Plasma functionalized hydroxyapatite incorporated in membranes for improved performance of osmotic processes

Abstract

Osmotic processes are base processes for water desalination by reverse osmosis and power generation by forward osmosis. The development of advanced membrane materials may be considered the main step to improve these processes. In this work, hydroxyapatite (Hap) particles were functionalized by plasma treatment and incorporated into cellulose acetate membranes synthesized by phase inversion method. Morphology and physical-chemical properties of the functionalized Hap and the synthesized membranes were characterized. Plasma functionalization was able to increase Hap hydrophilicity by insertion of hydroxyl groups on particle surfaces. The water permeability of nanocomposite membranes increased from 0.39 to 0.51 L·h−1m−2bar−1 with 1.0% (wt) Hapf in the reverse osmosis desalination system, maintaining high rejection of NaCl and MgSO4. In forward osmosis tests, the same membranes provided an increase from 4.5 to 7.5 L·h−1 m−2, representing a growth of 66%, maintaining reverse salt flux (Js) practically constant. This research revealed high-performance membranes with potential application in osmotic processes.