Extraction Of Fulvic Acid Research Articles

Effect of dilute acid on fulvic acid extracted from lignite

ABSTRACT To explore the effect of dilute acid on the extraction of fulvic acid by lignite using an alkali-soluble acid precipitation method, lignite was acid-precipitated by H2SO4, HNO3, HCl, and H3PO4, and the content, extraction rate, and structural characteristics of fulvic acid were analyzed. The results showed that the highest content of humic acid extracted by HNO3 is 0.3383 mg/mL, and the lowest content of humic acid extracted by sulfuric acid is 0.0817 mg/mL. The highest extraction rate of humic acid derived from lignite extracted by hydrochloric acid is 3.84%, and the lowest extraction rate of humic acid extracted by sulfuric acid is 0.89%. Fulvic acid extracted from lignite contained functional groups such as benzyl, carbonyl, methyl, and hydroxyl, but their contents varied; the benzene ring structure in fulvic acid precipitated by HNO3 was the most pronounced, but the aromatization degree was the lowest. By contrast, the aromatization degree of fulvic acid precipitated by H2SO4 was the highest. This indicates that the functional group contents in humic acid extracted from different dilute acids vary, although the types of functional groups are similar.

Extraction of fulvic acid by citric acid–ethanol method and its biochemical activity

AbstractBACKGROUNDWith the widespread application of fulvic acid (FA) in agriculture, improving the industrial yield of FA has become an urgent priority. Therefore, it is particularly important to explore efficient and clean process conditions for the factory production of FA from low‐rank coal, as undertaken in this study. Additionally, an in‐depth study of the biological activity of FA was performed to provide a theoretical reference for its practical application.RESULTSResults showed that, when the reaction temperature was 70 °C, the ratio of citric acid to coal was 0.03:1, the ratio of liquid to solid was 10:1 and the concentration of ethanol was 15%, the average yield of FA was about 80‰. Seed soaking with FA promoted seed germination and improved seedling quality. As the concentration of FA for seed soaking increased, the germination potential, amount of reduced tetrazole and root length were reduced, but the relative electrical conductivity and chlorophyll content were increased.CONCLUSIONCoal‐based FA was effectively extracted by the citric acid–ethanol method and the yield of FA was relatively high under the optimum conditions. The treatment of cucumber seeds and seedlings with different concentrations of FA effectively promoted seed germination and seedling growth. © 2021 Society of Chemical Industry (SCI).

Effect of levels of fulvic acid through foliar sprays on yield and quality of green chilli

A pot culture experiment was conducted with Chilli (cv. Phule Jyoti) at College of Agriculture, Pune (MS), during 2009-10. The soil used for experiment was alkaline in nature with medium in organic carbon, having low available N, medium available P and very high available K. The FYM used for extraction of fulvic acid had pH 7.63, EC 1.42 dSm-1 and C/N ratio 19.8 indicated good quality and maturity. The experiment was laid in completely randomized design (CRD) keeping water and fulvic acid sprays (water, 50, 100, 200, 300 and 400 mg L-1) with three replications. The recommended dose of fertilizers (100:50:50 kg ha-1N:P2O5:K2O) and FYM @ 20 t ha-1 were applied to all treatments. The water and fulvic acid sprays were applied at 30 and 45 days after transplanting of Chilli. The results of the experiment revealed that the application of 200 mg L-1 fulvic acid significantly increased yield of green Chilli and nutrient uptake over the other treatments. The significant increase in length of fruit (8.96 cm), girth of fruit (4.50 cm) number of fruits per plant (40.3), green fruit yield (89.9 g plant-1) and dry matter of stalk (39.6 g plant-1) and ascorbic acid content (109.8 mg 100-1 g) were reported under foliar spray of 200 mg L-1 fulvic acid with some few exceptions found at par with 100 mg L-1 FA. The results summarized that the application of 200 mgL-1 fulvic acid as foliar spray extracted from good quality FYM at 30 and 45 days after transplanting to Chilli along with recommended dose of fertilizers and 20 t FYM ha-1 found beneficial to improve the quality, yield and uptake of nutrients by chilli.

Effects of sulfuric acid pretreatment and liquid acids precipitation on the structure of fulvic acid extracted from peat

To achieve high-value utilization of peat, the process of coupling methane fermentation and extraction of fulvic acid was explored and the effects of sulfuric acid pretreatment before methane fermentation and different liquid acid precipitation on the spectral characteristic of fulvic acid was studied. The fulvic acid precipitated by nitric acid has a high content and a high degree of aromatization. The highest yield of fulvic acid samples is precipitated by phosphoric acid. The fulvic acid extracted from the residues after sulfuric acid pretreatment methane fermentation descends of yield while content increase. Meanwhile, methane fermentation would consume methyl, hydroxyl, and carboxyl groups without benzene rings consumed. In addition, sulfuric acid pretreatment would promote this process and consume more functional groups to produce more methane. The research results show that coupling methane fermentation of peat and extraction of fulvic acid is feasible, and the sulfuric acid pretreatment has a significant effect to fulvic acid. To sum up, sulfuric acid pretreatment would promote methane fermentation process and degrade more fulvic acid.

Extraction of Fulvic Acid from Lignite and Characterization of Its Functional Groups.

Fulvic acid (FA) is a complex organic mixture composed of small molecules. The structure and composition of FA vary greatly because of the different raw materials used for preparing FA. In this work, FA was extracted from shallow low-rank lignite by hydrogen peroxide (H2O2) in a microwave field, and the functional groups of FA were characterized. The optimal extraction process was determined, with the H2O2 concentration being the key factor affecting the yield of FA. Thermogravimetric analysis showed that FA was mainly composed of low molecular weight and readily pyrolyzed compounds. As shown by Fourier transform infrared spectroscopy, in the process of FA extraction by H2O2 oxidation of lignite, the content of −COOH increased, long-chain aliphatic compounds decreased, stretching vibrations of aromatic ring skeletons disappeared, and aromatic ring substitution became mainly tri- or disubstitution. Fluorescence spectroscopy indicated that FA had a low degree of aromaticity. X-ray photoelectron spectroscopy qualitatively and quantitatively revealed that the main modes of carbon–oxygen bonding in FA were C–O–, COO–, and C=O. Thus, this study not only lays a foundation for studying the composition and structure of coal-based FA but also opens a new avenue for a clean and efficient utilization of lignite.

Effects of Methane Fermentation on Spectral Properties of Fulvic Acid Extracted from Peat through Liquid Acid Precipitation

The effects of acid precipitation with different liquid acids on spectral properties of fulvic acid extracted from peat was studied to select the most appropriate liquid acid for the acid precipitation step of the alkali solution acid precipitation method, and the new process mechanism of peat utilization by coupling methane fermentation and extraction of fulvic acid was analyzed. The alkali solution acid precipitation method was adopted to extract fulvic acid from the methane-fermented group and methane-unfermented group. Different liquid acids were used to conduct acid precipitation during the extraction. And then, the characterizations of fulvic acid samples were conducted through Fourier infrared spectroscopy, UV-Vis spectroscopy, and fluorescence spectroscopy. The yield and content of fulvic acid decreased significantly after methane fermentation. During the methane fermentation process, some fulvic acid was consumed and utilized by microorganisms to promote the methane fermentation process, resulting both in the decrease of methyl, hydroxyl, and ether bonds and in the increase of methylene, carbonyl, conjugated double bond, benzene rings, and other groups. The E4/E6 ratio shows that the E4/E6 ratio of fulvic acid was decreased after methane fermentation, and the fermentation consumed the functional group with simpler structure such as aliphatic chain hydrocarbon of fulvic acid while the structure with a higher degree of aromatization and conjugate cannot be consumed. When conducting acid precipitation with different liquid acids, the yield of fulvic acid was the highest through acid precipitation with phosphoric acid. The fulvic acid obtained through acid precipitation with nitric acid has a higher content, more benzene rings, and the highest degree of aromatization.

Extraction and Functional Group Characterization of Fulvic Acid from Hami Lignite

AbstractThis research investigates the extraction of fulvic acid (FA) from Hami lignite from Xinjiang, China, by microwave‐hydrogen peroxide and microwave‐hydrogen peroxide‐formic acid methods. The effects of reaction time, oxidant concentration, oxygen‐coal ratio and microwave power on FA yield are determined. Sulfuric acid‐acetone was applied to purify the primary FA products. The results indicate that the oxidant concentration is a sensitive factor affecting the yield of FA, while reaction time has little effect. Formic acid can promote the extraction of FA from lignite by hydrogen peroxide, and under optimal experimental conditions, the yields of FA were 5.34% and 9.13%, respectively. UV‐Vis analysis shows that FA has a lower aromaticity and degree of carbonyl conjugation in the presence of formic acid. Additionally, Fourier transform infrared spectroscopy was used to characterize the purified FA. The results show that the benzene rings of FA have one, two, three and four substitutions, oxygen‐containing functional groups containing –COOH, C=O, ‐OCH3, C−O−C, Ar‐OH, and R‐OH and, furthermore, primary oxygen‐containing functional groups consisting of C=O and C–OH. The aliphatic functional groups contain symmetrical and anti‐symmetrical stretching vibrations of ‐CH2 and ‐CH3. Finally, the hydrogen bonds are mainly composed of phenolic hydroxyls and alcoholic hydroxyls, while some hydrogen carboxylate is present.

Molecular-scale investigation of soil fulvic acid and water-extractable organic matter by high-resolution mass spectrometry and 1H NMR spectroscopy

Environmental contextNotwithstanding the environmental and geochemical significance of soil dissolved organic matter (DOM), its molecular components are still not well characterised. This study investigates chemical similarities and differences between two widely used forms of soil DOM: water-extractable organic matter and fulvic acids. The findings will guide appropriate extraction and purification protocols in future studies related to soil DOM. AbstractDissolved organic matter (DOM) is the most active fraction of soil organic matter (SOM), which has both environmental and geochemical importance. However, the extraction of DOM from soils is still ambiguous. Instead, operational concepts, such as fulvic acid (FA) and water-extractable organic matter (WEOM), are widely used in practice. In this study, the molecular components of FA and WEOM extracted from two standard soils were investigated by using electrospray ionisation coupled with Fourier-transform ion cyclotron resonance mass spectrometry and proton nuclear magnetic resonance (1H NMR) spectroscopy to clarify the molecular similarities and differences between them. The results revealed that WEOM and FA shared many of the same molecules, which accounted for 64% and 82% of the total numbers of molecules for WEOM and FA respectively. However, WEOM displayed higher chemical and molecular diversities than FA. Detailed analysis revealed that the extraction and desalination procedure of FA led to the loss of lignin, protein and carbohydrate compounds, but induced preferential release of some tannin-like molecules from the aggregate- or organic mineral-associated SOM. Based on the results of the present study, water extraction combined with desalination through a functionalised styrene divinylbenzene polymer-based solid phase extraction is more reliable to retain the molecular diversity of soil DOM.

Study on the extraction of fulvic acid from lignite by microwave-assisted hydrogen peroxide

Study on the extraction of fulvic acid from lignite by microwave-assisted hydrogen peroxide

Study on the extraction of fulvic acid from lignite by microwave-assisted hydrogen peroxide

Extraction of fulvic acid (FA) from Hulun Buir (HB) lignite were carried out under the conditions of hydrogen peroxide and microwave-assisted hydrogen peroxide. The results showed that the microwave can greatly improve reaction rate and observably shorten reaction time, while the extraction yield of FA increased around 4%. Purification technology of FA was studied by sulfuric acid-acetone aqueous solution, and then structure of purified FA was evaluated. All results demonstrated that under the assistance of microwave, the oxidative degradation ability of hydrogen peroxide is stronger, the solvent gets higher permeation ability and the oxygen content in FA is higher. Among the oxygenic functional groups of FA, carboxyl group has the highest content, followed by hydroxyl group and the ester content is the lowest. Trisubstituted benzene is the major component in the aromatic structure of FA. In aliphatic structure, content of methylene is the highest. [Received: March 4, 2017; Accepted: October 17, 2017]

Indicative extent of humic and fulvic acids in soils determined by electronic nose

The principal humic substances present in soils like Humic Acid (HA) and Fulvic Acid (FA) are plant fertility components many of which basically are aromatic in nature. Assaying these components is a challenge. The present study aims at an enquiry to delineate aromaticity of soil extracted HA and extracted FA by capturing their odor. Since these soil components are bound to soil particles, an effort has been put to find out whether they are more released in dry or wet soil conditions. The aromaticity determination was explored by Electronic nose (E-nose) equipment that had specific array of metal oxide sensors. The other objective of the study was to profile the aromaticity of HA and FA by their extraction from garden soil and its subsequent amendment. The series of experiments comprised of extraction of HA and FA and profiling of Norm Aroma Index (NAI) by E-nose in both wet and dry conditions of soil. The findings were that the yield of HA was more compared to FA; the NAI noted was high in wet condition of the soil compared to dry soil; HA showed more aromaticity compared to FA; the amended soil showed more aromaticity compared to non-amended normal soils. Among the amendment exercises, HA amended soil showed maximum aromaticity. E-nose employment could indicate extent of HA and FA in soils.

Microwave-Assisted Extraction of Fulvic Acid from a Solid Dosage Form: a Statistical Approach

Purpose Fulvic acid is a polymer that acts as a carrier to a number of drugs by its great complexing ability, thereby augmenting their bioavailability. Conventional procedure of extraction is available, but it involves long extraction times and a number of rudimentary steps. The purpose of this study was to overcome this issue.

Evaluation of humic and fulvic acid extracts of compost, oilcake, and soils on complex formation with arsenic

Fulvic acid (FA) and humic acid (HA) were extracted from compost, oilcake, and surface soils collected from arsenic-contaminated and uncontaminated sites of West Bengal. These HA/FA samples were characterised by pH–potentiometric titrations, viscometric measurements, visible spectrophotometry, and surface tension determinations. The results were correlated with coiling–decoiling behaviour, as well as aliphatic/aromatic balance of HA/FAs. The stability constant (logK) of the complexes formed by the natural HA/FA fractions of the given soils were quite stable, and the HA/FA fractions of the organic manures with arsenate in aqueous phases suggested the dependence of such complexation on the nature and properties of the humic polymers, which, in turn, would affect the retention/release of arsenate in soil. The release potential of arsenic from the arsenate–HA/FA complexes by soluble sulfate and nitrate salts was also examined in terms of the appropriate exchange isotherms. In general, sulfate demonstrated a moderately greater degree of exchangeability with arsenate than did nitrate, at higher concentrations.

STUDY ON SENSITIZATION OF FULVIC ACID ON PHOTOREDUCTION OF Cr(VI) TO Cr(III) BY TiO<sub>2</sub> PHOTOCATALYST

Sensitization of fulvic acid (FA) on photoreduction of Cr(VI) to Cr(III) by TiO2 photocatalyst has been studied. Parameters influencing the sensitization, i.e., pH of medium, as well as FA concentrations, TiO2 concentrations and initial Cr(VI) concentrations were critically evaluated. Extraction of FA from peat soil sampled in Gambut, South Kalimantan, Indonesia, was performed using Amberlite XAD-7 resin. The FA extract then was purified by cation exchange method using Amberlite IRA-120 resin. The TiO2 produced by Merck was used as semiconducting photocatalyst and two 30-W UV lamps (Philips® model TUV) were used as photon source. The results showed that presence of FA on TiO2 suspensions could sensitize the photoreduction of Cr(VI), enhancing of the amount of reduced Cr(VI) more significantly than the sensitization by humic acid. The effectiveness of this sensitization increased with increasing initial concentrations of FA, TiO2, or Cr(VI) until certain concentration, but no further improvement can be observed in excess FA, TiO2, or Cr(VI) concentrations. On the contrary, the effectiveness of this sensitization decreased with increasing of the medium pH. Keywords: sensitization, fulvic acid, Cr(VI), photoreduction, TiO2.

Spectroscopic characterization of fulvic acids extracted from the rock exudate Shilajit

The present work describes the extraction of fulvic acids (FA) from Shilajit and its spectroscopic and mass spectrometric characterization. The spectral features obtained from FT-IR and 1HNMR were similar to those reported for humic substances from other sources. The molecular elemental composition analysis by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) in electrospray negative ion mode resulted in extraordinary high average O/C ratios (0.55) which might be caused by a significant contribution of carbohydrates in Shilajit. A very high average H/C ratio of 1.27 also points to dominant aliphatic or alicyclic structures and relatively low aromaticity. The average molecular formula of the nitrogen free elemental compositions measured by FT-ICR mass spectrometry is C 18.2H 23.0O 10.0.

Trace humic and fulvic acid determination in natural water by cloud point extraction/preconcentration using non-ionic and cationic surfactants with FI-UV detection.

A preconcentration and determination method for humic and fulvic acids at trace levels in natural water samples was developed. Cloud point extraction was successfully employed for the preconcentration of humic acid (HA) and fulvic acid (FA) prior to the determination by using a flow injection (FI) system coupled to a spectrophotometric UV-Vis detector. The quantitative extraction of HA and FA within the pH range 1-12 was obtained by neutralization of the anionic charge on the humic substances with a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB). This generated a hydrophobic species that was subsequently incorporated (solubilized) into the micelles of a non-ionic surfactant polyethylene glycol, tert-octylphenyl ether (Triton X-114). The FI method for HA and FA determination was developed by injection of 100 microl of the extracted surfactant-rich phase using an HPLC pump with spectrophotometric detection at 350 nm. A 50 ml sample solution preconcentration allowed an enrichment factor of 167. The limit of detection (LOD) obtained under the optimal conditions was 5 microg l(-1). The precision for ten replicate determinations at 0.2 mg l(-1) HA was 3.1% relative standard deviation (RSD), calculated from the peak heights. The calibration using the preconcentration system for HA and FA was linear with a correlation coefficient (r2) of 0.9997 at levels near the detection limits up to at least 1 mg l(-1). The method was successfully applied to the determination of HA and FA in natural water samples (river water).

Distribution of some major and minor elements between fulvic and humic acid fractions in natural soils

For the first time a method is presented to study the distribution of metals between humic and fulvic fractions in natural soils. Total organometallic complexes are separated by extraction with 0.1 M pyrophosphate. After acidification to pH 1.5 with H 2SO 4 the fraction associated with humic acids is separated by precipitation and the remaining solution contains the complexes associated with fulvic complexes. Concentrations of 11 elements (Al, Fe, Ca, Mg, K, Mn and the trace elements Cu, Pb, Zn, Cd, and Cr) were determined in the pyrophosphate and the fulvic acid extracts, and the fraction bound to humic acids was estimated by difference. Typical results from application of the method to andosols, cambisols, and podzols are presented. Fulvic acid is generally the main humic fraction reacting with metals, except for Ca where around 70% of the organic bound pool is found in the humic fraction. The corresponding figure is of the order of 30–40% for Al, Fe, Mn and Cr and even less for Pb, Cu, Zn, and Cd. For some elements the humic/fulvic distribution appears to be different between soil types. Some factors that may disturb the results obtained by the present method are discussed.

Pyrolysis gas chromatography - mass spectrometry of humic substances extracted from Canadian lake sediments

Humic substances (HS) were extracted with the aid of 0.1 M Na4P2O7 and 0.5 M NaOH solutions from the sediments of four lakes located in the Sudbury area in Ontario, Canada, namely, Tilton, Clearwater, Silver and Ramsey Lake. The humic acid (HA) and fulvic acid (FA) extracts, purified and characterized using classical methods i.e., elemental analysis, FTIR spectroscopy, and CPMAS 13C NMR (see N. Belzile, H.A. Joly, and H. Li. (1997)), were submitted to pyrolysis - gas chromatography - mass spectrometry (Py-GC-MS). The pyrolysates of the HA and FA extracts were found to be complex mixtures of at least 200 compounds. Results based on statistical analysis of the abundances of pyrolysis products (of known origin) revealed trends similar to those obtained from the classical bulk characterization techniques. The Py-GC-MS technique supported the observation, obtained from classical methods, that the chemical composition of HA extracts varied less significantly among the four lake sediments than for the FA extracts. The abundances of lignin and carbohydrate pyrolysates showed the highest variation among the FA extracts. Pyrolysis products originating from lignin, carbohydrates, proteins, and fatty acids were identified. Key words: humic substances, humic acid, fulvic acid, pyrolysis, pyrolysis – gas chromatography – mass spectrometry, lake sediments.

Phase behavior of Eu(III) in fulvic acid-Fe(III)−H20 system at pH 1–9

The method was developed allowing quantitative extraction of fulvic acids from soil samples in the form close to native. Formation of gel-like and soluble forms of iron(III) fulvates in the systems containing equivalent amounts of iron(III) and fulvic acid was studied within pH range 1–9. The molecular structure of fulvates and the mechanism of transformation of gel to soluble forms was analyzed by IR spectroscopy. Distribution of microamounts of europium between gel-like iron fulvates and their solutions was studied. The correlation between phase distribution of europium and solubilization of iron(III) fulvates was analyzed.

Study on the pathogenic factors of Kashin-Beck disease.

Kashin-Beck disease (KBD) is a chronic osteoarthritic disease, endemic in parts of China. Its etiology is unknown. Selenium deficiency, high concentration of organic matter (mainly fulvic acid) in drinking water, and severe contamination of grain by fungi have been proposed environmental causes. Free radicals, possible mediators between the environmental factors and origin of KBD, have been studied in this work. Drinking water from KBD-affected areas contains a higher level of semiquinone radicals than that from disease-free areas. In animal experiments, fulvic acid (FA) accumulated in the skeletal system as semiquinone radicals. Contamination of grain by Fusarium oxysporum or Alternaria alternata significantly increased the content of semiquinone radicals. Furthermore, corn grown in endemic areas had a higher content of radicals than that from disease-free areas. The g factor values for these radicals from contaminated corn were about 2.0040, in the range of semiquinone radical. In monolayer culture of human embryonic chondrocytes, FA and aqueous extracts of grain contaminated by Fusarium injured the chondrocytes and enhanced lipid peroxidation. Selenite and superoxide dismutase (SOD) protected the cells from injury by these toxins and reduced lipid peroxide. Lower glutathione peroxidase activities and higher levels of lipid peroxidation were also found in the children living in KBD-affected regions. Thus, FA and the mycotoxin, which are seen as exogenous free-radical carriers, are important environmental factors in the pathogenesis of Kashin-Beck disease; and selenium, vitamin C, and vitamin E, which inhibit free-radical formation, are considered to be protective.