Method for converting osmotic energy into hydraulic energy and for desalination
The method p1 for converting osmotic energy into hydraulic energy and the method p2 for desalination, include pressurisation/depressurisation and isochoric washing of an aqueous solution containing a salt in the presence of a selective hydrophobic nanoporous material of which the nanoporous volume within the material is only accessible to fresh water and which has a nanoporosity volume fraction ranging from 0.2 to 1 so as to convert osmotic energy into hydraulic energy or conversely to desalinate water, preferably sea water or brine.
1 . A process for converting osmotic energy into hydraulic energy, comprising:
1a) contacting (i) a first aqueous solution comprising a salt, and (ii) a selective hydrophobic nanoporous material having a nanopore volume within the material accessible only to fresh water and having a volume fraction of nanoporosity in a range from 0.2 to 1, to obtain a mixture,
1b) pressurizing the mixture to a pressure in a range from 10 to 1000 bar, wherein water intrudes into the nanoporous material, to obtain a pressurized mixture,
1c) carrying out a first isochoric washing of the pressurized mixture using a second aqueous solution comprising a salt, to obtain a washed mixture, and
1d) depressurizing the washed mixture, wherein water is expulsed from the nanoporous material, diluting the second aqueous solution, and collecting hydraulic energy,
wherein the first aqueous solution has a first salt concentration and the second aqueous solution has a second salt concentration greater than the first salt concentration, by a difference in a range from 0.5 to 25 mol/L.
2 . The process as claimed in claim 1 , wherein the second salt concentration is less than or equal to 25 mol/L.
3 . The process as claimed in claim 1 , wherein the first salt concentration is in a range from 0 to 2 mol/L.
4 . The process as claimed in claim 1 , wherein the nanoporous material is selected from the group consisting of metal organic framework (MOFs), zeolites, imogolites, mesoporous silicas, mesoporous organosilicon compounds and aerogels.
5 . The process as claimed in claim 1 , wherein the nanoporous material has pores having a mean diameter in a range from 0.5 to 5 nm.
6 . The process as claimed in claim 1 , wherein the nanoporous material has constrictions having a mean diameter in a range from 0.2 to 1 nm.
7 . The process as claimed in claim 1 , wherein the nanoporous material has a first volume and the reaction medium has a second volume wherein the first volume relative to the second volume represents a ratio (v/v) in a range from 0.2 to 1.
8 . The process as claimed in claim 1 , further comprising 1e) carrying out a second isochoric washing of the mixture obtained at the end of the depressurizing, diluting, and collecting 1d) using the first aqueous solution.
9 . The process as claimed in claim 1 , further comprising converting the hydraulic energy collected in the collecting 1d) into mechanical or electrical energy.
10 . The process as claimed in claim 8 , wherein the pressurizing 1b), the first isochoric washing 1c), the depressurizing, diluting, and collecting 1d), and the second isochoric washing 1e) are repeated a number n of iterations, n being an integer greater than or equal to 2.
11 . The process as claimed in claim 1 , wherein the process is performed at a temperature in a range from 5 to 150° C.
12 . A process for desalinating a solution comprising a salt, comprising:
2a) contacting (i) a first aqueous solution comprising a salt, and (ii) a selective hydrophobic nanoporous material having a nanopore volume within the material accessible only to fresh water and having a volume fraction of nanoporosity in a range from 0.2 to 1, to obtain a mixture,
2b) pressurizing the mixture to a pressure in a range from 10 to 1200 bar, wherein water intrudes into the nanoporous material, to obtain a pressurized mixture,
2c) carrying out a first isochoric washing of the pressurized mixture using a third second aqueous solution, the second aqueous solution being pure water or fresh water, to obtain a washed mixture, and
2d) depressurizing the washed mixture, wherein water is expulsed from the nanoporous material, diluting the second aqueous solution, and collecting salt-depleted water.
13 . The process as claimed in claim 12 , further comprising 2e) carrying out a second isochoric washing of the washed mixture obtained at the end of the depressurizing, diluting, and collecting 2d), the second isochoric washing being carried out using the first aqueous solution.
14 . The process as claimed in claim 13 , wherein the pressurizing 2b), the first isochoric washing 2c), the depressurizing, diluting and collecting 2d) and the second isochoric washing 2e) are repeated a number m of iterations, m being an integer greater than or equal to 2.
15 . The process as claimed in claim 12 , wherein, in the contacting 2a), the volume fraction of nanoporosity of the selective hydrophobic nanoporous material is in a range from 0.3 to 0.6.
16 . The process as claimed in claim 12 , wherein, in the pressurizing 2b), the mixture is pressurized to a pressure in a range from 200 to 800 bar.
17 . The process as claimed in claim 1 , wherein, in the contacting 1a), the volume fraction of nanoporosity of the selective hydrophobic nanoporous material in a range from 0.3 to 0.6.
18 . The process as claimed in claim 1 , wherein, in the pressurizing 1b), the mixture is pressurized to a pressure in a range from 10 to 500 bar.
19 . The process as claimed in claim 1 , wherein, in the first isochoric washing 1c), the second aqueous solution comprises the salt selected from alkali metal or alkaline earth metal salts or a combination thereof.
20 . The process as claimed in claim 1 , wherein the nanoporous material is selected from the group consisting of zeolitic imidazolate framework 8 (ZIF-8), Cu2(3,3′,5,5′-tetraethyl-4,4′-bipyrazolate (Cu2 (tebpz)), silicalite, chabazite and silicic zeolite with aluminophosphate-five (SSZ-24).