RU2547499C2 - Polyacrylamide-based flocculant for purifying natural water and waste water from oil refineries - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention can be used to purify natural water and waste water from oil refineries. The polyacrylamide-based flocculant includes polyacrylamide used in the form of an aqueous solution with molecular weight of 30 million, with hydrolysis degree of 70% and operating pH 5-11, wherein the polymer has swollen in water at room temperature for 1 day, a modifying agent - propylene glycol and water, with the following ratio of components, wt %: polyacrylamide 0.5-0.7; propylene glycol 0.15-0.3; water - the balance. To prepare the flocculant, propylene glycol is added to an aqueous polyacrylamide solution with said characteristics at room temperature while stirring in the disclosed ratio of components and then used to flocculate contaminated water.

EFFECT: flocculant provides faster and improved clarification of waste water owing to improved flocculating power of the composition of the reagent.

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Description

The invention relates to the production of effective polyacrylamide-based flocculants that can be used to purify natural waters and wastewater from oil refineries.

Known (SU, copyright certificate 1595850, publ. 09/30/1990) is a polyacrylamide-based flocculant when the reaction product of epichlorohydrin and a mixture of salts of higher C ₁₆ -C ₂₀ fatty acids are used as a modifying agent.

However, this mixture must be dispersed in a solution of a grafted copolymer of polyacrylamide with carboxymethyl cellulose, the interaction takes place at a fairly high temperature of 60-80 ° C, and a relatively small efficiency of the flocculant is achieved.

The closest analogue of the developed technical solution can be recognized (RU, patent 2330814, publ. 04/27/2006) a flocculant containing polyacrylamide used in the form of an aqueous solution with a molecular weight of 30 million, while the polymer swelled in water at room temperature for 1 day, water and a modifying agent is a mixture of propylene glycol and ethyl cellosolve at a ratio of 1: 2 in the following ratio of components, in weight. %:

polyacrylamide 0.5-99.0 the above mixture propylene glycol and ethyl cellosolve 0.15-0.3 water rest

A disadvantage of the known flocculant should be recognized as insufficient flocculating ability relative to the oil fraction present in water, since the known flocculant is intended mainly for processing a suspension of carbonates in water.

The technical problem solved by the developed technical solution consists in developing an effective and commercially available flocculant for separating oil products from water.

The technical result obtained by the implementation of the developed technical solution consists in increasing the flocculating ability of the composition based on polyacrylamide with respect to the separation of petroleum products from water.

To achieve the technical result, it is proposed to use a flocculant of the developed composition containing polyacrylamide, used in the form of an aqueous solution with a molecular weight of 30 million, the polymer swelling in water at room temperature for 1 day, the modifying agent propylene glycol and water, the polyacrylamide being used at a degree hydrolysis - 70% and a working pH range of 5-11 in the following ratio of components, in weight. %:

polyacrylamide 0.5-0.7 propylene glycol 0.15-0.3 water rest

A flocculant of the developed composition was prepared as follows: initially an aqueous solution of polyacrylamide (molecular weight 30 million, degree of hydrolysis - 70%, working pH range 5–11) was prepared, which swelled for 1 day at room temperature. Then, with stirring, propylene glycol was added to the polyacrylamide solution in the required amount.

It is known (“Chemical Encyclopedia”, any publication, section “flocculants”) that the molecular mass and the degree of ionization and conformation of flocculant macromolecules affect the kinetics and completeness of flocculation, as well as the structure and properties of flocculants.

It was found that a flocculant based on polyacrylamide with a molecular weight of 30 million, which swelled in water for 1 day at room temperature, with a hydrolysis degree of 70% and a working pH range of 5-11, did not practically change its properties when processing a suspension of carbonates in water. but significantly increased the flocculating ability in relation to the removal of the fraction of petroleum products in water.

This was probably due to a change in the configuration of the polyacrylamide macromolecules.

The effectiveness of the developed flocculant was tested during flocculation of wastewater from the Yaya oil refinery, which contain 0.1 g / l of oil fraction.

To the wastewater was added a composition based on polyacrylamide with the indicated characteristics, including water and a modifying agent - propylene glycol in the following ratio, wt. %:

polyacrylamide 0.5 modifying agent 0.15 water rest

2 ml of a 0.15% flocculant solution was added and the emulsion of wastewater from the Yaya oil refinery was stirred six times by tipping the cylinders.

The rate of formation of the oil film and the degree of clarification of wastewater were determined. The results are presented in table 1.

As can be seen from the above example, the rate of oil film formation by the flocculant of the developed composition is 2.5 times higher than when using the known flocculant. The degree of clarification in this case increases by 3%. The residual solids content in the discharge is reduced by a factor of 2.0, which makes it possible to better clarify the oil emulsion and obtain purified wastewater.

The technical result is achieved using polyacrylamide and propylene glycol in the concentration ranges indicated in the claims. When going beyond these ranges, flocculating abilities with respect to the removal of oil products from water are significantly reduced.

The value of the optimal concentration of the modifying agent depends on the physicochemical properties of the polymer and solvent (water), as well as on the nature of the added substances and is determined experimentally in each case. For each pair of polymer solution - additive there is its optimum concentration, below and above which the degree of crosslinking decreases and the efficiency of the flocculant decreases. This fact is explained by the degree of coagulation of the macromolecule globule, as well as by steric difficulties, when the modifying agent cannot sew individual strands of polymer macromolecules into blocks due to hydrogen bonds.

Claims (1)

Polyacrylamide-based flocculant for the treatment of natural waters and wastewater from oil refineries, including polyacrylamide, used in the form of an aqueous solution with a molecular weight of 30 million, while the polymer swelled in water at room temperature for 1 day, the modifying agent is propylene glycol and water, which differs the fact that polyacrylamide is used with a degree of hydrolysis of 70% and a working pH range of 5-11 in the following ratio of components, in wt. %:
polyacrylamide 0.5-0.7 propylene glycol 0.15-0.3 water rest