Salt extraction regeneration technologies

A salinity gradient power heat engine is a novel sustainable technology for the conversion of low-grade waste heat (T This chapter presents an overview of the main regeneration technologies based on the “salt extraction strategy” reported in the literature. A salt extraction regeneration unit takes advantage of the property of specific chemical compounds to shift from a soluble form to separable species in solution allowing the salt transfer between the exhausted solutions and aiding their regeneration. The regeneration processes reported here are classified into (i) switchable solubility salts and (ii) thermolytic salts. The first class includes compounds characterized by thermal-sensible solubility or by phase separation processes, while thermolytic salts are species that can be converted from their soluble form into gaseous species in specific conditions. Among the proposed processes, the use of thermolytic salts is the most studied and technologically advanced, thanks to the progress gained in the field of desalination by forward osmosis with thermally regenerable drawing agents.