RU2495829C1 - Method of producing water-soluble reagent for purifying natural and waste water (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to biotechnology. Disclosed are methods of producing a reagent, having both coagulant and flocculant properties (versions). In one version, the method involves reacting a liquid colloidal solution of aluminium hydroxochloride with dynamic viscosity of 50-80 Pa∙s with chitosan, while simultaneously adding AG grade aluminium until achieving dynamic viscosity of 90-180 Pa∙s. In another version, the method involves reacting aluminium hydroxochloride solution with dynamic viscosity of 90-180 Pa∙s with chitosan. In both cases, the weight ratio of aluminium hydroxochloride to chitosan is 1:(0.01-0.20).

EFFECT: invention enables to obtain a water-soluble reagent for purifying natural and waste water, which does not contain toxic, flammable and explosive substances, has high coagulation and flocculation activity, enables to efficiently eliminate ions of d-elements from the treated system and also has disinfectant properties.

2 cl, 1 tbl, 1 dwg, 2 ex

Description

The invention relates to methods for producing a reagent having the properties of both a coagulant and a flocculant. This reagent can be used to purify natural and waste water from suspensions, oil products, dissolved organic and inorganic substances, from heavy metal ions and has a disinfecting effect.

A known method of producing aluminum hydroxochloride (GOHA) by reacting aluminum with hydrochloric acid of various concentrations (AS USSR No. 618343, MKI C01F 7/56, 1978), as well as its use as a coagulant for the treatment of natural and waste waters (A. S. Kulyasova, T.N. Fomicheva, ZhPKh, 1997.V. 70. S.371-374).

A known method of producing polyacrylamide (PAA) by polymerization of an aqueous solution of acrylamide (AA) by radical initiators (MN Savitskaya, ZHPH, 1959. T. 32. S.1797).

These products have either only coagulation properties (GOA) or flocculation (PAA) and cannot be used independently, for example, for the treatment of low-turbid waters. In this case, the combined action of the coagulant and flocculant is necessary. The use of two ingredients requires their separate introduction into the purified water. In this case, the coagulant is first administered, and after 15-20 minutes, the flocculant. However, when flocculant is added due to vigorous stirring, the “network” is destroyed, which is a structure of GOHA hydrolysis products, which, during sedimentation, traps impurities and purifies water as a moving membrane, which can cause stabilization of the system. That is, a stable disperse system can be formed again from the products of GOX hydrolysis, and this leads to a sharp decrease in the degree of water purification.

The closest in technical essence to the proposed method is a method of producing a reagent having the properties of both a flocculant and a coagulant, including the radical polymerization of acrylamide in the presence of an initiating system in a solution of aluminum hydroxochloride (RF Patent No. 2174105, CL C02F 1/52, publ. 27.09. 2001, bull. No. 27).

The reasons that impede the achievement of the required technical result when using known methods include the following:

firstly, the separate introduction of a coagulant and a flocculant into the system to be cleaned due to double mixing leads to a decrease in the size of floccules from GOHA hydrolysis products, which are difficult to settle in sedimentation tanks, which reduces the performance of the filters;

secondly, acrylamide used according to the prototype is fire and explosive, and also toxic - it affects the nervous system, kidneys, liver, irritates the mucous membranes;

thirdly, organic peroxides, in particular used in the prototype as the initiating system oxyalkyl-tert-butyl peroxide, also refers to fire and explosive substances. When working with it, serious safety measures must be observed: do not leave it in the open air, prevent the product from heating above 50 ° C, avoid contact with acids, alkalis and metal salts of variable valency, which requires additional costs during its storage;

fourthly, hydroxyalkyl peroxide, when it is not completely decomposed during the polymerization, pollutes the purified water with unhealthy components;

fifthly, the reagent obtained from the prototype only slightly removes heavy metal ions from the system being cleaned.

The present invention solves the important task of developing a cost-effective method for producing a complex reagent with the properties of both a coagulant and a flocculant, which is used to purify natural and wastewater from suspensions, oil products, dissolved organic and inorganic substances, heavy metals, as well as compaction of sediments.

When implementing the proposed method for producing a reagent, the following technical result is obtained:

firstly, the reagent obtained, unlike the prototype, does not contain toxic, fire and explosive substances, which simplifies the technology of its synthesis, storage and use;

secondly, the resulting product has a higher coagulation-flocculation activity due to the highly branched structure of the flakes formed during the hydrolysis of this complex reagent, which increases the speed and degree of purification;

thirdly, the obtained reagent, in contrast to the prototype, can effectively remove ions of d-elements from the system being cleaned, in particular, iron cations;

fourthly, the resulting product, due to the presence of chitosan in it, has good disinfectant properties, which is important for producing drinking-quality water.

The specified technical result in the implementation of the invention according to the first embodiment is achieved in a method for producing a water-soluble reagent for purification of natural and waste waters using an aluminum hydrochloride solution by taking a liquid colloidal aluminum hydrochloride solution with a dynamic viscosity of 50-80 Pa · s and reacting with chitosan with the simultaneous addition of aluminum-containing raw materials to achieve a dynamic viscosity of 90-180 Pa · s with a mass ratio of aluminum hydroxochloride and chitosan 1: (0,01-0, twenty).

The specified technical result in the implementation of the invention according to the second embodiment is achieved in a method for producing a water-soluble reagent for purification of natural and waste waters using an aluminum hydroxide chloride solution by taking a liquid colloidal aluminum hydroxide chloride solution with a dynamic viscosity of 90-180 Pa · s and reacting with chitosan at their mass ratio is 1: (0.01-0.20).

The chitosan polyaminosaccharide used as a flocculating agent is a natural high molecular weight biopolymer. Russia has significant reserves of raw materials for the production of chitosan - crabs, shrimp, krill, gammarus, etc. (Chitin and chitosan: production, properties and applications / Edited by K.G. Skryabin, G.A. Vikhoreva, V.P. Varlamova . - M .: Nauka, 2002 .-- 368 p.). When it interacts with polymeric GOHA [Al ₂ (OH) ₅ Cl], a complex reagent is formed as a result of the fact that one part of the chitosan macromolecule fragments binds to the metal core of GOHA, and the other remains free, being in the solution in the form of “tails” and “loops” "Capable of forming polymer bridges between adjacent flakes. This leads to a more branched structure of the flakes of the complex reagent during its hydrolysis, which increases the coagulation-flocculation activity of the claimed product. Thus, the speed and degree of cleaning of objects increases. The resulting product is easy to tablet, which is convenient for individual use in extreme conditions for drinking water.

The method is as follows.

Chloroaluminous coagulant is obtained by the interaction of aluminum-containing raw materials (aluminum production waste, rolled sheet scrap, etc.) with hydrochloric acid (Patent Ru No. 225898 MKI C01F 7/00, 7/58, publ. 10.07.05, bull. No. 19). Chitosan polyaminosaccharide is added to the solution either at the stage of GOHA synthesis (first option) or added to the finished GOHA (second option).

The invention is illustrated by the following examples.

EXAMPLE 1. In this example, obtaining a complex reagent according to the first embodiment.

In a 1.5 L three-necked reaction flask equipped with a thermometer and a reflux condenser for collecting reaction gases, 800 ml of 10% hydrochloric acid were added and granulated aluminum was added in portions. In this example, aluminum grade AG TU 48-0107-95-90 is used. The reaction immediately begins to proceed very rapidly, with the release of a large amount of heat, therefore, to maintain the required temperature (70-95 ° C), the granules are loaded in a dosed manner. After about an hour, the reaction rate begins to drop, which is associated with a decrease in the concentration of hydrochloric acid and an increase in the viscosity of the solution. When the viscosity of the solution becomes 50-80 Pa · s, the calculated amount of chitosan is poured into the flask and aluminum is continued to be dosed until the viscosity reaches 90-180 Pa · s.

EXAMPLE 2. In this example, the preparation of the complex reagent according to the second embodiment is caused.

In a flask with a capacity of 200 ml make 100 ml GOHA with a viscosity of 90-180 Pa-s, prepared from aluminum grade AG TU 48-0107-95-90. Then add various amounts of chitosan powder according to table 1. The components are mixed and left for 2-3 hours for swelling and subsequent dissolution of chitosan.

Both in the first and in the second embodiment, reagent samples are obtained with an Al ³⁺ content of 10.5-12.3% and a pH of 4.4-4.6. Moreover, the mass ratio of GOA: chitosan in the finished product is 1: (0.01-0.20). The choice of the range of concentrations of introduced chitosan is limited by the upper and lower limits to the rate of deposition of flakes and the degree of purification (see table 1).

Several complex reagents with varying concentrations of active substances were obtained and comparative tests of their coagulation activity on model and real systems were carried out.

To exclude the influence of extraneous factors, for a preliminary assessment of the coagulating properties of the claimed product and comparison of these parameters with the prototype under the same conditions, a model kaolin dispersion with a concentration of the dispersion phase of 0.5% is used. This dispersion is prepared from kaolin and tap water, and then kept for 3 hours to swell. The kinetics of sedimentation is determined on a torsion balance, experiments are carried out at room temperature.

The figure shows the comparative kinetic curves of kaolin sedimentation when processing the model system with a pure GOHA coagulant, as well as complex reagents based on modified GOHA: GOXA + PAA (prototype) and GOXA + chitosan (claimed product). The dose of all reagents for Al (III) is 2.56 mg / L. For a better distribution of reagents throughout the system, they are pre-diluted with water 10-15 times, getting a working solution.

First of all, the high efficiency of both the GOX coagulant and its mixture with organic flocculants should be noted: the introduction of very small doses of these reagents (0.5-1.0 ml / l) leads to a sharp increase in the particle deposition rate compared to the blank experiment in the absence of reagents. However, various coagulation activity of the studied reagents is clearly visible. The angle of inclination of the sedimentation curve for the inventive reagent is significantly higher, which indicates the acceleration of the deposition process in this case. The bulk of kaolin after processing the suspension with pure GOA and GOA with PAA settles in the first 4-5 minutes, while for GOA with chitosan this parameter is only 1.5-2 minutes, that is, the deposition rate increased by 2.5 times. Such a high activity of the process is explained by the formation of large agglomerates from particles of the solid phase of the suspension and products of the hydrolysis of the complex reagent (GOXA + chitosan) having a very branched structure, which allows such particles to settle much faster under the influence of gravitational forces.

The results of sedimentation analysis are in good agreement with the data on the performance of each reagent on a real system. Table 1 presents the results of studies that were conducted on the effluents of a pipe plant using a reagent obtained according to the first and second options. The initial wastewater used in this series of experiments has the following parameters: chemical oxygen demand (COD) - 581 mg O ₂ / l, suspended solids - 432 mg / l, pH - 5.6, total iron content (Fe ²⁺ , Fe ³⁺ ) - 51.8 mg / L. The concentration of administered AHOC and the prototype reagent was chosen for the maximum degree of purification and is the base material for pure Al ³⁺ AHOC 45.6 mg / l, and the reagent (AHOC PAA +) - 31.8 mg / l. The concentration of the claimed reagent (GOA + chitosan) for Al ³⁺ was much lower - 11.2 mg / L.

The table shows that the use of complex reagents with both PAA and chitosan can improve effluent treatment compared to pure GOA. However, the modification of GOX with a flocculant polyaminosaccharide chitosan at a much lower dosage of Al ³⁺ allows a significantly higher degree of effluent treatment. This is especially true for purification from heavy metal ions, in particular from iron.

If pure GOA and GOA with PAA remove only 20-26% of iron ions from the system, then the complex reagent (GOA + chitosan) improves this indicator by 3.5 times. The explanation for this is the high thermodynamic rigidity of polysaccharide macromolecules in comparison with flexible-chain synthetic flocculants, which promotes the formation of bridges with a comparable and even significantly lower molecular weight.

The table clearly shows the optimal concentration range of the GOX modifier - chitosan. High cleaning results in all three parameters were achieved with a mass ratio of GOA: chitosan = 1: (0.01-0.20). A further increase in the mass fraction of chitosan does not lead to any significant improvement in the purification indices; therefore, it is not economically feasible.

Based on the above examples, it follows:

firstly, the method of obtaining a water-soluble reagent, which consists in the interaction of a liquid colloidal solution of GOA with chitosan, allows to obtain an effective product for the purification of natural and waste water with a higher degree and purification rate at a lower concentration of Al ³⁺ than in the prototype;

secondly, the resulting product, unlike the prototype, does not contain toxic, fire and explosive substances, work with which involves additional costs and does not allow using it for water treatment purposes;

thirdly, the resulting product, due to the presence of chitosan in it, has good disinfectant properties, which is important for obtaining drinking-quality water;

fourthly, the reagent obtained, in contrast to the prototype, can effectively remove heavy metal cations from the system being cleaned, in particular, iron cations that can be separated from the sludge for later use.

Table 1 The influence of the composition of the reagent on the degree of purification of effluents of the pipe plant Reagent Composition The ratio of GOA: flocculant, wt.h. COD, mg O ₂ / L Suspended Substances, mg / L The total iron content (Fe ²⁺ , Fe ³⁺ ), mg / l The degree of purification,% COD for suspended solids by iron ions GOX + chitosan 1: 0.005 279 168 40 52 61 23 1: 0.01 122 48 fifteen 79 89 71 1: 0.05 99 thirty eleven 83 93 79 1: 0.10 81 22 10 86 95 81 1: 0.20 64 17 7 89 96 87 1: 0.30 64 13 6 89 97 88 GOHA - 273 181 41 53 58 21 GOX + PAA (prototype) 1: 0.10 209 143 38 64 67 26

Claims (2)

1. A method of obtaining a water-soluble reagent for the purification of natural and waste waters using an aluminum hydroxychloride solution, characterized in that they take a liquid colloidal aluminum hydrochloride solution with a dynamic viscosity of 50-80 Pa · s and react with chitosan while adding AG grade aluminum to achieve dynamic viscosity of 90-180 Pa · s with a mass ratio of aluminum hydroxochloride and chitosan 1: (0,01-0,20). 2. A method of obtaining a water-soluble reagent for the treatment of natural and wastewater using a solution of aluminum hydroxychloride, characterized in that they take a liquid colloidal solution of aluminum hydroxychloride with a dynamic viscosity of 90-180 Pa · s and subjected to interaction with chitosan at a mass ratio of 1: (0 , 01-0.20).

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