RU2786549C1 - Sorbent for water cleaning from oil and from its fuel hydrocarbons - Google Patents

Abstract

FIELD: environmental protection and industrial ecology.

SUBSTANCE: invention relates to the field of environmental protection and industrial ecology and can be used in oil production, oil refining, production and storage of oil fuel hydrocarbons and in the elimination of emergency spills of oil and oil products. The sorbent for water purification from oil and its fuel hydrocarbons consists of a porous matrix hydrophobized with technical paraffin. Foam rubber with a bulk density of 0.02 g/cm³ is used as a porous elastic matrix.

EFFECT: reusable hydrophobic sorbent is provided, which makes it possible to purify water from oil and from its fuel hydrocarbons until the complete disappearance of the oil film on the water surface, which has a high sorption capacity.

5 cl, 2 tbl

Description

The invention relates to the field of environmental protection and industrial ecology and can be used in oil production, oil refining, production and storage of oil fuel hydrocarbons and in the elimination of emergency spills of oil and oil products.

When the sorbent comes into contact with the sorbate, it penetrates into the internal pores of the sorbent matrix. Sorption processes are equilibrium (sorption↔desorption), and their efficiency is determined by the concentration and solubility of sorbates in water, the temperature of the medium, the size of the matrix pore diameters, and the hydrophobicity (or hydrophilicity) of the sorbent matrix.

In the work (Veprikova E.V., Tereshchenko E.A., Chesnokova N.V., Shchipko M.L., Kuznetsov B.N. Features of water purification from oil products using oil sorbents, filter materials and activated carbons. // Journal of the Siberian Federal University, Chemistry, 2010, No. 3, pp. 285-304), it is shown that porous materials (natural organic, synthetic organic and inorganic materials) simultaneously have approximately the same oil and water capacity. Therefore, when such materials are used to remove oil from water, their pores are simultaneously filled with both water and oil, which, as a result, reduces the sorption capacity of the sorbent for oil.

Oil and oil products are a mixture of hydrocarbons with different solubility in water depending on the chemical composition and are (mg / l): oil - from 10 to 50, gasoline - from 9 to 505, kerosene - from 2 to 5, diesel fuel - from 8 to 22. (Oil pollution [Electronic resource] // Ecology of natural resources: [website]. [2021]. URL: https://oblasti-ckologii.ru/ecology/vozdejstvie-na-vodnuu-sredu/osnovnye-zagraznaushie -veschestva/neftyanoe-zagryaznenie (date of access: 11/15/2021).

The value of the sorption capacity for oil, in addition to the size of the matrix pores, also depends on the solubility of oil hydrocarbons (HC) in water. Aromatic hydrocarbons have a high solubility in water; therefore, to ensure a high sorption capacity of the sorbent, it is necessary to have a matrix with high hydrophobicity or minimal hydrophilicity.

In work (Pavlov A.V., Vasilyeva Zh.V. Study of oil and oil products sorbents for oil spill response in the seas of the Arctic region. // Problems of regional ecology. - 2019. - No. 5. - P.89-94.) the sorption capacities of some sorbents for oil, diesel fuel (DF) and motor oil, taken from various literature sources, are presented. It is shown that the experimentally determined values of the sorption capacity of sorbents are significantly lower than those declared by the manufacturers. For example, for the sorbent "Unisorb - extra" according to DT, the sorption capacity is 35 g / g, while the experimental value is 1.61 g / g. The sorption capacity of all the considered sorbents ("Lessorb", Unisorb - extra, "Sorbent >"), for all types of investigated hydrocarbons does not exceed 7.3 g/g.

Authors (Lim L.A., Reutov V.A., Rudenko A.A., Chudovsky A.S. Sorbent oil capacity: the problem of choosing a determination method // Successes of modern natural sciences. - 2018. - No. 10. P. 144-150 .) indicate that the value of the sorption capacity of the sorbent depends on the method of its determination and may differ from several to hundreds of percent. For example, according to one method of determination, the sorption capacity of the NE fiber for diesel fuel is 20.5 g/g, and according to another, it is 2.76 g/g.

In the method of cleaning the surface from oil and oil products (RU No. 2333793), the water surface is treated with a single-use sorbent based on sawdust, hydrophobized with paraffins isolated from reservoir or cork oil sludge. Sorption capacity for oil ranges from 2 to 7 g/g. The method allows you to completely remove the oil film. The maximum sorption capacity is achieved when using dried aspen sawdust of a fraction of 0.5-3.0 mm as a matrix, hydrophobized with reservoir (5% by weight of sawdust) or cork (1%) paraffins.

The disadvantage of this method is the low oil capacity of the sorbent. In addition, the sorbent matrix is inelastic, therefore, it is not squeezed out, and after a single use, the spent sorbent with oil is disposed of by burning in special furnaces. In addition, there is no information on the use of these sorbents for the removal of fuel oil hydrocarbons: gasoline, kerosene and diesel fuel. Therefore, the use of this sorbent in industry during the elimination of emergency oil spills and its fuel hydrocarbons is inappropriate both from an economic and environmental point of view.

Known "Polyurethane sorbent of hydrocarbons and a method for cleaning aqueous media and solid surfaces from hydrocarbon pollutants using it" (RU No. 2 188 072), which describes a sorbent with a polyurethane matrix and with an apparent density of not more than 0.02 g/cm ³ (from 0.01 to 0.016 g / cm ³ examples 2,3 and 4, respectively, the description) having (for one sorption cycle) sorption capacity for crude oil from water 31.25 g / g (example No. 4), and for diesel fuel (for 5 regeneration cycles) -6.25 g/g in terms of 1 sorption cycle (example No. 5), respectively. The disadvantages of this method are:

• the complexity of manufacturing the matrix by mixing the initial monomers at optimal proportions (polyesters 5003-2B-10, PEG-400, ester P-7 with grade B polyisocyanate);

• low sorption capacity from water to oil and diesel fuel;

• low regeneration rate.

The closest to the proposed is the work of Pashayan A.A., Nesterov A.V. Creation of oil-absorbing sorbents by joint utilization of sawdust and oil sludge. Vestnik tekhnologicheskogo universiteta. - 2017. - in T. 20. - No. 9. - P. 144-147), which shows that the maximum sorption capacity for oil was found in sorbents based on absolutely dry aspen sawdust (with a density of less than 650 kg / m ³ ) with a fraction diameter of 0.5-3.0 mm, paraffinized with technical ( purified) paraffin containing hydrocarbon molecules of intermediate size (C ₂₀ -C ₃₅ ), compared with drilling and reservoir oil sludge paraffins. It was revealed that the maximum oil capacity of such a sorbent (5-7 g/g) is achieved at a content of 3% technical paraffin by weight of dried sawdust. Such oil capacity practically does not change in the temperature range of water purified from oil from 5 to 25°C.

The disadvantage of this method is the low oil capacity of the sorbent. In addition, the sorbent matrix is inelastic, therefore, it is not squeezed out, and after a single use, the spent sorbent with oil is disposed of by burning in special furnaces. In addition, there is no information on the use of these sorbents for the removal of fuel oil hydrocarbons: gasoline, kerosene and diesel fuel. Therefore, the use of this sorbent in industry during the elimination of emergency oil spills and its fuel hydrocarbons is inexpedient from both economic and environmental points of view.

The technical problem to be solved by this invention is the creation of an effective reusable sorbent for purifying water from oil and its fuel hydrocarbons, which makes it possible to regenerate both the sorbent and oil hydrocarbons.

The technical result is a reusable hydrophobic sorbent with a sorption capacity from 15 g/g to 41.5 g/g, which makes it possible to purify water from oil and its fuel hydrocarbons until the oil film on the water surface completely disappears.

The technical problem is solved by using an effective resilient sorbent for removing oil and its fuel hydrocarbons from the water surface. To create such a sorbent, it is proposed to use a porous matrix of polyurethane foam with a bulk density of 0.02 g/cm ³ hydrophobized with technical paraffin as a porous matrix. The sorbent for 50 cycles allows you to regenerate up to 95% of the mass of absorbed oil and its fuel hydrocarbons, which is (g/kg): 0.74; 1.07; 1.46 and 2.0 of AI-72 gasoline, kerosene, diesel fuel and oil, respectively. To ensure the maximum capacity for oil and for the specified hydrocarbons, sorbents were created with a degree of hydrophobization (paraffin content, %) of 5.0; 10.0; 10.0 and 15.0, respectively, which provided the maximum capacity (g/g) for these hydrocarbons and oil: 15.6; 22.5; 30.8 and 41.87 respectively.

The process of manufacturing an elastic sorbent based on polyurethane foam - foam rubber was carried out in the following sequence. Pieces of foam rubber were sorted into different fractions by selecting approximately the same size, and the bulk density was determined. Foam rubber samples were impregnated with various amounts of solutions of technical paraffin. Samples of hydrophobized foam rubber were prepared with a paraffin content (by weight) of 2.5; five; 7.5; 10, 15 and 20%, determined the sorption capacity of the studied sample of the sorbent for oil hydrocarbons.

To clean the water surface from oil and from its hydrocarbons (HC): diesel fuel (DF), gasoline (AI-92) and aviation fuel (kerosene), pieces of the sorbent were immersed on a water surface containing a known amount of HC until the complete disappearance of the oil film on the surface. water surface)

The mass of the sorbent consumed in this case was determined. The sorption capacity for oil and its fuel hydrocarbons (H, g/g) from water was determined by the formula:

H \u003d m _(oil) / m _(sorbent) ,

where m _(oil) is the mass of absorbed oil, g;

m _(sorbent) is the mass of the used sorbent, g. Oil regeneration was carried out by pressing elastic sorbent samples saturated with oil.

The degree of oil regeneration ω (%) was determined by the formula:

ω=[m _{(∑reclaimed oil)} / m _{(original oil)} ]*100%,

where m _{(∑reclaimed oil)} is the mass of recovered oil, g;

m _{(original oil)} mass of original oil, g.

The volume of a foam rubber sample of known mass was determined geometrically (width*length*thickness).

The bulk density of foam rubber ρ (g/cm ³ ) was determined by the formula:

ρ=m _{(foam rubber)} / V _{(foam rubber)} ,

where m _{(foam rubber)} - mass of foam rubber, g;

V _{(foam rubber} - the volume of the foam rubber sample, cm ³ .

The degree of hydrophobization of foam rubber γ (%) was determined:

γ|m _(paraffin) /m _{(foam rubber)} |*100%

where m _(paraffin) is the mass of hydrophobic paraffin, g.

The regeneration rate (ε) of oil was determined by the number of regeneration cycles, after which the sample loses its operational qualities (sticks together and loses elasticity).

The absolute oil capacity [ _H0 , g/g] of sorbent samples with different hydrophobicity was determined by immersing foam rubber samples in pure oil or hydrocarbons, respectively, separating the saturated sorbent and standing the samples on a sieve at room temperature until the liquid completely drained from the saturated sorbent sample. H ₀ , (g/g) was determined by the formula:

H ₀ \u003d m _(oil) / m _(sorbent) .

Studies have shown that all samples of elastic sorbents for 45-50 regeneration cycles did not lose their performance. At the same time, after the first cycle, the degree of regeneration was 95% and practically did not change in subsequent cycles. The experimental results are summarized in Table 1.

*M - Mass of oil (kg) during its regeneration from 1 g of saturated sorbent with 50-fold use of the sorbent (ω=95%).

In pure foam with ρ=0.02 g/cm ³ (sample 6) oil capacity is approximately two times lower than its water capacity. With its hydrophobization by 5% (sample 8), the oil capacity increases by 100%, and the sorption capacity for oil from water by 152%.

In loose foam rubber (ρ=0.01 g/cm ³ ), which has wide pores, oil is poorly retained, and when the matrix is compacted (ρ=0.03 g/cm ³ ), the diameters and the total volume of internal foam rubber pores decrease. Therefore, the maximum oil capacity and sorption capacity of the sorbent for oil were found in foam rubber with ρ=0.02 g/cm ³ .

At the same time, the frequency of use of the sorbent saturated with oil is at least 50 times, with a loss of sorption capacity (degree of oil regeneration ω=97.24%) of 2.66%.

Table 2 summarizes the results of measuring the sorption capacity of elastic matrices and sawdust in relation to oil and its fuel hydrocarbons.

As can be seen from the data in tables 1 and 2, other things being equal, the maximum sorption capacity from water for oil (g/g) - 41.8 is achieved at 5% hydrophobization of foam rubber, for AI-92 gasoline - 15.65 is achieved at 15% , for kerosene - 22.5 and for diesel fuel - 30.8 are achieved with 10% hydrophobization of foam rubber.

At the same time, the capacity of the sorbent to hydrocarbons for 50 regeneration cycles is (kg / g) ~ 2.0 (for oil), 1.46 (for diesel fuel), 1.07 (for kerosene) and 0.74 (for AI-92) respectively.

The observed patterns in Table 2 are due to the fact that the average size of hydrocarbon molecules decreases in the series: oil>diesel fuel>kerosene>AI-92 gasoline. That is, the sorbent with 5% hydrophobicity retains large molecules of hydrocarbon oil inside its paraffinized pores. Whereas, small molecules from the composition of diesel fuel, kerosene and B-92 are easier to desorb from the matrix.

Therefore, to retain such small molecules, waxing is required 2 (in the case of kerosene and diesel fuel) and 3 times (in the case of gasoline) more than for oil.

At the same time, the increase in the sorption capacity for hydrocarbons from water before and after foam rubber waxing is (%); gasoline - 110, kerosene - 120, oil - 150 and diesel fuel - 200, respectively.

The increase in sorption capacity from water compared to sawdust (prototype) is 3.36 times for gasoline, 4.24 for kerosene, 4.7 for diesel fuel and 6.0 for oil.

Thus, the technical problem to which this invention is directed: the creation of an effective and elastic reusable sorbent that allows the recovery of oil hydrocarbons has been completed.

Claims (5)

1. A sorbent for water purification from oil and its fuel hydrocarbons based on a porous matrix hydrophobized with technical paraffin, which makes it possible to remove oil from water until the oil film completely disappears on the water surface, characterized in that in order to obtain a sorbent that can withstand 50 regeneration cycles, the degree of regeneration of 95% of oil and its fuel hydrocarbons, used a porous elastic matrix - foam rubber, with a bulk density of 0.02 g/cm ³ . 2. The sorbent according to claim 1, characterized in that to ensure the maximum sorption capacity of the sorbent for oil from water, equal to 41.85 g/g, foam rubber containing 5% by weight of technical paraffin is used. 3. The sorbent according to claim 1, characterized in that to ensure the maximum sorption capacity for diesel fuel from water, equal to 30.8 g/g, foam rubber containing 10% by weight of technical paraffin is used. 4. The sorbent according to claim 1, characterized in that to ensure the maximum sorption capacity for kerosene from water, equal to 22.5 g/g, foam rubber containing 10% by weight of technical paraffin is used. 5. The sorbent according to claim 1, characterized in that to ensure the maximum sorption capacity for gasoline from water, equal to 15.6 g/g, foam rubber containing 15% by weight of technical paraffin is used.