Liquid treatment systems

Abstract

A method of treating a liquid. The method comprises providing a feed liquid comprising at least one solvent and at least one solute to a first side of a membrane. A single-phase draw solution comprising at least one of an aminium salt, an amidinium salt, and a guanidinium salt is provided to a second side of the membrane. The at least one solvent is osmosed across the membrane and into the single-phase draw solution to form a diluted single-phase draw solution. At least one of CO 2 , CS 2 , and COS is removed from the diluted single-phase draw solution to form a first multiple-phase solution comprising a first liquid phase comprising the at least one solvent, and a second liquid phase comprising at least one of an amine compound, an amidine compound, and a guanidine compound. A liquid purification system is also described.

1 . A liquid treatment system, comprising:
 a forward osmosis device configured to transfer a solvent from a feed liquid into a draw solution to form a diluted draw solution;   a first solvent switching area downstream of the forward osmosis device and configured to process the diluted draw solution to produce a first concentrated draw solution and a liquid product;   a filtration device positioned downstream of the first solvent switching area and configured to filter the liquid product to form a second concentrated draw solution and a purified liquid product; and   a second solvent switching area positioned downstream of the first solvent switching area and the filtration device and configured to process one or more of the first concentrated draw solution and the second concentrated draw solution to produce the draw solution.   
     
     
         2 . The liquid treatment system of  claim 1 , wherein the first solvent switching area comprises:
 at least one of a heating device, a pressure reducing device, and a gas contacting device configured to expose the diluted draw solution to at least one of heat, reduced pressure, and a non-reactive gas to form a multiple-phase liquid comprising the liquid product and the first concentrated draw solution; and   at least one separation device configured to separate the liquid product of the multiple-phase liquid from the first concentrated draw solution of the multiple-phase liquid.   
     
     
         3 . The liquid treatment system of  claim 1 , wherein the filtration device comprises a reverse osmosis membrane configured to remove a trace amount of at least one of a hydrophilic solvent and a hydrophobic solvent from the liquid product. 
     
     
         4 . The liquid treatment system of  claim 1 , wherein the second solvent switching area comprises at least one device configured to expose one or more of the first concentrated draw solution and the second concentrated draw solution to one or more of CO 2 , CS 2 , and COS, and to one or more of water and alcohol to form the draw solution. 
     
     
         5 . The liquid treatment system of  claim 4 , wherein the second solvent switching area further comprises at least one device configured to separate an organic concentrate from the draw solution. 
     
     
         6 . The liquid treatment system of  claim 1 , wherein the forward osmosis device comprises:
 a first chamber configured to receive the feed liquid;   a second chamber configured to receive the draw solution; and   a semi-permeable membrane intervening between and separating the first chamber and the second chamber, the semi-permeable membrane configured to substantially prevent diffusion therethrough of compounds having a nitrogen atom to carbon atom ratio within a range of from about 1:2 to about 1:15.   
     
     
         7 . The liquid treatment system of  claim 6 , wherein the compounds comprise one or more of amidinium salts, guanidinium salts, and tertiary aminium salts. 
     
     
         8 . The liquid treatment system of  claim 1 , further comprising:
 the draw solution, the draw solution comprising one or more of a tertiary aminium salt, an amidinium salt, and a guanidinium salt;   the first concentrated draw solution, the first concentrated draw solution comprising one or more of a tertiary amine compound, an amidine compound, and a guanidine compound; and   the second concentrated draw solution, the second concentrated draw solution comprising one or more of the tertiary amine compound, the amidine compound, and the guanidine compound.   
     
     
         9 . The liquid treatment system of  claim 8 , wherein the draw solution comprises one or more of a tertiary aminium bicarbonate, a tertiary aminium carbonate, a tertiary aminium alkyl carbonate, an amidinium bicarbonate, an amidinium carbonate, an aminium alkyl carbonate, a guanidinium bicarbonate, a guanidinium carbonate, and a guanidinium alkyl carbonate. 
     
     
         10 . A liquid treatment system, comprising:
 a draw solution comprising a hydrophilic form of a switchable hydrophilicity solvent;   a forward osmosis device in fluid communication with the draw solution and configured to transfer a solvent from a feed liquid into the draw solution to form a diluted draw solution;   a solvent switching device downstream of the forward osmosis device and configured to expose the diluted draw solution to one or more of heat, reduced pressure, and non-reactive gas to form a first liquid comprising the solvent and a second liquid comprising a hydrophobic form of the switchable hydrophilicity solvent; and   another solvent switching device downstream of the solvent switching device and configured to receive the second liquid and to contact the second liquid with one or more of CO 2 , CS 2 , and COS to convert the hydrophobic form of the switchable hydrophilicity solvent to the hydrophilic form of the switchable hydrophilicity solvent and reform at least a portion of the draw solution.   
     
     
         11 . The liquid treatment system of  claim 10 , wherein the draw solution has a concentration of the hydrophilic form of the switchable hydrophilicity solvent within a range of from about 1.0 molal to about 14.0 molal. 
     
     
         12 . The liquid treatment system of  claim 10 , wherein the draw solution comprises one or more of a tertiary aminium bicarbonate, an amidinium bicarbonate, and a guanidinium bicarbonate. 
     
     
         13 . The liquid treatment system of  claim 10 , wherein the draw solution comprises cyclohexyldimethylaminium bicarbonate. 
     
     
         14 . The liquid treatment system of  claim 10 , further comprising a reverse osmosis device configured and positioned to receive the first liquid and to separate the solvent thereof from other components thereof. 
     
     
         15 . The liquid treatment system of  claim 10 , further comprising a mechanical separation device downstream of the solvent switching device and configured to separate the first liquid from the second liquid. 
     
     
         16 . A liquid treatment system, comprising:
 a forward osmosis device comprising a semi-permeable membrane configured to permit H 2 O of a feed liquid to diffuse therethrough and into a draw solution comprising a hydrophilic form of a switchable hydrophilicity material while substantially preventing back diffusion of the hydrophilic form of the switchable hydrophilicity material, the hydrophilic form of a switchable hydrophilicity material comprising one or more of a tertiary aminium bicarbonate, an amidinium bicarbonate, and a guanidinium bicarbonate; and   a solvent switching device downstream of the forward osmosis device and configured to convert the hydrophilic form of the switchable hydrophilicity material into a hydrophobic form of the switchable hydrophilicity material comprising one or more of a tertiary amine compound, an amidine compound, and a guanidine compound.   
     
     
         17 . The liquid treatment system of  claim 16 , further comprising an additional solvent switching device downstream of the solvent switching device and configured to interact the hydrophobic form of the switchable hydrophilicity material with CO 2  and additional H 2 O to convert the hydrophobic form of the switchable hydrophilicity material into the hydrophilic form of the switchable hydrophilicity material. 
     
     
         18 . The liquid treatment system of  claim 16 , further comprising a reverse osmosis device downstream of the solvent switching device and comprising a reverse osmosis membrane configured to separate H 2 O from the hydrophobic form of the switchable hydrophilicity material. 
     
     
         19 . The liquid treatment system of  claim 16 , further comprising the draw solution. 
     
     
         20 . The liquid treatment system of  claim 16 , wherein:
 the hydrophilic form of the switchable hydrophilicity material comprises cyclohexyldimethylaminium bicarbonate; and   the hydrophobic form of the switchable hydrophilicity material comprises cyclohexyldimethylamine.