Reaction schemes involving acids and bases; reactors comprising spatially varying chemical composition gradients; and associated systems and methods

Abstract

Reaction schemes involving acids and bases; reactors comprising spatially varying chemical composition gradients (e.g., spatially varying pH gradients), and associated systems and methods, are generally described.

1 . A method, comprising:
 establishing and/or maintaining a region comprising a spatially varying chemical composition gradient;   transporting a chemical compound to a first region of the spatially varying chemical composition gradient such that the chemical compound is dissolved and/or reacted in a liquid within the spatially varying chemical composition gradient; and   collecting a precipitate from a second region of the spatially varying chemical composition gradient, wherein the precipitate comprises one or more elements from the chemical compound dissolved and/or reacted within the spatially varying chemical composition gradient.   
     
     
         2 . A method of making cement, comprising:
 establishing and/or maintaining a region comprising a spatially varying pH gradient;   transporting calcium carbonate to an acidic region of the spatially varying pH gradient such that the calcium carbonate is dissolved and/or reacted in a liquid within the spatially varying pH gradient;   collecting solid calcium hydroxide from an alkaline region of the spatially varying pH gradient, wherein the solid calcium hydroxide comprises calcium from the calcium carbonate dissolved and/or reacted within the spatially varying pH gradient; and   heating the solid calcium hydroxide and/or solid calcium oxide derived from at least a portion of the solid calcium hydroxide within a kiln to make cement.   
     
     
         3 . The method of  claim 1 , wherein the spatially varying chemical composition gradient comprises a spatially varying pH gradient. 
     
     
         4 . The method of  claim 1 , wherein the first region comprises an acidic region. 
     
     
         5 . The method of  claim 1 , wherein the second region comprises an alkaline region. 
     
     
         6 . The method of  claim 1 , wherein the chemical compound comprises a metal salt. 
     
     
         7 . The method of  claim 1 , wherein the one or more elements comprises a metal element. 
     
     
         8 . The method of  claim 1 , wherein the chemical compound is dissolved and reacted within the liquid within the spatially varying pH gradient. 
     
     
         9 . The method of  claim 2 , wherein the calcium carbonate is dissolved and reacted within the liquid within the spatially varying pH gradient. 
     
     
         10 . The method of  claim 1 , wherein the chemical compound comprises metal carbonate. 
     
     
         11 . The method of  claim 10 , wherein the metal carbonate comprises calcium carbonate, magnesium carbonate, and/or nickel carbonate. 
     
     
         12 . The method of  claim 1 , wherein the precipitate comprises a metal hydroxide. 
     
     
         13 . The method of  claim 1 , wherein the method is part of a batch process. 
     
     
         14 . The method of  claim 1 , wherein the method is performed continuously. 
     
     
         15 . The method of  claim 1 , wherein the method produces a byproduct different from the precipitate, and the method further comprises collecting the byproduct. 
     
     
         16 . The method of  claim 2 , wherein the method produces a byproduct different from the solid calcium hydroxide and/or the solid calcium oxide, and the method further comprises collecting the byproduct. 
     
     
         17 . The method of  claim 15 , wherein the byproduct comprises CO 2 , O 2 , and/or H 2 . 
     
     
         18 . The method of  claim 15 , wherein the byproduct comprises CO 2  and the collecting the byproduct comprises sequestering the CO 2 . 
     
     
         19 . The method of  claim 15 , wherein the byproduct is used as fuel. 
     
     
         20 - 60 . (canceled) 
     
     
         61 . A system for producing cement, comprising:
 a reactor comprising a region comprising a spatially varying chemical composition gradient, the reactor comprising a reactor outlet configured to output solid calcium hydroxide; and   a kiln comprising a kiln inlet, wherein:
 the kiln is downstream from the reactor outlet, 
 the kiln inlet is configured to receive at least a portion of the solid calcium hydroxide and/or solid calcium oxide derived from at least a portion of the solid calcium hydroxide; and 
 the kiln is configured to produce cement using the solid calcium hydroxide and/or solid calcium oxide.