Separation media and methods especially useful for separating water-hydrocarbon emulsions having low interfacial tensions

Abstract

Separation media, separation modules and methods are provided for separating water from a water and hydrocarbon emulsion and include a fibrous nonwoven coalescence layer for receiving the water and hydrocarbon emulsion and coalescing the water present therein as a discontinuous phase to achieve coalesced water droplets having a size of 1 mm or greater, and a fibrous nonwoven drop retention layer downstream of the coalescence layer having a high BET surface area of at least 90 m 2 /g or greater sufficient to retain the size of the coalesced water droplets to allow separation thereof from the hydrocarbon.

1 . Separation media for separating water from a water and hydrocarbon emulsion comprising:
 a fibrous nonwoven coalescence layer for receiving the water and hydrocarbon emulsion and coalescing the water present therein as a discontinuous phase to achieve coalesced water droplets having a size of 1 mm or greater; and   a fibrous nonwoven drop retention layer downstream of the coalescence layer having a high BET surface area of at least 90 m 2 /g or greater sufficient to retain the size of the coalesced water droplets to allow separation thereof from the hydrocarbon.   
     
     
         2 . The separation media of  claim 1 , wherein the drop retention layer has a high BET surface area of at least 95 m 2 /g or greater. 
     
     
         3 . The separation media of  claim 1 , wherein the drop retention layer has a high BET surface area of at least 100 m 2 /g or greater. 
     
     
         4 . The separation media of  claim 1 , wherein the drop retention layer comprises a mixture of fibers having a high BET surface area and fibers having a low BET surface area. 
     
     
         5 . The separation media of  claim 1 , wherein the drop retention layer comprises a resin binder. 
     
     
         6 . The separation media of  claim 1 , wherein the resin binder includes a polar chemical group. 
     
     
         7 . The separation media of  claim 1 , which further comprises at least one additional layer adjacent to one of the coalescence and drop retention layers. 
     
     
         8 . The separation media of  claim 7 , wherein the at least one additional layer is positioned between the coalescence and drop retention layers. 
     
     
         9 . The separation media of  claim 7 , wherein the at least one additional layer is positioned upstream of the coalescence layer. 
     
     
         10 . The separation media of  claim 7 , wherein the at least one additional layer is positioned downstream of the drop retention layer. 
     
     
         11 . A separation module for separating water from a water and hydrocarbon emulsion comprising a housing having an inlet for the emulsion and respective outlets for water and dewatered hydrocarbon, and a separation media according to  claim 1  within the housing. 
     
     
         12 . A method for separating water from a water and hydrocarbon emulsion comprising:
 (a) passing a water and hydrocarbon emulsion through a fibrous nonwoven coalescence layer so as to coalesce the water present therein as a discontinuous phase to achieve coalesced water droplets having a size of 1 mm or greater; and   (b) passing the hydrocarbon and coalesced water droplets through a downstream droplet retention layer having a high BET surface area of at least 90 m 2 /g or greater sufficient to retain the size of the coalesced water droplets; and   (c) separating the coalesced water droplets from the hydrocarbon.   
     
     
         13 . The method of  claim 12 , wherein the hydrocarbon has an interfacial tension (γ) of less than 25 dynes/cm. 
     
     
         14 . The method of  claim 13 , wherein the hydrocarbon is a liquid fuel which comprises a surfactant. 
     
     
         15 . The method of  claim 14 , wherein the liquid fuel is a fuel which comprises biodiesel. 
     
     
         16 . The method of  claim 12 , wherein step (a) is practiced so that at least 90 wt. % of the water in the emulsion is coalesced into water droplets having a droplet size of 1 mm or greater. 
     
     
         17 . The method of  claim 16 , wherein step (b) is practiced so that the coalesced water droplets retain a droplet size of 1 mm or greater. 
     
     
         18 . The method of  claim 12 , wherein step (c) is practiced by allowing the water droplets to separate from the hydrocarbon by a density difference therebetween.