Improving extraction yield of humic substances from lignite with anthraquinone in alkaline solution

Abstract

Based on the characteristics of the lignite sample, effects of assistant anthraquinone (AQ) on extraction yield of humic substances (HS) and the action mechanisms of AQ in alkaline condition were studied by Fouvier transform infrared (FT-IR) spectroscopy. The results indicate that assistant AQ can not only increase the extraction yield of HS but also reduce the alkali dosage (NaOH) as well as the extraction temperature and extraction time. Under the optimal conditions of alkali dosage of 9%, AQ dosage of 0.75%, extraction temperature of 80 °C, extraction time of 30 min, stirring speed of 600 r/min and solid-to-liquid ratio of 1:3, the extraction yield of HS reaches 80.08%, which is increased by more than 20% compared with the conventional extraction. FT-IR spectra show that AQ is able to prevent dissolved HS from being destroyed into undissolved substance by alkali and HS obtained in the presence of AQ possesses more groups of -COOR and -COOH than that obtained without AQ.

Keywords

humic substances / extraction / lignite / FTIR / anthraquinone

References

[1] LiuG.-gen.Study on HA-type binders for direct reduction of cold bond pellets and its raw material characteristics [D], 1997, Changsha, Central South University

[2] ChenB.-b., ChiHai.. Talking about processing and utilization of brown coal [J]. Coal Technology, 2005, 24(11): 113-114

[3] YuanZ.-w., SunL.-p., LuY., WangJ.-wei.. Study on the content of humic acid extracting from grass peat [J]. Municipal Engineering Technology, 2006, 26(2): 154-156

[4] Be’atriceA.. A comparative study on the chemical composition of humic acids from forest soil, agricultural soil and lignite deposit bound lipid, carbohydrate and amino acid distributions [J]. Gendarme, 2006, 130: 77-96

[5] ZouJ., WangF.-h., ZhuH., WeiY.-sheng.. Study of the extraction of humic acid from weathered coal [J]. Chemical Industry Times, 2006, 20(6): 10-12

[6] GaoD.-z., WangL., LiuL.-h., LuJ.-ping.. Technologic experiment study of humic acid extracted from wali lignite [J]. Journal of Shandong University of Science and Technology: Natural Science, 2005, 40(3): 40-42

[7] PeuravuoriJ., ZbankovaP., PihlajaK.. Aspects of structural features in lignite and lignite humic acids [J]. Fuel Processing Technology, 2006, 87: 829-839

[8] ConteP., PiccoloA.. Conformational arrangement of dissolved humic substances: Influence of solution composition on association of humic molecules [J]. Environmental Science and Technology, 1999, 33: 1682-1690

[9] LiuG.-g., QiuG.-z., HuY.-hua.. Study on infrared spectra of coals [J]. Journal of Central South University: Natural Science Edition, 1999, 30(40): 371-373

[10] IbarraJ. V., MirandaJ. L.. Detection of weathering in stockpiled coals by Fourier transform infrared spectroscopy [J]. Vibrational Spectroscopy, 1996, 10: 311-318

[11] IbarraJ. V., MuñozE., MolinerR.. FTIR study of the evolution of coal structure during the coalification process [J]. Organic Geochemistry, 1996, 24: 725-735

[12] DIMMEL D R, SHEPARD D. Studies on the mechanism of action of anthraquinone as a pulping catalyst [C]// Canadian Wood Chemistry Symposium. Niagara Falls, 1982, 29–32.

[13] DIMMEL D R. Pulping with anthraquinone: Fundamental chemistry [C]// TAPPI Pulping Conference Proceedings. Nashville, 1996: 53–58.

[14] LiuG.-g., QiuG.-z., XuJ.-cang.. A study of technological parameters of extract in preparation process of HA series pellet binder [J]. Sintering and Pelletizing, 1998, 23: 22-24

[15] LangC.-s., DangZ., LauC.-qiang.. Structure characterization of soil humic acids and adsorption equilibria on phenanthrene [J]. Chinese Journal of Analytical Chemistry, 2006, 34(3): 288-292

[16] LiuG.-g., QiuG.-z., XuJ.-cang.. Study on spectroscopy of HA type binder [J]. Journal of Central South University: Natural Science Edition, 2003, 34(3): 238-241

[17] TatzberM., StemmerM.. FTIR-spectroscopic characterization of humic acids and humin fractions obtained by advanced NaOH, Na₄P₂O₇, and Na₂CO₃ extraction procedures [J]. J Plant Nutr Soil Sci, 2007, 70: 522-529