Eco-friendly superabsorbent hydrogels based on starch, gellan gum, citric acid, and nanoclays for soil humidity control

The increase in agricultural product demand has entangled the modernization of agriculture. Advances in research have improved production systems, machinery, fertilizers, and pesticides, among others, which are usually applied in an unsustainable way. In this context, hydrogels are attractive materials. Generally, they can be defined as three-dimensional structures formed from crosslinked hydrophilic polymers with high water absorption capacity. The crosslinks of polymeric chains maintain their structure, letting them absorb large amounts of water without dissolving. This work presents new eco-friendly superabsorbent hydrogels composed of starch and gellan gum crosslinked with citric acid (CA) and incorporating bentonite (BET) and halloysite (HAL) nanoclays. The addition of nanoclays aimed at developing better soil conditioners, while controlling water management for crop production. Hydrogels with compositions ranging from 100%, 75%, 25%, and 0% of gellan gum to starch, all crosslinked with 10%, 5%, and 2% (w/w) of CA. The samples were characterized by Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The water swelling properties were studied.