Carbon dioxide sequestration through novel use of ion exchange fibers (IX-fibers)

Abstract

Electrical power generation and metal removal processes are practiced globally and share two common attributes that make them ideal candidates to be incorporated in a novel carbon dioxide sequestration scheme using ion exchange fibers (IX-fibers). First, the softening of boiler feed water used in power generation and the removal of metals from finishing wastewaters often employs the use of ion exchange for the purpose of selective separation. Second, both processes represent significant point source CO 2 emissions. This investigation demonstrated that using IX-fibers it is possible to sequester a portion of the CO 2 produced in these practices as carbonate alkalinity during the regeneration step of both the water softening and the trace heavy metal removal processes. Weak acid IX-fibers were used for hardness removal while hybrid cation exchange fibers (HCIX-F) loaded with hydrated Zr(IV) oxide (HZO) were used to remove toxic heavy metals such as zinc, cadmium and copper. IX-fibers offer the unique capability to use and consume CO 2 during the efficient regeneration of IX-fibers, whereas commercial ion exchange resins are not amenable to regeneration with CO 2. A much shorter intraparticle diffusion path length in cylindrical IX-fibers as compared to resin beads is the underlying reason for a highly efficient regeneration of the fibers. In addition to sequestering carbon dioxide, no hazardous or aggressive chemicals/brine solutions are present in the regenerant wastes as compared with traditional ion exchange processes.