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

Abstract

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.

Acetone fractionation: a simple and efficient method to improve the performance of lignin for dye pollutant removal

“…Compared with the other modied natural materials such as banana pseudostem, Platanus orientalis leaf and Luffa cylindrica bers, [37][38][39] the advantage of AIKL is that the aromatic ring of lignin could have p-p interaction with MB which is benecial to the adsorption. As for lignin-based hydrogels prepared by crosslinking poly used methyl vinyl ether co-maleic acid, 35 the preparation of AIKL only requires one step of dissolution, the entire process is simple to operate and can be easily scalable.…”

Potential of Polymeric Films Loaded with Gold Nanorods for Local Hyperthermia Applications

“…Furthermore, films were immersed in NaOH 5M, dried, and the IR spectrum was once again recorded ( Figure 9B). The same aforementioned peak displacement from 1699 to 1713 cm −1 could be seen, but peaks at 1849 and 1773 cm −1 disappeared and were replaced by one at 1563 cm −1 , confirming the formation of anhydride groups when films were crosslinked, which then turned into sodium salts [40,41]. Approaches where the potential of GnRs can be used without exposing the body directly to them should be followed while strong evidence regarding their safety and toxicity is acquired.…”

Lignin-Based Hydrogels: Synthesis and Applications

“…This strategy is based on the esterification reaction of hydroxyl groups of lignin with the carboxylic acids of maleic acid units. Domínguez-Robles et al [60] analyzed the properties of the hydrogels prepared with different types of lignins (organosolv lignin, straw soda lignin and kraft lignin) for removing cationic dyes from waste water.…”