Porous carbon has been intensively used for microwave absorption in merits of its outstanding specific surface area and dielectric properties. This study investigates the microwave absorption capacity of saturated wood-based activated carbon (SWAC) which was used for methylene blue treatment. The results demonstrate that SWAC, subjected to high temperature calcination, exhibits excellent microwave absorption properties. The structure, composition, micro-morphology, and electromagnetic parameters of SWAC were comprehensively analyzed using various techniques. The findings reveal that after calcination, SWAC possesses a rich pore structure, optimized material impedance matching, and the introduction of N atoms from the organic substance methylene blue into the carbon lattice of SWAC, thereby providing dipole polarization loss. These properties significantly contribute to its microwave absorption performance. The optimal reflection loss of SWAC at 6 GHz reaches −50.29 dB with an effective absorption bandwidth of 2.01 GHz, achieved at a calcination temperature of 700 °C and a paraffin matrix additive amount of 25%. The one-step treatment of SWAC proves to be a competitive and cost-effective method for producing microwave absorbers, which holds significant importance for the recovery of SWAC.

One-step preparation of N-doped porous carbon materials with excellent microwave absorption properties based on methylene blue saturated wood-based activated carbon
    Abstract
    1 Introduction
    2 Experimental
        2.1 Materials
        2.2 Synthesis of SWAC​
        2.3 Characterization
    3 Results and discussion
        3.1 Microstructure and composition
        3.2 Electromagnetic absorption performance analysis
    4 Conclusion
    Acknowledgements 
    References

• Yukun Cao(School of Materials Science and Engineering, Anhui University of Science and Technology, 168#, Taifeng Rd. Tianjiaan District, Huainan 232001, Anhui, China , Anhui International Joint Research Center for Nano Carbon-Based Materials and Environmental Health, Huainan 232001, China)
• Mengke Fan(School of Materials Science and Engineering, Anhui University of Science and Technology, 168#, Taifeng Rd. Tianjiaan District, Huainan 232001, Anhui, China , Anhui International Joint Research Center for Nano Carbon-Based Materials and Environmental Health, Huainan 232001, China)
• Yanghui Ke(School of Materials Science and Engineering, Anhui University of Science and Technology, 168#, Taifeng Rd. Tianjiaan District, Huainan 232001, Anhui, China , Anhui International Joint Research Center for Nano Carbon-Based Materials and Environmental Health, Huainan 232001, China)
• Wenbo Guo(School of Materials Science and Engineering, Anhui University of Science and Technology, 168#, Taifeng Rd. Tianjiaan District, Huainan 232001, Anhui, China , Anhui International Joint Research Center for Nano Carbon-Based Materials and Environmental Health, Huainan 232001, China)
• Yixian Yang(School of Materials Science and Engineering, Anhui University of Science and Technology, 168#, Taifeng Rd. Tianjiaan District, Huainan 232001, Anhui, China , Anhui International Joint Research Center for Nano Carbon-Based Materials and Environmental Health, Huainan 232001, China)
• Zhenfei Lv(School of Materials Science and Engineering, Anhui University of Science and Technology, 168#, Taifeng Rd. Tianjiaan District, Huainan 232001, Anhui, China , Anhui International Joint Research Center for Nano Carbon-Based Materials and Environmental Health, Huainan 232001, China, Anhui Industrial Generic Technology Research Center for New Materials From Coal-Based Solid Wastes, Huainan 232001, China)
• Chong Lan(School of Materials Science and Engineering, Anhui University of Science and Technology, 168#, Taifeng Rd. Tianjiaan District, Huainan 232001, Anhui, China , Anhui International Joint Research Center for Nano Carbon-Based Materials and Environmental Health, Huainan 232001, China, Anhui Industrial Generic Technology Research Center for New Materials From Coal-Based Solid Wastes, Huainan 232001, China)
• Xiulin Shen(School of Materials Science and Engineering, Anhui University of Science and Technology, 168#, Taifeng Rd. Tianjiaan District, Huainan 232001, Anhui, China , Anhui International Joint Research Center for Nano Carbon-Based Materials and Environmental Health, Huainan 232001, China, Anhui Industrial Generic Technology Research Center for New Materials From Coal-Based Solid Wastes, Huainan 232001, China)