Highly selective and efficient lignin-magnesium for removing cationic dyes from wastewater

• Published in: Journal of environmental chemical engineering 2020-10, Vol.8 (5), p.104283, Article 104283
• Main Authors: Dai, Kun, Peng, Xiaoqiang, Yang, Pengpeng, Li, Ming, Tang, Chenglun, Zhuang, Wei, Ying, Hanjie, Wu, Jinglan
• Format: Article
• Language: English
• Subjects: Adsorption; Lignin-magnesium; Methylene blue; Regeneration
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2020.104283

[Display omitted] •Lignin-magnesium (LM) was first facilely prepared by one-step flocculation.•LM possessed high selectivity of cationic dyes compared to anionic ones.•LM exhibited excellent adsorption performance toward MB with Qmax (536.6 mg/g).•The removal of MB by LM remained at a high level (﹥98 %) within pH range from 3 to 11. Lignin-magnesium was manufactured facilely by one-step method to eliminate cationic dyes. Various characterization methods were used for obtained adsorbent, such as FT-IR, XRD, SEM, TEM and XPS. Results indicated lignin-magnesium showed a more coarse surface with many protuberances compared to that of sodium lignin. Methylene blue adsorption by lignin-magnesium conformed to Langmuir isotherm with a maximum adsorption amount of 536.6 mg/g. The homogeneous surface diffusion model (HSDM) was used to predict the kinetic adsorption process. The surface diffusion coefficient was obtained as 2.0 × 10−11 cm2/min, which indicated the intraparticle resistance was the rate-limiting step. Surprisingly, the adsorbent displayed outstanding performance toward methylene blue within pH range of 3−11 with a good regeneration. Removal of MB by lignin-magnesium still achieved 98 % even after 6 cycles. Furthermore, lignin-magnesium possessed a high selectivity for cationic dyes. The adsorption process may be elucidated by electrostatic attraction, hydrogen bonding as well as n-π/π-π interaction between lignin-magnesium and methylene blue. On the whole, lignin-magnesium shows great potential in selectively and effectively clearing cationic dyes from sewage.