One-step synthesis of novel nitrogen-doped biochar from N-rich waste straw particleboard for efficient Pb(Ⅱ) adsorption

• Published in: Microchemical journal 2024-12, Vol.207, p.112206, Article 112206
• Main Authors: Li, Chengyu, Wang, Qihang, Lai, Zongyuan, Mu, Jun
• Format: Article
• Language: English
• Subjects: Adsorption mechanism; Biochar; N-doping; Pb(Ⅱ) removal; Waste straw particleboard
• ISSN: 0026-265X
• DOI: 10.1016/j.microc.2024.112206

[Display omitted] •The NBC for Pb(Ⅱ) removal was prepared by pyrolysis of N-rich WSP.•The presence of MDI resulted in N loading and improved pore structure.•7NBC-5 exhibited superior removal capacity towards Pb(Ⅱ) (205.76 mg/g).•7NBC-5 regenerated by NaOH exhibited good recycling ability after four cycles.•7NBC-5 showed high uptake supported by oxygen groups, pyridinic N and graphitic N. Converting agricultural waste into biochar through pyrolysis toward water pollution remediation fully embodies the “waste control by waste”. Herein, the N-rich waste straw particleboard was converted into N-doped biochar (NBC) as Pb(Ⅱ) adsorbent by one-step pyrolysis. Results showed that the presence of 4,4-diphenylmethane diisocyanate (MDI) successfully introduced N heteroatoms (pyridinic N, pyrrolic N, and graphitic N) and promoted the formation of pore structure. The obtained 7NBC-5 exhibited promising adsorption performance for Pb(Ⅱ) with maximum adsorption capacity of 204.66 mg/g, and high tolerance to various co-existing ions. Moreover, the adsorption efficiency of Pb(Ⅱ) by 7NBC-5 remained consistent at approximately 81.5 % after four successive adsorption–desorption cycles, showing good reuse performance. The adsorption of Pb(Ⅱ) on 7NBC-5 was well described by Langmuir isotherm model and pseudo-second-order kinetic model, implying that the Pb(Ⅱ) was adsorbed onto 7NBC-5 by monolayer, and chemisorption was the main rate-limiting step. The mechanism of Pb(Ⅱ) adsorbed on 7NBC-5 involved electrostatic attraction, surface complexation, pore filling, cation-π interactions, and ion exchange. N doping significantly enhances the complexation and cation-π interaction between 7NBC-5 and Pb(Ⅱ). This study proposes a method to simultaneously address the issues of waste resource utilization and heavy metal pollution in a non-harmful manner.