Evaluation of nitrate controlled release systems based on (acrylamide-co-itaconic acid) hydrogels

In order to mitigate the nitrate water pollution and nitrogenous gases emissions to the atmosphere, different types of highly swelling hydrogels based on acrylamide and itaconic acid have been prepared by using two different crosslinking agents: NMBA and EGDMA. Controlled release systems were evaluated by loading potassium nitrate into the hydrogels. The swelling and nitrate release kinetics were evaluated in Milli-Q water and saline medium, and various diffusion parameters were also calculated by applying the Ritger-Peppas equations, one of which modified by the authors for the diffusion process due to the innovative and non-described conical shape of the hydrogels used in this study. The hydrogels showed swelling and release characteristics highly dependent on their chemical composition and ionic strength of the medium, having the type of crosslinker the major impact on their behaviour, which can be related to the hydrophilic/hydrophobic characteristics of the crosslinkers. So, these hydrogels showed good potential applications for being used as soil conditioners and controlled release systems in agriculture.