Synthesis and characterization of an innovative sodium alginate/flaxseed gum green hydrogel for forward osmosis desalination

Abstract

Recently, fresh water resources have been limited globally. Thus, desalination has been the most recommended solution to overcome this issue. Forward osmosis (FO) is an affordable and developing desalination technique. In this current study, a cutting-edge green hydrogel was prepared from a polymer blend of flaxseed gum (FG) and sodium alginate using epichlorohydrin (ECH) as a crosslinker and polyethylene glycol (PEG) as a semi-interpenetrating network polymer. The impact of PEG incorporation on the hydrogel’s response was investigated, and the influence of different mass contents of FG and ECH on the swelling measurements of the hydrogel was studied to optimize the composition of the hydrogel. The optimum hydrogel was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction and the compressive strength test. Furthermore, the behavior of the present hydrogel was examined as a draw agent in a batch FO unit. The water flux and the reverse solute flux were measured at various values of average hydrogel particle size and feed solution (FS) temperature and concentration. The optimal hydrogel of 0.3 PEG/polymer blend mass ratio, 12% FG, and 0.95 ECH/polymer blend mass ratio exhibits a swelling ratio (%) of 1800 after an hour and an equilibrium swelling ratio (ESR) (%) of 5300. The results of the FO experiments revealed that raising FS temperature and reducing FS concentration and average hydrogel particle size enhance water flux.