LV12570B - Method for producing humic acids - Google Patents

Abstract

The present invention relates to the field of producing humic acids from peat by using alkaline extraction of them with potassium carbonate. The amount of peat is treated with oxidising agent giving oxygen during extraction-process. 2,5-10% solution of potassium carbonate is used for extraction at the temperature of 60 to 100 C.

Description

METHOD OF OBTAINING HUMANIC ACID

The invention relates to a process for the production of humic acids from peat by its extraction in an alkaline medium.

Previous methods for extraction of humic acids from peat used peat extraction with alkali metal hydroxides (alkali), which made the implementation of the method more expensive. However, these methods were characterized by the low yield of humic substances, the destruction of humic substances in the presence of an alkaline reagent, but even with significant extraction solvent extraction efficiencies from peat were low, but significant amounts of aggressive wastewater were formed.

Methods are also known for the extraction of / 2 / humic acids from peat by alkali extraction which, in order to increase the yield of the product, involves treating the peat mass at 225-275 ° C with its decomposition product gas atmosphere followed by gasoline and alkali extraction. However, the process is characterized by its complexity, high energy consumption and the use of aggressive substances in high concentrations.

Known methods / 3 / for the separation of oxidised humic substances from peat and other humic substances by treating their alkaline slurries at 100-200 ° C with air oxygen (oxidation), which provides high humic yields but uses high process temperatures and high concentrations the use of an alkaline solution, as well as the sophisticated process performance required by the aeration of the reaction mass at elevated temperature (above the boiling point of the solvent water used) at elevated pressure in an aggressive medium.

The developed humic substances extraction method foresees the extraction of humic substances from peat, but possibly also other humic substances (coal, lignite, iononardite, soil, sediment). In order to increase the yield of humic substances before the extraction of humic substances, it is intended to oxidize the raw material as oxidants using oxidizing compounds in the process, thus ensuring the production of low molecular weight, highly water soluble, oxidized humic substances. The use of oxidizing agents such as hydrogen peroxide, nitric acid, and possibly other compounds that release oxygen during the process (for example, metal peroxides), provides a high degree of oxidation of humic substances, which allows the subsequent extraction process to increase their effective extraction from the feedstock. The presence of the oxidant in solution in the reaction mass upon saturation ensures good contact between the reactants and the formation of an increased humic yield. The increase in process efficiency (increase in humic acid yield) can be achieved with relatively low oxidant concentrations (> 5%), but on the other hand the use of oxidants such as hydrogen peroxide does not lead to waste water contamination since these substances decompose without harmful environmental pollutants. The following humic substances are to be extracted using potassium carbonate solutions at concentrations ranging from 2.5 to 10% by weight of the reaction. Potassium carbonate as an extraction solvent is considerably less aggressive than alkali metal hydroxides, which are traditionally used for the extraction of humic substances and thus have a number of technological advantages. At the chosen concentration of potassium carbonate, the entire amount of potassium is used to form potassium salts of highly soluble humic acids, providing rational reagent consumption. On the other hand, the pH of the reaction medium does not exceed 8, which significantly reduces its aggressiveness, simplifies the process and reduces the requirements for the necessary technological equipment. Reducing the aggressiveness of the media used to produce humic acid also improves the environmental friendliness of the extraction process, since the effluent formed is either neutral or requires a minimal amount of reagents to neutralize it. Extraction of humic substances at temperatures up to 100 ° C significantly simplifies the process of extraction of humic substances, allowing it to be carried out at normal pressure while reducing the energy consumption for the production of humic substances. After the peat extraction process, the peat mass is separated using known separation methods (filtration, centrifugation, decantation, etc.). This results in a peat mass saturated with potassium salts and pH close to neutral (pH 7-8.5), which can thus either be treated in the same way as treatment plant sludge or directly used to improve acidic soils. The resulting high concentration humic acid solution (ΙΟΙ 8%) can be used directly as a humic acid concentrate as its pH is basically neutral and can be evaporated using known methods (spray drying, lyophilization, evaporation under vacuum, evaporation) to obtain humic potassium salts , in solid form, characterized by high water solubility and a wide range of applications. From the humic extract, humic acids are high purity preparations, which can be isolated by known methods, for example or by acidification to pH 2 and precipitated as free acids, or can be liberated using ion exchange resins. The resulting oxidized humic acid preparations are characterized by high stability over time, good water solubility, high oxidation rate, high content of carboxyl groups. The final product, when converted to carbon, yields not less than 70%.

Examples

10.0 g of peat are treated with 50 ml of oxidant solution at room temperature, then potassium carbonate solution is added and treated at elevated temperature. The resulting mass is filtered. Peat mass, pH 6.5-8.5, which can be used for soil improvement or added to municipal waste, but the filtrate is evaporated to obtain the potassium salt of humic acids or acidified to pH 6N with HCl

2. The resulting humic acids are rinsed with distilled water on the filter and dried.

Oscillator Oxidizer concentration,% K ₂ CO ₃ concentration,% T, ^U C % Yield of humic acid * H ₂ O ₂ 5 5 80 72 h ₂ o ₂ 10th 5 80 78 h ₂ o ₂ 15th 5 80 90 hno ₃ 5 5 80 73 hno ₃ 10th 5 80 79 h ₂ o ₂ 5 2.5 80 73 h ₂ o ₂ 5 10th 80 92 h ₂ o ₂ 5 5 60 72 h ₂ o ₂ 5 5 100 93 * - Yield% of total humic substances d in the raw material

Literature

1. Swift R.S. Organic matter characterization pp. 1018-1020 In: D.L.Sparks et al (eds) Methods of Soil Analysis Part 3. Chemical methods. Soil Sci. Am. Book Series: 5, Soil. Sci. Soc. Am. Madison, Wl

2. USSR Author Certificate 1509393, C 10 F 9/00; C 07 C 63/33; C 10 G 73/00, publ. September 23, 1989

3. European Patent EP 0786 491 A2 to Lebo S.E., Wirtz, K.R., Dickman S.L. Production of oxidized humic acids by an exogenous-alkaline process Cl C08H 5/00, publ. 7/30/1997., Prototype.

Claims (1)

Formula of the Invention A process for extracting humic acid from peat using its extraction in an alkaline medium with potassium carbonate, characterized in that to simplify the extraction process and to reduce the formation of environmental contamination, the peat mass prior to extraction is treated with an oxidizing agent which liberates -10% potassium carbonate solution at a temperature of 60-100 ° C.