Reverse osmosis and electrodialysis are truly the only water desalination processes currently in practice for the entire range of total dissolved solids (TDS) from 400–40,000 mg/L. For high recovery of 80% or more, membrane processes are energy intensive even for a feedwater with a TDS of 1000 mg/L and demand significant pretreatment to avoid precipitation and consequent membrane fouling. In this study, we present for the first time a hybrid ion exchange desalination (HAIX-Desal) process that does not require any semipermeable membrane and can desalinate lean brackish water (TDS ≤ 1500 mg/L) using CO2 as the sole source of energy and chemical regenerant. A hybrid anion exchanger with dispersed ZrO2 nanoparticles (HAIX-NanoZr) and a shell–core weak-acid cation exchange (SC-WAC) resin form the heart of the process. Carbon dioxide or CO2 at 10 atm pressure is the only chemical needed to sustain the process. In contrast to a conventional deionization plant, the anion exchanger, i.e., HAIX-NanoZr, precedes the...