Development of Kraft Lignin Chemically Modified as a Novel Crosslinking Agent for the Synthesis of Active Hydrogels

Abstract

In this research a chemical modification of kraft lignin was carried out using a basic nucleophilic substitution reaction (NSA) in order to functionalize it as a novel crosslinking agent for the synthesis of active hydrogels. The chemical modification success of the synthesized crosslinker was demonstrated by using several techniques such as volumetry probes, FTIR, 1H-NMR and DSC. Thus, the obtained materials were employed during the synthesis of acrylic acid-based hydrogels, due to its high-water absorption capacity to evaluate their retention potential of heavy metal ions. Characterization of the active hydrogels were performed by FTIR and SEM, showing the specific signals corresponding to the base monomers into the polymer skeleton and the efficiency of modified kraft lignin as a novel crosslinking agent. Additionally, to demonstrate the potential use of these hydrogels in wastewater treatment, metal ions adsorption experiments were conducted, showing adsorption percentages higher than 90% and 80% for Pb2+ and Cu2+, respectively.

Study on the Degradation of a Semi-Synthetic Lignin–Acrylic Acid Hydrogel with Common Bacteria Found in Natural Attenuation Processes

“…The lignin modification was carried out according to the procedure proposed by Rico-Garcia et al [ 16 ]. A solution was prepared by adding 2.5 g of lignin with a low sulfonate content to 25 mL of distilled water and stirring at 1000 ppm until dissolution.…”

Evaluation of Acute Toxicity and Antioxidant Response of Earthworm Exposed to a Lignin-Modified Crosslinked Hydrogel

“…Alkali kraft lignin (AKL) modification was performed according to Rico et al [ 31 ]. A solution was prepared with 2.5 g of AKL in 25 mL of distilled water with a stirring speed of 1000 rpm.…”

“…The swelling kinetics were obtained from the swelling percentage (%H) of the synthesized hydrogel as a function of time, which was determined gravimetrically. The typical methodology used by some authors [31] consisted of immersing 0.1 g of xerogel with a grain size ranging from 600 to 1000 µm in 50 mL of distilled water (pH = 5.6) at 25 • C. The hydrogel was weighed at different time intervals; at each interval, excess water on the surface was removed with absorbent paper. This was carried out until no increase in swelling was observed, indicating that physicochemical equilibrium had been reached.…”

Avaliar frações de lignina kraft em biofilmes de acetato de celulose

“…O principal motivo de seu uso como combustível está relacionado ao seu elevado poder calorífico e que, no processo, a lignina é o componente da madeira que necessita ser removido para obtenção de fibras individualizadas e de polpa branqueada comercial (MANDLEKAR et al, 2018;KELLEY;VENDITTI, 2016). Vem sendo usada na produção de outras substâncias como fertilizantes, pesticidas, fibras de carbono, aglutinantes, resinas, nanocompósitos, espumas de carbono, surfactantes, adsorventes, filmes para embalagens e hidrogéis (CULEBRAS et al, 2018;SZABÓ et al, 2021;PETRIE et al, 2021;SOARES et al, 2021;FANG et al, 2021;MONTEIRO et al, 2021, RICO-GARCÍA et al, 2021, assim como, para produtos químicos, como a vanilina, aromáticos hidroxilados, quinina, aldeídos e ácidos graxos (ALMADA et al, 2021;VU et al, 2021;WALCH et al, 2021).…”