Synthesis and Investigation of a Novel pH- and Salt-Responsive Superabsorbent Hydrogel Based on Pectin

In the present paper, attention is paid to synthesis and investigates swelling behavior of a superabsorbent hydrogel based on Pectin (Pec) and polyacrylic acid (PAcA). acrylic acid (AcA) was graft copolymerized onto Pectin backbones by a free radical polymerization technique using ammonium persulfate (APS) as initiator and methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for hydrogel formation was suggested and the structure of the product was established using FTIR and SEM spectroscopies. Under the optimized conditions concluded, maximum capacity of swelling in distilled water was found to be 348 g/g. Absorbency of the synthesized hydrogels was also measured in NaCl and CaCl2 salt solutions. Results indicated that the swelling ratios in compare to water decreased with an increase in the ionic strength of solution. In addition, swelling capacity was conducted in solutions with pH ranged from 1 to 13. The H-Pec-poly(sodium acrylate) hydrogel exhibited a pH-responsiveness character so that a swelling-deswelling pulsatile behavior was recorded at pHs 3 and 9.