Electrolysis Process

Abstract

Electrolysis process in which the anode compartment of an electrolytic cell is fed with at least one brine which has been subjected to a stripping treatment in the presence of at least one stripping agent at a pH less than or equal to the pH of the anode compartment of the electrolytic cell, such brine comprising at least one organic compound before the treatment.

1 . An electrolysis process in which an anode compartment of an electrolytic cell is fed with at least one brine which has been subjected to a stripping treatment in the presence of at least one stripping agent at a pH less than or equal to the pH of the anode compartment of the electrolytic cell, said brine comprising at least one organic compound before the stripping treatment. 
     
     
         2 . An electrolysis process comprising:
 (a) supplying a brine that comprises at least one organic compound;   (b) at least one stripping treatment of the brine from (a) in the presence of at least one stripping agent so as to obtain a stripped brine;   (c) feeding the anode compartment of an electrolytic cell with the stripped brine from (b);   and in which the stripping treatment from (b) is carried out at a pH less than or equal to the pH of the anode compartment of the electrolytic cell from (c).   
     
     
         3 . The electrolysis process according to  claim 1 , in wherein the brine, before the stripping treatment, contains at least sodium chloride at a content greater than or equal to 140 g of NaCl per kg of brine. 
     
     
         4 . The electrolysis process according to  claim 1 , wherein the organic compound is a monocarboxylic acid, the number of carbon atoms of which is greater than or equal to 4 and less than or equal to 20. 
     
     
         5 . The electrolysis process according to  claim 4 , wherein the monocarboxylic acid is a fatty acid. 
     
     
         6 . The electrolysis process according to  claim 4 , wherein the organic compound is a monocarboxylic acid with a number of carbon atoms being greater than 6 and less than or equal to 20. 
     
     
         7 . The electrolysis process according to  claim 4 , wherein the monocarboxylic acid is selected from the group consisting of butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and mixtures of at least two thereof. 
     
     
         8 . The electrolysis process according to  claim 1 , wherein the content of organic compound in the brine before the stripping treatment expressed in g of carbon per kg of brine is greater than or equal to 0.005 g/kg and less than or equal to 20 g/kg. 
     
     
         9 . The electrolysis process according to  claim 8 , wherein the content of organic compound in the brine before the stripping treatment expressed in g of carbon per kg of brine is greater than or equal to 0.75 g/kg 
     
     
         10 . The electrolysis process according to  claim 1 , wherein the pH of the stripping treatment is below the pH of the anode compartment of the electrolytic cell by at least 0.1 pH unit. 
     
     
         11 . The electrolysis process according to  claim 1 , wherein the stripping agent is selected from the group consisting of air, oxygen-depleted air, nitrogen, oxygen, chlorine, hydrogen chloride, steam, carbon dioxide and mixtures of at least two thereof. 
     
     
         12 . The electrolysis process according to  claim 11 , wherein the stripping agent is steam, wherein the stripping treatment is carried out in continuous mode in a stripping zone fed with said brine and with said stripping agent circulating vertically and countercurrently, and wherein the ratio (τ) between the flow rate of ascending steam (V) expressed in kg of steam per hour and that of the descending brine (W) expressed in kg of brine per hour, corresponds to the following formula:
   τ=α.[1/( K   W −1)].{1+( X   W   /X   F )[ K   W ( q− 1)−1]}
 
 where: 
 α is greater than or equal to 0.9 and less than or equal to 5; 
 K W =(P org /P) (1/S org ) td  (M org /V brine ); 
 q=1+[C PIf *t f −C PIF*t   F )]/(ΔH vap )t f ; 
 P org  is the vapor pressure of the organic compound contained in the brine; 
 P is the total pressure of the stripping zone; 
 S org  is the solubility of the organic compound in brine expressed in g of carbon/l of brine; 
 M org  is the molar mass of the organic compound in g of carbon/mol of organic compound; 
 V brine  is the molar volume of the brine in 1/mol; 
 X W  is the organic compound content of the brine at the bottom of the stripping zone expressed in g of carbon/kg of brine; 
 X F  is the organic compound content of the brine entering at the top of the stripping zone expressed in g of carbon/kg of brine; 
 C PIf  is the specific heat of the brine entering at the top of the stripping zone at the brine inlet temperature t f , expressed in kJ/(kg brine.K); 
 C PIF  is the specific heat of the brine exiting at the bottom of the stripping zone at the brine outlet temperature t F , expressed in kJ/(kg brine.K); and 
 (ΔH vap )t f  is the latent heat of vaporization of the water at the brine inlet temperature t f , expressed in kJ/kg of vapor. 
 
     
     
         13 . The electrolysis process according to  claim 1 , comprising at least one operation other than the stripping treatment selected from the group consisting of dilution, concentration, distillation, evaporation, liquid-liquid extraction, filtration, crystallization, adsorption, oxidation, reduction, neutralization, complexation, precipitation, aerobic bacterial treatment, anaerobic bacterial treatment, salt addition, and combinations of at least two thereof. 
     
     
         14 . The electrolysis process according to  claim 1 , wherein the electrolytic cell is a cell selected from the group consisting of mercury cell; a diaphragm cell; and a membrane cell of a chlor-alkali electrolysis, and wherein the brine originates from a process selected from the group consisting of manufacture of epichlorohydrin, manufacture of an epichlorohydrin derivative, manufacture of 1,2-dichloroethane, manufacture of polycarbonates, and combinations of at least two thereof. 
     
     
         15 . The electrolysis process according to  claim 14 , wherein the electrolytic cell is a membrane cell of a chlor-alkali electrolysis, and wherein the brine originates from a process for the manufacture of epichlorohydrin. 
     
     
         16 . The electrolysis process according to  claim 15 , wherein the brine originates from a process for manufacturing epichlorohydrin by dehydrochlorination of dichloropropanol in which at least one portion of said dichloropropanol is obtained from glycerol, at least one fraction of said glycerol being obtained from renewable raw materials. 
     
     
         17 . The process according to  claim 2 , wherein the brine, before the stripping treatment, contains at least sodium chloride at a content greater than or equal to 140 g of NaCl per kg of brine, and wherein the organic compound is a monocarboxylic acid selected from the group consisting of butyric acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and mixtures of at least two thereof. 
     
     
         18 . The process according to  claim 2 , wherein the content of organic compound in the brine before the stripping treatment expressed in g of carbon per kg of brine is greater than or equal to 0.005 g/kg and less than or equal to 20 g/kg. 
     
     
         19 . The process according to  claim 2 , wherein the pH of the stripping treatment is below the pH of the anode compartment of the electrolytic cell by at least 0.1 pH unit. 
     
     
         20 . The process according to  claim 2 , wherein the electrolytic cell is a membrane cell of a chlor-alkali electrolysis, and wherein the brine originates from a process for the manufacture of epichlorohydrin by dehydrochlorination of dichloropropanol in which at least one portion of said dichloropropanol is obtained from glycerol, at least one fraction of said glycerol being obtained from renewable raw materials.