JP5121868B2 - Cleaning agent for separation membrane and cleaning method - Google Patents

Description

  The present invention relates to a separation membrane cleaning agent containing an oxidizing agent and an azaadamantane-type nitroxyl radical, and a separation membrane cleaning method using the same.

  Conventionally, a separation technique using a membrane has been used in various fields including the food industry, the medical field, and the water treatment field. There are several types of separation membranes, such as microfiltration membranes, ultrafiltration membranes, reverse osmosis membranes, and pervaporation membranes, depending on their purpose and application. There are various types of membranes such as flat membrane types, tubular types, and hollow fiber types. is there.

  By the way, when filtration is performed using a separation membrane, insoluble matter suspended in the liquid to be treated and solid matter deposited from the liquid to be treated adhere and accumulate on the surface and inside of the separation membrane and become clogged ( Fouling) occurred, causing problems such as a decrease in filtration flow rate and an increase in transmembrane pressure.

Therefore, various means for removing clogging substances adhering to and depositing on the separation membrane and restoring the filtration capability of the separation membrane have been proposed.
For example, Patent Document 1 discloses that a separation membrane is washed with an aqueous solution of an inorganic acid such as hydrochloric acid, sulfuric acid or phosphoric acid, or an organic acid such as oxalic acid or citric acid, and then an oxidizing agent such as hydrogen peroxide or sodium hypochlorite. A method of washing with an aqueous solution of has been proposed.
In Patent Document 2, in order to enhance the oxidative decomposition action of hypohalite (note: for example, hypochlorous acid, hypobromous acid, and salts thereof) and increase the cleaning power of the detergent,
2,2,6,6-tetra-methylpiperidine-N-oxyl,
4-oxo-2,2,6,6-tetra-methylpiperidine-N-oxyl,
4-hydroxyl-2,2,6,6-tetra-methylpiperidine-N-oxyl,
4,4-dimethyloxazolidine-N-oxyl,
Detergents using cyclic nitroxyl radicals such as 2,2,5,5-tetra-methylpyrrolidine-N-oxyl as catalysts have been proposed.

JP-A-1-307407 Special Table 2000-511218

  An object of the present invention is to provide a cleaning agent for a separation membrane containing an oxidizing agent as an active ingredient and further improving the cleaning power, and a method for cleaning the separation membrane using the same.

  The present inventor has conducted extensive research to solve the above-mentioned problems. As a result, in order to enhance the oxidative decomposition action of the oxidizing agent that is the active ingredient of the cleaning agent and increase the cleaning power of the cleaning agent, It has been found that the intended purpose can be achieved by using the azaadamantane type nitroxy radical represented by the chemical formula (I) of Chemical Formula 1 together, and the present invention has been completed.

（但し、Ｒ_１およびＲ_２は、水素原子または炭素数１〜６の直鎖状もしくは分岐鎖状のアルキル基を表す。）

(However, R ₁ and R ₂ represent a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.)

That is, the first invention is a separation membrane cleaning agent characterized by containing an oxidizing agent and an azaadamantane-type nitroxyl radical represented by the chemical formula (I).
A second invention is the cleaning agent for separation membrane according to the first invention, characterized by containing bromide or iodide. A third invention is a separation membrane cleaning method, wherein the separation membrane cleaning agent according to the first invention or the second invention is brought into contact with the separation membrane.

  According to the present invention, the azaadamantane-type nitroxyl radical acts as a catalyst when the oxidizing agent, which is an active ingredient of the cleaning agent, chemically oxidatively decomposes the clogging substance of the separation membrane, so that the cleaning power of the cleaning agent Can be increased. As a result, the removal of clogging substances firmly adhered to and deposited on the separation membrane is promoted, the amount of oxidant used can be reduced, and the cleaning time can be shortened. It is expected that the load will be reduced and the life of the device will be extended.

Hereinafter, the present invention will be described in detail.
In the practice of the present invention, a cleaning agent is prepared by dissolving an oxidizing agent and the azaadamantane-type nitroxy radical represented by the above chemical formula (I) or these and bromide or iodide in a solvent. Are preferably used, and an organic solvent or a mixed solvent of an organic solvent and water can also be used.

The oxidizing agent used in the practice of the present invention can be used without particular limitation as long as it generates oxygen at the nascent stage and thereby the oxidation reaction is allowed to proceed.
(A) oxygen, ozone, hydrogen peroxide, manganese dioxide;
(B) permanganates such as sodium permanganate and potassium; and dichromates such as sodium dichromate and potassium;
(C) halogen atoms such as chlorine, bromine and iodine;
(D) halogen oxides such as ClO, ClO ₂ , Cl ₂ O ₆ , BrO ₂ , Br ₃ O ₇ ;
(E) nitrogen oxides such as NO, NO ₂ , N ₂ O ₃ ;
(F) Hypochlorous acid, hypobromous acid, hypoiodous acid, chlorous acid, bromous acid, iodic acid, perchloric acid, periodic acid, or a lithium salt, sodium salt, potassium salt thereof, etc. Alkaline earth metal salts such as alkali metal salts, magnesium salts and calcium salts of
(G) persulfates such as sodium persulfate, potassium persulfate, ammonium persulfate, sodium hydrogen persulfate, potassium hydrogen persulfate, potassium monohydrogen persulfate double salt (manufactured by DuPont, trade name “OXONE”);
(H) percarbonates such as ammonium percarbonate, sodium percarbonate, potassium percarbonate;
(I) perborates such as sodium perborate monohydrate and tetrahydrate;
(J) Hydrogen peroxide adducts and superphosphates of sodium sulfate and sodium silicate;
(K) 1,3-dibromo-5,5-dimethylhydantoin, 1-bromo-3-chloro-5,5-dimethylhydantoin, 3-bromo-1-chloro-5,5-dimethylhydantoin, 1,3- Halogenated hydantoin compounds such as dichloro-5,5-dimethylhydantoin and 1,3-dichloro-5-ethyl-5-methylhydantoin;
(L) Halogenated isocyanuric acid compounds such as trichloroisocyanuric acid, dichloroisocyanuric acid, tribromocyanuric acid, dibromocyanuric acid, sodium dichloroisocyanurate, sodium dibromoisocyanurate, sodium dichloroisocyanurate, potassium dichloroisocyanurate ,
(M) N-chlorosuccinimide, N-bromosuccinimide;
(N) sodium salt of trichloromelamine, tribromomelamine, N-chloro-p-toluenesulfonamide (chloramine T);
(O) Peracetic acid, peroxybenzoic acid, peroxy-α-naphthoic acid, peroxylauric acid, peroxystearic acid, phthalimidoperoxycaproic acid, 1,12-diperoxidedecanedioic acid, 1,9-diperoxyazelineic acid, di Preferably used are organic peroxides such as peroxybrassic acid, diperoxysebacic acid, diperoxyisophthalic acid, 2-decyldiperoxybutane-1,4-dioic acid, lauroyl peroxide, benzoyl peroxide, sodium perphthalate, etc. Two or more selected from these may be used in combination.

Of these, sodium hypochlorite, which is commercially available as an aqueous solution and is available at a low cost, is preferably used if any one is selected from the viewpoint of ease of handling and drug cost.
The ratio of the oxidizing agent contained in the cleaning agent is preferably 100 to 10,000 mg / l, more preferably 500 to 7500 mg / l, for example, in terms of effective chlorine. If this concentration is lower than 100 mg / l, satisfactory detergency cannot be obtained, and even if it is higher than 10000 mg / l, detergency that matches the amount of use cannot be obtained, and the drug cost increases. is there.

The azaadamantane-type nitroxy radical used in the practice of the present invention is a substance represented by the above chemical formula (I), for example,
2-azaadamantane-N-oxyl,
1-methyl-2-azaadamantane-N-oxyl,
1,3-dimethyl-2-azaadamantane-N-oxyl and the like can be preferably used.

The concentration of the azaadamantane type nitroxyl radical contained in the cleaning agent is preferably 0.01 to 150 mg / l, more preferably 0.1 to 30 mg / l.
If this concentration is lower than 0.01 mg / l, a satisfactory catalytic effect cannot be obtained, and even if it is higher than 150 mg / l, a catalytic effect corresponding to the amount used cannot be obtained, and the drug cost increases. It is only.

The azaadamantane-type nitroxy radical used in the practice of the present invention can further exhibit a catalytic effect in the presence of bromide or iodide, and can enhance the cleaning power of the cleaning agent.
The bromide or iodide is not particularly limited as long as it generates a bromine or iodine anion in water, but sodium bromide, potassium bromide, ammonium bromide, sodium iodide, potassium iodide and the like are preferable. Can be used. The concentration of bromide or iodide contained in the cleaning agent is preferably 0.1 to 1000 mg / l, more preferably 1 to 200 mg / l.
If this concentration is lower than 0.1 mg / l, the further catalytic effect of the azaadamantane-type nitroxy radical cannot be fully exerted. The catalytic effect cannot be obtained, and the drug cost is increased.

  In the cleaning agent of the present invention, an acid or an alkali may be used in combination as a surfactant, a chelating agent, or a pH adjuster.

By bringing the cleaning agent of the present invention into contact with the separation membrane used in the membrane filtration apparatus, the clogging substance of the separation membrane is oxidized and decomposed, and the clogging of the separation membrane can be eliminated.
Although there is no restriction | limiting in particular in the method of making a cleaning agent and a separation membrane contact, For example, the contact method by immersion or liquid passage is mentioned. Immersion refers to immersing the separation membrane in a cleaning agent (liquid), and liquid passage refers to passing the cleaning liquid through the separation membrane instead of the liquid to be treated in the same manner as in a normal filtration operation.
In addition, before or after the cleaning method of the present invention is performed, the separation membrane is cleaned by chemical means such as conventional alkali cleaning, acid cleaning, and enzyme cleaning, or is physically applied by air bubbling, ultrasonic irradiation, or the like. The separation membrane may be cleaned by means

  The cleaning conditions in the cleaning method of the present invention, for example, the cleaning temperature, the cleaning time, etc., depend on the degree of clogging of the separation membrane to be cleaned, the type and nature of the clogging substance, the cleaning power and life of the cleaning agent, etc. Those skilled in the art may determine appropriately.

  The present invention can be applied to separation membranes of various specifications, types, and applications regardless of the type of membrane filtration device and the field in which the device is used, but the weight of the solid-liquid separation process in the manufacturing process is high. Milk, dairy products, beer, soy sauce, sake, shochu, honey, fruit juices and vegetable drinks that require high-quality quality control such as flavor and aroma after reliably removing clogging substances derived from various contaminants And the like in the field of food production.

  Separation membranes to which the present invention can be applied include reverse osmosis membranes, ultrafiltration membranes, microfiltration membranes classified by pore size, flat membranes, hollow fiber membranes, tubular membranes, bags classified by shape differences And the like, and those membranes that are modularized by being fixed in the casing or in the housing are particularly limited as long as they are used for solid-liquid separation. Not.

  Examples of the material for the separation membrane include, but are not limited to, polyolefins, polysulfones, polyacrylonitriles, polyesters, polycarbonates, nylons, polyvinyl alcohols, celluloses, silicons, fluoropolymers, and ceramics.

The azaadamantane-type nilotoxy radical used in the practice of the present invention is chemically stable because of its robust structure compared to the conventionally known cyclic nitroxyl radicals. Compared to a small amount of use, it is estimated that a high catalytic effect is exhibited.
In addition, as an advantage of the azaadamantane-type nitroxyl radical over the cyclic nitroxyl radical, strong penetration into the hydrophobic clogging substance and stability in the alkaline region are also expected.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to these. The raw materials and the evaluation test methods used in the examples and comparative examples are as follows.

[raw materials]
Separation membrane: hollow fiber membrane module manufactured by Asahi Kasei Chemicals, trade name “Microza MF module UMP-053”, material polyvinylidene fluoride, inner diameter 2.6 mm, nominal pore diameter 0.2 μm, effective membrane area 70 cm ²
・ Non-filtered beer: Product name “The Premium NON-FILTER”
Sodium hypochlorite (may be abbreviated as NaOCl): aqueous solution, manufactured by Wako Pure Chemical Industries, Ltd. 2-azaadamantane-N-oxyl (abbreviated as AZADO): manufactured by Wako Pure Chemical Industries, 2, , 6,6-tetra-methylpiperidine-N-oxyl (abbreviated as TEMPO): Sigma-Aldrich

[Separation membrane cleaning test]
The separation membrane was washed with ion-exchanged water at 25 ° C./transmembrane differential pressure of 35 kPa, and the pure water permeation flux (abbreviated as PWF) was measured (this PWF is referred to as PWF before use).
Subsequently, the separation membrane was attached to a membrane filtration tester, and the beer was circulated and filtered for 30 minutes using non-filtered beer from which carbon dioxide gas had been degassed in advance. Thereafter, it was washed with water for 15 minutes to measure PWF (this PWF is referred to as PWF before washing).
Next, a cleaning agent was circulated in the membrane filtration tester to wash the separation membrane, and PWF was measured every 15 minutes (this PWF is called PWF after washing).
The cleaning recovery rate was calculated from the PWF before use, PWF before cleaning, and PWF after cleaning according to the following formula, and is shown in Table 1. This parameter represents the degree of recovery of the filterability of the separation membrane. The larger the value, the better the cleaning power of the cleaning agent.

Cleaning recovery rate (%) = (PWF after cleaning−PWF before cleaning) / (PWF before use−PWF before cleaning)

[Example 1]
Sodium hypochlorite and AZADO were dissolved in ion-exchanged water to prepare cleaning agents each containing 5000 mg / l (effective chlorine equivalent) and 15 mg / l. A cleaning test of the separation membrane was performed using this cleaning agent, the cleaning recovery rate was calculated, and the cleaning power of the cleaning agent was evaluated. The test data obtained was as shown in Table 1.

[Examples 2 to 4]
In the same manner as in Example 1, a cleaning agent having the composition shown in Table 1 was prepared, a separation membrane cleaning test was performed, and a cleaning recovery rate was calculated. The test data obtained was as shown in Table 1.

[Comparative Examples 1-3]
The cleaning agents listed in Table 2 were prepared in the same manner as in Example 1, and the separation membrane cleaning test was performed to calculate the cleaning recovery rate. The test data obtained was as shown in Table 2.

Example 2 is an example using sodium bromide with AZADO.
Examples 3 to 4 are examples in which the concentration of AZADO in Example 1 was lowered.
Comparative Examples 1 and 2 are examples in which TEMPO was used instead of AZADO in Examples 1 and 2.
Comparative Example 3 is an example in which only sodium hypochlorite is used and no catalyst is used.

  According to these test results, it is recognized that the catalytic effect by which AZADO enhances the oxidative decomposition action of sodium hypochlorite is superior to that when TEMPO is used. Furthermore, the catalytic effect when sodium bromide is used in combination with AZADO is recognized as being superior to that when combined with TEMPO.

ADVANTAGE OF THE INVENTION According to this invention, the cleaning agent for separation membranes and the washing | cleaning method of a separation membrane which were excellent in the detergency can be provided.

Claims (3)

A cleaning agent for a separation membrane comprising an azaadamantane-type nitroxyl radical represented by chemical formula (I) of Chemical Formula 1 with an oxidizing agent.

(However, R ₁ and R ₂ represent a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.) The cleaning agent for a separation membrane according to claim 1, comprising bromide or iodide. A cleaning method for a separation membrane, comprising bringing the cleaning agent for a separation membrane according to claim 1 or 2 into contact with the separation membrane.