Robust modified nylon mesh for the separation of crude-oil/water emulsion based on the coupling of squeezing coalescence demulsification and sieving separation

Abstract

Membrane separation is an appropriate method for the treatment of emulsified wastewater. But emulsified wastewater always contains oil droplets with a broad size distribution, and the tiny oil droplets can easily intrude into the pore of membranes during the separation process, which can cause internal fouling of membranes. Reducing the pore size can alleviate this fouling, however, the strategy may cause a decline in flux. Therefore, a more efficient strategy should be proposed. Herein, modified nylon mesh with well mechanical properties and low crude-oil adhesion was chosen for crude-oil/water emulsion. Before the sieve separation, a preprocessing strategy of squeezing coalescence is applied to the emulsion, resulting in the preprocessed emulsion with large and homogeneous crude-oil droplets. And the preprocessed emulsion can be continuously and efficiently separated by the sieving membrane. Compared with directly separating the original emulsion, separating the preprocessed emulsion can prolong the service life of the sieving membrane. The prepared modified nylon mesh and the coupling of the squeezing coalescence process and the sieving process have the practical application value for industrial crude-oil/water emulsion separation.