WO2018168641A1

WO2018168641A1 - Cleaning fluid, detergent, and cleaning method for water-contact member

Info

Publication number: WO2018168641A1
Application number: PCT/JP2018/008978
Authority: WO
Inventors: 貴子岩見; 孝博川勝; 愛理田中
Original assignee: 栗田工業株式会社
Priority date: 2017-03-15
Filing date: 2018-03-08
Publication date: 2018-09-20
Also published as: JP6610776B2; TW201902563A; CN110248723A; TWI734898B; CN110248723B; JPWO2018168641A1

Abstract

A cleaning fluid and detergent for water-contact members which both contain free chlorine and a combined-chlorine compound, wherein the molar ratio of the total chlorine (Cl2) to the nitrogen atoms N derived from the combined-chlorine compound, Cl2/N, is 1 or higher, the cleaning fluid having a pH of 9 or higher and the detergent having a pH of 12 or higher. The cleaning fluid can be prepared by diluting the detergent with water. Also provided is a cleaning method for water-contact members which comprises using the cleaning fluid to clean a water-contact member.

Description

Cleaning liquid, cleaning agent and cleaning method for wetted parts

The present invention relates to a cleaning liquid, a cleaning agent, and a cleaning method for cleaning a wetted member such as a UF membrane (ultrafiltration membrane), an MF membrane (microfiltration membrane), a filter, a pipe, a pressure gauge, and a flow meter.

In membrane separation devices (turbidity membrane devices) that use UF membranes or MF membranes, dirt is attached to the separation membrane, so cleaning fluid (water and / or gas) is usually supplied intermittently every 30 seconds to 60 minutes. Then, the membrane is physically cleaned.

Since dirt that cannot be removed even by this physical cleaning is deposited on the film, the filtration capacity of the film gradually decreases.

Therefore, chemical cleaning using chemicals is required regularly or irregularly in the turbidity removal membrane device.

Patent Document 1 describes that a film that is susceptible to oxidative degradation is washed with a combined chlorine agent. In Patent Document 1, the concentration of the chloramine compound is 0.005 to 0.5 M, and the molar ratio (Cl ₂ / N) of effective chlorine (Cl ₂ ) to nitrogen atom N derived from the chloramine compound is 0.00. There is a description of 1-1. Therefore, in the cleaning method of Patent Document 1, the membrane is cleaned under conditions where almost no free chlorine exists.

Patent Document 2 describes that a cooling water system, a wastewater treatment water system, and a paper pulp water system are sterilized by using a combined chlorine agent having Cl ₂ / N larger than 1. Patent Document 2 describes that the free chlorine concentration during the sterilization treatment is 0.05 mg / L or more. Patent Document 2 does not describe the use of the cleaning agent for the selective permeable membrane.

Japanese Patent Laid-Open No. 2015-97991 JP 2009-195823 A

An object of the present invention is to provide a cleaning liquid, a cleaning agent, and a cleaning method having a high cleaning effect.

The gist of the present invention is as follows.

The cleaning solution for a water contact member of the present invention is a cleaning solution containing free chlorine and a chloramine compound, and the molar ratio (Cl ₂ / N) of nitrogen atoms N derived from total chlorine and the chloramine compound is 1 or more, and the pH is 9 That's it.

In one aspect of the cleaning liquid of the present invention, the chloramine compound includes at least one sulfamic acid compound selected from bound chlorine type sulfamic acid and a salt thereof.

In one aspect of the cleaning liquid of the present invention, the water contact member is at least one of an MF membrane, a UF membrane, a filter, a pipe, a pressure gauge, and a flow meter.

In one aspect of the cleaning liquid of the present invention, the pH of the cleaning liquid is 11 or more.

In one embodiment of the cleaning liquid of the present invention, the combined chlorine concentration of the chloramine compound and chlorine is 100 mg / L or more, and the free chlorine concentration is 20 mg / L or more.

The cleaning agent for a water contact member of the present invention is a cleaning agent containing free chlorine and a chloramine compound, and the molar ratio (Cl ₂ / N) of nitrogen atoms N derived from total chlorine and the chloramine compound is 1 or more. , PH 12 or more.

In one aspect of the cleaning agent of the present invention, the chloramine compound includes at least one sulfamic acid compound selected from bound chlorine type sulfamic acid and a salt thereof.

In one embodiment of the cleaning agent of the present invention, it is obtained by mixing sulfamic acid and an alkali agent and then adding a chlorine agent to form a combined chlorine compound.

In one embodiment of the cleaning agent of the present invention, the concentration of sulfamic acid relative to the final cleaning agent weight is 5% by mass or less.

In one aspect of the cleaning agent of the present invention, the water contact member is at least one of an MF membrane, a UF membrane, a filter, a pipe, a pressure gauge, and a flow meter.

The cleaning solution for the water contact member of the present invention is obtained by diluting the above-described cleaning agent of the present invention with water.

The water contact member cleaning method of the present invention cleans the water contact member using the cleaning liquid of the present invention.

The cleaning solution, cleaning agent, and cleaning method for the water contact member of the present invention have both the oxidizing power of the free chlorine agent and the strength of penetration of the bound chlorine agent (chloramine compound) into the water contact member. Therefore, it is more effective than the combined chlorine agent and has a higher cleaning effect than the free chlorine agent. Moreover, the cleaning liquid and the cleaning agent of the present invention also have an excellent sterilizing effect.

It is a schematic diagram which shows the structure of the test apparatus used in the Example. It is a graph which shows the result of an Example and a comparative example. It is a graph which shows the result of an Example and a comparative example. It is a graph which shows the result of an Example and a comparative example. It is a graph which shows the result of an Example and a comparative example. It is a graph which shows an experimental result. It is a graph which shows an experimental result.

Hereinafter, embodiments of the present invention will be described in detail.

The present invention relates to a cleaning liquid, a cleaning agent, and a cleaning method. In the present invention, “cleaning liquid” and “cleaning agent” are distinguished as follows.
In the present invention, the cleaning liquid is a liquid used during cleaning. On the other hand, the cleaning agent in the present invention is a product used for distribution. In some cases, the cleaning agent may be used as it is as a cleaning solution, but usually the cleaning agent is diluted with water or the like and used as a cleaning solution for cleaning.

The cleaning liquid of the present invention contains free chlorine and a combined chlorine compound. The cleaning liquid of the present invention has a molar ratio (Cl ₂ / N) of nitrogen atoms N derived from total chlorine (Cl ₂ ) and combined chlorine compounds of 1 or more and a pH of 9 or more.

Cleaning solution of the present invention, preferably, the total chlorine concentration _5,000mg-Cl 2 / L or less, more preferably _{200 ~ 5,000mg-Cl 2 / L} , particularly preferably 1,000 ~ _2,000mg-Cl 2 / L, bound chlorine concentration of 100 mg-Cl ₂ / L or more, more preferably 100 to 4,980 mg-Cl ₂ / L, particularly preferably 300 to 1,980 mg-Cl ₂ / L, free chlorine concentration of 20 mg-Cl ₂ / L L or more, more preferably 20 to 4,900 mg-Cl ₂ / L, particularly preferably 20 to 1,700 mg-Cl ₂ / L.

The cleaning agent of the present invention is a cleaning agent containing free chlorine and a chloramine compound, and the molar ratio (Cl ₂ / N) of total chlorine (Cl ₂ ) to nitrogen atom N derived from the chloramine compound is 1 or more. , PH 12 or more.

The cleaning agent of the present invention preferably has a total chlorine concentration (Cl ₂ equivalent concentration) of 10% by mass or less, more preferably 1 to 8% by mass, particularly preferably 3 to 8% by mass. The combined chlorine concentration (Cl ₂ equivalent concentration) is 0.1% by mass or more, more preferably 0.5 to 3% by mass, particularly preferably 1 to 2.8% by mass, and the free chlorine concentration (Cl ₂ equivalent concentration) is 0. 0.02% by mass or more, more preferably 0.1 to 10% by mass, particularly preferably 1 to 5% by mass.

In the present invention, the total chlorine concentration and the free chlorine concentration are measured by the DPD method defined in JIS K 0400-33-10: 1999. The bound chlorine concentration is determined by subtracting the free chlorine concentration from the total chlorine concentration determined above.

The present invention makes it possible to apply a chlorine-based cleaning liquid and a cleaning agent to a water contact member under alkaline conditions. In the present invention, the organic substance decomposing action by the combined chlorine compound and the immediate sterilizing and washing effect by free chlorine are synergistically added to the organic substance peeling action and hydrolysis action by washing under alkaline conditions. For this reason, according to this invention, the effect of alkali washing | cleaning can be improved and performances, such as a contaminated permselective membrane and a filter, can fully be recovered | restored.

<Wetted parts>
Examples of the water contact member include, but are not limited to, a UF membrane, an MF membrane, a filter, a pipe, a pressure gauge, and a flow meter. Examples of the filter include those using granular filter media such as sand and anthracite.
In the present invention, when the MF film and the UF film are to be cleaned, the cleaning effect is effectively exhibited. However, the selective permeable membrane is not limited to these, and the present invention can be applied to other selective permeable membranes, and the membrane material is not limited. Moreover, there is no restriction | limiting also in the form of a membrane etc., This invention is applied effectively to the washing | cleaning of the selective permeable membrane for water treatment in a wide field | area.

<Free chlorine>
As free chlorine, hypochlorous acid and / or hypochlorite is used. As hypochlorite, alkali metal salts of hypochlorous acid such as sodium hypochlorite, alkaline earth metal salts of hypochlorous acid such as calcium hypochlorite, and the like can be used. These may be used alone or in combination of two or more.

<Combined chlorine compounds>
The bound chlorine compound is obtained by reacting hypochlorous acid (HOCl) with a compound having a primary amino group (XNH ₂ ) by the reaction shown in the following reaction formulas (1) and (2). A compound (XNHCl) in which a hydrogen atom of an amino group is substituted with a chlorine atom is preferred. Since this compound has a weak oxidizing action, it can be used as a cleaning liquid and a cleaning agent even for aromatic polyamide RO membranes with low chlorine resistance. Also penetrates and exerts a decomposing action inside.
XNH ₂ + HOCl⇔XNHCl + H ₂ O (1)
XNH ₂ + OCl ⁻ ⇔XNHCl + OH ⁻ (2)

In the present invention, the bonded chlorine compound is any one of a compound having a primary amino group, ammonia, and an ammonium salt (hereinafter referred to as “NH ₂ -based compound”), hypochlorous acid and / or the following. It is preferable to produce by mixing with chlorite. Examples of the compound having a primary amino group include aliphatic amines, aromatic amines, sulfamic acids, sulfanilic acids, sulfamoylbenzoic acids, and amino acids. Examples of ammonium salts include ammonium chloride and ammonium sulfate. These may be used alone or in combination of two or more. Of these NH ₂ compounds, sulfamic acid (NH ₂ SO ₂ OH) is preferable. When monochlororosulfamine is produced using sulfamic acid, a stable bound chlorine compound is obtained. Since sulfamic acid does not contain carbon, it does not increase the TOC value of the cleaning agent. By using sulfamic acid and an alkaline agent in combination, a very effective cleaning solution and cleaning agent are obtained.

Hypochlorite to be reacted with NH ₂ compounds includes alkali metal salts of hypochlorous acid such as sodium hypochlorite, alkaline earth metal salts of hypochlorous acid such as calcium hypochlorite, etc. Can be used. These may be used alone or in combination of two or more.
When sulfamic acid is used as the compound having a nitrogen atom that forms bonded chlorine, the weight concentration of sulfamic acid used is preferably 5% by mass or less based on the weight of the final cleaning agent. If the concentration of sulfamic acid is higher than 5% by mass, chlorine may be easily decomposed.

<Ratio of free chlorine and combined chlorine compounds>
In the present invention, the Cl ₂ / N molar ratio, which is the molar ratio of available chlorine derived from free chlorine (Cl ₂ ) and nitrogen atom N derived from the combined chlorine compound, is 1 or more, preferably 1 to 10, particularly preferably 1 to 5. By setting it within this range, an immediate cleaning action of free chlorine and an osmotic cleaning action of the combined chlorine compound can be obtained in a balanced manner.

<PH>
The cleaning liquid of the present invention comprises an aqueous alkaline solution containing free chlorine and a combined chlorine compound, and has a pH of 9 or more. If the pH of the cleaning liquid is less than 9, sufficient cleaning properties cannot be obtained. The higher the pH of the cleaning solution is, the better the cleaning effect is. However, when the cleaning solution is too high, the handling property as the cleaning solution is deteriorated, and the film to be cleaned is deteriorated or the risk of corrosion of the metal is increased. The pH of the cleaning liquid is preferably 11 or more and 13 or less.

The alkali agent used to adjust the cleaning liquid of the present invention to pH 9 or more, particularly 12 or more, is preferably an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide.

The cleaning agent of the present invention comprises an aqueous alkaline solution containing free chlorine and bound chlorine, and has a pH of 12 or more. When the pH of the cleaning agent is less than 12, the storage stability is deteriorated, and the cleaning effect may be insufficient when diluted. The pH of the cleaning agent is preferably 13 or more. If the pH of the cleaning agent is too high, the total chlorine concentration becomes low, and the balance with the pH when diluted is poor. The upper limit of the pH of the cleaning agent of the present invention is 14.

<Manufacturing method of cleaning liquid and cleaning agent>
The cleaning liquid and cleaning agent of the present invention are prepared by adding and dissolving an NH ₂ -based compound such as sulfamic acid in the aqueous solution of the alkali agent described above, and adding hypochlorous acid and / or hypochlorous acid to the resulting NH ₂ -based compound aqueous solution. A combined chlorine compound aqueous solution can be prepared by adding and mixing chlorate, and hypochlorous acid and / or hypochlorite can be added to and mixed with this combined chlorine compound aqueous solution. .

A compound having a primary amino group such as sulfamic acid may be added in the form of a salt. As this salt, sodium sulfamate, potassium sulfamate, ammonium sulfamate, etc. can be used.

The cleaning liquid of the present invention may be obtained by diluting the cleaning agent produced as described above with water, preferably with pure water as necessary.

<Other ingredients>
To the cleaning liquid and the cleaning agent used in the present invention, other cleaning component may be added as long as the cleaning effect is not impaired.

For example, surfactants and chelating agents such as EDTA (ethylenediaminetetraacetic acid), EGTA (ethyleneglycolbis (aminoethylether) tetraacetic acid), IDA (iminodiacetic acid), etc. to enhance the peeling effect of membrane contaminants You may add 1 type, or 2 or more types of the other washing | cleaning-agent component.

<Washing method>
In the method of cleaning the water contact member using the cleaning liquid of the present invention, the water contact member is brought into contact with the cleaning liquid. In the case where the water contact member is an MF membrane or a UF membrane, after stopping water flow to the membrane device, the cleaning liquid is introduced into the membrane device. The cleaning liquid may be introduced from the raw water inlet of the membrane device, or may be introduced from the treated water outlet and pushed out to the raw water side. After the cleaning liquid is introduced into the apparatus, the membrane is immersed in the cleaning liquid or the cleaning liquid is circulated. When the cleaning liquid is circulated, air may be blown into the cleaning liquid. Including immersion and circulation, the contact time between the cleaning solution and the selective permeable membrane is preferably about 1 to 24 hours, particularly about 1 to 18 hours. Also in the case of a water contact member other than a membrane, the contact time between the cleaning liquid and the water contact member is preferably about 1 to 24 hours, particularly about 1 to 18 hours.

[Comparative Examples 1 to 4, Example 1]
Using a membrane (effective membrane length 100 mm) obtained from a UF hollow fiber membrane module (HFU-2008, membrane material PVDF, pore diameter 0.01 μm) manufactured by Toray Industries, Inc., a single membrane module (single yarn module) was created. . Thereafter, the membrane was contaminated by passing water for industrial use (hereinafter referred to as “Yamakura Kosui”) in the Hara area of Goi City, Chiba Prefecture with the single-thread module water flow device shown in FIG.

The membrane 1 is arranged in the column 2 with its upper and lower ends held by holding

members

3a and 3b made of a potting material. The upper end of the film 1 is embedded in the holding member 3a. The lower end of the membrane 1 passes through the holding member 3b and communicates with the chamber 4 below the column 2. Yamakura industrial water is supplied to the lower part of the column 2 (above the holding member 3b) via the pipe 5, the pump 6 and the valve 7, and the permeated water passes through the valve 8 and the pipe 9 from the chamber 4 at the lower end of the column 2. Leaked. The concentrated water flows out from the upper part of the column 2 (just below the holding member 3a) through the pipe 10 and the valve 11. The backwash water is introduced into the chamber 4 at the lower end of the column 2 through the pipe 12, the pump 13 and the valve 14 and flows into the membrane 2. The backwash drainage flows out through the pipe 15 and the valve 16 branched from the pipe 10.

Water flow for membrane contamination was performed by repeating the following four steps as one cycle and repeating 200 cycles.
Process 1: Water filling (30 seconds)
Step 2: Filtration (permeation flux 2-4 m ³ / m ² / d, 28 minutes)
Step 3: Backwash (water volume 0.6-1.4 mL / min, 30 seconds)
Process 4: Drainage (30 seconds)

Pure water was passed through the contaminated membrane and the transmembrane differential pressure at a permeation flux of 4 m ³ / m ² / d was measured to obtain the transmembrane differential pressure value before cleaning. Thereafter, the cleaning liquid shown in Table 1 was introduced into the column 2 and immersed therein. After soaking for a predetermined time, the chemical solution is drained, flushed with pure water, and then passed with pure water to measure a transmembrane differential pressure at a permeation flux of 4 m ³ / m ² / d. The differential pressure value was used. After measuring the transmembrane pressure difference, the chemical solution was introduced again, and the operation was repeated until the total immersion time was 6 to 8 hours. The chemical solution was newly prepared for each introduction. The measurement result of the transmembrane pressure value (relation between the immersion time and the transmembrane pressure value) is shown in FIG. Each cleaning solution has a pH of 12 and a total chlorine concentration of about 1200 mg. Free chlorine concentration was measured by the DPD method.

[Discussion]
In the cleaning with sodium hypochlorite in Comparative Example 1, the pressure difference immediately after cleaning is remarkably reduced (high immediate effect), but the final pressure difference is higher than the combined chlorine agent of Comparative Examples 2 to 4, and the cleaning effect Is inferior to bound chlorine. In the cleaning with the combined chlorine agent in Comparative Examples 2 to 4, the final ultimate differential pressure of the cleaning is low and the cleaning effect is high, but the cleaning immediate effect is inferior to that of the sodium hypochlorite of Comparative Example 1. The cleaning with the cleaning liquid of Example 1 (bonded chlorine + free chlorine agent) exhibits an immediate effect equivalent to that of sodium hypochlorite and also has the same cleaning effect as that of the combined chlorine agent.

[Comparative Example 5, Examples 2 to 4]
The membrane was cleaned under the same conditions as in Comparative Examples 1 to 4 and Example 1 except that the cleaning solution was as shown in Table 2. (However, since the experimental date is different from Comparative Examples 1 to 4 and Example 1, the quality of the raw water is slightly different, and the state of contamination of the membrane is also slightly different.) All the cleaning solutions have a pH of 12 and a total chlorine concentration of about 1200 mg- Cl ₂ / L. The results are shown in FIG.

[Discussion]
Examples 2 to 4 showed an immediate effect equivalent to that of sodium hypochlorite of Comparative Example 5 and a lower transmembrane pressure difference (high cleaning effect) than sodium hypochlorite in the final ultimate pressure difference. .

[Comparative Examples 6 to 8, Example 5]
The cleaning agent shown in Table 3 was diluted to a total chlorine concentration of 1000 mg-Cl ₂ / L, and a cleaning solution was prepared in which the pH was adjusted to 12 with NaOH.
Further, the total immersion time in the chemical solution cleaning step was set to 400 min. Except these, the same experiment as the comparative example and the example was performed. However, since the experiment date is different from the comparative examples and examples, the quality of the raw water is slightly different, and the contamination of the membrane is also slightly different.

Fig. 4 shows the relationship between cleaning time and differential pressure. It can be seen that the cleaning liquid prepared by diluting the cleaning agent of Example 5 has the fastest difference pressure drop and the lowest ultimate pressure difference. In Comparative Example 6, the ultimate differential pressure remains high. In Comparative Examples 7 and 8, the ultimate differential pressure is close to that of Example 5, but the method of decreasing the differential pressure is slow.

<Experimental Examples 1-3>
The sterilizing effect of the following aqueous solutions was evaluated. The agent shown below was diluted so that effective chlorine might become a predetermined density | concentration, it was made to contact for 15 minutes or 1 h with evaluation microbe, and the number of viable bacteria was measured. Aspergillus niger was used as an evaluation bacterium.
Experimental example 1: Sodium hypochlorite aqueous solution (effective chlorine 12%)
Experimental example 2: Aqueous solution of sulfamic acid-based bound chlorine agent Cl ₂ / N ratio = 0.56 pH 14.0 Experimental example 3: Sulfamic acid-based free chlorine, bound chlorine agent Cl ₂ / N ratio = 2.08 of pH 14.1 Aqueous solution

The result at 15 min is shown in FIG. The result in 1 h is shown in FIG. In Experimental Examples 1 and 3, sterilization is completed at an effective chlorine concentration of 10 m / L and 15 min, whereas in Experimental Example 2, most bacteria survive even at effective chlorine of 200 mg / L and 1 h. It was recognized that Although Experimental Example 1 also has a high bactericidal effect, it is the same agent as Comparative Example 6 described above and has a poor cleaning effect.
From the above, it was shown that the cleaning disinfectant of the present invention has a high cleaning effect and a disinfecting effect.

[Measurement experiment of chlorine decomposition rate]
A cleaning agent having the composition shown in Table 4 was produced using sulfamic acid, an aqueous sodium hypochlorite solution (effective chlorine 12% by mass), 48% sodium hydroxide, and pure water. The weight concentration of sulfamic acid is 2.5 to 5.0% by mass. FIG. 7 shows the relationship between the molar concentration of sulfamic acid and the residual effective molar concentration of chlorine in the detergents obtained by the formulations (i) to (iv), and the decomposition rate of chlorine. As shown in FIG. 7, the higher the weight concentration of sulfamic acid, the greater the decomposition rate of chlorine. When the weight concentration of sulfamic acid is 5.0 mass%, the ratio of (effective chlorine molar concentration) / (sulfamic acid molar concentration) is 1.01, which is slightly over 1. Accordingly, the weight concentration of sulfamic acid is preferably 5.0% by mass or less. The reason why the decomposition rate of chlorine increases is presumably because unstable dichlorosulfamic acid is easily formed.

Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application No. 2017-050165 filed on Mar. 15, 2017, which is incorporated by reference in its entirety.

1 Selective membrane 2 Column

Claims

A cleaning liquid containing a free chlorine and a chloramine compound, wherein the molar ratio (Cl 2 / N) of nitrogen atoms N derived from total chlorine and the chloramine compound is 1 or more and the pH is 9 or more.
The cleaning liquid according to claim 1, comprising at least one sulfamic acid compound selected from bound chlorine type sulfamic acid and a salt thereof as the chloramine compound.
The cleaning liquid according to claim 1 or 2, wherein the water contact member is at least one of an MF membrane, a UF membrane, a filter, a pipe, a pressure gauge, and a flow meter.
The cleaning liquid according to any one of claims 1 to 3, wherein the pH is 11 or more.
The cleaning liquid according to any one of claims 1 to 4, wherein the combined chlorine concentration of the chloramine compound and chlorine is 100 mg / L or more and the free chlorine concentration is 20 mg / L or more.
A cleaning agent containing free chlorine and a chloramine compound, the cleaning agent for a water contact member having a molar ratio (Cl 2 / N) of nitrogen atoms N derived from total chlorine and a chloramine compound of 1 or more and a pH of 12 or more .
The cleaning agent according to claim 6, comprising at least one sulfamic acid compound selected from bound chlorine type sulfamic acid and a salt thereof as the chloramine compound.
The cleaning agent according to claim 6 or 7, which is obtained by mixing a sulfamic acid and an alkali agent and then adding a chlorine agent to produce a combined chlorine compound.
The cleaning agent according to claim 7 or 8, wherein the concentration of sulfamic acid relative to the weight of the final cleaning agent is 5% by mass or less.
The cleaning agent according to any one of claims 6 to 9, wherein the water contact member is at least one of an MF membrane, a UF membrane, a filter, a pipe, a pressure gauge, and a flow meter.
A cleaning solution for a water contact member, wherein the cleaning agent according to any one of claims 6 to 9 is diluted with water.
A method for cleaning a water contact member, wherein the water contact member is cleaned using the cleaning liquid according to any one of claims 1 to 5 and claim 11.