Nitrohumic Acids Research Articles

Preparation, characterization and nitrogen availability of nitrohumic acid as a slow-release nitrogen fertilizer

ABSTRACT Nitrohumic acids (NHAs) are considered as promising slow-release N fertilizers. In this study, NHA was produced from six organic feedstocks, including coal, leonardite, municipal waste compost, sewage sludge, and apple and beech biochars via nitration using nitric acid. The nitration process was conducted in two ways: (i) after humic acid (HA) extraction (NHAD), and (ii) before HA extraction (NHAID). The prepared NHAs were then characterized using FT-IR and CHNS analysis. Additionally, N mineralization of NHAs was investigated in a sandy loam soil sample. The FT-IR spectra showed that both methods of nitration loaded nitro (NO2) groups into the HA structure. However, the CHNS analysis indicated the highest rate of N increase for NHAD (106%) and NHAID (113%) extracted from leonardite. Moreover, on average, the total acidity and carboxylic groups of the HAs increased by 7.5% and 14.5% after the nitration processes, respectively. The highest extraction yields of NHAD (26.1%) and NHAID (42.1%) were also obtained from leonardite. Although the extraction yield of NHAID was on average two times higher than that of NHAD, NHAD indicated a higher soil N availability (1.4 times). We concluded that the NHAD extracted from leonardite could be considered as an alternative slow-release N fertilizer.

OBTAINING DERIVATIVES OF HUMIC SUBSTANCES FROM OXIDIZED COAL AND STUDY OF PHYSICO-CHEMICAL AND ADSORPTION PROPERTIES

In the work, a chemical analysis of humic substances based on oxidized coal of the Maikuben basin (Kazakhstan) is carried out. Humic acids were obtained on the basis of potassium humates by acidification with a 20% acid solution to pH = 3-4.5. The optimal conditions for obtaining nitrohumic acids from oxidized coals are: the duration of the process is 3 hours, the ratio of S:L = 1:5, the content of nitric acid is 64%, sulfuric acid is 96% and the composition of the nitrating mixture is 1:1 (g/g). Amminohumic derivatives were obtained in the presence of a 3% aqueous solution of ammonia using mechanical activation and ultrasonic treatment. The samples obtained were tested as an adsorbent for water purification from heavy metals. Humic acids and aminohumate showed the highest degrees of purification for zinc (99.0-100.0%) and cadmium (80.0-96.7%), and nitrohumic acid showed a high adsorption capacity for heavy metals like copper - 100.0 % and lead 82.9%. This is due to the fact that when interacting with heavy metals, humic acids and their derivatives (amino and nitro) form chelate complexes due to carboxyl, phenolic, nitro and amino groups. As a result of the study, the possibility of using them as non-toxic available sorbents for the purification of heavy metals in aqueous media has been shown.

Nitrosation and Nitration of Fulvic Acid, Peat and Coal with Nitric Acid.

Nitrohumic acids, produced from base extraction of coals and peats oxidized with nitric acid, have received considerable attention as soil ammendments in agriculture. The nitration chemistry however is incompletely understood. Moreover, there is a need to understand the reaction of nitric acid with natural organic matter (NOM) in general, in the context of a variety of environmental and biogeochemical processes. Suwannee River NOM, Suwannee River fulvic acid, and Pahokee Peat fulvic acid were treated with 15N-labeled nitric acid at concentrations ranging from 15% to 22% and analyzed by liquid and solid state 15N NMR spectroscopy. Bulk Pahokee peat and Illinois #6 coal were also treated with nitric acid, at 29% and 40% respectively, and analyzed by solid state 15N NMR spectroscopy. In addition to nitro groups from nitration of aromatic carbon, the 15N NMR spectra of all five samples exhibited peaks attributable to nitrosation reactions. These include nitrosophenol peaks in the peat fulvic acid and Suwannee River samples, from nitrosation of phenolic rings, and N-nitroso groups in the peat samples, from nitrosation of secondary amides or amines, the latter consistent with the peat samples having the highest naturally abundant nitrogen contents. Peaks attributable to Beckmann and secondary reactions of the initially formed oximes were present in all spectra, including primary amide, secondary amide, lactam, and nitrile nitrogens. The degree of secondary reaction product formation resulting from nitrosation reactions appeared to correlate inversely with the 13C aromaticities of the samples. The nitrosation reactions are most plausibly effected by nitrous acid formed from the reduction of nitric acid by oxidizable substrates in the NOM and coal samples.

Structural elucidation of humic acids extracted from Pakistani lignite using spectroscopic and thermal degradative techniques

The present paper describes the characterization of Pakistan lignite coal, derived humic acids (HAL) and nitrohumic acids (NHA) along with the standard leonardite humic acids (LHA). The study utilized chromatographic and spectroscopic techniques to characterize the structure of coal and derived materials. Pyrolysis coupled to gc/ms was conducted with and without methylating agent (tetramethyl ammonium hydroxide). The pyrolysis study resulted in releasing mainly fatty acid methyl esters, different series of hydrocarbons and α, ω-dicarboxylic acid methyl esters. Triterpenoids, syringic and ρ-coumaric compounds and aromatic compounds derived from lignin moieties were also detected. Fourier transform infrared (FT-IR) and NMR data helped to evaluate the influence of coal rank on regeneration and nitration processes with respect to chemical structural composition of coal and derived materials. FT-IR spectra of four materials were similar except that NHA showed an absorption band at 1532cm−1, thus confirming the presence of -NO2 groups. 13C NMR indicated higher aromaticity and less hydroxylalkyl material in HAL than NHA. The elemental composition and acid functional group content of four materials were also reported.The combination of results from different analytical techniques gives an improved understanding of the Pakistan coal nature and helpful for its future utilization.

Reuse of nitric acid in the oxidative pretreatment step for preparation of humic acids from low rank coal of Mukah, Sarawak

Nitric acid is an effective material for production of humic acids. Nevertheless, it is an expensive item that renders the process unfavorable industrially. Study indicated that there was a possibility to reuse the nitric acid for oxidation however the resulting structures of humic acids was not studied. Therefore, the objective of this study was to investigate the chemical and spectroscopic properties of nitrohumic acids prepared with reused nitric acid. The coal sample was oxidized with 5%, 10% and 15% of nitric acid and subjected to extraction for nitrohumic acids. Concentration of nitric acid with the most yields was reemployed for another 2 cycles of oxidation. The chemical and spectroscopic properties of nitrohumic acids were evaluated. The results indicated that oxidation process generally improved the acidic functional properties of the nitrohumic acids with 10% nitric acid producing the most promising yield. The nitric acid was reused for extraction and the percentage yield remained good at an average of 78%. Structurally, the nitrohumic acids produced with the reused nitric acid demonstrated larger molecular size and fewer acidic functional groups suggesting lesser extent of structure fractionation.

Molybdenum (VI) binded to humic and nitrohumic acid models in aqueous solutions. Salicylic, 3-nitrosalicylic, 5-nitrosalicylic and 3,5 dinitrosalicylic acids: part 2

In this work electrochemical and Ultraviolet-Visible studies were performed in solutions of salicylic acid models of humic and nitrohumic acids, a laboratory artifact, and molybdenum in order to determine the affinity of these models towards the metal ion. Molybdenum, which plays a very important role in the soil chemistry, and together with humic substances, impart fertility to soil and water and is a key element in the activity of nitrogenase. The obtained results showed that at least one complexed species is present at the pH range of 6.3 to 8.0, even for the less basic chosen models, the nitrosalicylic acids. Previous study showed that phthalic and nitrophthalic, also humic and nitrohumic acids model compounds, presented complexed species with molybdenum only till pH 6.5. The calculated formation constants showed that the substitution of the nitro group in the orto position was less favoured than in the para substitution, probably due to a steric hindrance in the former, which was clearly seen in the double substituted salicylic nitro derivative. The cyclic voltammetry as well as the Ultraviolet-Visible obtained spectra were able to show that the chemistry of molybdenum in aqueous solutions as the pH is increased is very complex, and the molybdate stops acting as an anion only after pH around 4, when it finally becomes a cation MoO2(2+) (M).

Characterization of the coal derived humic acids from Mukah, Sarawak as soil conditioner

In Malaysia, abundant coal resources were found in Sarawak and Sabah. The utilization of coal resources, to date, is emphasized on the energy productions. The non-energy utilization as soil conditioner is unexplored. Therefore, this study attempted to characterize the coal humic acids extracted from Mukah coal and to evaluate its properties as soil conditioner. The coal humic acids from the regenerated sample were also assessed. The results revealed that different extractants and concentrations influenced the properties of humic acids. The extraction with KOH at 0.5 mol L-1 produced humic acids with low ash content and high acidic functional groups, which are substantial as soil conditioner. However, the yield was low. Regeneration of coal sample with 10% nitric acids improved the yield to an average of 83.45%. The acidic functional groups of nitrohumic acids were improved with the ash content remained at a low level.

Model compounds of humic acid and oxovanadium cations. Potentiometric titration and EPR spectroscopy studies

The stability constants and the isotropic EPR parameters Ao (hyperfine splitting constant) and go (g value) were obtained by potentiometric titrations and EPR spectroscopy, respectively, of 85%v/v aqueous solutions of model compounds of humic acids - salicylic acid (SALA) - and both nitrohumic acids, a laboratory artifact - nitrosalicylic acids, 3-nitrosalicylic acid (3-NSA), 5-nitrosalicylic acid (5-NSA) and 3,5-dinitrosalicylic acid (3,5-DNSA) and oxovanadium cations. It was possible to record EPR spectra of those model compounds and the ion VO2+ (V(IV)), and the stability constants were obtained from a solution of VO3+ (V(V)), the values for the logarithms of the stability constants ranging from 12.77 ± 0.04 to 7.06 ± 0.05 for the species ML, and from 9.90 ±0.04 to 4.06 ± 0.05 for the species ML2 according to the decrease in the acidity of the carboxylic and the hydroxyl groups in the aromatic ring of the model compounds studied as the -NO2 substituents were added. Species distribution diagrams were also obtained for the equilibria studied. The EPR parameters showed that as the logarithm of the overall stability constants increase, go values also increase, while Ao values show a tendency to decrease.

Electrochemical and spectroscopic studies of the complexed species of models of nitrohumic acids derived from phthalic acid

The study of model compounds is necessary in order to obtain information about complex organic substances as in the case of humic substances (HS). These substances are potential organic fertilizers and have other important functions in soils, natural waters and organic sediments. The main chemical properties of the complexes formed from 3-nitrophthalic and 4-nitrophthalic acids and the metal ions Fe(III) and Zn(II) were studied using potentiometric titrations, ultraviolet-visible spectroscopy (UV-Vis) and cyclic voltammetry (CV). A trial potentiometric titration was done with a mixture of the models for nitrohumic acids and Cu(II). Equilibrium constants for the systems were calculated and UV-Vis and CV were employed to monitor the formation of the species. Comparative studies involving chelating centres of nitrosalicylic acids and nitrocatechols with Fe(III), Zn(II) and Cu(II) are presented. The initial studies involving the nitrohumic substances (NHS), a laboratory artifact of HS have been made and good evidence was found for the further use of NHS as a potential organic fertilizer as well as HS. In this present work one of the observed advantages of NHS over HS was that some aromatic nitro- centres can bind some metal ions at p[H] values of normal soils, near 7.0 to 7.5.

Nitrohumic acids from Victorian brown coal

Nitrohumic acids, produced by nitric acid oxidation of low rank coals have been advocated for a variety of applications including nitrogenous humic fertilizers, fertilizer additives to enhance plant yields, plant growth stimulators and a variety of non-agricultural uses. Nitrohumic acids were produced from a Victorian brown coal. A number of reaction conditions were manipulated in order to optimize the yield of acid insoluble material. It was found that reaction temperature and acid concentration had the greatest effect on yield. The action of nitric acid on Loy Yang Victorian brown coal caused nitrogen to be incorporated into the coal, predominantly as nitro groups with associated degradation of phenolic structures in the coal. Preliminary soil incubation studies involving urea indicated possible nitrification inhibition in one of three soils examined.

Action of nitric acid on lignites: mathematical models: 2. Nitrogen forms

Influences of the factors, reaction time, temperature, nitric acid concentration and nitric acid/coal ratio were studied by factorial analysis in relation to the response in the total, hydrolysable and available nitrogen contents of the nitrohumic acids obtained when two Spanish lignites were treated with nitric acid. Correlations between the hydrolysable and the available nitrogen, and the optical properties of the nitrohumic acids have been studied to obtain a more simple and rapid index to determine the available nitrogen of the nitro-lignites.

Gel permeation chromatography applied to the study of the nitrohumic acids from coal

Gel permeation chromatography on Sephadex (G-types) was applied to nitrohumic acids (NHA) from lignites. Deionized water and TRIS (Tris-hydroxymethylaminomethane) buffer were tested as eluents. Deionized water provided the same number of fractions and better resolution than TRIS. In both cases, interactions between the gel matrix and the NHA occurred. Five NHA fractions were obtained and characterized by elemental and spectral analysis, which showed significant differences between them. Molecular weights of the fractions, calculated from Cameron's calibration for soil humic acids, are < 9000 or > 100 000 with no significant fractions having molecular weights in the range 9000–100 000.

Amino-acids in humic, nitrohumic and nitrofuvic acids from coal

The humic acids, HA, extracted from a Spanish lignite and the nitrohumic acids, NHA, and nitrofulvic acids, NFA, extracted from the same lignite after its nitration, are hydrolysed with 6N HCI under reflux. The α-amino acids present in the hydrolysates are determined and thirteen α-amino acids are identified. The amounts of nitrogen in the amino-acids released by the hydrolysis increase according to the sequence: NFA > NHA > HA.

Polarographic characterization of nitrohumic acids prepared by nitric acid oxidation of coal

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolarographic characterization of nitrohumic acids prepared by nitric acid oxidation of coalJohn B. Green and Stanley E. ManahanCite this: Anal. Chem. 1979, 51, 8, 1126–1129Publication Date (Print):July 1, 1979Publication History Published online1 May 2002Published inissue 1 July 1979https://doi.org/10.1021/ac50044a009RIGHTS & PERMISSIONSArticle Views88Altmetric-Citations16LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (497 KB) Get e-Alerts Get e-Alerts

Utilizations of Nitro-humic Acids

Utilizations of Nitro-humic Acids