Method for producing sorbent for wastewater treatment from multicomponent contaminants

Abstract

FIELD: sorption water purification.SUBSTANCE: present invention relates to a method for producing a sorbent for purifying wastewater from multi-component contaminants, in particular mixing crushed flask with additional components to form a plastic mass, granulating the mass, drying, cooling, washing with water and re-drying under natural conditions. The method is characterized in that a flask with a particle size of 0.01-1 mm is used, a finely dispersed sorption filler in the form of tobacco dust and a suspension of bentonite clay on a water basis is used as additional components with a mass ratio of bentonite clay:water equal to 3:5, and the resulting granules are subjected to chemical treatment with a 5 wt.% solution of sulfuric acid and heat treatment at a temperature of 750-900 °C.EFFECT: increasing the sorption capacity and simplifying the process of manufacturing the sorbent.1 cl, 1 tbl, 2 ex

Description

[0001] The present invention relates to the field of sorption water purification, namely to the production of sorbents, and can be used to purify wastewater from various industrial plants from multicomponent contaminants.

[0002] A method for producing a sorbent is known (patent RU 2548409, IPC B01J 20 / 12, B01J 20 / 30, published 04 / 20 / 2015), which includes mixing bentonite clay pre-activated with a solution of sodium salt and crushed paraffin at a temperature of 60-70°C for 20 minutes and forming particles of 2-5 mm in size by stirring the mass at room temperature with an anchor stirrer at a rotation speed of 50-60 rpm.

[0003] The disadvantage of this method is its narrow scope of application – only for additional water purification.

[0004] A method for producing a granulated nanosorbent is known (patent RU 2428249, IPC B01J 20 / 20, B01J 20 / 16, B82B 3 / 00, published on 13.07.2009), which includes mixing bentonite clay, glauconite, thermally expanded carbon with the subsequent addition of water until a plastic mass is formed, granulating the mass, heat treatment of the obtained granules, including drying the granules with infrared radiation at a temperature of 70-150 ° C and microwave heating of the granules, preliminarily placed in a closed heat-insulating volume made of quartz ceramics, to a temperature of no more than 1000 ° C, and subsequent cooling of the granules by blowing with an air flow at a temperature of 15-25 ° C.

[0005] The disadvantages of this method are the need to create excess pressure, increased requirements for the tightness of the equipment, and the need to maintain a high processing temperature.

[0006] The closest method is for producing a sorbent for purifying natural and waste water (patent RU 2399412, IPC B01J 20 / 16, B01J 20 / 30, published on 20.09.2010), which includes mixing 1 kg of flask crushed to a size of 0.001 mm in diameter, 0.2 kg of finely ground cation exchanger KU-2-8, 0.2 kg of finely ground anion exchanger AV-17, 1 kg of Portland cement-500 and 1.5 kg of 10% sodium chloride solution until a dough-like mass is obtained, which is passed through a screw grinder, and the resulting “sausages” are dried, treated with live steam at 180 ° C until completely set and kept in running water until a negative reaction to chloride ions.

[0007] The disadvantages of this process are the relatively low capacity for organic matter and the complexity of manufacture.

[0008] The objective of the invention is to develop a technologically optimized method for obtaining a highly effective sorbent from tobacco production waste.

[0009] The technical result consists in increasing the sorption capacity and simplifying the sorbent manufacturing process.

[0010] The said technical result is achieved by the fact that in the method for producing a sorbent for purifying wastewater from multi-component contaminants, which includes mixing crushed flask with additional components until a plastic mass is formed, granulating the mass, drying, cooling, rinsing with water and re-drying under natural conditions, a flask with a particle size of 0.01-1 mm is used, as additional components a finely dispersed sorption filler is used - cellulose-containing waste from tobacco production of plant origin in the form of tobacco dust, and a suspension of bentonite clay on a water basis with a mass ratio of bentonite clay: water equal to 3:5, and the resulting granules are subjected to chemical treatment with a 5 wt.% solution of sulfuric acid and heat treatment at a temperature of 750-900 °C.

[0011] The essence of the method consists of mixing the initial finely dispersed sorption fillers with the subsequent addition of a binder, evaporation of moisture until a plastic mass is formed, granulation of the mass, drying, chemical and thermal treatment of the resulting granules, followed by their cooling.

[0012] The binder used is a water-based suspension of bentonite clay with a montmorillonite content of 35-55% by weight with a bentonite clay:water mass ratio of 3:5 and a humidity of no more than 85%.

[0013] Cellulose-containing waste from tobacco production of plant origin in the form of tobacco dust is used as finely dispersed sorption fillers, with mixing being carried out until a plastic mass is formed with a moisture content of no more than 48% and a composition of 45-70 wt.% tobacco dust, as well as 15-30 wt.% finely ground opoka with a size of no more than 0.01-1 mm, which is a marine sedimentary siliceous rock of Cretaceous-Paleogene age, 15-25 wt.% suspension of bentonite clay containing montmorillonite.

[0014] The formed plastic mass is granulated by pressing through dies of 1...3 mm in size, the resulting granules with a diameter of 1...3 mm and a length of 4...7 mm are dried at a temperature of 20...50 °C for 24 hours, then treated with a modifier solution for 45-60 minutes, which is a 5 wt.% sulfuric acid solution, and then heat treated by calcination at a temperature of 750-900 °C for 140-240 minutes.

[0015] After the sorbent has cooled naturally, it is washed with water and dried under natural conditions to a residual moisture content of 2-3%.

[0016] The starting component used as a sorbent filler in the production of the sorbent is a large-tonnage waste product from the tobacco industry, the main component of which is cellulose. Cellulose is a natural polymer whose elementary units are C6H. 10 C5- are linked into long linear macromolecules via a glucosidic bond or an -O- oxygen bridge. A characteristic feature of cellulose is the presence of three hydroxyl groups (OH-) in each elementary unit. The functional hydroxyl group is capable of interacting with heavy metal ions, retaining them in the pores and on the surface of the sorbent. Macromolecules of dissolved organic compounds can also be sorbed on the micropore walls.

[0017] The starting component used as a natural binder is a water-based suspension of bentonite clay containing 35-55% by weight of montmorillonite. Bentonite clay is known to possess a number of specific properties due to the montmorillonite it contains: good plasticity and swelling, hydrophilicity, high ion-exchange capacity and sorption capacity, alkalinity due to the structure of the montmorillonite crystal lattice, a large specific surface area, and electrokinetic potential. Montmorillonite, which is part of bentonite clay, is mainly represented by layered silicates of the 2:1 structural type with a swelling crystal lattice. The montmorillonite crystal lattice consists of three layers - two silicon-oxygen layers and one hydroxyl layer. Individual packets of this clay touch planes with identical atoms, and a weak covalent bond arises between them, as in the tetrahedral layer of Si 4+can be replaced by Al 3+ Up to 15%, silicon can be replaced by phosphorus, and in the octahedral lattice, aluminum is replaced by magnesium, iron, zinc, nickel, lithium, etc. This reduces the positive charge of the lattice, resulting in an excess of negative charges. The negative charge can be balanced by exchangeable metal cations, which easily enter the interlayer space, resulting in significant cation exchange capacity (up to 1.5 mmol eq / g). Sodium, calcium, and magnesium ions can penetrate the interlayer space. The high binding capacity of bentonite clay, which includes montmorillonite, is explained by the fact that when it is moistened, water molecules easily penetrate the interlayer gap, increasing it to 20⋅107 mm or more.

[0018] This marine sedimentary chert of Cretaceous-Paleogene age consists primarily of silicon dioxide and calcium carbonate. Microscopic examination revealed that it is rich in organic silica. Other main components include calcite, quartz, clay minerals, and amorphous silicon dioxide. High-temperature firing not only activates the raw material's sorption capacity by removing moisture from its internal pores but also burns out organic matter and any contaminants that may be present in the raw material, reducing bulk density and increasing overall porosity.

[0019] Finely ground opoka powder with a size of 0.01-1 mm will be the basis for the formation of sorbent granules and also allows to increase the strength characteristics of the sorbent.

[0020] The main sorption properties of the composite granular sorbent are determined by the thermophysical parameters of the activation process with a modifier solution and carbonization (acid and temperature treatment, residence time of the activated material in the acid and furnace). These granules are obtained from plant waste—tobacco dust, screened suspensions of bentonite clay with a water-based montmorillonite content of 35-5% by weight. A characteristic feature of industrial adsorbents is their large micropore volume, the walls of which absorb the majority of the adsorbed substance. Therefore, micropores play a crucial role in the adsorption of dissolved substances.

[0021] It has been established that during acid and heat treatment, carbonization of tobacco dust occurs, followed by enrichment of clay with carbon and other pyrolysis products, as well as partial chamotization of clay and transformation of montmorillonite into metamontmorillonite in the form of dehydroxylated montmorillonite residue, while under thermal exposure. After chemical activation of the obtained granules with sulfuric acid and subsequent heat treatment at a temperature of 750-900 °C, dehydration and incomplete dehydroxylation of montmorillonite and illite occur, decomposition of cellulose contained in tobacco dust, resulting in the release of carbon dioxide, organic resins and water vapor, followed by combustion of organic substances contained in the original components, the release of combustible substances (methane, carbon monoxide, hydrogen), coke formation, dehydroxylation of layered silicates, and the formation of a micromesoporous sorbent structure.If the process is carried out below 750°C, only partial combustion of carbon is observed.

[0022] The minerals that make up the bentonite clay with a montmorillonite content of 35-55 wt.% cover the particles of carbonized tobacco dust, resulting in the enrichment of the surface of the montmorillonite crystal lattice with carbon, which leads to the formation of a material with a graphite-like disordered structure with increased porosity in comparison with the prototype, which ensures an increase in the sorption properties of the proposed sorbent.

[0023] After the carbonization process is completed, the resulting sorbent is cooled, washed with water and then dried under natural conditions to a residual moisture content of 2-3%.

[0024] The efficiency of wastewater treatment by the obtained sorbent is shown in Table 1.

[0025] Table 1

[0026] Pollutant Initial concentration, mg / l After the adsorber with the sorbent according to example 1, mg / l After the adsorber with the sorbent according to example 2, mg / l Petrol 5 0,25 0,2 Fats 8 0,5 0,7 Alamin 20 0,8 1 Zn2+ 0,5 0,05 0,16

[0027] Example 1

[0028] The initial raw materials were taken at a mass ratio, wt.%, equal to: tobacco dust - 45, finely ground flask with a size of 0.01-1 mm - 30%, bentonite clay suspension - 25%, then mixed until a plastic mass with a moisture content of no more than 48% was formed, the formed plastic mass was granulated by pressing through dies of a given size, the resulting granules with a diameter of 1-3 mm and a length of 4-7 mm were dried at room temperature for 24 hours, then the resulting sorbent was subjected to acid treatment with a 5% sulfuric acid solution for 40 minutes, after which the sorbent was heat treated by calcination at a temperature of 900 ° C for 240 minutes, the resulting sorbent was brought to readiness by cooling to ambient temperature, after which it was washed with water until free sulfate ions were washed out and subsequent drying under natural conditions to a residual moisture content of 2%.

[0029] Values ​​of the maximum sorption capacity of the sorbent manufactured according to example 1:

[0030] butanol – 30 mg / g;

[0031] hydroquinone - 28 mg / g;

[0032] iron - 32 mg / g;

[0033] copper – 48 mg / g.

[0034] Wastewater in the amount of 8 liters was passed in a downward flow through a filter column with a sorbent loading of 100 cm 3 at a rate of 5 l / h⋅dm 3 .

[0035] The results of the sorbent tests are presented in Table 1.

[0036] Example 2

[0037] The initial raw materials were taken at a mass ratio, wt.%, equal to: tobacco dust - 70, finely ground flask with a size of 0.01-1 mm - 15%, bentonite clay suspension - 15%, then mixing was carried out until a plastic mass with a moisture content of no more than 48% was formed, the formed plastic mass was granulated by pressing through dies of a given size, the resulting granules with a diameter of 1-3 mm and a length of 4-7 mm were dried at room temperature for 24 hours, then the resulting sorbent was subjected to acid treatment with a 5% solution of sulfuric acid for 60 minutes, after which the sorbent was heat treated by calcination at a temperature of 750 ° C for 140 minutes, the resulting sorbent was brought to readiness by cooling to ambient temperature, after which it was washed with water until free sulfate ions were washed out and subsequent drying under natural conditions to a residual moisture content of 3%.

[0038] Values ​​of the maximum sorption capacity of the sorbent manufactured according to example 2:

[0039] butanol – 34 mg / g;

[0040] hydroquinone - 20 mg / g;

[0041] iron - 18 mg / g;

[0042] copper – 29 mg / g.

[0043] Wastewater in the amount of 8 liters was passed in a downward flow through a filter column with a sorbent loading of 100 cm 3 at a rate of 5 l / h⋅dm 3 .

[0044] The results of the sorbent tests are presented in Table 1:

[0045] Thus, the method for producing a sorbent for purifying wastewater from multi-component contaminants, including mixing crushed flask with a particle size of 0.01-1 mm, a finely dispersed sorption filler - cellulose-containing waste from tobacco production of plant origin in the form of tobacco dust, and a water-based suspension of bentonite clay with a mass ratio of bentonite clay: water equal to 3:5, until a plastic mass is formed, granulating the mass, drying, cooling, washing with water, chemical treatment with a 5 wt.% solution of sulfuric acid, heat treatment at a temperature of 750-900 °C, repeated washing with water and drying under natural conditions, provides an increase in the sorption capacity and simplifies the process of manufacturing the sorbent.

Claims

A method for producing a sorbent for purifying wastewater from multi-component contaminants, including mixing crushed flask with additional components until a plastic mass is formed, granulating the mass, drying, cooling, rinsing with water and re-drying under natural conditions, characterized in that flask with a particle size of 0.01-1 mm is used, and as additional components a finely dispersed sorption filler is used - cellulose-containing waste from tobacco production of plant origin in the form of tobacco dust and a suspension of bentonite clay on a water basis with a mass ratio of bentonite clay: water equal to 3:5, and the resulting granules are subjected to chemical treatment with a 5 wt.% solution of sulfuric acid and heat treatment at a temperature of 750-900°C.