Facile preparation of cross-linked lignin for efficient adsorption of dyes and heavy metal ions

• Published in: Reactive & functional polymers Vol. 143; p. 104336
• Main Authors: Chen, Fenggui, Shahabadi, Seyed Ismail Seyed, Zhou, Dan, Liu, Wanshuang, Kong, Junhua, Xu, Jianwei, Lu, Xuehong
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2019; Elsevier BV
• Subjects: Adsorbents; Adsorption; Annealing; Copper; Cross-linking; Crosslinking; Dyes; Freeze drying; Functional groups; Heavy metals; Ions; Leaching; Lignin; Low temperature; Metal ions; Morphology; Pollutants; Rhodamine; Water pollution; Water treatment; Lignin; Annealing; Adsorption; Cross-linking; Freeze-drying
• ISSN: 1381-5148; 1873-166X
• DOI: 10.1016/j.reactfunctpolym.2019.104336

In this article, we report a simple and environmentally friendly method to produce cross-linked lignin as efficient adsorbents for organic dyes and heavy metal ions. The cross-linked lignin is simply prepared by freeze-drying of lignin followed by low-temperature annealing. It is found that freeze-drying can provide increased surface areas while abundant functional groups of lignin can be retained at lower annealing temperatures like 300 °C, which give the annealed freeze-dried lignin high adsorption capacities for model pollutants, rhodamine B and Cu2+ ions, which reach 156.4 mg/g and 290 mg/g, respectively. Freeze-drying and low-temperature annealing also leads to much higher product yields than carbonization at high temperatures, greatly improving the quantity of adsorbents produced. Furthermore, the morphology of the freeze-dried lignin facilitates the evaporation of small molecules produced in cross-linking reactions, promoting the formation of cross-linking lignin to avoid secondary pollution caused by leaching of contaminated molecules. Thus, this is a promising approach to sustainable low-cost adsorbents for water treatment.