Selective extraction of metal ions associated with humic acids

Lignite is brown coal, which in its composition contains humic acids. Humic acids are produced by coal combustion, which leads to the enrichment of coal humic acids. Lignite, from the opet pit mine Sikulje, lignite ore ?Kreka?, Bosnia and Herzegovina, was fragmented and sieved to the appropriate size and used as a base material. The isolation of humic acid was carried out from pre-oxidized and dried lignite after which it was refined. Identification thus obtained humic acids was carried out by FTIR spectroscopy and its characterization of UV analysis which is determined by optical density of isolated humic acid and its complexation with metal cations. Data obtained by FTIR spectroscopic analysis of isolated humic acids show no significant structural and chemical difference in relation to the spectrum obtained for standard humic acids (Sigma Aldrich). UV analysis showed that isolated and standard humic acid have E4/E6 ratio in an appropriate range of 3?5, which indicates the presence of a large number of aliphatic structure. Based on the degree of humification was found that the isolated humic acids belong to the type B standard while humic acids belong to type A. The most important property of the humic substances is the ability to interact with the metal ions forming soluble or insoluble complexes which possess different chemical and biological properties and stability. The nature of the complex between humic acid and metal cation derived from the heterogeneous, polyelectric and polydispersive character humic acids that occurs due to the presence of a large number of functional groups. Complexation of humic acid is carried out with different concentrations of metal nitrate solutions and at different pH values. Different amounts of humic acids were used for the complexation. The amount of the free metal ions was measured with the ICP-OES methode. The data were also statistically analyzed with ANOVA. The results showed that increasing the pH reduces the concentration of metal ions adsorbed on humic acid and by increasing the concentrations and amounts of metal humic acid that power increases. On the basis of the difference in absorbance between metals and humic acids can be said that there is an interaction between the metal and the ligand and is based on absorbance values obtained can be determine the next set of metal binding to humic acids Pb>Zn>Ni>Cu.

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A multi-method analysis of the interaction between humic acids and heavy metal ions

Journal of Environmental Science and Health Part A ◽

10.1080/10934529.2018.1444971 ◽

2018 ◽

Vol 53 (8) ◽

pp. 740-751 ◽

Cited By ~ 4

Author(s):

Tao Ke ◽

Lu Li ◽

Krishnamoorthy Rajavel ◽

Zhenyu Wang ◽

Daohui Lin

Keyword(s):

Heavy Metal ◽

Metal Ions ◽

Humic Acids ◽

Heavy Metal Ions ◽

Method Analysis

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Selective extraction of trace metals associated with hydrous aluminum oxides

Canadian Journal of Chemistry ◽

10.1139/v87-168 ◽

1987 ◽

Vol 65 (5) ◽

pp. 984-989 ◽

Cited By ~ 7

Author(s):

Janece Slavek ◽

William Frederick Pickering

Keyword(s):

Metal Ions ◽

Selective Extraction ◽

Metal Species ◽

Initial Surface ◽

Aluminum Oxides ◽

Hydrous Oxides ◽

Soil Sediment ◽

Trace Metal Content ◽

Chemical Solutions ◽

The Relationship

In soil/sediment analysis, subdivision of trace metal content into different categories is usually based on selective extraction schemes. To assess the disposition of metal ions bound to aluminum hydrous oxides in such schemes, suspensions of Al(OH)3gel, gibbsite, or alumina were loaded with up to 5 μ mol of Cu, Pb, Cd, or Zn ions prior to being extracted for 24 h with one of fifteen different chemical solutions. The percentage of sorbed ion retrieved varied along the reagent sequence: NaCl, CaCl2 < MgCl2, NH4NO3 < CH3COONH4, Na citrate, Na4P2O7 < EDTA, DTPA < CH3COOH, H2C2O4, HCl, HNO3. In each system, the recovery value varied with the initial surface loading (a function of sorption pH) and reflected changes in metal species form, e.g., bonded M2+, (MOH+), M(OH)2. With low loading levels up to 40% was displaced by salt solutions; with 1 to 2 μ mol sorbed, as little as 10% was displaced by acids or complex formers but this increased to ~90% with higher loadings. The relationship between sorption pH, amount sorbed, and extraction value was complex, and since in selective extraction schemes classification is based on recovery values, changes in initial retention parameters (e.g. system pH) lead to varying fractions of the different metal ions being classified as "ion exchangeable", "chemisorbed", and "incorporated in the lattice".

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Changes in aggregate stability and associated organic matter properties after direct drilling and ploughing on some Australian soils

Soil Research ◽

10.1071/sr9800027 ◽

1980 ◽

Vol 18 (1) ◽

pp. 27 ◽

Cited By ~ 35

Author(s):

AP Hamblin

Keyword(s):

Metal Ions ◽

Aggregate Stability ◽

Selective Extraction ◽

Continuous Cropping ◽

Neutral Salt ◽

Structural Improvement ◽

Trivalent Metal Ions ◽

Direct Drilling ◽

The Stability ◽

Humic Fractions

After 3-8 years' continuous cropping with conventional cultivation and direct drilling, five Australian soils were examined for changes in structural stability attributable to tillage methods. Some increase in organic carbon was found in four direct drilled soils, and the proportion of carbon in the greater than 2 �m fractions was also higher in these soils after short ultrasonic treatment. Direct drilled soils had significantly greater stability with at least one of the stability tests used, but no soil showed consistently greater stability to five different tests. One direct drilled soil was more stable than its ploughed equivalent after alkaline and neutral salt extraction of metal ions and associated humic substances. One direct drilled soil was more dispersed by polysaccharide extraction. Three direct drilled soils retained greater stability after selective extraction of trivalent metal ions complexed to humic fractions. Structural improvement takes place in Australian soils after several years of direct drilling, but may be at a slower rate and to a lesser extent than has been reported for wetter environments.

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