Redes poliméricas de macromoléculas naturais como hidrogéis superabsorventes

Abstract

New hydrogels based on natural macromolecules such as gellan gum, chitosan, alginate, gelatin and lysine were synthetized and characterized by spectroscopic, thermal and microscopic analysis. The samples were also investigated in terms of water absorption and fertilizers release. The samples were obtained by crosslinking reactions of gellan gum (GGHA and GGLA) with (i) chitosan ( For the sample GGHA:CH the water retention time was 100% higher and about 60% higher for the hydrogels GGHA:LYS, GGHA:JEF and GGHA:GEL. The samples were charged with commercial fertilizers such as phosphate monopotassium (MKP) and phosphate monopotassium (MKP), and they were tested as controlled fertilizer release materials for agriculture. It was observed for all samples that a complete release of MKP occurred after 8 h of its immersion in water and was estimated in about 400 mg per one gram of polymer. The controlled release of NPK was in about 300 mg per one gram of hydrogel, independent of the hydrogel composition. In conclusion, all the obtained results revealed that the natural macromolecules-based hydrogels are very promising alternatives for humidity control system and controlled fertilizers release in agriculture.

Hydrogels in Brazilian Agriculture

“…Hydrogels, also known as hydroabsorbent polymers or water-retaining gels, are capable of absorbing and retaining large amounts of water and/or biological fluids, due to their chemically or physically crosslinked hydrophilic polymer networks (BRITO et al 2013), which change with hydration as shown in Figure 1, modified from Sabadini (2015). Aouada et al (2009) define such polymers as hydrophilic systems formed by two or more components joined by covalent and/or electrostatic bonds arranged in one or more three-dimensional structured networks surrounded by molecules of a given solvent, generally water.…”

“…Devido a isso, os polímeros hidroabsorventes podem ser utilizados na atividade agrícola como condicionadores de solo, aumentando a capacidade de armazenamento de água e a retenção de nutrientes, reduzindo o número de irrigações, a perda de nutrientes e custos de produção (SAAD et al, 2009). Sabadini (2015). Figura 1 -Hidrogel natural produzido a partir do intercruzamento de goma gelana liofilizada (A) e não liofilizada (B) com aumento de 300x em microscópio eletrônico de varredura.…”

“…Figura 1 -Hidrogel natural produzido a partir do intercruzamento de goma gelana liofilizada (A) e não liofilizada (B) com aumento de 300x em microscópio eletrônico de varredura. Fonte: Sabadini (2015).…”

“…However, hydrogels based on clay minerals, such as montimorilonite, vermiculite and kaolin, in addition to their natural source origins, have also aroused interest because they have advantages in terms of low cost and lowering of environmental contamination risks (BRITO et al, 2013, SABADINI, 2015.…”

“…Although such results have economic interest, hydrogels prepared from natural components may have unsatisfactory mechanical properties as to their capacity for hydro-retention (BORTOLIN et al, 2012;SABADINI, 2015).…”