title: Evaluation of different methods to prepare superabsorbent hydrogels based on deacetylated gellan.
abstract: This study stands out for analyzing distinct ways of preparing hydrogels from deacetylated gellan gum that have high swelling capacity and good thermal resistance. We carried out a thorough investigation, applying various combinations of different experimental parameters. Two preparation methods were evaluated, in which the pH was adjusted before or after thermal treatment of the gellan solution, with subsequent addition of the crosslinking agent, to assess the influence of preparation method on the conformation of the gellan chains regarding formation of double helices. The pH range tested varied from acid (2, 3 or 4) to basic (8, 9 or 10). Gellan solution was prepared in different concentrations. Both pure gellan and hydrogel samples were characterized by Fourier-transform infrared spectroscopy and thermogravimetry. Pure gellan was also characterized by atomic absorption spectroscopy. The swelling degree of the hydrogels was analyzed. The results showed that all the hydrogels had high swelling capacity (>400%), so they can be considered superabsorbent materials. Hydrogels prepared with acid pH in general had lower thermal resistance than samples prepared in alkaline pH, regardless of the preparation method. Samples prepared with alkaline pH tended to have initial decomposition temperature similar to that of pure gellan.
authors.affiliation: Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, PHLC, sala 310, Maracanã, Rio de Janeiro, RJ 20550-900, Brazil. Electronic address: souzafs@gmail.com.
authors.forename: Flavio Silva
authors.initials: FS
authors.lastname: de Souza
authors.affiliation: Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, PHLC, sala 310, Maracanã, Rio de Janeiro, RJ 20550-900, Brazil. Electronic address: ivanamello@uerj.br.
authors.forename: Ivana Lourenço
authors.initials: IL
authors.lastname: de Mello Ferreira
authors.affiliation: Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, PHLC, sala 310, Maracanã, Rio de Janeiro, RJ 20550-900, Brazil. Electronic address: marcos.costa@uerj.br.
authors.forename: Marcos Antonio
authors.initials: MA
authors.lastname: da Silva Costa
authors.affiliation: Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, PHLC, sala 310, Maracanã, Rio de Janeiro, RJ 20550-900, Brazil. Electronic address: analuiza789@yahoo.com.br.
authors.forename: Ana Luiza Ferreira
authors.initials: AL
authors.lastname: de Lima
authors.affiliation: Instituto de Química, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, PHLC, sala 310, Maracanã, Rio de Janeiro, RJ 20550-900, Brazil. Electronic address: mpmcosta@outlook.com.
authors.forename: Marcia Parente Melo
authors.initials: MP
authors.lastname: da Costa
authors.affiliation: Teadit do Brasil, Av. Pastor Martin Luther King Junior, 8939, Colégio, Rio de Janeiro, RJ 21530-012, Brazil. Electronic address: gustavo.monteiro@teadit.com.br.
authors.forename: Gustavo Monteiro
authors.initials: GM
authors.lastname: da Silva
keywords: Deacetylated gellan; Superabsorbent; Swelling degree; Temperature; Thermal resistance; pH