Preparation and Properties of Superabsorbent Nanocomposite of Acrylamide/Acrylic Acid/Bentonite for Uses in Agriculture with Different Soil Salinities

Scarcity of water as well as shortage of water reservoirs is a major global issue excruciating by an increase in population. Saving water in irrigation is a vital solution in protecting water reservoirs and takes high priority among other possible solutions. Superabsorbents are cross-linked hydrophilic polymers with the ability to reversibly swell in water as well as absorbing high volume of water, thus superabsorbents have attractive application in agriculture. In this research, the effect of synthesis factors such as acrylamide and acrylic acid monomers, the amount of bentonite and the ratio of cross-linker to initiator on swelling behavior and water absorbency of hydrogel were investigated and their absorbtion and desorbtion in sour solution and soil was determined. Superabsorbents were synthesized by solution polymerization and their chemical structures were characterized by FTIR, SEM, XRD, TGA, and DSC. The results showed that an increase in cross-linker would decrease the equilibrium swelling, and by using the optimum of the initiator, an increase in acrylamide and acrylic acid, the equilibrium swelling would increase. An increase in bentonite would increase equilibrium swelling, but additional bentonite will decrease it. By optimizingmentioned additives, a superabsorbent was prepared with the water absorbency of 1125 g/g. The results of absorbtion and desorbtion of optimized superabsorbent in highly sour solutions and soil have showed that the synthesized superabsorbent is highly practical in sour solutions, thus suitable in highly sour soils.