Two Birds with One Stone: One-Pot Conversion of Waste Biomass into N-Doped Porous Biochar for Efficient Formaldehyde...

Area of Science:

• Materials Science
• Environmental Chemistry
• Chemical Engineering

Background:

• Agricultural solid waste conversion to biochar offers a sustainable approach for waste management.
• Pristine biochar exhibits limited formaldehyde (HCHO) adsorption due to inadequate surface activity and porosity.
• Developing efficient adsorbents is crucial for mitigating HCHO pollution.

Purpose of the Study:

• To synthesize nitrogen-doped porous biochar (NBC) from waste jujube pits and melamine for enhanced HCHO adsorption.
• To investigate the effect of nitrogen doping and porosity on HCHO adsorption performance.
• To elucidate the HCHO adsorption mechanism at a molecular level using DFT calculations.

Main Methods:

• One-step pyrolysis of melamine and waste jujube pit at varying mass ratios (NBC-x, x=4-12).
• Characterization of synthesized biochars for nitrogen content, porosity, and surface area.
• Formaldehyde (HCHO) adsorption experiments.
• Density Functional Theory (DFT) calculations to study adsorption mechanisms.

Main Results:

• Nitrogen doping enhanced HCHO adsorption capacity compared to pristine biochar (BC).
• Optimal nitrogen content and porosity were achieved with the NBC-8 sample (19.81 wt.% N, 223 m²/g SSA).
• NBC-8 exhibited a maximum HCHO uptake of 6.30 mg/g, 6.4 times higher than BC.
• DFT calculations confirmed enhanced HCHO affinity with N-doped carbon models, particularly pyrrolic-N.

Conclusions:

• Nitrogen doping and optimized porosity are key to enhancing biochar's HCHO adsorption capacity.
• The synthesized NBC material presents an efficient, eco-friendly solution for HCHO pollution remediation.
• This study provides a facile route for high-value utilization of waste biomass resources.