SU1370084A1 - Method of removing cation dyes from waste water - Google Patents

Abstract

The invention relates to methods for the purification of wastewater by sorption from synthetic cationic dyes and can be used in the chemical and textile industry. The aim of the invention is to increase the degree of wastewater treatment with a dye concentration below 1.3 g / l. To carry out the process, the purification is carried out in two stages; first, in non-equilibrium conditions, the effluents with a dye concentration within 1.7-2.5 g / l are purified in an alkaline medium by hydrolyzing lignin before filling its sorption volume by 15-25%, then under equilibrium conditions, effluents with a dye concentration below 1.3 g / l are purified using hydrolysis lignin from the first stage as a sorbent. Such a regime of wastewater treatment makes it possible to increase the efficiency of the sorption process by a factor of 5-6 as compared with the known method, and also to eliminate the effects of secondary contamination of wastewater by water-soluble hydrolytic lignin fractions by coagulation and sedimentation on the lignin. 2 tab. o (l

Description

TO

one

The invention relates to sorption-based wastewater treatment methods and can be used in textile and chemical industries to clean sewage from synthetic cationic dyes,

(The purpose of the invention is to increase the degree of purification of wastewater from synthetic cationic dyes when the content of the latter in the effluent is below 1.3 g / l.

In order to implement the method of purification of wastewater from synthetic cationic dyes, including the sorption of the latter by hydrolysis lignin activated in alkaline medium, wastewater with a high dye concentration in the range of 1.7-2.5 g / l or aqueous solutions with the same concentration of the dye is subjected to sorption cleaning in non-equilibrium conditions, activated in an alkaline medium with hydroxybniM lignin before filling its sorption volume by 15-25%, after which the hydrolytic lignin is used as a sorbent for further purification s from krsiteli, which lead in equilibrium conditions by known methods.

In the process of partial sorption of hydrolyzed lignin cationic dyes of a certain concentration (1.7-2.5 g / l) processed in an alkaline medium, water-soluble fractions coagulate (colloid-soluble lignin, lignohumic substances) coagulate and precipitate on the lignin to prevent these fractions back into solution.

At the same time, the sorption capacity of the sorbent remains sufficient (75-85%) which provides an effective adsorbent of the dye (for example, methylene blue 300-370 mg / l), which is more than 6 times greater than the adsorption of the same dye by the sorbent, processed by a known method .

The comparative sorption activity of hydrolysis lignins, depending on the treatment (relative to motilylene blue), is presented in Table. one ,

In order to determine the sorption volume of lignin at equilibrium conditions, the hydrolytic lignin with a moisture content of bO / J is treated with a 5% solution of sodium hydroxide at a water ratio of 1: 6 for 60 minutes at. Then lignin section

from the solution, washed with water, neutralized before and again washed with water.

A portion of 1 g (in terms of absolutely dry matter) of the treated lignin is poured into each 50 ml of an aqueous solution of methylene blue with a concentration of 2.5 g / l, 2 g / l,

1.7 g / l, 2.8 g / l and 1.5 g / l. Sorption is carried out in static conditions for 10 days. A photocalorimetric method for determining the concentration of the dye in the solution was used to determine the sorption value. The sorption of methylene blue hydrolysis lignin at equilibrium conditions is respectively 390 mg / l, 380 mg / g, 377 mg / g, and 360 mg / g.

Example 1. A portion of the treated lignin, 1 g (in terms of absolutely dry substance) pour 50 MP of an aqueous solution of methylene blue with a concentration of 2.5 g / l,

exposure time 20 min. The sorption of the dye, determined by the photo calorimetric method, is 90 mg / g, which corresponds to the sorption volume of the sorbent by 23%. Then

250 ml of a solution with a concentration of 1 g / l of methylene blue is fed into the sorbent-sorbate system. The exposure time is 10 days.

As a control, the equilibrium sorption of the same dye was carried out using as a sorbent hydrolysis lignin, subjected to only alkaline treatment (by a known method).

The sorption according to the proposed method is: 1 stage — 90 mg / g; Stage 2 - 250 mg / g. Total sorption is 340 mg / g.

The total sorption in the control (by a known method) is 61 mg / g. PRI mme R 2. A portion of the treated lignin 1 g pour 50 ml of an aqueous solution of methylene blue with a concentration of 2 g / l. Sorption is carried out before filling 17% of the total sorption volume.

Then the system sorbent sorbate serves 250 ml of a solution with a concentration of methylene blue of 1.25 g / l.

The exposure time is 10 days.

The sorption according to the proposed method is: Stage 1 - 66 mg / g, Stage 2 - 312 mg / g. Full sorbsi - 378 mg / g.

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EXAMPLE 3 The activation of hydrolyzed lignin is carried out analogously to Example 1.

A portion of the treated lignin 1 g pour 50 ml of an aqueous solution of methylene blue with concentration

1.7g / l. Sorption is carried out before filling 16% of the total sorption volume.

Then the system sorbent sorbate serves 250 ml of a solution with a concentration of methylene blue 1 g / l. The exposure time is 10 days.

The sorption according to the proposed method is: Stage 1 — 60 mg / g; Stage 2 - 248 mg / g. Full sorbsi - 308 mg / g.

EXAMPLE 4 The activation of hydrolytic lignin is carried out analogously to example 1.

A portion of the treated lignin 1 g pour 50 ml of an aqueous solution of methyl blue with a concentration

2.8g / l. Sorption is carried out before filling to 30% of the total sorption volume.

Then the system sorbent sorbate serves 250 ml of a solution with a concentration of methylene blue 1 g / l. The exposure time is 10 days.

Sorption is: 1- stage - 120 mg / g, 2- stage - 150 mg / g. Total sorption is 270 mg / g.

Thus, a high percentage of filling the sorption volume in stage 1 impairs the sorption capacity of lignin upon its further use as a sorbent (stage 2).

EXAMPLE 5 Hydrolysis lignin is activated as in Example 1.

A portion of the treated lignin 1 g pour 50 ml of an aqueous solution of methylene blue concentration of 1.5 g / l. Sorption is carried out before filling 12.5% of the total sorption volume. Then the system sorbent-sorbate serves 250 ml of a solution of methyl blue with a concentration of 1 g / l. The exposure time is 10 days.

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Sorption is; 1- with reptiles - 45 mg / g, 2-stage - 250 rir / r. Total sorption is 295 mg / g. 5 In table. 2 cites the test results of the sorption capacity of alkali-activated lignin according to the proposed method (in stage 2).

Analysis of the data presented in Table 10, 2 shows that, when the sorption is carried out in two stages using in the first stage (non-equilibrium conditions) solutions of dye or waste water with a concentration in the interval of 1.7-2.5 g / l (S 1,2,3) sorption volume of lignin is filled in the range of not more than 25% and not less than 15% of the total sorption volume. In this case, the goal of the invention is achieved - 20 PIA - an increase in the degree of wastewater treatment. The total sorption reaches 310-370 mg / g, which is 5-6 times higher than sorption by a known method. In addition, sorption is carried out by a known method 25 to secondary contaminants.

The use of a dye solution with a concentration above 2.5 g / l (No. 4) at the 1st stage of the process leads to the filling of the sorption volume more than 30%, which reduces the sorption capacity of the sorbent at the 2-1 stage of the process.

The use of a dye solution with a concentration of less than 1.7 g / l (example 5) at the 1st stage of the process causes the appearance of secondary contaminants in the solution.

Claims (1)

Invention Formula 40 The method of purification of wastewater from cationic dyes, including sorption on hydrolysis lignin activated in an alkaline medium, is about the fact that, in order to increase the degree of wastewater treatment with a concentration below 1.3 g / l, sorption is carried out on activated lh-- Nina, pre-treated solution of dye concentration 1.7-2.5 g / l to fill the sorption volume of lignin by 15-25%. Table 1 Continuation of table 1 Source Hydrolytic Lignin Hydrolyzed lignin treated with sodium hydroxide Hydrolyzed lignin treated with trisodium phosphate (known method) The method according to the examples 1 2 3 4 5 Hydrolyzed lignin treated with alkali and dye solution with a concentration of 2 g / l in non-equilibrium conditions (stage 1) 66 with subsequent sorption of the dye from solution 15 with a concentration of 1.25 g / l (2-stage) 312 Full sorption capacity (proposed method) 378 THOSE and “2.