RU2628396C2 - Sorbent for cleaning water environments from ions of arsenic and method of its production - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: sorbent for clearing of water environments from an arsenic is offered. The sorbent contains 98-99 wt % of iron nanoparticles and starch. To produce the sorbent, ferric sulphate and starch are dissolved in water to form a complex of iron ions with starch, nitrogen is passed through the solution, the iron-containing complex is reduced by borohydride to obtain iron nanoparticles. Further, centrifugation, washing of the precipitate with ethanol and drying are carried out.

EFFECT: sorbent possesses high adsorption activity in relation to arsenic ions.

2 cl

Description

The invention relates to nanotechnology and the treatment of domestic, industrial and wastewater enterprises. When poisoning with arsenic ions, the central and peripheral nervous system, skin, and peripheral vascular system are affected. Inorganic arsenic ions are more dangerous than organic, trivalent ion is more dangerous than pentavalent. The maximum permissible concentration of arsenic ions in water according to SanPiN 2.1.4.1074-01 “Drinking water. Hygienic requirements for water quality of centralized drinking water supply systems. Quality control ”- 0.05 mg / l. This value reflects the very high toxicity of arsenic.

Nanoscale objects have a very large specific surface and therefore adsorb ions well. An article (Iran. J. Environ. Health Sci. Eng. 2011, 8 (2): 175-180) presents a comparison of the adsorption capacity of nano- and micro-sized iron particles with respect to arsenic (III). Adsorption on iron nanoparticles was better. However, it is difficult to remove the adsorbent consisting only of nanoparticles from the purified solution due to the smallness of the object.

Known nanosized sorbent for water purification from heavy metal ions, including arsenic ions of different valencies, and a method for its production (RF patent 2328341, publ. July 10, 2008). The sorbent consists of ground zeolite, nanosized iron hydroxide and nanosized boehmite. The disadvantages of the method of producing the sorbent include its multi-stage and the complexity of the adsorbent, which leads to its high cost. First, nanosized boehmite is obtained by hydrolysis of aluminum nanopowder. Then, nanosized iron hydroxide is obtained by hydrolysis of a solution of iron chloride with a solution of ammonium hydroxide. Next, the crushed zeolite is mixed with H ₂ O, nanoscale powder of boehmite and iron hydroxide, triturated and then the resulting mixture is dried for 2 hours at 50-75 ° C, and then 6 hours at 190 ° C. In all known methods, iron hydroxide is obtained by hydrolysis of iron salts, which is a multi-stage method. First, iron salts are obtained, and then from Fe (OH) ₃ salts.

The sorbent for the purification of water from arsenic (RF patent 2520473), taken as a prototype, contains iron oxyhydroxide (OGF), isolated from waste from deferrization stations of underground waters, a water-soluble polymer and glycerin in the following ratio of components,%:

OGZH (nanoscale) 45.9-53.3;

polymer 2.2-6.8;

glycerin rest.

As a water-soluble polymer, it contains polyvinyl alcohol, or polyacrylamide, or methyl cellulose, or polyethylene glycol. To obtain the sorbent, wastes were used that were isolated at groundwater deferrization stations, which are a gel-like mass (paste) containing 10–12% of dry coolant with a particle size of 30–50 nm, which is modified with water-soluble polymers containing plasticizer . As a water-soluble polymer, it is recommended to use polyvinyl alcohol, polyacrylamide, methyl cellulose, polyethylene glycol, and glycerol as a plasticizer.

The prototype has several drawbacks: the waste from which the sorbent is obtained varies in composition and this affects the adsorption capacity; waste and water-soluble polymers do not allow the use of a sorbent for use in the human body, the food industry.

An object of the invention is to improve the quality of the sorbent.

The technical problem according to the invention is solved in that the sorbent for cleaning arsenic from aqueous media contains iron nanoparticles and starch in the following ratios of components,% by weight: iron nanoparticles - 98-99, starch - 2-1.

A method of producing a sorbent for cleaning arsenic from aqueous media is that iron sulfate and starch are dissolved in water to form a complex of iron and starch ions, nitrogen is passed through the solution, the complex is reduced with borohydride to iron nanoparticles, centrifuged, the precipitate is washed with ethanol and the adsorbent is dried under a vacuum.

Iron nanoparticles coated with starch are not toxic to the body and can be used to purify blood, juice, wine in the food industry. The amount of starch in the sorbent is limited by its solubility in water at the synthesis temperature. In the sorbent it is bound by covalent bonds with iron nanoparticles and does not dissolve in water. To obtain the sorbent, it is better to use iron sulfate, rather than ferric chloride.

The invention is illustrated by an example.

In a 0.5 L flask, 0.12 M FeSO ₄ -7H ₂ O is thoroughly mixed with 0.2% by weight. potato starch in 100 ml of water until complete dissolution of the contents with the formation of a complex between iron and starch ions. Nitrogen was passed through the mixture to remove dissolved oxygen. Then, 100 ml of a 0.5 M borohydride solution are added dropwise to the solution with continued stirring. The mixture is continued to mix until complete recovery of the complex with the formation of a black suspension of the sorbent. The suspension is centrifuged at 6000 rpm for 5 min, the precipitate is washed 3 times with ethanol with centrifugation. The sorbent precipitate is dried under vacuum, large particles are crushed. On a GBS EMMA powder x-ray diffractometer, the presence of zero-valence iron is determined from a broad peak of two theta 44.5 °. According to the well-known formula, the size of crystalline iron nanoparticles of 8 nm is determined by the width of the peak. On a JEOL JSM-6610 scanning microscope, the particle size of the sorbent 70-95 nm is determined, and on an energy dispersion attachment to it, the iron content is 99 ± 0.1%.

To determine the adsorption capacity of arsenic ions, solutions with a sorbent in a flask are shaken at an incubator-shaker of 200 rpm for periods of 5 minutes, 120 minutes. A suspension for analysis was taken with a 5 ml syringe, centrifuged at 3000 rpm for 5 minutes, filtered through a 0.2 μm filter. The dry residue is analyzed for arsenic content in accordance with Federal Law 1.31.2005, 01.553 (according to the Gosstandart of methods approved for use).

Adsorption increases with increasing dose of the sorbent and the time of contact with the solution. At a dose of 0.3 g / l pH = 7 and a concentration of arsenic (V) ions of 1 mg / l, 100% removal in 5 minutes is achieved. For a concentration of 10 mg / l, 100% removal is achieved in 120 minutes. When the concentration of arsenic (III) is 10 mg / l, 100% removal is achieved in 120 minutes.

Thus, the proposed sorbent is of better quality compared to the known sorbent. The sorbent of iron nanoparticles coated with starch can be used in the food industry. The sorbent has good adsorbing properties with respect to iron ions.

Claims (2)

1. Sorbent for the purification of aqueous media from arsenic, containing inorganic nanoparticles and a water-soluble polymer, characterized in that it contains iron nanoparticles and starch in the following ratio of components, wt.%: Iron nanoparticles 98-99, starch 2-1. 2. A method of producing a sorbent for cleaning arsenic from aqueous media, characterized in that iron sulfate and starch are dissolved in water to form a complex of iron and starch ions, nitrogen is passed through the solution, the complex is reduced with borohydride to form iron nanoparticles, centrifuged, the precipitate is washed with ethanol and dried sorbent in vacuum.