Method and device for separating and recycling acetonitrile waste liquid

The invention relates to the field of acetonitrile recovery, in particular to an acetonitrile waste liquid separation and recovery method and device. The method comprises the following steps: adjusting the pH value of the acetonitrile waste liquid to 6-8; the acetonitrile waste liquid with the pH adjusted to 6-8 is sent to a first rectifying tower, and primary separation acetonitrile is obtained through rectification; feeding the first-stage separated acetonitrile to a gas-liquid separator, and separating to obtain second-stage separated acetonitrile; the second-stage separation acetonitrile is sent to a pervaporation membrane assembly, and third-stage separation acetonitrile is obtained after separation; and feeding the three-stage separated acetonitrile to a second rectifying tower, and rectifying to obtain acetonitrile. Water in the acetonitrile-water azeotrope is removed through the gas-liquid separator and the pervaporation membrane assembly, the two devices are low in working energy consumption, and the