Extraction and Chemical Characterization of Humic Acid from Nitric Acid Treated Lignite and Bituminous Coal Samples

Noureen Fatima, Asif Jamal, Zaixing Huang, Rabia Liaquat, Bashir Ahmad, Rizwan Haider, Muhammad Ishtiaq Ali, Tayyba Shoukat, Zeid A. ALOthman, Mohamed Ouladsmane, Tariq Ali, Shafqat Ali, Naseem Akhtar and Mika Sillanpää
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Noureen Fatima: Department of Microbiology, Quaid-i-Azam University Islamabad, Islamabad 45320, Pakistan
Asif Jamal: Department of Microbiology, Quaid-i-Azam University Islamabad, Islamabad 45320, Pakistan
Zaixing Huang: School of Chemical Engineering and Technology, University of Mining and Technology, Xuzhou 221116, China
Rabia Liaquat: U.S. Pakistan Centre for Advanced Studies in Energy, National University of Sciences and Technology, Islamabad 45320, Pakistan
Bashir Ahmad: Department of Biological Sciences, International Islamic University, Islamabad 44000, Pakistan
Rizwan Haider: Institute of Energy & Environmental Engineering, University of Punjab, Lahore 54590, Pakistan
Muhammad Ishtiaq Ali: Department of Microbiology, Quaid-i-Azam University Islamabad, Islamabad 45320, Pakistan
Tayyba Shoukat: Department of Chemistry, Government College University, Faisalabad 38000, Pakistan
Zeid A. ALOthman: Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
Mohamed Ouladsmane: Chemistry Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
Tariq Ali: Department of Chemistry, The University of Lahore, Lahore 54590, Pakistan
Shafqat Ali: Department of Environmental Science and Engineering, Government College University, Faisalabad 38000, Pakistan
Naseem Akhtar: Department of Chemistry, The Government Sadiq College Women University, Bahawalpur 63100, Pakistan
Mika Sillanpää: Department of Civil and Environmental Engineering, Florida International University, Miami, FL 33199, USA

Sustainability, 2021, vol. 13, issue 16, 1-15

Abstract: Currently, conversion of coal into alternative fuel and non-fuel valuable products is in demand and growing interest. In the present study, humic acid was extracted from two different ranks of coal, i.e., low rank and high rank (lignite and bituminous), through chemical pretreatment by nitric acid. Samples of lignite and bituminous coal were subjected to nitric acid oxidation followed by extraction using KOH and NaOH gravimetric techniques. The chemical pretreatment of both types of coal led to enhanced yields of humic acid from 21.15% to 57.8% for lignite low-rank coal and 11.6% to 49.6% bituminous high rank coal. The derived humic acid from native coal and nitric acid treated coal was analyzed using elemental analysis, E4/E6 ratio of absorbance at 465 nm and 665 nm using UV-Visible spectrophotometry and Fourier transformed infrared spectroscopy FTIR. The chemical characteristics of coal treated with nitric acid have shown increased molecular weight and improved aromaticity with more oxygen and nitrogen and lower C, H, and sulphur content. The E4/E6 ratio of nitric acid-treated low and high ranks of coal was high. The FTIR spectroscopic data of nitric acid-treated lignite coal indicates an intensive peak of carboxyl group at 2981.84 cm −1 , while bituminous coal was shown in cooperation with the N-H group at 2923.04 cm −1 . SEM was performed to detect the morphological changes that happen after producing humic acid from HNO 3 treatment and native coal. The humic acid produced from HNO 3 treated coal had shown clear morphological changes and some deformations on the surface. SEM-EDS detected the major elements, such as nitrogen, in treated humic acid that were absent in raw coal humic acid. Hence, the produced humic acid through HNO 3 oxidation showed a more significant number of humic materials with improved efficiency as compared to native coal. This obtained humic acid can be made bioactive for agriculture purposes, i.e., for soil enrichment and improvement in growth conditions of plants and development of green energy solutions.

Keywords: lignite coal; bituminous coal; pretreatment; nitric acid (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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