EA028334B1 - Method for producing hybrid composite sorbent for wastewater treatment - Google Patents

Abstract

The invention relates to the production of polymer sorbents and can be used for wastewater treatment from different water pollutants, including organic dyes. A method comprises intercalation of butadiene rubber (BR) into interlaminar space of bentonitic clay, modification of BR mixture and bentonite with phosphorus trichloride by oxidative chlorophosphorylation in the presence of oxygen with further hydrolysis of the reaction product. As the result a hydrophobic material is produced due to cross-linking of macromolecules of polymeric matrix, and HCl release at modification using PClprovides bentonite activation and increase of the composite adsorptivity, due to higher aeration of inorganic component. The invention provides to produce a hybrid composite sorbent, having sorption activity relative to the organic dye Rhodamine 6G, the sorptive capacity of the sorbent is 32.2 mg/g.

Description

The invention relates to the field of producing hybrid composites (organic-inorganic nature) based on a polymer matrix of divinyl rubber and layered silicate of bentonite, which can be used as sorbents for purifying water from organic pollutants.

Montmorillonite clay, the main component of bentonite, is the most promising among layered silicates existing in nature, since under certain conditions it is able to exfoliate into separate plates with a thickness of the order of 1 nm and a diameter of 20-250 nm. Intercalation into inorganic layers of montmorillonite is an excellent way of constructing new organic - inorganic nano-assemblies [1].

In the authors' work [2], an amine functionalized composite of the composition polyacrylamide / bentonite / amine was obtained as a result of directed intercalation during polymerization and is used as an adsorbent for wastewater treatment.

In the patent [3], a hybrid material polyacrylate / acrylamide / bentonite was obtained by the method of intercalating copolymerization, with a high ability to retain water, which makes the material highly demanded in various industries, including oil production, agricultural, medical, etc.

The patent [4] describes the process of producing a composite by modifying bentonite with a water-soluble polymer, which makes it possible to obtain a material with high water absorption, which can be used as an agricultural fertilizer, directly as a water source, and also as an additive controlling the fertilizer supply.

To achieve good compatibility of the organic and inorganic components, the filler is activated by various surfactants. As activating surfactants, various amines and ammonium compounds are used. In the method for producing the sorbent [5], radical initiators — ammonium or potassium persulfate — are used to activate the surface of bentonite.

The activation of montmorillonite by guanidine acrylate / methacrylate was disclosed in [6]. The disadvantages of using such compounds to activate the surface of layered aluminosilicates are the high cost, complex manufacturing technology and scarce modifiers.

In the European patent [7], quaternary ammonium salts are used as a modifying additive in the preparation of a nanocomposite based on a hybrid - organoclay.

The Chinese work [8] describes the preparation of an adsorbent based on a bentonite-containing copolymer having a high sorption capacity with respect to organic pollutants and heavy metal ions.

The disadvantage of this method is the need to use a torus asset for bentonite clay.

A known method of producing organomineral cation exchange resin [9], which consists in processing bentonite of the Monrakskoye deposit (in Kazakhstan) 20% Н ₂ §0 ₄ when heated for 6 hours in a water bath. Then, after additional manipulations, including processing with a solution of benzoyl peroxide, vacuum drying and mixing with an aqueous solution of monomer, polymerization is carried out under appropriate conditions to obtain bentonite activated with polyacrylic acid, which exhibits the properties of a weakly acid cation exchanger.

The disadvantage of this method is the treatment of bentonite with an inorganic acid, which destroys the octahedral layers of the clay mineral, contributes to a profound change in the structure and properties, and as a result of dissolution of the oxides of aluminum, magnesium and iron, the H-form of bentonite transforms into the ΑΙ - form, which is accompanied by a loss of activity.

A known method of producing a composite sorbent based on a mixture of methacrylic acid, guanidine and bentonite clay for the purification and disinfection of water [10]. The resulting composition has the properties of an effective filter material, and the ion-exchange properties determine the properties of the polyampholyte polymer, as well as the cation-exchange properties of bentonite clay.

The disadvantages of the method of producing a composite sorbent include the high swelling ability of the sorbent, as well as the scarcity and high cost of the reagents used.

The closest in technical essence to the present invention is a method for producing a composite sorbent based on polyacrylamide and bentonite clay for the extraction of heavy metal ions from waste and industrial waters [11].

A method of obtaining a composite sorbent involves intercalating bentonite clay and acrylamide for 6 hours at a ratio of AA: BG = 10: 1-10 wt.%, Adding potassium persulfate initiator in an amount of 1% of the amount of monomer, and a crosslinking agent - Ν, Ν'- methylene bis acrylamide in an amount of 0.25 wt.%, polymerization for 2 hours at a temperature of 60 ° C, washing and drying. Get a solid composite sorbent with a low degree of swelling, capable of adsorbing heavy metal ions from wastewater and industrial waters. The disadvantages of this method include the need to use a crosslinking agent in order to reduce the swelling of the polymer matrix.

The objective of the present invention is to reduce material consumption, as well as expanding the range of sorbents for wastewater treatment.

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The task is achieved by the fact that butadiene rubber is intercalated into the interlayer space of bentonite clay, the resulting organoclay is modified with PC1 ₃ phosphorus trichloride by oxidative chlorophosphorylation in the presence of oxygen, with further hydrolysis of the reaction product.

This technical solution, in contrast to a close analogue, allows to obtain a hydrophobic material due to the crosslinked structure of the polymer matrix without the use of a crosslinking agent. The invention is illustrated by the following graphic material:

FIG. 1 - laboratory installation for obtaining a hybrid composite sorbent;

FIG. 2 - dependence of C _{d of the} dye on sorption time and temperature (C _o = 43.55 mg / L Κ6Θ, Y = 0.05 L, t = 0.05 g, ΐ = 180 min);

FIG. 3 - dependence of sorption Κ6Θ by the hybrid composite BK + bentonite synthesized in experiment No. 1 on sorption time and temperature (С ₀ = 43.55 mg / L Κ6Θ, Y = 0.05 L, t = 0.05 g, ΐ = 180 min );

FIG. 4 - IR spectrum of a hybrid composite sorbent;

FIG. 5 - IR spectrum of the hybrid composite sorbent after sorption of the dye.

The method is as follows. In a 4-necked round-bottom reaction flask 1 (Fig. 1) equipped with a reflux condenser 2, a mechanical stirrer 3, a thermometer 4 and a bubbler 5, a 2% solution of butadiene rubber (BC) is prepared (SKD rubber, grade II, TU 38.40 3750- . 2001, Voronezh, Russia, performance are presented in Table 1) in CC1 _4, to which was added with stirring the inorganic component - bentonite. The resulting suspension is kept for a day so that the penetration of the polymer solution into the clay layers occurs as fully as possible. Then, blowing the reaction zone with oxygen with an oxygen supply rate of 7 l / h, PC13 (product of Vekton, St. Petersburg) is portioned into the BK / bentonite mixture. After 3 hours, a color change of the reaction medium to dark brown is observed. The oxidative chlorophosphorylation reaction is carried out for 8 hours, after which the heterogenization of the reaction medium is observed with the release of a dark solid phase - the reaction product. After distillation of the liquid phase, including the solvent, unreacted PC1 ₃ and POC1 ₃ (intermediate), the reaction product is hydrolyzed by immersing it in ice-cold distilled water, followed by stirring the mixture for 2 hours at room temperature. Then the modifier is filtered off and washed with distilled water (heated to 30-40 ° C) to a neutral pH. The result is a hydrophobic hybrid polymer composite sorbent, which is a solid powdery mass of dark brown. Oxidative chlorophosphorylation, accompanied by an exothermic effect and the release of gaseous HC1, promotes foaming of the composite on the one hand, and the formation of a spatially network structure (due to interaction with the active centers of the polymer matrix: π - bond, as well as a hydrogen atom in the α-position to the double bond ), with another. Hydrolysis of phospho-dichloride groups resulting from the modification leads to the formation of acid groups, which also contribute to better compatibility of the organic matrix with bentonite. In addition, the released HC1 activates the surface of the clay material, contributing to better homogenization of the organic and inorganic phases, and, ultimately, helps to increase the adsorption capacity due to greater loosening of the inorganic component during modification.

Table 1

Name of indicator skd Mooney viscosity, MB 1 + 4 (100 °) 40-50 Scatter in viscosity within the batch, no more 8 Mass fraction of ash,%, no more 0.3 Mass loss during drying,%, no more 0.8 Conditional tensile strength, MPa (kgf / cm ² ), not less 19.1 (195) Elongation at break,%, not less than 480 Relative residual deformation after rupture,% not less 12 Bounce elasticity,%, not less than 0.3 Conditional stresses at 300% elongation, MPa (kgf / cm ² ), not less 6.9 (70) Mass fraction of antioxidants,%, no more 0.4-0.1

The invention is illustrated by the following examples.

Example 1

To a 2% solution of BK in CC14 (2 g of BK, 100 ml CC14), previously prepared in a reaction flask, 2 g of bentonite are added with vigorous stirring. The resulting suspension is left for a day. Then, when bubbling the reaction zone with oxygen, a metered supply of PC13 begins with constant stirring of the contents of the flask. The exothermic nature of the reaction is manifested in a rise in temperature from 21 (room temperature) to 47 ° C. The total amount of PC13 is 24 ml, the duration of the reaction is 8 hours. Upon completion of the oxidative chlorophosphorylation, the dark brown powdery reaction product is separated from the liquid phase by distillation by a water-jet pump, after which the reaction product is hydrolyzed (as described previously), filtered off, washed with distilled water to a neutral pH value and dried, first in air, and then in a vacuum drying oven (8h11bh Schobe1 1425-2, at a temperature of T = 50 ° C and a pressure of P = -292, 2 kPa). CCE (static sorption capacity) of the hybrid sorbent is 4.050 mEq / g. The determination of CCE was carried out in accordance with the known method [12-13]. The phosphorus content in the sorbent is 4.2%.

Example 2

Bentonite, which in this case was pretreated with acetone to remove traces of moisture, is added to a 2% solution of BC in CC1 ₄ (2 g of BC, 100 ml of CC1 ₄ ) (2 g of bentonite is kept for 20 days in 20 ml of acetone and dried under mild conditions (45 -50 ° C) in a vacuum oven). Then, oxidative chlorophosphorylation is carried out as in Example 1. The reaction time is 4 hours. The amount of added PC1 ₃ is 19 ml. A temperature increase was observed in the reaction zone from 21 to 55 ° C. The reaction product is a light brown powder. Its processing was carried out as in example 1. The CCE of the hybrid sorbent is 3.798 mEq / g. The phosphorus content in the composite is 3.7%.

The synthesized hybrid polymer composite was studied as an adsorbent for the organic dye Rhodamine 6G, the characteristics of which are presented in Table. 2

table 2

Chemical formula dye Ο ₂₈ Η ₃ ιΝ ₂ Ο ₃ Ο1 The chemical structure of the dye Molecular mass dye 479.02 ^{C |} Absorption Horseshoe 528 csh Emission % 1ax 551 μητ Temperature melting 290 ° C Density 1.26 g / cm ³ Solubility water (20 g / l, 25 ° C), ethanol, methanol (400 g / l)

To conduct comparative studies of sorption activity, three samples were taken, namely: bentonite; a sample of the composite obtained in experiment 1 (example 1) and a sample of the composite obtained in experiment 2 (example 2). For this purpose, 0.05 g of each of the samples is placed in three 30 ml containers, then 0.015 ml of Rhodamine 6G dye solution is added to them (dye concentration 6.7 mg / L) and kept under static conditions for 24 hours. Then the samples are filtered off and the equilibrium concentration of the Rhodamine 6G dye is determined in each of the filtrates using a KFK-2 photocolorimeter (wavelength 490 nm, cuvettes 1 = 1.0 cm, background — water). The results are presented in table. 3 and 4.

Table 3

Sample Dye concentration Before sorption After sorption C _about , mg / l Optical density £) = 490 nm Concentration, C _p , mg / l 6.7 Bentonite 0.04 0.58 Experience No. 1. BK + bentonite 0.015 0.22 Experience No. 2. BK + bentonite (pre-treated with acetone) 0,035 0.51

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Table 4

Sample Sorption capacity, p, mg / g The degree of sorption, E% Bentonite 1.84 91.3 Experience No. 1 BK + bentonite 1.94 96.7 Experience No. 2 BC + bentonite, pre-treated with acetone 1.86 92.4

As can be seen from the table. 3 and 4, the sample of the composite obtained in experiment 1 possesses the highest sorption activity with respect to the Rhodamine 6G dye; therefore, the regularities of the sorption process were studied using this particular sample.

To study the dependence of the sorption ability of the obtained composite on the sorption time and temperature, we studied the change in the dye concentration in the solution at different sorption times and temperatures. To do this, 0.05 L of a Rhodamine 6G dye solution of known concentration (in this case 43.55 mg / L) is added to 0.05 g of a composite (sorbent) sample placed in a flask. Then the contents of the flask are mixed at different temperatures (293, 309, 323 K) at a speed of 95 rpm, and every 10 minutes a sample of the solution is taken from the flask above the sorbent to determine the dye concentration in it (KFK-2, wavelength 490 nm, cuvettes 1 = 1.0 cm, background water). Research lasted 180 minutes. The temperature error was ± 2K. Based on the obtained data, the equilibrium dye concentration was calculated and the sorption capacity and degree of sorption were determined. The obtained experimental data are summarized in table. 5.

Table 5

1 minute T = 293 ± 2K T = 309 ± 2K T = 323 ± 2K Optical density C „, mg / l C _p , mg / l in mg / g L% Opt. density Co, mg / l C _p , mg / l β mg / g th,% Opt. raft. Co, mg / l Wed mg / l Oh mg / g th,% Calc. Indications instrument Calc. Indications instrument Calc. Indications instrument 0 0.15 47,902 43.55 43.55 0 0 0.15 47,902 43.55 43.55 0 0 0.15 47,902 43.55 43.55 0 0 5 odz 37.74 5.81 13.3 0.12 34.84 8.71 20,0 0.1 29.03 14.52 33,4 10 0.12 34.84 8.71 20,0 0.11 30.7 12.85 29.5 0.09 26.13 17.42 40,0 twenty 0.11 32,7 10.85 24.9 0,097 28.3 15.25 35.0 0.08 23.5 20.05 46.1 thirty 0.104 30,2 13.35 30.7 0.09 26.13 17.42 40,0 0,07 21,2 22.35 51,4 40 0,099 28.8 14.75 33.9 0,084 24.6 18.95 43.5 0,065 18.9 24.65 56.6 fifty 0,092 26.8 16.75 38.5 0.08 23,23 20.32 46.7 0.059 17.3 26.25 60.3 60 0,085 24.7 18.85 43.3 0,074 21,4 22.15 50.9 0.056 16.3 27.25 62.6 70 0,081 23.7 19.85 45.6 0,068 19.8 23.75 54.5 0,052 fifteen 28.55 65.6 80 0,078 22.6 20.95 48.1 0,063 18,4 25.15 57.7 0,048 14 29.55 67.9 90 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 one hundred 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 110 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 120 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 130 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 140 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 150 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 160 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 170 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8 180 0,074 21.5 22.05 50.6 0,0596 17.3 26.25 60.3 0,047 13.6 29.95 68.8

The research results allowed us to build on their basis the graphs presented in FIG. 2 and 3.

As can be seen from FIG. 2 and 3, at different temperature conditions in the first 50 min of sorption, the process is very active, thanks to free active sorption centers on the surface of the composite. With an increase in the temperature of the sorption process, a decrease in the equilibrium concentration of the dye and an increase in the degree of sorption are observed, which can be explained by an increase in the mobility of dye cations and an increase in the number of active centers on the surface of the sorbent.

In FIG. Figures 4 and 5 show the IR spectra of the composite before and after sorption of the dye. IR studies were carried out on a Wapap 3600 спект spectrophotometer in the wavelength range of 400-4000 cm ^-1 .

As can be seen from FIG. 4, the following signals are observed in the spectrum of the hybrid composite (obtained according to Example 1): 580 cm ^-1 (P-C1), 670 cm ^-1 (C-C1), 781 cm ^-1 (-C-C-), 1035 cm ^-1 (-P-O-C-) (which indicates the attachment of PO (OH) 2 groups to the main chain through oxygen). 1357 ^cm-1 band can be attributed to deformation vibrations (-P = O) groups, and a band of 2350 cm ^-1 - stretching vibrations to P-OH groups. Along with this, the absorption band in the region of 1500 cm ^{– 1} confirms the possibility of the presence of a (–C = C–) double bond in the hybrid composite. Absorption bands with maxima at 3600 and 1600 cm ^–1 relate to deformation and stretching vibrations of –OH groups of free water molecules sorbed by the composite. The absorption band at 2960 cm ^-1 can be attributed to stretching vibrations of asymmetric CH2 groups.

As can be seen from FIG. 5, after sorption of the dye, changes in some characteristic signals and the appearance of new ones are observed in the spectrum of the composite. So, the appearance of a new signal in the region of 432 cm ^-1 is due to the fact that functional groups on the surface of the composite polarize the positively charged dye cation. The weakening of transmission signals in the region of 1600 and 1035 cm ^–1 can be explained by the formation of a hydrogen bond between the = Ν + Η group of the dye and the –OH and P = O groups of the composite [14].

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Thus, the present invention provides a composite sorbent based on a polymer and clay material for purifying water from an organic dye without additional use of a crosslinking agent to obtain a hydrophobic polymer matrix and an activating reagent for clay material.

Literary sources

1. Ro1uteg - C1au - Maiosotrozyes / Eb. Wu Rtiaua1a T.T., Bea11 O. No. \ ν Wogk: \ UPs. 2000, Rooter, Apocalyptus without: §уу1ке818, СагасУп / аОоп apб Мобе1опд. AC8 8out. §Eg, 804 / Eb. L.K. \ UAZipdYup I.S.: At. Eat. §Os, 2001

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Claims (7)

1. A method of obtaining a hybrid composite sorbent for wastewater treatment, including intercalating the organic component in the interlayer space of bentonite clay, mixing, washing and drying, characterized in that butadiene rubber is intercalated into the interlayer space of bentonite clay, the resulting suspension is modified with phosphorus PST trichloride chlorophosphorylation in the presence of oxygen, with further hydrolysis of the reaction product. 2. The method according to claim 1, characterized in that a 2% solution of butadiene rubber in carbon tetrachloride is used for intercalation. 3. The method according to claim 1, characterized in that the resulting suspension of bentonite clay and a solution of butadiene rubber are incubated for a day. 4. The method according to claim 1, characterized in that the mass ratio of butadiene rubber to bentonite clay is 1: 1. 5. The method according to claim 1, characterized in that the modification is carried out with 28-36 wt.% Of the reaction mass by the amount of PC1 ₃ for 4-8 hours 6. The method according to claim 1, characterized in that the hydrolysis of the reaction product is carried out with ice distilled water with stirring the mixture for 2 hours at room temperature. 7. The method according to claim 1, characterized in that the reaction product is dried in a vacuum oven at a temperature of T = 50 ° C and a pressure of P = -292.2 kPa.