RU2800460C1 - Iron-magnesium composite for wastewater treatment - Google Patents

Abstract

FIELD: environmental protection.

SUBSTANCE: invention is aimed at making products from industrial waste in order to clean waste from heavy metal ions. An iron-magnesium composite composition for wastewater treatment is presented, characterized in that it comprises a mixture of iron-magnesium waste with diatomite as a sorbent in the following ratio of components in the mixture, wt %: iron-magnesium waste 95-97; diatomite 3-5.

EFFECT: invention provides creation of a composite composition based on iron-magnesium production waste having the ability to actively neutralize heavy metal ions (Cu²⁺, Zn²⁺, Fe³⁺, Mg²⁺) from industrial waste water.

7 cl, 7 dwg, 6 tbl, 1 ex

Description

The invention relates to the protection of the environment, the technical solution of which is aimed at obtaining products from industrial waste in order to clean waste from heavy metal ions.

A known method for producing an alkaline aluminosilicate sorbent includes processing coarsely ground clayey rock with natural moisture, lime or its mixture with sodium carbonate at a weight ratio of clay rock to lime, equal to from 1:0.25 to 1:1, with continuous stirring until dry uniformity is achieved. mixture and ensuring the flow of an exothermic reaction, followed by exposure of the resulting product for 1-3 hours until it cools down. The invention simplifies the technology and provides a sorbent with a long shelf life [US Pat. RU 2409417 C2, 02.11.2006].

A known method for the production of a sorbent of heavy metals and other pollutants based on clay rocks, the technical essence of which lies in the treatment of sedimentary, for example, aluminosilicate rocks, with chemical reagents to obtain a viscoplastic mass, characterized in that the aluminosilicate rock is treated with an acidic reagent for 0.5-1 h , after which it is neutralized with an alkaline reagent to pH 12-14 with the simultaneous introduction of peptizing additives, while the treatment with acidic and alkaline reagents is carried out at normal or elevated temperatures up to 150°C and pressure up to 5 at. [Pat. RU 2096081 C2, 13.04. 1993].

A known method for producing a magnetic composite sorbent includes deposition on the surface of wood fiber, which is a waste product of the production of MDF boards, particles of magnetite. The precipitation process is carried out with ammonia water from a solution containing a mixture of ferric and ferrous chlorides, under the influence of ultrasonic vibrations with a frequency of 35 kHz at a temperature of 25±5°C. The mass ratio of wood fiber waste, FeCl ₃ and FeCl ₂ is 10:2, 23:0.99. The product obtained is washed with water and dried in vacuo at 110°C. EFFECT: invention makes it possible to obtain an effective sorbent for the joint extraction of heavy metal ions and oil products from wastewater. [Pat. RU 2626363 C1, 06/21/2016].

Known sorbent containing a polymeric binder in the form of humic acids and a magnetic filler-magnetite. Magnetite particles have a size of 7-30 nm. The mass ratio of magnetite to humic acids is from 1:4 to 4:1. The resulting product has magnetic properties and increased sorption capacity. The efficiency of purification of natural aquatic environments from contaminants obtained by the sorbent depends on the type of contaminants and is 97-100% [US Pat. RU 2547496 C2, 07/10/2012].

A known method of obtaining a granular composite humic sorbent of heavy metals on a mineral carrier, including the treatment of the mineral carrier with an aqueous suspension of humic acids at the rate of 0.5-10.0 wt. % of humic acids on the dry matter of the carrier, characterized in that crushed stone-like expanded clay with a granule size of 1-10 mm is used as a mineral carrier, humic acids with a pH _of 4 are used as humic acids, a suspension of humic acids is added to the carrier in portions, the resulting mixture is kept at room temperature for 3 hours and dried at a temperature not exceeding 60°C. [Pat. BY 10647 C1, 06/30/2008].

Known magnetically separated composite adsorbent material and method for its production, which consists of Fe ₃ O ₄ and activated carbon fiber. The material is an iron oxide nanocomposite fibrous material that uses common organic solvents as the reaction medium and controls synthesis with a simple low temperature solvothermal system. It can be used as magnetic separation adsorbent material to adsorb and purify organic or inorganic pollutants in wastewater. [Pat CN 101940910 A, 10/22/2010].

The listed inventions have a number of significant drawbacks: the need for modification, multicomponent composition and the complexity of their production on an industrial scale.

The closest in technical essence to the claimed invention is a ceramic filter granular material KFGM-7. It is a granule from white, light gray to light pink, ranging in size from 1.5 to 2.5 mm. They are made from kaolin, grade KAH-2, which has unique properties, after granulation, dehydration, and special heat treatment [1-2].

The disadvantages of this method include the complexity and multi-stage production technology, which leads to high energy consumption.

The aim of the invention is to create a composite composition based on iron-magnesium production waste, which has the ability to actively neutralize heavy metal ions (Cu ²⁺ , Zn ²⁺ , Fe ³⁺ , Mg ²⁺ ) from industrial waste water.

As a feedstock for the iron-magnesium composite composition, iron-magnesium production waste was used (Fig. 1), which is a pasty substance of red-brown color and has the following chemical composition (Table 2).

Diatomaceous earth according to TU 5761-001-59266087-2005, humidity not more than 3% (Table 1, Fig. 2) in the form of flour with a fraction of less than 0.1 mm. Diatomite increases the degree of adsorption due to its high porosity and is the fossilized remains of diatoms, more than 80% consists of silica.

Table 1
The chemical composition of diatomite Name of indicator Indicator value _SiO2 content Not less than 82% The content of Al ₂ O ₃ No more than 7% Fe ₂ O ₃ content No more than 4% Humidity No more than 3% Loss on ignition 2.5% - 3.0%

The efficiency of wastewater treatment using an iron-magnesium composite composition was studied on industrial wastewater at pH 2.33, with a zinc content of 50.12 mg/l, cobalt - 1.734 mg/l, and cadmium - 0.2 mg/l, etc. (Table 2 ). Water for research was taken in the summer of 2021 on the territory of the former Kaban 1 mine in the Sverdlovsk region, Verkhne-Turinsky urban district (Fig. 3, 58.445363, 59.627523).

table 2
Elemental composition of the studied materials Material Cu2 ⁺ Mg2 ⁺ Fe3 ⁺ Zn2 ⁺ CD ²⁺ Co2 ⁺ Ni2 ⁺ Ca2 ⁺ K2 ⁺ Wastes of iron-magnesium production, mg/kg 41.25 175000 52000 77.7 0 119.75 3083.05 43211.5 30140 Waste industrial water "Boar 1", mg/l 78.1 322.5 147.71 50.12 0.2 1.734 0.231 33.209 5.267

Iron-magnesium composite composition can be obtained as follows:

The original iron-magnesium waste with a moisture content of not more than 50%, with a fraction size of 0 to 50 mm, is dried at a temperature of 95-105 ° C to a moisture content of not more than 5%, after which the waste is crushed to a fraction of not more than 0.5 mm. Next, diatomite flour is added to the iron-magnesium waste with stirring, with the following ratio of components in the mixture, wt. %: iron-magnesium waste - 95-97; diatomite - 3-5.

Table 3
Characteristics of the iron-magnesium composition Product Bulk density, kg / m ³ Color Humidity, % pH ZHMKS 400-450 Red-brown 3-5 8.0-8.5

Example:

Weighed samples (0.1, 0.2, 0.5, 1, 1.5, and 2 g) were weighed and placed in conical falcon tubes. Industrial waste water, 50 ml in volume, was added to them. Next, the samples were mixed (99 rpm) for 120 minutes using an ELMI RM-1L rotary mixer (ELMI LTD., Latvia). The resulting solutions were filtered using blue ribbon filters.

The concentrations of metal ions in the resulting solutions were determined by atomic absorption in an air-acetylene flame (Varian AA 240 FS, Varian Australia Pty Ltd, Australia). Hanna HI 99121 (Hanna Instruments, Germany) was used to determine pH and temperature.

Ashing of solid samples was carried out in a MARS 5 Digestion Microwave System (CEM Corporation, USA).

The number of ions adsorbed on the surface of the sorbent, COE (mg/g), as well as the degree of extraction of the pollutant from solutions (E, %) were calculated using the following equations:

where SOE - static exchange capacity, mg/g;

g is the weight of the dry sample of the substrate, g;

V is the volume of the model solution added to the sorbent, l;

C _ref - initial concentration of copper ions in solution, mg/l;

C _equal is the equilibrium (residual) concentration of copper ions in the filtrate, which is established in the water after mixing the water and the substrate, mg/l.

E - The degree of extraction of the pollutant from the solution,%,

The results of calculating the indicators of the degree of extraction of pollutants from the solution are given in table. 4.

Equilibrium time is an important parameter when conducting research on wastewater treatment. The adsorption of Cu ²⁺ , Zn ²⁺ , Fe ³⁺ , Mg ²⁺ ions by the iron-magnesium composite was studied in order to determine the necessary equilibrium time.

The elemental composition obtained as a result of the interaction of iron-magnesium composite waste with wastewater is given in Table. 4.

Table data. 4 show the content of metal ions in filtrates in mg/l, for copper these values vary from 5.203 mg/l to 43.19 mg/l, for zinc from 9.055 to 43.01 mg/l, and for iron from 0.0 mg/l to 1.559 mg/l l.

Table 4
The results of the chemical analysis of the obtained filtrates, (0.2 g sample) mg/l No. Contact time, min mg/l pH Cu2 ⁺ Zn2 ⁺ Fe3 ⁺ Mg2 ⁺ 1 5 43.19 43.01 1.559 530.88 4.05 2 10 19.18 39.48 0 539.84 4.1 3 15 17.85 38.48 0 558.4 4.33 4 thirty 16.85 37.52 0 604.24 4.78 5 60 6.745 10.62 0 1016.88 4.89 6 120 5.253 9.61 0 979.04 4.99 7 180 5.203 9.055 0 980 5.01

In FIG. 4 shows the effect of contact time on the degree of removal of Cu ²⁺ , Zn ²⁺ , Fe ³⁺ ions from filtrates using iron-magnesium production waste. We notice that the removal of the studied elements from solutions increases after 60 minutes of interaction with the sorbent and reaches equilibrium at 120 minutes. The exception is the Fe ³⁺ recovery for this element reaches 100% after 10 minutes.

Effect of pH and Sorbent Dosage

pH is the most important environmental factor affecting both the chemical composition of the solution and the efficiency of sorption.

Table 5
The results of the chemical analysis of the obtained filtrates, mg/l No. Hinge, g mg/l pH Cu2 ⁺ Zn2 ⁺ Fe3 ⁺ Mg2 ⁺ 1 0.1 36.832 42.11 0 429.8 4.06 2 0.2 5.981 30.24 0 642.6 4.52 3 0.5 0.093 0.129 0 849.6 5.87 4 1 0.086 0.1006 0 1176.2 6.76 5 1.5 0.08 0.099 0 1539.27 7.37 6 2 0.08 0.1034 0 2153 8.01

The resulting filtrates were measured pH (table. 4-5).

The pH index increases depending on the weight of the sample of the tested sorbent; the larger the sample, the higher the pH of the filtrates (Table 5). This is due to the fact that iron-magnesium production wastes have an alkaline pH - 8.7, so they contain a large amount of magnesium (Fig. 6) and thereby dilute acidic wastewater (pH - 2.33).

The dosage of the sorbent, like pH, is one of the important parameters for sorption. The influence of the weight of the sorbent on the removal of heavy metal ions from wastewater has been studied and shown in Fig. 4 and 5. Indicators of the degree of extraction of the pollutant from the solution (E, %) and static exchange capacity (SOE, mg/g) are given in Table. 6.

Table 6
Contaminant recovery from solution and static volumetric capacity No. Hinge, g E, % SOE, mg/g Cu2 ⁺ Zn2 ⁺ Fe3 ⁺ Cu2 ⁺ Zn2 ⁺ Fe3 ⁺ 1 0.1 52.78 15.78 100 20.58 3.95 74.00 2 0.2 92.33 39.52 100 18.00 4.94 37.00 3 0.5 99.88 99.74 100 7.79 4.99 14.80 4 1 99.89 99.79 100 3.90 2.49 7.40 5 1.5 99.90 99.80 100 2.60 1.66 4.93 6 2 99.90 99.79 100 1.95 1.25 3.70

In FIG. 4, it can be seen that the percentage of removal of metal ions from the solution increases with increasing dosage of the sorbent. The minimum values of the E index (%) were recorded at a sorbent dosage of 0.1 g and are: for copper - 52.78%, zinc - 15.78%, when with an increase in dosage to 0.5 g this indicator increases to: copper - 99.3%, zinc - 99.74% and reach equilibrium. For iron, equilibrium is reached starting from a sample of 0.1 g.

The presented graphs (Fig. 4-5) clearly show a trend towards an increase in the percentage of removal of heavy metal ions from wastewater, the static volumetric capacity decreases with an increase in the dosage of the sorbent (Fig. 7., Table 6). For example, for zinc, the SEC with a sample of 0.1 g is 3.95 mg/g, and with a sample of 2 g it is 1.25 mg/g, for copper for a sample of 0.1 g it is 20.58 mg/g, and decreases to 1, 95 mg/g at a weight of 2 g. This can be explained by the fact that with an increase in the weight of the weight of the sorbent, the number of active adsorption centers that are ready to accept metal ions also increases [3-4], which leads to the fact that the adsorption centers do not have time to be saturated with ions during the process [3-5].

conclusions

As a result of the studies of the iron-magnesium composite composition for wastewater treatment, it can be argued that this composition effectively removes metal ions (Cu ²⁺ , Zn ²⁺ , Fe ³⁺ ) from industrial wastewater and can be used in both mining and and in various filtration systems.

Sources:

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4.V.S. Putilina, I.V. Galitskaya, and T.I. Yuganova, Adsorption of heavy metals by soils and rocks. Characteristics of the sorbent, conditions, parameters and mechanisms of adsorption. Novosibirsk: GPNTB SO RAN, 2009. 155 p.

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Claims (10)

1. Iron-magnesium composite composition for wastewater treatment, characterized in that it contains a mixture of iron-magnesium waste with diatomite as a sorbent in the following ratio of components in the mixture, wt.%: iron-magnesium waste - 95-97; diatomite - 3-5. 2. Iron-magnesium composite composition according to claim 1, characterized in that the size of the iron-magnesium waste fraction is not more than 0.5 mm. 3. Iron-magnesium composite composition according to claim 1, characterized in that diatomite is used in the form of diatomite flour with a fraction size of less than 0.1 mm. 4. Iron-magnesium composite according to claim 1, characterized in that its moisture content is not more than 5%. 5. Iron-magnesium composite according to claim. 1, characterized in that its bulk density is not more than 450 kg/m ³ . 5. Iron-magnesium composite composition according to claim 1, characterized in that the content of Fe ³⁺ in it is not more than 52,000 mg/kg. 6. Iron-magnesium composite composition according to claim 1, characterized in that the content of Mg ²⁺ in it is not more than 175,000 mg/kg. 7. Iron-magnesium composite composition according to claim 1, characterized in that its pH is not more than 8.5.