SU1611863A1 - Method of purifying common salt solutions from heavy metal impurities - Google Patents

Abstract

The invention relates to the field of chemical technology for purification of salt solutions from heavy metal impurities, such as arsenic, copper and cadmium, and contributes to an increase in the degree of purification while reducing the amount of collector. According to the invention, the purification of solutions from heavy metal impurities is carried out by co-precipitating them on a magnesium hydroxide collector when exposed to ultrasonic vibrations with an intensity of 1.7-3.5 W / cm ² with a frequency of 22-44 kHz at pH 12-13 for 20-25 s . At the same time, the degree of purification for mice reaches 99.5%, for copper 99.5% and cadmium 99.0%. 7 tab.

Description

The invention relates to a chemical process for purifying solutions of sodium chloride from heavy metal impurities, such as arsenic, copper and cadmium, and can be used in the food and chemical industries.

The purpose of the invention is to increase the degree of purification of solutions while reducing the number of collectors.

Example. 140 g preliminarily analyzed table salt is placed in a 1500 ml beaker, dissolved in bidistilled water, and diluted to 1000 ml. 1 mmol of chloride is poured in: magnesium brand H.H. and a solution of sodium hydroxide to pH 12. Expose the solution to ultrasonic vibrations at a frequency of 22 kHz and an intensity of 3.5 W / cm2 for 20 s. The precipitate is separated from the solution by filtration or centrifugation and the content of metal impurities in the precipitate and in the purified solution is determined. Copper and cadmium are determined by atomic absorption in a flame acetylene - air on a C-112 spectrometer, and mouse - by a spectrophotometric method with silver diethyldithiocarbaminate.

In the following examples, the concentration of sodium chloride (Table 1) is changed when exposed to ultrasonic vibrations (Table 2), when the frequency (Table 3) changes, the intensity (Table 4) and the exposure time (Table 5) ultrasonic vibrations, The pH of the solution (Table 6) and the amount of the collector (Table 7).

The use of magnesium hydroxide as a collector for co-precipitating arcuate, copper and cadmium is due to the following. On magnesium hydroxide

X

but

&about

3 16

quantitatively (98%) these trace impurities are coprecipitated. Magnesium is included as a major impurity in the composition of table salt, therefore the risk of contamination of the product being purified is reduced by impurities contained in the injected reagents.

Comparative data with a known method show that coprecipitation with magnesium hydroxide is carried out at a pH of 10.8–11.0 and under these conditions the degree of purification over the mouse does not exceed 6, 5% Purification from copper and cadmium is possible only with NaCl concentration up to 100 g / l and does not exceed y8% for copper, and 90% for cadmium. According to the proposed method, the degree of coprecipitation and, consequently, purification will increase to 99.5, 99.5 and 99.0%, respectively.

Claims (1)

Invention Formula e ni The method of cleaning salt solutions from heavy metal impurities, including their coprecipitation on magnesium hydroxide collector with subsequent separation of the precipitate from the solution, characterized in that, in order to increase the degree of purification of the solutions while reducing the quantity of the collector, coprecipitation is carried out when exposed to ultrasonic vibrations of 1.7 - 3.5 W / cm2 frequency 22 kk kHz with OH 12-13 for 20-25 s. Mouse to note The averaged results of six experiments are presented., The volume of the purified sodium chloride solution is 000 ml. The proposed method introduced: magnesium sulfate 1 mmol, sodium hydroxide to pH 12; ultrasound frequency 22 kHz, ultrasound intensity 3.5 W / cmg, treatment time 20 s, pH 12, According to a known method, sodium sulfate 1 mmol, sodium carbonate 5 mmol, magnesium chloride 5 mmol, sodium hydroxide to pH 11, 0; agitation time 10 min. Table 1 Ny to Note. Ultrasonic cleaning: solution volume 100U ml; the amount of magnesium hydroxide collector 1 nmol; ultrasound frequency of 22 kHz; intensity 3.5 W / cm2; sonication time 20 s; pH of the solution is 12. Cleaning without ultrasonic treatment: 1000 ml solution; the amount of magnesium hydroxide collector is 3 mmol; solution temperature stirring time 10 min; The pH of the solution is 12o. The averaged data of six measurements are presented. NaCl g / l; amount of collector hydropi magnesium 1 swamp | volume of solution 1000 4L | pH of solution 2; ultrasound intensity of 3.5 W / cmg ,, CT gpeigote in enmk NaCl solutions used drug x, Chs, dp spectra of the analysis of two meals peoarphisalliosO8aNY Y. Note, The number of cholelector magnesium hydroxide 1 mmol; p, H solution tZj concentration JIaei g / l; ultrasound frequency of 22 kHz; solution volume 1000 ml, Presented averaged data from six experiments. A solution of sodium sulfide is prepared from an XS4o preparsed calcination for the spectral analysis of the deacted g-8grmsg) d) lysogenic T a l l c a L R E N U E. Averaged data of six measurements are presented. The amount of hydroxide collector, magnesium 1 imol ||; 1000 ml solution; salt concentration in terms of IlaCl 1 "0 g / l; ultrasound frequency of 22 kHz; intensity 3.5 W / cm; pH of 12. Note. Presents averaged data of six measurements. The volume of the purified solution is 1000 mg; the content of salt g / l; magnesium chloride is introduced 1 mmol; ultrasound frequency of 22 kHz; intensity 3.5 W / cm; processing time 20 s. t a b l and M a Table 6 Table 7 and 1611863 Note. The averaged data of six measurements are given. Solution sodium chloride is prepared from the preparation of the classification of h.ch. for spectral analysis, double recrystallized. Ultrasonic cleaning: concentration 50 g / l; ultrasound frequency of 22 kHz; intensity 3.5 W / cm2; volume of solution is 1000 ml; The pH of the solution is 12. Purification without ultrasound: a concentration of 50 g / l; temperature 90 С; mixing time 10 min; pH of 12. 12 1. Continuation of the table. 7