Membrane aromatic recovery system (MARS): lab bench to industrial pilot scale

This article describes a novel process for recovery of aromatic amines and phenolic compounds form wastewaters, the membrane aromatic recovery aromatic system (MARS). Laboratory work on wastewaters containing aniline and phenol will be presented, including data demonstrating removal and recovery of each chemical in a sufficiently pure form to allow recycling into a chemical production process. This article also describes successful scale-up and operation of the process through pilot trials at Solutia, UK. Process economics are discussed and data showing the potential for application of the process to a wide range of organic chemicals are presented.

MARS is a novel process coupling detoxification and recovery. It is capable of achieving high recovery efficiencies and producing a relatively pure stream of recovered organics. At the laboratory scale, MARS has proven to be a successful process for removing and recovering aniline and phenol, with water contents of 5 and 13.5 wt% respectively At pilot plant scale MARS was proven able to recover aniline from an industrial wastewater in a good purity. MARS was shown to be easily scaled-up based on membrane area. Using different configurations, MARS was adapted to deal with a key problem for membrane technology applied to chemical processes, that is, membrane blockage by tarry solids or organics precipitation. The MARS process can utilise very simple nonporous rubber tubes as membranes. MARS has low energy requirements because it exploits the acid-base functionality of aromatic acids and bases to produce a driving force based on the chemical energy contained in NaOH or HCl. The process can be carried out at conditions of pressure and temperature that are near ambient throughout all items of equipment. MARS does not rely on volatility of organics (or any phase transition), so one can recover organics that membrane technologies such as pervaporation cannot reach. Finally, MARS has been shown to be promising in the industrial application to recovery a larger range of aromatics than phenol and aniline. Examples include amines, phenolics and pyridines.