Enhancement of water absorption properties of potassium polyacrylate-based hydrogels in CaCl ₂ -rich soils using potassium di- and tri-carboxylate salts

Abstract A series of potassium polyacrylate hydrogels (KPAHs) hyperabsorbents of water 0.08, 0.21, and 0.46 wt% of triethylene glycol dimethacrylate (TEGDMA) crosslinker were prepared by a free radical polymerization route of potassium acrylate in the presence of TEGDMA in deionized water. The prepared KPAHs were characterized by Fourier-transform infra-red spectroscopy, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. The aim of this study is to improve the water absorbability of KPAH in heavily loaded soils containing 3–9 g L ‒1 CaCl 2 . To achieve this goal, potassium di- and tri-carboxylate salts were in situ separatly incorporated at different contents in the KPAHs in order to recover the swellability of these hydrogels lost due to the excessive presence of CaCl 2 in the soil. Among the most significant results obtained it was revealed that the best absorbability in water containing CaCl 2 is obtained by the KPAH hydrogel containing 0.08 wt% of TEGDMA. When the dipotassium oxalate is added to the KPAH (1:4.5 by weight) this hydrogel resists the shrinkage in 3 g L −1 CaCl 2 saline water. It was also found that the hydrogel system containing 0.21 wt% crosslinker and KO (1:13.5 by weight) showed the best performance in the swellability in the higher saline water (9 g L −1 CaCl 2 ).