Desalination by In-Situ Crystallization
Sandia has developed low cost inorganic ion exchange materials that can desalt brackish water using an in-situ precipitation approach. This technology uses inexpensive raw materials to form anion and cation materials for in-situ deionization of oil-field produced waters.
For anion exchange, we have focused on hydrotalcite (HTC), a low-cost layered hydroxide similar to clay in structure. For cation removal, we have developed an amorphous silica material (permutite) that has enhanced cation (in particular Na+) selectivity. In the case of produced waters with high concentrations of Ca2+, a lime softening step is included.
Sandia is testing the use of capacitive deionization technology from Biosource Inc
. The patented charge barrier electrode technology has been used to deionize produced water from a coal-bed methane well.