RU2659285C1 - Sorbent based on modified graphene oxide and method of its production - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: group of inventions relates to production of sorbents and can be used for sewage treatment from dyes and salts of heavy metals. Sorbent is graphene oxide modified with polyhydroquinone. Method for producing the sorbent comprises mixing under the action of ultrasound the initial components, wt%: graphene oxide – 40–50, quinone – 3–4, distilled water – the rest. Reaction space is purged with inert gas, followed by sealing. Initial mixture was heated to 95±2 °C followed by holding for 6 hours with mechanical stirring at a speed of 150 rpm in an inert gas atmosphere. Resultant mixture was cooled to room temperature, filtered to separate a solid phase consisting of graphene oxide, the structure of which was modified with polyhydroquinone. Sorbent is washed and dried.EFFECT: group of inventions provides production of sorbent based on graphene oxide with improved performance properties by increasing the sorption capacity while simplifying the technology of sorbent production.2 cl, 1 tbl, 2 ex

Description

The field of technology. The group of inventions relates to the field of organic and inorganic chemistry, in particular to the preparation of sorbents based on modified graphene oxide, and can be used to purify wastewater from dyes and heavy metal salts.

Prior art. In recent years, sorbents based on thermally expanded graphite have been used to clean various media from petroleum products and other hydrocarbons. A method of producing a sorbent based on thermally expanded graphite and a sorbent, RF patent №2564354, IPC B01J 20/20, B01J 20/30, publ. 09/27/2015. A method for producing a sorbent based on thermally expanded graphite modified with iron-containing phases with ferrimagnetic properties, includes the following steps: iron salts in solution ranges from 10 to 50 mass. %; (B) separating from the resulting mixture the liquid phase to obtain a solid phase in the form of intercalated graphite coated with iron compounds; (C) drying the solid phase to a free flowing state; and (D) thermal expansion of intercalated graphite coated with iron compounds to obtain the desired product. The invention allows to obtain a sorbent based on thermally expanded graphite containing a magnetic phase, represented by ferrimagnetic magnetite (Fe ₃ O ₄ ) and maghemite (γ-Fe ₂ O ₃ ) with improved performance properties.

However, this method is characterized by insufficient sorption capacity of the material during the treatment of industrial effluents and purification of industrial water.

Genuine interest in graphene oxide as a sorption material arose during the study of its properties, the main of which are:

- large mechanical strength and the value of the specific surface, which theoretically confirms the high sorption capacity;

- simplicity of production (no special devices and complex in composition catalytic systems are required) of the material and relatively cheap raw materials (graphite).

The large sorption capacity of graphene oxide can also be interpreted as the result of chemisorption of target components from aqueous solutions based on various types of interaction of functional surface groups with molecules or ions of extracted substances (establishment of strong chemical bonds, electrostatic interaction with the surface of the sorbent, ion exchange, etc. .).

A hybrid nanomaterial based on graphene oxide and cationic chitosan, which forms a quaternary base, according to the application WO 2014142757 A1, IPC А61Р 31/00; B82Y 30/00; B82Y 5/00; СВВ 31/00; С08В 37/08, publ. September 18, 2014. According to the method, chitosan (1 g, 6.2 mmol) is pre-dissolved in acetic acid (1%, 100 ml), then decanal (0.97 g, 6.2 mmol) is added and stirred for 1 hour at room temperature. temperature After that, the pH is increased to 4.5 by adding sodium borohydride (9.3 mmol) and the mixture is stirred for 1.5 hours. Then the pH is increased to 10 by adding sodium hydroxide (NaOH solution) (1 M). The white precipitate formed during the reaction was filtered and washed with distilled water until the medium was neutral. Further extraction of the mixture on a Soxhlet apparatus using ethanol and diethyl ether is performed to remove unreacted reagents. As a result, H-decyl chitosan (1 g, 6.2 mmol) was then added to N-methyl pyrolidone (MP) (50 ml) and NaOH solution (1.5 m, 15 ml). After 30 minutes of stirring at 50 ° C., methylation was carried out as follows: sodium iodide (1.08 g, 7.2 mmol) and methyl iodide (1.2 g, 78.7 mmol) were added to chitosan / NMP / NaOH in the mixture, the reaction occurred with stirring for 24 hours at 50 ° C. Then the solution was filtered on a suction filter. After removing the filtrate in acetone (400 ml), the resulting precipitate is filtered and then dried under vacuum to obtain a product.

In this technical solution, a cationic polysaccharide - chitosan is used as a modifying agent. The technology of obtaining material in the presented patent is characterized by multistage, at each stage a large number of organic precursors are used (solvents, acids, reducing agents, etc.), which greatly complicates the technology of sorbent production.

As the prototype of the object "sorbent" selected methyl orange sorbent according to Chinese patent CN No. 104307491 A, IPC B01J 20/24, B01J 20/30, C02F 1/28, C02F 103/30, publ. 01.28.2015, according to the patent, in the methyl orange dye sorbent as an effective modifier of graphene oxide is used a water soluble quaternary ammonium salt chitosan. The modification process is carried out at pH 3-11 in an aqueous solution in the form of a stable dispersion. Due to the synergistic effect of the electrostatic interaction of the quaternary ammonium salt and a large specific surface area of graphene, the modified graphene has an obvious high adsorption of the organic dye, methyl orange, and the adsorption of methyl orange at a temperature of 10 ~ 50 ° C is 80% ~ 98.93%.

As a prototype of the method of obtaining the adsorbent, the technical solution for China patent CN No. 104307491 A, IPC B01J 20/24, B01J 20/30, C02F 1/28, C02F 103/30, publ. January 28, 2015. According to the patent on the obtained modified graphene, which uses commercial graphene oxide and the static forces of non-caletic bonds of chitosan with the surface of graphene, by chemical reduction of graphene oxide, while the quaternary ammonium salt of chitosan remains on the surface of graphene; in particular, the modification steps include:

1. First, according to the Hummer method, a mixture of graphite, graphite oxide is prepared, to which sodium hydroxide solution is then added, and dispersion of graphene oxide with a concentration of 2 ~ 5 mg / ml is obtained by ultrasonic dispersion.

2. In the second stage, an aqueous solution of quaternary ammonium salt chitosan with a concentration of 3 ~ 7 mg / ml is added to the graphene oxide dispersion, the reaction mixture is stirred at room temperature, then sodium hydroxide solution is added with a concentration of 0.01-0.06 mol / l for adjusting the pH to a value of about 10, the method of chemical oxidation reduces the heating of the reducing agent and the resulting precipitate of black flocculant is filtered, washed and dried. The specified modifier is a water-soluble quaternary ammonium salts of chitosan, which is a 2-hydroxypropyltrimethylammonium chloride chitosan, H-trimethyl quaternary chitosan, forming a quaternary base of n- (4-pyridylmethyl) chloride of chitosan or quaternary ammonium N-betaine of N H - two methyl aminobenzyl) chitosan chloride. The mixture is subjected to ultrasonic dispersion for 1.5 ~ 2 hours. At room temperature, the reaction time is 2 ~ 12 hours, the high-temperature reaction time is 1 ~ 5 hours. In the second stage, the reducing agent is 2 to 6 times more hydrazine hydrate graphite oxide, heating temperature 60 ~ 100 ° C, drying temperature 30-70 ° C.

The adsorption process is carried out at a pH of 3 ~ 11 methyl orange solution, a stirring speed of 90 ~ 150 rpm, a stirring time of 0.5 ~ 24 hours and an adsorption temperature of 10 ~ 50 ° C.

The use of modified graphene for the sorption of methyl orange with an initial concentration of the solution in the range of 0.5-1.5 g / l, at a temperature of 10 ~ 50 ° C ensures the sorption process with the degree of extraction of methyl orange from 80 to ~ 98.93%.

DISCLOSURE OF INVENTION

The object of the invention is to obtain a sorbent based on graphene oxide with improved performance properties due to an increase in sorption capacity.

The object of the invention on the method of obtaining a sorbent is to simplify the technology for producing a sorbent based on graphene oxide by reducing the range of reagents used, the number of operations and the use of a minimum amount of equipment.

The task of the object "sorbent" is solved by the fact that polyhydroquinone is used as the modifying substance of graphene oxide.

The task of the method of obtaining a sorbent is solved by the fact that the method of obtaining a sorbent based on modified graphene oxide includes the following process steps:

(A) a mixture of initial components wt. %:

- graphene oxide - 40-50;

- quinone - 3-4

- distilled water - the rest.

The mixing is carried out with ultrasonic exposure with an oscillation frequency of 22 ± 0.4 kHz for 40-70 minutes;

(B) purging the reaction space with an inert gas (argon) for 30 minutes, followed by sealing;

(C) heating the initial mixture to 95 ° C, followed by aging for 6 hours with continuous mechanical stirring at a speed of 150 rpm in an inert gas environment;

(D) cooling to room temperature, filtering the resulting mixture with the separation of the target product in the form of a solid phase of graphene oxide, the structure of which is modified with polyhydroquinone;

(E) washing the material with distilled water preheated to 50–70 ° C, evacuating for 3–7 minutes to remove moisture from the surface and drying at room temperature 22–25 ° C.

The level of technology

The qualitative modification of the graphene oxide surface by polyhydroquinone is determined by the delocalized electronic system of graphene, which gives rise to a high affinity for aromatic compounds.

The implementation of the invention

To implement the invention used the following source components:

graphene oxide in the form of a 1% dispersion in distilled water produced by NanoTehCentre, Tambov;

P-benzoquinone (C) - granular bulk material obtained according to TU 6-09-07-1638 (OOO Laverna);

distilled water GOST 6709-72. This standard applies to distilled water obtained in the distillation apparatus and used for the analysis of chemical reagents and the preparation of solutions of reagents.

The invention consists in the following. To obtain a graphene oxide modified with polyhydroquinone, a mixture of initial components is prepared from graphene oxide, quinone and distilled water, the mixture is carried out under ultrasound exposure at an oscillation frequency of 22 ± 0.4 kHz for 40-70 minutes Then the reaction space is purged with an inert gas (argon) for 30 minutes, followed by sealing to ensure the reduction of graphene oxide, excluding access of atmospheric oxygen, after which the initial mixture is heated to 95 ± 2 ° C, followed by aging for 6 hours speed of 150 rpm in inert gas. The resulting mixture is cooled to room temperature, filtered to separate the target product in the form of a solid graphene oxide phase, the structure of which is modified with polyhydroquinone. The target product is washed with pre-heated to 50-70 ° C distilled water, vacuum for 3-7 minutes to remove moisture from the surface and dried at room temperature 22-25 ° C.

Example 1. A mixture of graphene oxide starting components was prepared - 250 g, quinone - 15 g and distilled water - 250 ml. Mixing was performed under ultrasonic action at an oscillation frequency of 22 ± 0.4 kHz for 40 minutes, after which the reaction space was purged with an inert gas (argon) for 30 minutes, followed by sealing, and the initial mixture was heated to 95 ° C, followed by exposure 6 hours with continuous mechanical stirring at a speed of 150 rpm in an inert gas environment. The resulting mixture was cooled to room temperature, filtered to separate the target product as a solid phase of graphene oxide, the structure of which is modified with polyhydroquinone. The target product was washed with pre-heated to 70 ° C distilled water, was evacuated for 3 minutes to remove moisture from the surface and dried at room temperature 22-25 ° C.

The resulting product is a black paste that can form a two-component dispersion in contact with water.

Example 2. The process was carried out analogously to example 1 with the following changes: a mixture of graphene oxide starting components was prepared — 200 g, quinone — 30 g, and distilled water — 300 ml. The initial mixture was heated to 97 ° C, followed by aging for 6 h with continuous mechanical stirring at a speed of 150 rpm in an inert gas environment. The target product was washed with pre-heated to 50 ° C distilled water, evacuated for 7 minutes to remove moisture from the surface and dried at room temperature 22-25 ° C.

The resulting product is a black paste that can form a two-component dispersion in contact with water.

To carry out experimental studies aimed at establishing the key sorption characteristics of the polygidroquinone sample being studied for the extraction of Cu ⁺² ions from aqueous solutions, the following procedure was used:

Copper solution (sorbate) with an initial concentration of 100 mg / l (C _ref ) was prepared by diluting in a universal buffer system (1 liter volume, pH6) of the calculated amount of Cu (NO ₃ ) ₂ ⋅3H ₂ O classification of analytical grade, GOST 4163-78 with room temperature T = 23 ± 1 ° С. The weight of the sample of polyhydroquinone is m = 0.03 g, the corresponding volume of solution _Vex = 30 ml. To determine the equilibrium concentration of Cu ^{+ 2} ions, we used atomic absorption spectroscopy with electrothermal atomization. The equilibrium concentration of ions Cu ⁺² was 55 mg / l.

For experimental studies on the sorption of an organic dye (methylene blue) from water, the following regime parameters were used:

A solution (sorbate), with an initial concentration of 1500 mg / l (C _ref ), was obtained by diluting 1.5 g (± 0.001 g) of methylene blue analytical grade classification (TU 6-09-29-76) in one liter of distilled water GOST 6709-72 ( pH 6.5 ± 0.5) at room temperature T = 23 ± 1 ° C. To carry out experimental studies on the sorption of an organic dye, we prepared samples of polyhydroquinone weighing 0.03 g (m), as well as 30 ml (V _out ) of a solution with an initial concentration of 1500 mg / l. The equilibrium concentration of methylene blue in the solution was 780 mg / l.

To carry out experimental studies on the sorption of organic dye (methylene orange) from water, the following regime parameters were used:

A solution (sorbate), with an initial concentration of 1500 mg / l (C _ref ), was obtained by diluting 1.5 g (± 0.001 g) of methylene orange analytical grade classification (TU 6-09-51171-84) in one liter of distilled water GOST 6709-72 ( pH = 6.5 ± 0.5) at room temperature T = 23 ± 1 ° C. To carry out experimental studies on the sorption of an organic dye, we prepared samples of polyhydroquinone weighing 0.03 g (m), a solution of an initial concentration of 1500 mg / l with a volume of 30 ml (V _out ). The equilibrium concentration of methylene blue in the solution was 1095 mg / l.

Samples of the obtained product of known mass in the form of powder were placed in a grid basket with a cell size of 1 mm ² and placed in a glass container containing sorbate with a 5 cm liquid layer. After keeping for 15 minutes, the grid basket was removed from the container and settled for 30 seconds. Next, the sample was weighed and determined the sorption capacity (S) in units of g absorbed substance.

Below are the experimental values obtained for the sorption capacity of graphene oxide modified with polyhydroquinone (the inventive sorbent) in comparison with other sorbents.

The group of inventions provides for obtaining a sorbent based on graphene oxide with improved performance properties by increasing the sorption capacity while simplifying the technology of obtaining the sorbent by reducing the range of reagents used, the number of operations and the use of a minimum amount of equipment.