Environmentally Friendly Chitosan-g-poly(acrylic acid-co-acrylamide)/Ground Basalt Superabsorbent Composite for Agricultural Applications

This paper investigates on the preparation of a novel eco-friendly composite hydrogel, chitosan-g-poly(acrylic acid-co-acrylamide)/ground basalt and its potential application as a soil ameliorant. Synthesis was undergone using microwave irradiation. N,N′-methylene bisacrylamide MBA was used as a cross-linker, whereas potassium peroxydisulfate KPS and N,N,N′,N′-tetramethylene diamine TEMED were used as radical initiator and reaction accelerator, respectively. The incorporation of ground basaltic rocks into the hydrogel was very beneficial: (i) It lowers the cost of the final hydrogel, (ii) It enhances the mechanical strength of the hydrogel, (iii) It boosts the maximum water absorbency of the composite, 650 g/g versus 450 g/g for the hydrogel without basalt and (iv) It promotes the thermal stability of the composite in comparison with the hydrogel alone. The prepared composite hydrogel was characterized by FTIR, X-ray diffractometer and scanning electron microscope SEM. The effects of pH and ionic strength on water absorbency were also investigated. The role of the prepared composite as a soil conditioner is performed using eggplant (Solanum melongena) as a model.