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Evaluation of Integrated Anaerobic Digestion and Hydrothermal Carbonization for Bioenergy Production
Published on: June 15, 2014
Hydrothermal Humification for Producing Humic-like Acids and Nitrogen-Enriched Humic-like Acids from Recycled Wheat
Xiaoyue Xu1, Yichen Liu1, Jiangtao Hu2
1Jiangsu Provincial Key Lab of Sustainable Pulp and Paper Technology and Biomass Materials, Nanjing Forestry University, Nanjing 210037, China.
Polymers
|July 15, 2026
Summary
Researchers converted pulping black liquor into humic-like acids (HLAs) and nitrogen-enriched humic-like acids (N-HLAs) via hydrothermal humification. The N-HLAs promoted radish seed germination and seedling growth, offering sustainable valorization for the pulp and paper industry.
Area of Science:
- Green Chemistry
- Materials Science
- Biotechnology
Background:
- Pulping black liquor presents a significant waste stream in the pulp and paper industry.
- Sustainable utilization of black liquor is crucial for industrial ecology and resource efficiency.
- Non-wood sources like wheat straw offer potential for novel material development.
Purpose of the Study:
- To valorize concentrated black liquor from KOH-pretreated wheat straw chemi-thermomechanical pulp (CTMP).
- To synthesize humic-like acids (HLAs) and nitrogen-enriched humic-like acids (N-HLAs) using hydrothermal humification.
- To optimize synthesis conditions and evaluate the properties and bioactivity of the synthesized N-HLAs.
Main Methods:
- Hydrothermal humification of concentrated black liquor.
- Optimization of temperature, time, and urea concentration.
- Characterization using elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and particle size analysis (PSA).
- Bioactivity assay on radish seed germination and seedling growth.
Main Results:
- Optimal hydrothermal conditions identified as 180 °C for 4 h, yielding 15.75% HLA.
- Addition of 1 mol/L urea increased yield to 16.81% for 1N-HLA.
- Hydrothermal treatment enhanced molecular condensation and aromaticity.
- Successful incorporation of nitrogen functional groups into HLAs via urea modification.
- 1N-HLA demonstrated a significant promoting effect on radish seed germination and growth at 100 mg/L.
Conclusions:
- Hydrothermal humification is an effective method for converting pulping black liquor into valuable humic-like materials.
- Nitrogen enrichment via urea enhances the yield and functionality of HLAs.
- Synthesized N-HLAs show potential as biostimulants, supporting sustainable agriculture and waste valorization.
- This research provides a pathway for the high-value utilization of non-wood pulping waste.
Keywords:
hydrothermal humificationnitrogen-enriched humic-like acidsrecycled wheat straw CTMP black liquorurea modificationMore Related Videos
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