RU2447922C1 - Filtration material for cleaning water of iron, manganese and hydrogen sulphide and method of its production - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to water treatment, namely, to cleaning water of iron, manganese and hydrogen sulphide and may be used in downhole water cleaning. Filtration material comprises char rock whereon catalytically active layer is formed containing mix of oxide-hydroxide compounds of manganese: Mn(OH)₂ and Mn₂O₃ and MnO₂ at the weight ratio of (1-0.5):(3-2):(6-5), respectively. Method of producing said material comprises processing said char rock by, at least, two solutions containing manganese salts. First solution contains salts of divalent manganese while second solution represents potassium permanganate. Note here that, prior to processing by potassium permanganate solution, char rock is processed by alkaline solution then, finally, it is processed by solution of reagent that facilitates reduction of manganese (VII) and formation of the mix of manganese oxide compounds on char rock surface.

EFFECT: production of material removing simultaneously iron, manganese and hydrogen sulphide.

5 cl, 8 tbl

Description

The invention relates to the field of water treatment of drinking water, namely, the purification of natural waters from iron, manganese and hydrogen sulfide, and can be used to purify well water.

Russia, and especially a region such as Western Siberia, has significant groundwater reserves, which contain large amounts of iron, manganese and hydrogen sulfide, which prevents the use of such water for drinking needs.

In accordance with the requirements of the Sanitary Norms and Rules, GOST 2.1.4.559-96 and the recommendations of the World Health Organization, the concentration of iron in water should not exceed 0.3 mg / l, manganese 0.1 mg / l, hydrogen sulfide 0.005 mg / l.

The presence of hydrogen sulfide in water gives it an unpleasant odor. Removal of hydrogen sulfide from water can occur both as a result of oxidation of hydrogen sulfide by atmospheric oxygen and catalytic decomposition. Under the influence of strong oxidizing agents, hydrogen sulfide is oxidized to sulfur dioxide or to free sulfur, depending on the conditions: pH of the solution, temperature, concentration of the oxidizing agent.

Currently, filtering media based on natural dispersed materials such as sand, anthracite, sulfonated coal, expanded clay, pyrolusite, as well as filtering materials treated with catalysts that accelerate the oxidation of iron, manganese, and hydrogen sulfide are widely used to purify natural water.

The most widely used filter media with catalytic properties: Manganese Greensand, MTM and MZHF.

The catalytic properties of the above downloads are due to the presence of manganese oxides on the surface of their base (natural granular materials). The mechanism of the catalytic action of manganese oxides is based on the redox processes of iron, manganese and hydrogen sulfide compounds.

To obtain a layer of higher manganese oxides on the surface of natural dispersed materials, as a rule, potassium permanganate solution is used.

Greensand began to be used in the USA from the 20s of the last century as a natural zeolite for softening water by ion exchange, and Manganese Greensand - from the 50s to remove iron, manganese and hydrogen sulfide from water.

Manganese Greensand - glauconite green sand, which is natural sand, covered with manganese compounds [James A. Hunt. A Referevce quide for dealers. Water Conditioning and Purification, May 2001, p. 34].

The manufacturing technology of Manganese Greensand includes pre-treatment of sodium glauconite (Na ₂ Z) with a solution of manganese chloride:

Na ₂ Z + MnCl ₂ <-> MnZ + 2NaCl.

The divalent iron and manganese compounds dissolved in water are oxidized upon contact with higher manganese oxides and are retained on the surface of Manganese Greensand grains. At the same time, hydrogen sulfide is oxidized to free sulfur. Retained impurities are removed from the filler by backwashing.

MTM is a granular filter medium with a catalytic coating of manganese dioxide MnO ₂ . This filler is used to remove iron, manganese and hydrogen sulfide from water.

MZhF - filtering material, which is a product of processing rocks containing dolomite. This is a porous material consisting of a mixture of oxides and carbonates of calcium and magnesium, as well as aluminum and silicon oxides. A catalytic component, manganese dioxide, is fixed in the pores of the filler. MJF, acting as a catalyst, accelerates the oxidation of air oxygen as divalent iron and manganese, hydrogen sulfide.

The disadvantage of the above materials for the removal of manganese salts dissolved in water is the need for pretreatment with potassium permanganate solution before operating these downloads. To restore their oxidizing ability, it is also necessary to use periodic or continuous regeneration with a solution of potassium permanganate or to carry out its constant dosing in water.

A known method of purifying water from compounds of manganese and iron [SU 1546435 A1]. The invention relates to the purification of water by ozonation and can be used in the purification of natural and waste water from iron and manganese. The aim of the invention is to increase the degree of purification, increase the duration of the filter cycle, reduce ozone consumption. To implement the method, the initial water is ozonated in a mode providing a residual ozone concentration of 0.3-0.5 mg / l and filtered through a granular charge, then unzoned water is fed to the charge. As a filter load, a composition is used consisting of a carrier (expanded clay, or zeolite, or quartz sand) - 94-98% and manganese (IV) hydroxide - 2-6 wt.%.

The disadvantage of this filter media is that only manganese (IV) hydroxide is deposited on the surface of the natural material. Such a layer provides water purification only in the presence of ozone, since only in this case is the formation of manganese oxides from hydroxide.

A known filter [JP 11128742 A], comprising a filter medium comprising a porous support and a catalytic layer consisting mainly of manganese oxide hydrate. This filter medium has the same disadvantages as the previous counterpart.

As a prototype for the material and method, a filter material was selected for purifying water from manganese and iron [RU 2275335 C2], containing as a basis a granular material of natural origin, while a catalytically active layer consisting of a mixture of MnO, Mn ₂ oxides was formed on its surface O ₃ and MnO ₂ in their mass ratio, respectively, equal to (5-6) :( 3-2) :( 2-1). The prototype also claimed a method of obtaining a filter material for water purification from manganese and iron, in which the granular material of natural origin is subjected to treatment with a solution of a modifying reagent containing manganese salts, while the treatment is carried out sequentially with two reagents containing manganese ions, while first processing the material a solution containing salts of divalent manganese, and then a solution of potassium permanganate and additionally carry out processing with a reagent solution, posobstvuyuschim recovery of manganese (VII), and formation of a mixture of compounds of manganese oxide on the surface of the particulate material.

This material does not allow the effective removal of hydrogen sulfide from water.

The objective of the invention is to develop a filter material based on natural materials, the so-called filter granular loads with a catalytically active layer based on oxide-hydroxide compounds of manganese.

EFFECT: simultaneous effective oxidation of iron and manganese and redox decomposition of hydrogen sulfide.

The problem is achieved in that, like the well-known, the proposed filter material for purifying water from iron, manganese and hydrogen sulfide contains as a basis a granular material of natural origin, namely burnt rock.

New is the fact that a catalytically active layer containing a mixture of manganese oxide-hydroxide compounds: manganese hydroxide Mn (OH) ₂ and manganese oxides Mn ₂ O ₃ and MnO _{2 is} formed on the surface of the base.

The mass ratio of manganese hydroxide Mn (OH) ₂ and manganese oxides Mn ₂ O ₃ and MnO ₂ in the mixture, respectively, is (1-0.5) :( 3-2) :( 6-5).

The task is also achieved by the fact that, as in the known, in the proposed method for producing filter material for water purification from iron, manganese and hydrogen sulfide, the burned rock is subjected to sequential treatment with at least two solutions containing manganese salts, while first processing burned rock in a solution containing salts of divalent manganese, and then with a solution of potassium permanganate and additionally carry out processing with a solution of a reagent that promotes the restoration of manganese (VII) formation of a mixture of compounds of manganese oxide on the surface of the particulate material.

What is new is that the first solution additionally contains sodium salts, while the burned rock is treated with an alkali solution before being treated with a potassium permanganate solution. As the alkali solution, NaOH and / or KOH are used.

In addition, as the first solution using a mixture of solutions of salts of manganese dichloride (MnCl ₂ ) and sodium sulfate: (Na ₂ SO ₄ ) at their following concentrations, g / l:

manganese dichloride 15-25 sodium sulfate 20-10

As an alkali solution, NaOH at a concentration of 6-10 g / L is used.

In addition, the reduction of manganese permanganate is carried out by processing the material in a solution of 0.1-2.0% sodium sulfite.

The method of processing filter granular charge proposed in this invention, which is used as a burned rock (natural dispersed material with a grain size of 0.1 mm to 40 mm), by modifying reagents containing both manganese compounds of different valencies and additional reagents, allows to obtain on its surface, a complex of not only manganese oxide compounds, but also an additional manganese hydroxide compound.

When implementing the method of the present invention, on the surface of the filter granular charge, for which the rock is selected, a mixture was obtained consisting of manganese hydroxide Mn (OH) ₂ and manganese oxides Mn ₂ O ₃ , MnO ₂ .

It was experimentally established that to remove hydrogen sulfide, a higher total content of manganese oxides and hydroxides on the surface of the burned rock is necessary. The sorption capacity of such a natural form as burned rock, mainly calcium, and it is much lower than sodium. The presence of sodium salts (Na ₂ SO ₄ ) during processing of the charge (burnt rock) in a solution of divalent manganese salt leads to an increase in the sorption capacity of the burnt rock. To obtain samples with the same degree of substitution of exchange cations for Mn ^{2+ ions} for a burnt rock, solutions are required 3-5 times more concentrated than for the Na form (adding Na to the burnt rock allows to obtain a larger amount of the aforementioned Mn compounds on its surface). The complex of these compounds determines the high catalytic activity of the charge with respect to iron, manganese, and hydrogen sulfide dissolved in water.

The process of formation in the inventive method of manganese hydroxide on a rock can be considered in accordance with the following two mechanisms:

I. The equations of sorption of Na ₂ SO ₄ and MnCl _{2 by the} surface of the burned rock with the participation of NaOH:

CaC (burned rock) + Mn ²⁺ → MnC + Ca ²⁺

NaC + Mn ²⁺ → MnC + Na ⁺

MnC + NaOH → Mn (OH) ₂ + NaC

II. And the second mechanism is the mechanism of direct chemical interaction of reagents:

MnCl ₂ + NaOH → Mn (OH) ₂ + NaCl

The appearance, in comparison with the prototype, in the catalytic layer of manganese hydroxide contributes to a more efficient decomposition of hydrogen sulfide while maintaining catalytic activity in relation to various compounds of iron and manganese dissolved in water.

The resulting complex of manganese oxide-hydroxide compounds on the surface of the filter charge interacts with iron compounds dissolved in water to form insoluble compounds that precipitate on the surface of the charge. Oxygen dissolved in water is adsorbed on the loading surface, then it interacts with manganese ions dissolved in water to form the corresponding oxides.

In water, a solution of hydrogen sulfide H ₂ S is a hydrogen sulfide dibasic weak acid. Acids are known to react with bases, basic oxides and salts, in our case, with Mn (OH) ₂ . The increase in the efficiency of water purification from hydrogen sulfide occurs due to the following chemical reactions:

H ₂ S + Mn (OH) ₂ → Mn (HS) ₂ + H ₂ O

Mn (HS) ₂ + Mn (OH) ₂ → MnO ₂ + S + H ₂ O

Thus, hydrogen sulfide is oxidized to elemental sulfur.

As a basis (filter granular load), the present invention proposes the use of such a natural granular material as a "burnt rock", which is approved for use and has a hygienic conclusion on suitability for drinking needs.

In the inventive method, at the first stage, the charge is treated with a solution of a salt of divalent manganese and sodium sulfate in order to deposit ions of divalent manganese and manganese hydroxide on the surface of the charge. At the second stage, the charge is treated with a solution of potassium permanganate in order to replace divalent manganese ions with heptavalent manganese ions. Before treatment with a solution of potassium permagnanate, the burned rock is treated with a solution of alkali NaOH and / or KOH. The reduction of heptavalent manganese ions is carried out at the third stage by treatment with sodium sulfite loading, which leads to the formation of a complex of manganese oxide-hydroxide compounds. Processing the charge with a solution of sodium sulfite also helps to fix these compounds to the surface.

Processing of the filter load can take several hours, which is determined by the nature and dispersion of the filter medium. Solution treatment is recommended to be followed by bubbling or stirring of the filter medium for a more complete deposition of reagents in the pores.

The invention is further illustrated by examples of obtaining a filter medium based on such natural material as burnt rock, and examples of its use for purifying water from iron, manganese and hydrogen sulfide.

Natural material - “burned rock” with a fraction of 0.8-2.0 mm (Kiselevskoye deposit in the Kemerovo region) was washed to remove dust and fine particulate matter.

The “burned rock” thus prepared was treated with a 3.5% solution of a mixture of salts of divalent manganese and sodium sulfate, then treated with a 0.8% alkali solution (NaOH), and then with a 4.0% solution of potassium permanganate. The final charge was treated with a 1.5% sodium sulfite solution.

During processing, air was blown, and the solutions were mixed and pumped through the charge.

Table 1 shows examples of the preparation of filter material with the inventive catalytically active layer at various concentrations of reagents.

In all cases, a layer was obtained containing oxide-hydroxide compounds of manganese, but with different intensities of staining, depending on the amount of precipitated oxide-hydroxide compounds, wt.%:

Table 1 Name Concentration, g / l example 1 example 2 example 3 manganese dichloride fifteen twenty 25 sodium sulfate twenty fifteen 10 caustic soda 6 8 10 potassium permanganate thirty 40 fifty sodium sulfate 10 fifteen twenty ratio of Mn (OH) ₂ : Mn ₂ O ₃ : MnO ₂ 0.5: 2: 5 0.7: 2.5: 5.5 1: 3: 6 staining intensity light beige with a reddish tint brown with a reddish tint dark brown with a reddish tint

Example I. The intensity of the staining - light beige with a reddish tint; the catalytically active layer consists of Mn (OH) ₂ , Mn ₂ O ₃ , MnO ₂ , in a weight ratio (0.5: 2: 5).

Example 2. The intensity of the staining - brown with a reddish tint consists of Mn (OH) ₂ , Mn ₂ O ₃ , MnO ₂ in a weight ratio (0.7: 2.5: 5.5).

Example 3. The intensity of the staining - dark brown with a reddish tint consists of Mn (OH) ₂ , Mn ₂ O ₃ , MnO ₃ with a weight ratio of (1: 3: 6).

The content of the mixture of oxide-hydroxide compounds of manganese is 0.8-1.2% by weight of the base for all examples.

Comparative laboratory studies of the sorption of sulfide ions on the filter material obtained by the prototype and the proposed method were carried out.

Research was conducted under static conditions. Model solutions were prepared by diluting an S ² basic solution with a concentration of 100 mg / L prepared from a GSO of 1000 mg / L sulfide ions. Filter material weighing 0.2000 g was placed in a dry conical flask with a thin section of 250 ml, 100.0 ml of model solution was added there (the ratio of filter material: solution = 1: 500), mixed on a THYS 2 universal vibration machine (Germany) for 60 min, then the solution was separated by decantation and the mass concentration of S ^{2- was} determined according to RD 52.24.450-95 by the extraction-photometric method with N, N-dimethyl-p-phenylenediamine on a PE-5400v spectrophotometer (NPO Ekros, Russia). Conducted 2 parallel measurements. The equilibrium concentration of sulfide ions was determined by the results of a “blank” experiment — a model solution of the same concentration, but without filter material to account for the loss of S ^2– due to volatilization of hydrogen sulfide.

The static exchange capacity was calculated by the equation:

COE = V _sol. (C _equ. -C _con. ) / M _sorb. mg / g

table 2 N C _S ^-2 ex., Mg / l C _S ^-2 equal., Mg / l The filter material of the prototype Suggested filter media C _S ^-2 con, mg / l SOYE, mg / g C _S ^-2 con, mg / l SOYE, mg / g one 0.10 0.015 0.011 0.002 0.007 0.004 2 0.30 0.20 0.13 0,035 0.011 0.0945 3 0.40 0.37 0.22 0,0775 0.012 0.178 four 0.80 0.69 0.38 0.154 0.024 0.333 5 1,0 0.90 0.57 0.164 0,036 0.431 6 1,2 1.17 0.78 0.195 0,097 0.536

From table 2 it follows that the concentration of hydrogen sulfide after sorption on the proposed filter material is less than after sorption on the material prototype in 10-20. The static exchange capacity of the proposed filter material is greater than the corresponding indicator for the material according to the prototype 2-2.7 times.

Below are the comparative results of operational tests of borehole water samples of the enterprise LLC Major + (Tomsk), borehole water of Nizhne-Lugovaya St. (Tomsk) and borehole water of 4 Vavilova St. (Kislovka village, Tomsk region) before and after water purification using the proposed material obtained in example 3.

Table 3 Water sample before cleaning. LLC "Major +", Tomsk No. p / p Item to be defined The result of the analysis, mg / l MPC, mg / l SanPin 2.1.1074-01 Analysis error,% ND on the analysis method one pH 6.65 6-9 ± 0.2 PNDF 14.1: 2: 4.121 2 total iron 67 0.3 ± 25 GOST 4011 3 manganese (II) 2,4 0.1 ± 25 GOST 4974 four permanganate oxidizability 8.5 mg O / L 5.0 mg O / L ± 30 PNDF 14.1: 2: 4.154 5 hydrogen sulfide 0.52 0.005 ± 25 RD 52.24.45

Table 4 Water sample after cleaning. LLC "Major +", Tomsk No. p / p Item to be defined The result of the analysis, mg / l MPC, mg / l SanPin 2.1.1074-01 Analysis error,% ND on the analysis method one pH 6.65 6-9 ± 0.2 PNDF 14.1: 2: 4.121 2 total iron less than 0.05 0.3 ± 25 GOST 4011 3 manganese (II) 0.04 0.1 ± 25 GOST 4974 four permanganate oxidizability 0.6 mg O / L 5.0 mg O / L ± 30 PNDF 14.1: 2: 4.154 5 hydrogen sulfide 0.002 0.005 ± 25 RD 52.24.45

Table 5 Well water sample before treatment. Tomsk district, Kislovka village, 4 Vavilova St. No. p / p Item to be defined The result of the analysis, mg / l MPC, mg / l SanPin 2.1.1074-01 Analysis error,% ND on the analysis method one pH 7.65 6-9 ± 0.2 PNDF 14.1: 2: 4.121 2 total iron 1,5 0.3 ± 25 GOST 4011 3 manganese (II) 0.04 0.1 ± 25 GOST 4974 four permanganate oxidizability 3.6 mg O / L 5.0 mg O / L ± 30 PNDF 14.1: 2: 4.154 5 hydrogen sulfide 0.21 0.005 ± 25 RD 52.24.45

Table 6 Water sample after cleaning. Tomsk district, Kislovka village, 4 Vavilova St. No. p / p Item to be defined The result of the analysis, mg / l MPC, mg / l SanPin 2.1.1074-01 Analysis error,% ND on the analysis method one pH 7.67 6-9 ± 0.2 PNDF 14.1: 2: 4.121 2 total iron 0.1 0.3 ± 25 GOST 4011 3 manganese (II) 0.04 0.1 ± 25 GOST 4974 four permanganate oxidizability 0.6 mg O / L 5.0 mg O / L ± 30 PNDF 14.1: 2: 4.154 5 hydrogen sulfide 0.004 0.005 ± 25 RD 52.24.45

Table 7 Well water sample before cleaning Tomsk, Nizhne-Lugovaya St. No. p / p Item to be defined The result of the analysis, mg / l MPC, mg / l SanPin 2.1.1074-01 Analysis error,% ND on the analysis method one pH 6.45 units pH 6-9 ± 0.2 PNDF 14.1: 2: 4.121 2 total iron 16.5 0.3 ± 25 GOST 4011 3 manganese (II) 9.6 0.1 ± 25 GOST 4974 four permanganate oxidizability 3.6 mg O / L 5.0 mg O / L ± 30 PNDF 14.1: 2: 4.154 5 hydrogen sulfide 0.23 0.005 ± 25 RD 52.24.45

Table 8 Well water sample after treatment, Tomsk, Nizhne-Lugovaya st. No. p / p Item to be defined The result of the analysis, mg / l MPC, mg / l SanPin 2.1.1074-01 Analysis error,% ND on the analysis method one pH 7.10 units pH 6-9 ± 0.2 PNDF 14.1: 2: 4.121 2 total iron 0.18 0.3 ± 25 GOST 4011 3 manganese (II) 0,03 0.1 ± 25 GOST 4974 four permanganate oxidizability 1.02 mg O / L 5.0 mg O / L ± 30 PNDF 14.1: 2: 4.154 5 hydrogen sulfide 0.003 0.005 ± 25 RD 52.24.45

Water analyzes were carried out in accordance with regulatory documents:

GOST 2761-84 Sources of centralized drinking water supply. Hygienic, technical requirements and selection rules.

GOST 4011-72 Drinking water. Methods for measuring the mass concentration of total iron.

GOST 4974-72 Drinking water. Methods for measuring the mass concentration of manganese.

GOST R 51232-98 Drinking water. General requirements for organization and quality control methods.

PNDF 14.1: 2: 4.121-97 Quantitative chemical analysis of water. Procedure for measuring pH in waters by potentiometric method (amend. 1-2001)

PNDF 14.1: 2: 4.154-99 (2004 edition) Quantitative chemical analysis of water. Methodology for measuring permanganate oxidizability in samples of drinking, natural and wastewater.

RD 52.24.450-95 Guidelines. The method of measuring the mass concentration of hydrogen sulfide and sulfides in water by the photometric method with

N, N-dimethyl-p-phenylenediamine.

The advantage of the proposed material, in comparison with the filtering materials existing on the market today for the comprehensive purification of water from iron, manganese and hydrogen sulfide, for example Manganese Greensand, MTM and MZHF, are:

- there is no need for pre-treatment with such strong oxidizing agents as potassium permanganate, ozone or sodium hyposulfite;

- in comparison with MOLF, the material has a solid base, does not cake and does not collapse in water during its long-term operation;

- the technology for obtaining the material is import-substituting, which is reflected, respectively, in its price;

- the material effectively removes iron, manganese and hydrogen sulfide from well water;

- tenfold increase in the decomposition of hydrogen sulfide on the proposed filter material in comparison with the filter material of the prototype.

Claims (5)

1. The filtering material for water purification from iron, manganese and hydrogen sulfide, containing burned rock as a base, characterized in that a catalytically active layer containing a mixture of manganese oxide-hydroxide compounds: manganese hydroxide Mn (OH) ₂ and oxides is formed on the surface of the substrate manganese Mn ₂ O ₃ and MnO ₂ in their mass ratio, respectively, equal to (1-0.5) :( 3-2) :( 6-5). 2. The method of obtaining filter material for water purification from iron, manganese and hydrogen sulfide according to claim 1, in which the burned rock is subjected to sequential treatment with at least two solutions containing manganese salts, the burned rock is first treated in a solution containing divalent salts manganese, and then with a solution of potassium permanganate, and additionally carry out processing with a solution of a reagent that promotes the recovery of manganese (VII) and the formation of a mixture of oxide compounds of manganese on the burned surface rocks, and the first solution additionally contains sodium salts, while before treatment with a solution of potassium permanganate, the burned rock is treated with a solution of alkali NaOH and / or KOH. 3. The method according to claim 2, characterized in that the mixture of solutions of manganese salts of dichloride (MnCl ₂ ) and sodium sulfate (Na ₂ SO ₄ ) is used as the first solution at the following concentrations, g / l:
manganese dichloride 15-25 sodium sulfate 20-10 4. The method according to claim 2 or 3, characterized in that NaOH at a concentration of 6-10 g / L is used as the alkali solution. 5. The method according to claim 2, characterized in that the recovery of manganese permanganate is carried out by treating the burned rock in a solution of 0.1-2.0% sodium sulfite.