Lignin-based hydrogels with “super-swelling” capacities for dye removal

• Published in: International journal of biological macromolecules Vol. 115; pp. 1249 - 1259
• Main Authors: Domínguez-Robles, Juan, Peresin, María Soledad, Tamminen, Tarja, Rodríguez, Alejandro, Larrañeta, Eneko, Jääskeläinen, Anna-Stiina
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2018
• Subjects: Dye removal; Lignin hydrogels; Water absorption; Lignin hydrogels; Water absorption; Dye removal
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2018.04.044

Lignin is a complex natural polymer and it is one of the main constituent of the lignocellulosic biomass. Moreover, it is a bio-renewable material and it is available in large amounts as by-product from the forest industry. Lignin-based hydrogels with high swelling capabilities were prepared by crosslinking poly (methyl vinyl ether co-maleic acid) and different technical lignins in ammonium and sodium hydroxide solutions. The produced hydrogels showed a wide range of water absorption capacities varying from 13 to 130 g of water per 1 g of sample. It was observed that the higher the water uptake the poorer mechanical performance, as evaluated in terms of storage and loss modulus (G′ and G″, respectively) of the materials. Methylene blue (MB) was used as a model dye to evaluate the adsorption and release capabilities of the lignin hydrogels. Results suggested that these hydrogels showed a high MB removal efficiency, which ranged from 12 to 96%. On the contrary, the percentages of MB released depended on the negative surface charge of the hydrogels, showing values which ranged from 0.06 to 0.35%. Thus, these materials have potential to be used as adsorbents for the removal of organic dyes from waste water. [Display omitted] •Technical lignins from three different processes were used to produce the hydrogels.•Hydrogels were synthetized by crosslinking lignin with PMVE/MA.•Lignins and hydrogels were deeply characterised.•Structural features of lignin samples affected the performance of hydrogels.•Lignin based hydrogels were used to successfully remove an organic dye.