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Updated: Aug 15, 2025
Quantification of Humic and Fulvic Acids in Humate Ores, DOC, Humified Materials and Humic Substance-Containing Commercial Products
Published on: March 18, 2022
Parametric optimization and structural feature analysis of humic acid extraction from lignite
Tazien Rashid1, Farooq Sher2, Mazura Jusoh3
1Department of Chemical Engineering Technology, Government College University, Faisalabad 38000, Pakistan; Institute of Bioproduct Development, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia.
This study optimized humic acid (HA) extraction from lignite coal using Response Surface Methodology (RSM), achieving high yields at low pH. The findings offer a new pathway for efficient, clean lignite utilization in agriculture and green energy.
Area of Science:
- Organic Chemistry
- Materials Science
- Environmental Science
Background:
- Humic acid (HA) is a complex organic compound with variable structure depending on its source.
- Current HA extraction methods face challenges in efficiency and scalability.
- Optimizing extraction is crucial for unlocking HA's potential in various applications.
Purpose of the Study:
- To optimize the extraction of humic acid from lignite coal using Response Surface Methodology (RSM).
- To investigate the impact of various parameters (KOH concentration, KOH-coal ratio, time, pH) on HA extraction efficiency.
- To evaluate the developed RSM model for predicting HA extraction yield.
Main Methods:
- Nitric acid oxidation of coal samples followed by extraction with varying KOH concentrations (2.5-3.5%).
- Application of Response Surface Methodology (RSM) to model and optimize extraction parameters.
- Characterization of extracted HA using elemental analysis, UV-Vis, FTIR, and SEM.
Main Results:
- Maximum HA extraction efficiencies of 89.32% and 87.04% were achieved for the two coal samples.
- Optimal extraction occurred at significantly low pH values (1.09 and 1) compared to conventional methods.
- RSM models demonstrated high accuracy with R² values of 0.9795 and 0.9758, indicating suitability for prediction.
Conclusions:
- The study successfully optimized HA extraction from lignite coal, yielding high efficiencies at low pH.
- The developed RSM model provides a reliable tool for predicting and optimizing HA extraction.
- The extracted HA has potential for agricultural applications (soil enrichment, plant growth) and green energy solutions, promoting clean lignite utilization.
