Composition and method of producing porous pvfm-based filter

FIELD: process engineering.

SUBSTANCE: invention relates to filters intended for separation of inhomogeneous systems, in particular, to fabrication of filtration PVFM-based materials to be used in cleaning fluids and gases of water, mechanical impurities and biological contaminants. Composition for filter fabrication includes the following components, in wt %: polyvinyl alcohol - 5-20, porophore - 2-10, paraformaldehyde cross-linking agent - 2-15, catalyst - 1-15, water making the rest. Porophore mat represent a mix of starches with average grain size, or mix of starch with dextrin. Preset amount of polyvinyl alcohol is diluted in water. It is heated to 75-95°C with continuous mixing. Porophore suspension in cold water is added to obtained solution and kept at 55-80°C for 15-30 min with continuous mixing. Preset amount of cross-linking agent is added thereto and mixed for 10-30 min. Preset amount of catalyst is added thereto at 30-40°C and mixed for 10-20 min. Obtained reaction mix is poured in the mould, kept in temperature controlled cabint at 55-80°C for 5-20 h. Produced element is withdrawn from said mould, washed of catalyst and porophore. Drying is carried out at 15-25°C and, then, at 30-50°C to constant weight.

EFFECT: simplified process, possibility to vary filter porosity, reduced contamination.

4 cl, 4 tbl, 16 ex

The invention relates to filtration devices, with which the separation of heterogeneous systems, more specifically, to methods for producing a filtering material on the basis of porous polyvinylformal, and can be used for the purification of liquids and gases from water, mechanical impurities and biogarantie.

A method of obtaining porous filter material (SU # 134021, 27.09.1960) from aqueous solution of polyvinyl alcohol containing 5-20% of the polymer by chemical modification of aqueous solutions of aldehydes (2-15 wt.% formaldehyde), mineral acids (2-30 wt.% sulfuric acid) and organic acids and their anhydrides, and salts (e.g. ammonium sulfate)at which to give a modified high-molecular substance, a gel-like mesh temporiti structure of the modifying additive is mixed with solution of high-molecular compounds at temperatures below 30°C, at which the modifying reaction is slow, then the temperature was raised to 50 to 90°C and above, can withstand 1-60 minutes the Obtained gel is treated with solutions of the corresponding salts at elevated temperature, after which it is washed and dried. Changes of mechanical properties reach by soaking formed of a porous material additional amounts of the initial solution containing modifitsiruyutsya supplements and re-heat treatment, leading to the formation of secondary polymer network in the pores of the originally formed. The obtained filter material is a dense grid firmly fused fibers, has a macroscopic uniformity, significant sorption capacity and high permeability (about 4-6 mg/cm²hour - shifted moisture at 30°C).

A known method of producing proprienitrile (SU # 267896, 1970) by foaming an aqueous solution of polyvinyl alcohol, followed by curing formaldehyde in the presence of acidic catalysts, to obtain a foam with uniform porosity and improve the physical-mechanical properties in the reaction mixture is injected aqueous solution of methyl cellulose in an amount of from 10 to 60 parts per 100 parts of polyvinyl alcohol. Propresidential with the addition of methylcellulose has a much more uniform pores, has a pure white color and has good hydrophilicity and mechanical strength.

Also known is a method of obtaining porous sorption material (RU # 2151615, 27.06.2000), consisting in the preparation of liquid disperse system consisting of a dispersed phase in the form of air bubbles or foaming agent, and dispersing the aqueous reaction medium comprising aqueous solutions polivinil the alcohol, cross-linking agent, sodium chloride and a mineral acid. After completion of the reaction receive the porous material in the highly elastic state, which is washed with distilled water from the unreacted crosslinking agent, acid, chloride of sodium and foaming agent.

The disadvantages of these methods include the difficulty and complexity of obtaining polyvinylformal caused by the use of additives that require separation prior preparation of liquid dispersion system and the dispersion aqueous reaction medium.

Similar to the proposed composition for porous filtering material on the basis of polyvinylformal is a composition comprising polyvinyl alcohol, potato starch, formaldehyde and water in the following ratio, wt.%: polyvinyl alcohol - 7-9, potato starch - 4-6, formaldehyde - 3-5, water - the rest (certificate for utility model RU # 13539, 27.04.1999 year).

The disadvantage of the use of this composition is that the use of only starch is not possible to adjust the porosity obtained polyvinylformal to the extent necessary. At the same porosity obtained filtermaterial or separates water or absorbs it. The only use of formalin in the specified composition reduces resource base to receive the deposits of polyvinylformal, in addition, the high volatility of formaldehyde requires constant monitoring of its content in the solution and counting the number of downloadable raw materials with each new synthesis.

A known method of obtaining a filter for the purification of hydrocarbon fuels, oils, emulsified oil from water and solids by condensing structure and heat treating a homogenized in water composition, including at least polyvinyl alcohol and aldehyde. The obtained porous filter material has a high cleaning efficiency fuels and gaseous petroleum products from water, and increased service life (patent RU №2267346, 10.01.2006,)

The closest analogue to the method of obtaining porous polyvinylformal is a method characterized by chemical modification of an aqueous solution of polyvinyl alcohol by means of a crosslinking agent and a mineral acid, in which 5-20% aqueous solution of polyvinyl alcohol is heated to a temperature of 80-90°C with constant mechanical stirring, after which it add cold water starch solution and the resulting mixture is cooled to a temperature of 30-40°C., while continuing the stirring for 25-30 minutes, then the obtained solution is poured crosslinking agent is an aqueous solution of formalin, and after 20-30 min - sulfuric acid. The obtained mass of the polymer is poured into a form and stand at least 6 hours at a temperature of 50-70°C, after which the formed material with cellular structure is extracted from the mold, washed from starch and residue input modifying components and then dried at a temperature of 25-30°C ventilation in the closet (patent RU №2292223, 10.09.2005 - prototype).

In the method prototype receive material with solid, homogeneous, porous fine structure at low cost receive polyvinylformal. The technology of the method is simplified by eliminating foaming agent and sodium chloride.

The disadvantage of this method is the inability to control the porosity obtained polyvinylformal to the extent necessary and the need to exercise control over the content of formaldehyde in the solution of downloadable materials. In addition, the starch solution is impossible to obtain in cold water, you must first obtain its paste in hot water and then dilute it. It is time-consuming and unnecessary operation.

To expand the possibilities of varying the porosity of the obtained filter element on the basis of oliviformis, expanding the resource base for its production and reduce pollution production facilities formaldehyde, and simplify the production technology proposed as pore-forming to obtain to use a mixture of starches with different what elicina grain, and as a cross-linking agent is paraformaldehyde in the following ratio, wt.%:

- polyvinyl alcohol - 5-20;

the pore - forming - 2-10;

- crosslinking agent - 2-15;

catalyst - 1-15;

- water - the rest.

As the catalyst composition contains inorganic acid (donor b), a water-soluble organic acid (donors N), base (donor), salts of strong acids with weak bases, salts of weak acids with strong bases.

As pore-forming composition comprises a mixture of starch and dextrin. From the specified composition of the receive filter material by chemical modification of the composition when dissolved in water given quantity of polyvinyl alcohol by heating to a temperature of 75-95°C and continuous stirring, is added to the resulting solution of suspension of the pore-forming in cold water, the extract mixture with constant stirring at a temperature of 55-80°C for 15-30 minutes, adding a calculated quantity of a crosslinking agent and stirring for 10-30 minutes. Then at a temperature of 30-40°C add the calculated amount of catalyst and a further stirred for 10-20 minutes, the reaction mixture is poured into molds and incubated at a temperature of 55-80°C for 5-20 hours, the resulting element is extracted from the mold, washed on the catalyst and blowing agent, dried first at a temperature of 15-25°C for 24-48 hours, and then at a temperature of 30-50°C to constant weight.

Industrial applicability the receive filter based on porous polyvinylformal of the proposed structure is confirmed by the following examples.

Example 1

In a clean beaker with a capacity of 2 liters, installed in a fume cupboard, fill in 560 ml of hot water at a temperature of 95-97°C and load of 105 g (8,6%) of polyvinyl alcohol. Include a mixer and adjusting the temperature of the solution up to 86-88°C.

In a conical flask with a capacity of 250 ml of the prepared suspension of 35 g (2,9%) corn starch in 140 ml of water, loaded into a glass with a solution of polyvinyl alcohol when operating the stirrer and stirred at a temperature of 80-85°C for 10 minutes.

In a conical flask with a capacity of 250 ml of the prepared suspension of 35 g (2,9%) potato starch in 140 ml of water, loaded into a glass with a solution of polyvinyl alcohol and corn starch when operating the stirrer and stirred at a temperature of 75-80°C for 10 minutes.

Bring the temperature in the beaker to 50°C and load 82 ml (6,7%) formalin, and then at a temperature of 40°C 72 ml (11%) sulfuric acid. The reaction mass is stirred for 10 min, stop the mixer and discharged in the form, which is then loaded into thermostat, pre-heated to a temperature of 60°C. the Form is kept in Ter what the mod 16 h, then unload the machine, bring the temperature of the shape with a natural cooling to 25°C and remove filterelement.

Example 2

In a clean beaker with a capacity of 2 liters, installed in a fume cupboard, fill in 560 ml of hot water at a temperature of 95-97°C and load 155 g (14,3%) of polyvinyl alcohol. Include a mixer and adjusting the temperature of the solution up to 86-88°C.

In a conical flask with a capacity of 150 ml of the prepared suspension of 25 g (2,3%) of rice starch in 100 ml of water, loaded into a glass with a solution of polyvinyl alcohol when operating the stirrer and stirred at a temperature of 83-85°C for 10 minutes.

In a conical flask with a capacity of 150 ml of the prepared suspension of 15 g (1,4%) corn starch in 100 ml of water, loaded into a glass with a solution of polyvinyl alcohol and corn starch when operating the stirrer and stirred at a temperature of 75-80°C for 10 minutes.

In a conical flask with a capacity of 150 ml of the prepared suspension of 25 g (2,3%) potato starch in 150 ml of water and loaded into a glass with a solution of polyvinyl alcohol and corn starch when operating the mixer, stirred at a temperature of 70-75°C for 10 minutes and load 33 g (3%) of paraformaldehyde, stirred for 25 minutes and then at a temperature of 35°C 50 ml (8,5%) sulfuric acid. The reaction mass is stirred for 10 min, stop the mixer and discharged formu, which is then loaded into thermostat, pre-heated to a temperature of 60°C. Form incubated 16 h, after which unload the machine, bring the temperature of the shape with a natural cooling to 25°C and remove filterelement.

Example 3

In a clean beaker with a capacity of 2 liters, installed in a fume hood, pour 700 ml of hot water at a temperature of 85-87°C when operating the mixer load 175 g (12,7%) of polyvinyl alcohol.

In a conical flask with a capacity of 250 ml of the prepared suspension of 50 g (3,6%), potato dextrin in 150 ml of water, loaded into a glass with a solution of polyvinyl alcohol when operating the stirrer and the temperature of 65-70°C. and stirred for 15 minutes.

In a conical flask with a capacity of 100 ml are prepared in a suspension of 20 g (1.5%) of potato dextrin in 80 ml of water and loaded into a glass with a solution of polyvinyl alcohol and potato starch when working stirrer and a temperature of 65-70°C, stirred for 10 minutes and load 45 g (3,3%) of paraformaldehyde, stirred for 30 minutes, cooled to 30°C and load 90 ml (12,1%) sulfuric acid. The reaction mass is stirred for 10 min, stop the mixer and discharged in the form, which is then loaded into thermostat, pre-heated to a temperature of 70°C. Form incubated 12 h, after which unload the machine, bring the temperature of the form PR is a natural cooling to room and remove filterelement. Put it in a wash tub in which preloads the warm water, washed with water until neutral universal indicator, press and placed in an oven, preheated to a temperature of 35-40°C. Filterelement dried to constant weight.

Other examples for the various components and conditions the receipt of filtermaterial based on them and the results are given in table 1, 2.

The ability to clean up the fuel from biogarantie was determined as follows. In accordance with GOST 9.023-74 in mineral environments for Pseudomonas aeruginosa, Cladosporium resinae, Mycobacterium, cumulative crops and Candida growing biogarantie in commodity diesel fuel L GOST 305. Samples were taken Bioorganic fuel, it was filtered through filterelement of declared material and samples were taken clean fuels. The degree of purification of the fuel was determined by counting of microbial cells contained in the fuel, before and after cleaning.

The number of microbial cells (bacterial and fungal) was determined by the method of Koch by plating on a solid nutrient medium:

- meat nutrient agar (MPA);

dry nutrient agar (SPA) with 2 wt.% glucose;

environment of čapek with 2 wt.% glucose;

- Wednesday, Saburo.

The results presented in the table.

Microbial contamination of samples of diesel fuel are given in tab is itzá 3

In the presented results show that the samples of diesel fuel with biogarantie inoculated bacterial cultures (5×10⁵and 4×10⁵cells/ml, respectively) and filamentous fungi (1×10⁵and 8×10⁵cells/ml, respectively). Filtering contaminated with microorganisms samples of fuel through the filter of declared material provides effective cleaning of fuel 99.4 to 99.9%.

The filter of the claimed material was shown cleaning the sludge from the fuel tank with gasoline AI-92 tank farm "PTC-Terminal". When direct disposable filtration through the filter of the claimed material is the simultaneous purging fuel from water and mechanical impurities. Refined fuels, clean, transparent, no traces of water and mechanical impurities, can be directly used for its intended purpose.

The main part separated by a mechanical filter impurities are corrosion products, in particular the oxides of iron.

In the laboratory Tuapse refinery was conducted clearing artificial mixture of the following composition:

After cleaning bench with filters of declared material according to the analysis CPL plant water and mechanical impurities in the filtrate are missing.

To confirm the effectiveness of the proposed method of obtaining filtermaterial us was prepared diesel GOST 305 with 2% of artificial contaminant - quartz dust with a specific surface area of 1050 square meters/kg

Received the contaminated fuel was filtered through a pair of filterelements obtained in experiments 1 and 2 and 6 and 9, respectively (see table 1). These pairs of filterelements have almost the same porosity (see table 2).

Differences between 1 and 2 filterelements are cross-linking agent is formaldehyde and paraformaldehyde, respectively, and between 6 and 9 filterelements are pore-forming - in filterelement 6 is used potato starch and filterelement 9 a mixture of potato and corn starch in a ratio of 1:1.

In a purified diesel fuel were determined mechanical impurities according to GOST 6370. The number of mechanical impurities are shown in table 4

In accordance with GOST 6370 solids content of less than 0,005% qualifies as a lack of mechanical impurities. However, the class definition of clean diesel fuel GOST 17216 showed a noticeable difference in the cleanliness of the fuel. At almost the same porosity as part of filterelement starch with less grain makes for a clean fuel.

The advantage of the method of producing filter from the proposed structure is the technology of obtaining material, reducing hazards in the premises, the opportunity to get filterelement with a given porosity.

In the claimed composition and the method for obtaining a filter based on the East polyvinylformal managed not only to effect coalescence of water droplets by passing the cleaned fluid through the filter element, but cleaning fluid from biological contamination.

1. The composition to obtain a filter-based porous polyvinylformal for the purification of liquids and gases from water, mechanical impurities and biogarantie comprising polyvinyl alcohol, a blowing agent, a crosslinking agent, a catalyst and water, characterized in that it contains pore-forming mixture of starches with different average grain size or starch and dextrin, and as cross-linking agent contains paraformaldehyde in the following specified components, wt.%:

2. The composition according to claim 1, characterized in that as the catalyst it contains industrial inorganic acid (such as H₂SO₄H₃PO₄, HCl, HNO₃).

3. The composition according to claim 1, characterized in that as the catalyst it contains industrial inorganic bases (e.g. NaOH, KOH, LiOH, CA(Oh what) ₂).

4. A method of producing filter-based porous polyvinylformal, including the dissolution of polyvinyl alcohol in water when heated to a temperature not higher than 95°C and stirring, adding to the resulting solution of suspension of the pore-forming in cold water, cooling the reaction mass to a temperature not lower than 30°C, the sequential introduction of cross-linking agent and catalyst under stirring, followed by pouring the reaction mixture into the mold, keeping them at least 5 hours at a temperature not lower than 55°C, cooling to room temperature, removing the given item from the form, the washing of the catalyst and blowing agent, drying to constant weight, characterized in that as the pore-forming a mixture of starches with different average grain sizes or a mixture of starch to dextrin, and as cross-linking agent used paraformaldehyde.