Hydrogels prepared from pineapple peel cellulose using ionic liquid and their characterization and primary sodium salicylate release study

Hydrogels and polyvinyl pyrrolidone (PVPP) composite hydrogels were prepared from pineapple peel cellulose with 1-allyl-3-methylimidazolium chloride via different heating and cooling processes. The prepared hydrogels were characterized via the methods of texture profile analysis, Fourier infrared transform, X-ray diffraction, thermogravimetry analysis, differential scanning calorimetry and field emission scanning electron microscope. Swelling kinetics of the prepared hydrogels and their release kinetics were also compared in vitro with sodium salicylate (NaSA) as model drug. The results showed the hydrogels and PVPP-doped composite hydrogels exhibited differences in characterizations and NaSA release. PVPP increased the mechanical properties and thermal stability of the composite hydrogels. The freeze-dried hydrogels exhibited higher equilibrium swelling ratio and NaSA load ratio than the oven-dried hydrogels. PVPP addition decreased the equilibrium swelling ratio and NaSA load ratio of the freeze-dried hydrogels but increased those of the oven-dried hydrogels. Oven-drying processing and PVPP were propitious for slowing NaSA release.