SU1836297A3 - Method of desalting of boron containing waters - Google Patents

Description

The invention relates to the field of water treatment, in particular to desalination, and can be used for desalination of boron-containing water.

The closest in technical essence and the achieved result to the claimed method is a desalination method, which consists in the desalination of water having a pH of more than 10 at room temperature in the desalination chamber of the electrodialysis apparatus formed by heterogeneous membranes MK-40 and MA-40, other total salinity 200- 300 mg / dm ³ When processed using this method, marine-type water (initial boron content is less than 4.5 mg / dm ³ ), the degree of boron extraction reaches 80.0-92.5%. However, we have shown that when using this method for desalination of water with a high content of boron (40 mg / dm ³ ), the degree of extraction of boron is much lower. Thus, the boron content in the dialysate and brine obtained by desalination by the method of the model solution of thermal water of the Pauzhetskaya GEOTES served up. is respectively 32 and 360-380 mg / dm ³ with a degree of boron extraction of 20%.

Thus, the disadvantage of this method is the low efficiency in terms of extraction and concentration of boron compounds during desalination of water with a high content.

Increasing the degree of extraction and concentration of boron compounds in the process of desalination of boron-containing water is an urgent task, the solution of which will, firstly, protect the human and animal organism from the negative effects of boron compounds, and, secondly, expand the raw material base for the production of the latter, since ore Boron reserves are limited.

The essence of the invention lies in the fact that the desalination of boron-containing water is carried out by passing water with a pH of greater than 10 through electrodes desalination chambers; lysis apparatus, formed by anionite and cationite - fluorocarbon sulfonic acid homogeneous membranes. The desalination process is carried out at a temperature less than or equal to 45 ° C.

A distinctive feature of the proposed method is the use for desalination of a homogeneous fluorocarbon sulfocationite membrane (MF-4SK).

1836297 AZ

We have shown that its use for desalination of water with a high boron content allows a 2.0-2.5-fold increase in the degree of extraction and concentration of this element. At the same time, the content of other components in the dialysate practically does not change, and the salinity of the brine increases only by 15-17%. Carrying out the process at elevated temperature leads to an additional increase in the degree of concentration and extraction of boron.

The method is implemented as follows.

The experiments were carried out in a five-chamber electrodialysis apparatus containing 2 electrode chambers, 2 desalination chambers and 1 concentration chamber. The chambers are separated from each other by alternating cationite and anionite membranes. The working surface of one membrane is 9.7 cm ² , the intermembrane distance is 5 mm. Platinum was used as the cathode and anode. A 0.1 M sodium sulfate solution circulated through the electrode chambers. A model boron-containing solution was supplied to the desalination chambers. The degree of concentration of boron was judged by its concentration in samples periodically taken from the concentration chamber. Before the start of the experiment, the concentration chamber was filled with a model boron-containing solution. The brine flowed out of the upper chamber fitting spontaneously due to an increase in its volume due to electroosmotic and osmotic water transfer. The experiments were carried out in galvanostatic mode. Boron was determined by the colorimetric method using carmine.

Characteristics of the materials and substances used.

Membrane MF-4SK, prepared according to GOST 17553-72 in H ⁺ form. Membrane MA40 / TU 6-05-1203-88), prepared according to GOST 17553-72 in OH * form. Sodium sulfate chda in accordance with GOST 4166-76. Sodium chloride ”hch according to GOST 4233-77. Boric acid, chemical grade according to GOST 18704-78. Potassium chloride analytical grade according to GOST 4234-77.

An example (according to the invention). Model solution containing 2473 mg / L NaCI, 164 mg / L KCI, 110 mg / L Na2SO ₄ . 220 mg / L HbO3 (40 mg / L boron), and having a pH of 10.2, was supplied with a linear velocity of 0.02 cm / s to desalination chambers bounded by MF-4SK cation exchange membranes and MA-40 anion exchange membranes. Before the start of the experiment, the concentration chamber was filled with a model boron-containing solution with a pH of 7.8. The lower chamber fitting was covered with mohair. The brine spontaneously flowing from the upper choke of the chamber was collected in a measuring cylinder. 2 L of 0.1 M Na2SO ₄ solution circulated through the electrode chambers. The electric current density was 0.75 A / dm ² . The solutions fed into the chambers were thermostatically controlled in the 1TZh-0-03 thermostat at a temperature of 25 ° C. The duration of the experiment is 12.5 hours. The total volume of brine is 11.8 ml. The boron concentration in brine and dialysate was 800 and 23 mg / L, respectively. The total salinity of the brine and dialysate is 111 and 0.25 g / l, respectively.

PRI me R 2 (prototype). The example is carried out analogously to example 1, however, the MK-40 heterogeneous membrane is used as a cation exchange membrane. The total volume of brine is 15.2 ml. The concentration of boron in brine and dialysate is 360 and 33 mg / l, respectively. The total salinity of the brine and dialysate is 96.0 and 0.25 g / l, respectively. The advantage of the described method in comparison with the prototype is confirmed by the table.

It has been established that the use of a homogeneous fluorocarbon sulfocationite membrane for desalination of boron-containing waters with a high concentration of boron (40 mg / l) provides high efficiency for the removal and concentration of boron: the degree of extraction is 41-51%; the concentration ratio of 19.0-23.8 (boron content in brine 750960 mg / l). The optimum temperature for the process is 15-45 ° C. An increase in temperature above 45 ° C leads to a significant decrease in the total salinity of the brine, as well as the degree of concentration of boron.

The advantage of the described method of desalination of boron-containing water is that. that the achieved increase in the degree of extraction and concentration of boron significantly reduces the consumption of reagents used to regenerate boron selective sorbents used to condition dialysate according to the content of boron, and also significantly simplifies the process of processing brine into boron-containing products, which is caused by an increase in the capacity of the boron selective resin with an increase in boron content in the solution .

Claims (2)

Claim 1. A method for desalination of boron-containing water, comprising supplying desalinated water with a pH> 10 through desalination chambers of an electrodialyzer, formed by cation exchange and anion exchange membranes, distinguished by the fact that a homogeneous fluorocarbon sulfocation ion membrane is used as a cation exchange membrane. 2. The method according to claim 1, characterized in that the process is carried out at a temperature less than or equal to 45 ° C. The content of boron in desalinated solution, mg / l t, ° C The concentration of boron The degree of extraction of boron, % Total brine, g / l Common dialysate, g / l By pic rethen ju 40 fifteen 19.0 41 112 0.30 25 20.0 43 111 0.25 32 20.6 45. 113 0.30 38 23.8 fifty 113 0.28. 45 19.5 51 93 0.25 Beyond mode 40 fifty 1bl 52 74 0.30 According to the prototype 4 25 - 80 - 0.20 40 25 9.0 19 96 0.25 thirty · 9.5 20 97 0.25 Compiled by L. Melnik Editor Tehred M. Morgenthal Corrector S. Patrusheva Order 3001 Circulation Subscription VNIIIPI of the State Committee for Inventions and Discoveries under the State Committee for Science and Technology of the USSR 113035, Moscow, Zh-35, Raushskaya nab., 4/5 Production and Publishing Plant Patent, Uzhgorod. Gagarin St. 101