If I used chloralkali electrolysis of brine to produce hydrogen, and can't use the other products (or not all of them), what route(s) can I take to revert them back to brine? I figured, since I have to put in energy to take the brine apart, it should have some desire to reform.
With the $H_2$ taken away, the remaining products are:
$2 NaOH_\text{(aq)} + Cl_2$
If I just mix them, I get sodium chlorate or hypochlorite. Can I process those further?
Both $H_2O$ and $NaCl$ have a negative $\Delta H_f^\theta$ (-285.8 and -407.0, respectively), and $Cl_2$ is already in its standard state, so we would need to overcome the $\Delta H_f^\theta$ of the $NaOH$, which is negative as well (-470.1). Can I use ion filters to some benefit?
Routes that allow retrieval of some of the energy spent for the electrolysis are favored (i. e. the more exothermal, the better).