1·K−1.