CS239244B1 - A method for flocculating colloidal impurities in water - Google Patents

Abstract

A method of flocculating colloidal impurities in water using an organic flocculant in combination with an inorganic coagulant, the essence of which is that flocculation is carried out with a synthetic complex of polyvinylpyrrolidone and dichloroalane, the functional unit of which has the formula

Description

The invention relates to a method of flocculating colloidal impurities in water using an organic flocculant in combination with an inorganic coagulant.

Organic natural and synthetic polymeric flocculants have been used for water treatment for a long time. The effectiveness of these polymers in forming large and solid flocs depends on their ability to reduce the electrokinetic potential of the surface of impurity particles to a value that allows their aggregation, or on the ability to allow the adsorption of polymer molecules on more than one particle and thus the formation of a bond between these particles (Walles W.E.: J.Coll.Interface Sci. 27. 797 (1968); Hesly T.W., La Mer V.K.. J.Phys.Chem. 66, 1835 (1962)). Natural organic flocculants are gradually being replaced by more active synthetic flocculants, a number of which are available on the world market (Vostrčil J.í Chem.listy 63, 1110 (1969). In the treatment of water for industrial purposes and in the treatment of wastewater, acrylamides are most often used.

In waters with a low content of suspended solids, organic flocculants are combined with inorganic coagulants, salts of iron, aluminum or calcium (Kirk-Othmer: Encyclopedia of Chemical Technology, vol.22, J.Wiley and Sons, New York 1970, p.65; Ademoroti C.M.A.: Effluent Wafcer Treat.J. 20, 541 (1980); Kodaka K.í Jap.pat.vykl.spis 77 110 872 (1977), Chem.Abstr. 88 91353 (1978); Umase N.: Brit.pat.příhl. 2 021 551 (1979), Chem.Abstr. 92, 216 429 (1980); Azorlosa J.L., Williams E.P.: USA pat. 3 951 792 (1976), Chem.Abstr. 86, 57 445 (1977); Mailler

F., Le Du Y.: French patent application 36,644 (1978), Chem.Abstr. 93,210,069 (1980)).

No organic synthetic flocculant containing chemically bound inorganic has been used in water purification.

- 2. nic coagulant

239 244

The subject of the invention is a method of flocculating colloidal impurities in water using an organic flocculant in combination with an inorganic coagulant. The essence of the invention lies in the fact that the flocculation of colloidal impurities is carried out by a synthetic complex of polyvinylpyrrolidone and dichloroalane, the functional unit of which has the formula

N

The bound inorganic coagulant causes the organic flocculant chain to straighten. During hydrolysis of this complex, ionic particles with better adsorption capabilities are formed on the surface of the suspension particles, which leads to its more complete removal.

The preparation of the complex for flocculation is carried out under inert conditions under a nitrogen atmosphere in an apparatus equipped with a stirrer, a cooler and a dosing drop device. An 8% toluene solution of polyvinylpyrrolidone is introduced into the apparatus up to a maximum of 25% of the usable volume and an equimolar amount of a 10% ethereal solution of dichloroalane is slowly dosed. After the reaction, the precipitate is washed with toluene and dried to constant weight.

An example of an embodiment of the method according to the invention is described below.

Flocculation was carried out on a flocculation bench under stirring (60 revolutions per minute) for 35 min. A stock solution of raw river water was used for flocculation. The precipitate after flocculation in the water sample was filtered off and the oxidizability was determined in the water sample using the Kubel method. Organic substances in the sample are oxidized in a strongly acidic environment with potassium permanganate, the excess of which is retitrated with oxalic acid. The results are given in mg (Og), equivalent to the consumption of the oxidizing agent per 1 liter of solution (OL). For each type of flocculant and suspension, it is necessary to find the optimal dose of flocculant. The obtained values are given in the table.

The optimal amount of polyvinylpyrrolidone-dichloroalane complex for flocculation of the tested river water was in the range of 11 to 17 mg/1. This complex has significantly better flocculation properties.

- 3 239 244 ability (CL - 3.2) compared to polyvinylpyrrolidone alone (OL - 6.2), even after adding to the found optimal amount of 10 mg/1 polyvinylpyrrolidone various amounts of a simple inorganic coagulant AlCl^, which is a product of dichloroalane hydrolysis. The optimal amount of this combination per 1 liter of tested river water was 10 mg polyvinylpyrrolidone and

22.3 mg A1C1 ₃ (OL - 5.5).

Table

Flocculation of a river water sample with various flocculants. I amount of given flocculant; II complex of polyvinylpyrrolidone with dichloralane; III polyvinylpyrrolidone; IV 10 mg/1 polyvinylpyrrolidone and aluminum chloride

I mg/1 II OL (mg 0 ₂ ) III OL (mg 0 ₂ ) rv OL (mg 0 ₂ ) 0 9.4 9.4 9.4 3 5.8 6 4.4 - - 7 6.5 - 9 3.8 - 10 6.2 - 11 3.4 - 12 - 6.3 N» 14 3.3 - 15 - 7.4 5.8 17 3.2 18 8.3 5.7 20 3.4 22.3 - 5.5 26 4.5 - 2.7 - 6>7 31 5.1 - w. 32 - 37 5.4

- . L, ~

Claims (1)

P fi E D Mfi T OF THE INVENTION 239 244 Process for the flocculation of colloidal impurities in water by means of an organic flocculant in combination with an inorganic coagulant, characterized in that the flocculation of colloidal impurities is carried out by a synthetic complex of polyvinylpyrrolidone and dichloralan, whose functional unit has the formula - (CH ₂ -CH) X / ^x CH-O 1 -Cl ₂