CN112326383A

CN112326383A - Modified nano SiO2 water quality processor turbidity labeling substance and preparation method thereof

Info

Publication number: CN112326383A
Application number: CN202011190006.1A
Authority: CN
Inventors: 官杰; 高翠玲; 贺祥珂; 彭晓辉; 范红梅
Original assignee: Shandong Institute for Product Quality Inspection
Current assignee: Shandong Institute for Product Quality Inspection
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2021-02-05
Anticipated expiration: 2040-10-30
Also published as: CN112326383B; AU2021102663A4

Abstract

The invention belongs to the technical field of standard substance preparation, and relates to modified nano SiO₂A turbidity labeling substance of a water quality processor and a preparation method thereof. The added standard substance is modified nano SiO subjected to modification treatment₂Said SiO₂Is spherical particles with the average particle diameter of 100-500 nm. The invention reduces the nanometer SiO by modifying the 3-chloropropyltrimethoxysilane and the hydrochloric acid under the synergistic action₂The acting force between the surface hydroxyl groups forms a clear particle surface to prevent the nano SiO₂The agglomeration and the standing stability are good. The modified nano SiO prepared by the invention₂The concentration of the solution has a better linear relation with the turbidity, and the solution has the characteristic of being used as a turbidity adding standard substance of the water quality processor. And can prepare modified nano SiO with different particle diameters according to the requirements of filter elements with different precisions₂The aqueous solution has good particle size controllability. Prepared by the inventionModified nano SiO₂The solution has no influence on oxygen consumption and pH value of water.

Description

Modified nano SiO2 water quality processor turbidity labeling substance and preparation method thereof

Technical Field

The invention belongs to the technical field of standard substance preparation, and particularly relates to modified nano SiO₂A turbidity labeling substance of a water quality processor and a preparation method thereof.

Background

Turbidity is an important physical index for representing the turbidity degree of water quality. The turbidity of source water is due to scattering or absorption behavior in optical terms caused by suspended or colloidal matter, or both. The household and similar water purifier can eliminate the surface water pollution, the by-product of tap water disinfection and the secondary pollution of water pipeline to the drinking water of residents. In order to standardize the inspection work of drinking water sanitary safety products and strengthen the supervision and management of the quality of a water quality processor, the Ministry of health establishes the inspection regulation of drinking water sanitary safety products in the Ministry of health in 2001. The turbidity is required to be detected in the sanitary safety and sanitary functional tests of water delivery and distribution equipment (pipes, pipe fittings, water storage containers and water stop materials), protective materials (coatings, linings and the like), water treatment materials and general water quality processors which are required to be in contact with the drinking water. The turbidity standard adding experiment is required for the common water quality processor of the activated carbon filter element and the membrane filtration component, but the turbidity standard adding substance and the configuration method thereof are not indicated in the specification. Different labeling objects are selected by each detection mechanism when a general water quality processor is used for turbidity detection according to the inspection regulations of sanitary products related to drinking water sanitation safety of Ministry of health, so that the detection results have larger difference and objective judgment on the performance of the water quality processor cannot be made. The national standard QB/T4143 issued by the Ministry of industry and communications in 2019, namely ' general water quality processor for household and similar applications ' and QB/T4144 ' 2019 ' pure water processor for household and similar applications ' stipulate that a 25 NTU formalin solution is used as a water quality processor and a standard substance for turbidity test of the pure water processor. Since the formalin suspension is an unstable suspension system as an inhomogeneous suspension system, there are obvious disadvantages in the use process.

Formalin turbidity standard is the standard of turbidity commonly used. The difference of environmental temperature in the preparation process can cause the difference of particle size, and the difference of the temperature of the placing time and the placing environment can cause the particle size to be changed continuously, thus causing the particle size of the formalin in the suspension to be uncontrollable. Because the particle diameter of the formalin solution is larger and the sedimentation speed is high, after the formalin solution is placed for a period of time, the particles in the formalin solution can be sedimentated to form larger concentration difference, and the defect of poor standing stability exists. The ideal standard substance required in the standard addition experiment of the water quality processor can not change other physicochemical indexes of water quality except that the concentration of the standard substance reaches the standard requirement, and simultaneously has certain stability and reasonable turbidity removal rate. In the prior art, no relevant record exists for modifying silicon dioxide to be used as a turbidity adding substance of a water quality processor.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a modified nano SiO₂The turbidity of the water quality processor is added with a standard substance.

The invention also provides a modified nano SiO₂A preparation method of a turbidity adding standard substance of a water quality processor.

The technical scheme adopted by the invention for realizing the purpose is as follows:

the invention provides a modified nano SiO₂A turbidity labeling substance of the water quality processor, the SiO₂Is spherical particles with the average particle diameter of 100-500 nm.

The invention also provides a modified nano SiO₂The preparation method of the turbidity standard substance of the water quality processor is characterized by comprising the following steps:

(1) weighing nano SiO₂Dissolving in absolute ethyl alcohol, performing ultrasonic oscillation, and performing magnetic stirring to obtain silicon dioxide ethanol solution for later use;

(2) adding 3-chloropropyltrimethoxysilane into the dispersed nano SiO₂Performing constant-temperature water bath reaction in an ethanol solution, adding a proper amount of hydrochloric acid with the volume concentration of 3%, continuously reacting, continuously stirring in the reaction process, after the reaction is finished, performing centrifugal separation, washing for 3 times by using absolute ethyl alcohol, performing vacuum drying, and weighing a proper amount of modified nano SiO₂Powder, adding into three stagesWater, ultrasonic dispersion for 1h, and preparing into a standard solution.

Further, in the step (1), the nano SiO₂The ratio of the ethanol to the absolute ethyl alcohol is 1 g: 30 mL.

Further, in the step (1), the time for ultrasonic oscillation and magnetic stirring is 60 min.

Further, in the step (2), the 3-chloropropyltrimethoxysilane and the nano SiO₂The mass ratio of (A) to (B) is 2-3: 1.

In the preparation method provided by the invention, the constant-temperature water bath reaction is carried out for 0.5h at 85 ℃.

Further, the addition amount of the hydrochloric acid is 1g of nano SiO₂1mL of the solution was added.

In the reaction process, after a proper amount of 3% hydrochloric acid is added, the reaction is continued for 3.5 h.

Further, the vacuum drying is drying at 55 ℃ for 8 h.

The invention also provides the nano SiO prepared by the preparation method₂The water quality processor turbidity adding standard substance is used.

The invention selects the nano silicon dioxide powder with controllable grain diameter as a matrix, improves the dispersibility and stability of the nano silicon dioxide powder in aqueous solution by modifying the nano silicon dioxide powder by organosilane, and simultaneously discusses SiO by comparing a formalin added standard substance and modified nano₂The influence of the aqueous solution on the oxygen consumption and the pH value of water quality has more excellent performance as a turbidity adding substance of a water quality processor.

The invention has the beneficial effects that:

(1) the invention successfully and covalently combines the modifier to the nano SiO under the synergistic action of 3-chloropropyltrimethoxysilane and hydrochloric acid₂Surface, reduced nano SiO₂The acting force between the surface hydroxyl groups forms a clear particle surface to prevent the nano SiO₂The agglomeration and the standing stability are good.

(2) The modified nano SiO prepared by the invention₂The concentration of the solution has a better linear relation with turbidity, and the correlation coefficient R²0.9995; modified nano SiO₂The solution has better dilution characteristic and linear relation to the correlation coefficient R²Is 0.9979. Modified nano SiO₂The aqueous solution has better stability and dilution characteristics, has higher linear relation between the concentration and the turbidity, and has the characteristic of serving as a turbidity adding standard substance of the water quality processor. And modified nano SiO with different grain diameters can be prepared according to the requirements of different filtering membranes₂The aqueous solution has good particle size controllability.

(3) The modified nano SiO prepared by the invention₂The solution does not affect the oxygen consumption and the pH value of the water quality.

Drawings

FIG. 1 shows the nano SiO before and after modification of 3-chloropropyltrimethoxysilane prepared in example 1₂SEM picture of (1);

wherein, (a) unmodified nano SiO₂(b) modified nano SiO₂。

FIG. 2 shows a view of nano SiO₂Infrared spectra before and after modification with 3-chloropropyltrimethoxysilane;

wherein 1: is not modified; 2: only 3-chloropropyltrimethoxysilane is used for modification; 3: 3-chloropropyltrimethoxysilane and HCL are synergistically modified.

FIG. 3 nanometer SiO preparation of example 1₂Particle size distribution diagram of (c).

FIG. 4 is a particle size distribution diagram of a Formazin solution.

FIG. 5 is a graph of the trend of Formazin solution Dav over time.

FIG. 6 shows modified nano SiO₂Trend graph of solution Xav over time.

FIG. 7 shows modified nano SiO₂Turbidity value of aqueous solution.

FIG. 8 shows modified nano SiO₂Dilution profile of aqueous solution.

FIG. 9 shows a modified nano SiO₂Standing the solution (412 NTU) and the Formazin solution (400 NTU).

FIG. 10 shows modified nano SiO₂The turbidity of the solution varied from that of the Formazin solution.

Detailed Description

The technical solution of the present invention is further explained and illustrated by the following specific examples.

Reagents and instruments used in the invention:

reagent: nano SiO₂(Shanghai Changbai nanometer materials science and technology Limited, average particle size 100-

The instrument comprises the following steps: magnetic control stirring heater (Tianjin Seidelis test analyzer manufacturing factory), analytical balance (Sedoulis Scientific instruments (Beijing) Co., Ltd.), Fourier transform micro infrared spectrometer (Thermo Scientific), scatterometer (Shanghai Xinrui instruments Co., Ltd.), centrifuge (Hunan instruments centrifuge in the development area of Changsha high tech industry Co., Ltd.), vacuum drying oven (Shanghai Bowey industries Co., Ltd.), digital display constant temperature water bath (Changzhou Nuo Ji instruments Co., Ltd.), standard light source box (Xilai-Asia Tailas Co., Ltd.), nanometer particle size analyzer Winner802 (Jinnan micro nano particle technology Co., Ltd.), laser particle size analyzer Winner2000ZD (Jinnan micro nano particle technology Co., Ltd.), thermal field emission scanning electron microscope SUPPA^TM55 (zeiss, germany).

Example 1

Weighing 2g of nano SiO₂Dissolving in 60mL of absolute ethyl alcohol, ultrasonically shaking for 60min, and magnetically stirring for 1 h. 4.324g of 3-chloropropyltrimethoxysilane is added to the dispersed nano SiO₂And (3) adding 2mL of 3% hydrochloric acid after reacting in a constant-temperature water bath at 85 ℃ for 0.5h in the ethanol solution, continuing to react for 3.5h, continuously stirring in the reaction process, after the reaction is finished, performing centrifugal separation for 15min, and washing for 3 times by using absolute ethyl alcohol. Drying in a vacuum drying oven at 55 deg.C for 8 hr, grinding into powder, and weighing appropriate amount of modified nanometer SiO₂Adding three-stage water into the powder, performing ultrasonic dispersion for 1h, and preparing a standard addition stock solution with certain turbidity of about 400 NTU.

Comparative example 1

Weighing 2g of nano SiO₂Dissolving in 60mL of absolute ethyl alcohol, ultrasonically shaking for 60min, and magnetically stirring for 1 h. Adding 4 mL of 3-chloropropyltrimethoxysilane into the dispersed nano SiO₂Reacting in ethanol solution in a constant temperature water bath at 85 ℃ for 4h, continuously stirring in the reaction process, centrifugally separating for 15min after the reaction is finished, and washing with absolute ethyl alcohol for 3 times. Drying in a vacuum drying oven at 55 deg.C for 8 hr, grinding into powder, and weighing appropriate amount of modified nanometer SiO₂Adding three-stage water into the powder, and ultrasonically dispersing for 1h to prepare a standard solution with certain turbidity.

Results and discussion

(one) the 3-chloropropyltrimethoxysilane prepared in example 1 is modified to prepare nano SiO₂Is shown in fig. 1. As can be seen from FIG. 1, the unmodified nano SiO₂The particles exist in an agglomerated form due to stronger acting force of hydroxyl groups among the particles, so that the surfaces of the particles are not obvious, and 3-chloropropyltrimethoxysilane is cooperated with hydrochloric acid to modify SiO₂The introduction of the middle hydrophobic group reduces the nano SiO₂The force between the surface hydroxyl groups forms a clear particle surface.

(II) modifying SiO by adopting Fourier infrared transform infrared spectrometer₂The characterization is carried out, the scanning times are 32 times, and the resolution is 4cm^-1Wave number range 4000-400cm^-1。

Nano SiO₂The infrared spectra of the particles before and after modification with 3-chloropropyltrimethoxysilane are shown in FIG. 2. 3446cm in the curve^-1And 1634cm^-1The nearby absorption peaks respectively correspond to the antisymmetric vibration and the bending vibration of water-OH; 1103cm^-1The absorption peak of (a) is antisymmetric stretching vibration of a Si-O-Si bond; 799cm^-1And 471cm^-1The absorption peaks in the vicinity correspond to the symmetric stretching vibration and bending vibration of the Si-O-Si bond, respectively. The modified nano silicon dioxide particles have methylene (-CH) in 3-chloropropyltrimethoxysilane at 2925cm-1 and 2853cm-1₂-) and methyl (-CH)₃) The characteristic absorption peak shows that the 3-chloropropyltrimethoxysilane used for modification is covalently bonded with the surface of the nano-silica, so that the modifier is successfully covalently bondedTo the surface of the nano-silica. It can be seen from curve 3 that the addition of hydrochloric acid solution advantageously enhances the modification effect.

(III) modifying the nano SiO₂Preparing into aqueous solution, placing in a laser particle size analyzer, testing the particle size distribution as shown in figure 3, modifying with modified nanometer SiO₂Has an average particle diameter Xav of 304.71 nm. The particle size distribution of 400NTU of the Formazin standard solution was measured in a laser particle size analyzer as shown in FIG. 4, and the average particle size was 0.998 nm.

In the test process, the nano SiO before modification is found₂The powder is easy to agglomerate in aqueous solution under the action of hydroxyl on the surface of silicon dioxide, the increase speed of the particle size change is high, and the stability is difficult to achieve; modified nano SiO₂Due to the introduction of surface water-repellent groups, the nano SiO is reduced₂The acting force of surface hydroxyl reduces the modified nano SiO₂The agglomeration in the aqueous solution enhances the stability of the solution.

Placing the sample in an analytical instrument, and recording the particle size of the sample, the Formazin standard solution and the modified nano SiO every five minutes in a standing state₂The particle diameter of the solution changes with time as shown in Table 1, and the change trend is shown in FIG. 5 (the change trend of the particle diameter of formalin in the Formazin standard solution) and FIG. 6 (the modified nanometer SiO₂SiO in solution₂Particle size trend graph). As can be seen from FIG. 3, the Formazin standard solution is agglomerated in a static state, the particle size of the Formazin standard solution is gradually increased, and in a test state, the particle size of the Formazin standard solution reaches a highest value after about 100 min and then is sharply reduced, because the Formazin standard solution is precipitated due to the agglomeration, and the particle size of the residual Formazin in water is small. Compared with the Formazin standard solution, the modified nano SiO₂As the particle size thereof gradually becomes larger; has better stability of grain size (figure 4), and SiO with larger grain size due to gravity action along with the time₂The particles are slightly settled, the change rate of the particle size is 2.3 percent, and the modified nano SiO is seen₂The solution has better stability.

TABLE 1 Formazin standard solution and modified nano SiO₂Variation of particle size of solution with time

(IV) Linear relationship of modified silica solution concentration to turbidity: the turbidity of the water body is quantitatively characterized according to the scattering or attenuation degree of the suspended particles in the water body to light without strict conversion relation between a scattering turbidity unit (NTU) and a mass concentration unit (mg/L). The variation of the scattered light is caused by the microscopically different shapes and particle size distributions of different suspended particles. Empirical formula is turbidity value (NTU) =0.13 × particulate matter concentration (mg/L). The invention corrects the empirical formula through experiments. Weighing modified silica with different qualities, and preparing aqueous solutions with different turbidity degrees by using three-stage water. Calibrating scatterometer with formalin standard solution to modify nanometer SiO₂The concentration (mg/L) of the aqueous solution is used as the abscissa, the measured turbidity value (NTU) is used as the ordinate, and a correlation curve is drawn, as shown in FIG. 7, so as to obtain the modified nano SiO₂The linear equation relationship between aqueous solution concentration (mg/L) and turbidity (NTU) is: y =0.1361x-2.2126, correlation coefficient R²Is 0.9995.

(V) modified silica solution dilution characteristics: to investigate the modified nano SiO₂The dilution characteristic of the aqueous solution is to prepare modified nano SiO with turbidity of 813.7 NTU₂The solution is diluted in different proportions, and the turbidity of the diluted solution is respectively tested by using turbidimeters of the same model. Taking the calculated value of water solubility after dilution according to the proportion as the abscissa and the measured turbidity value (NTU) as the ordinate, and drawing a correlation curve, as shown in FIG. 8, to obtain the modified nano SiO₂The aqueous solution dilution characteristic equation is as follows: y =1.01x +5.6076, correlation coefficient R²Is 0.9979. Thus, the modified nano SiO can be seen₂The aqueous solution has good dilution characteristics.

(VI) Formazin solution and modified SiO₂Study of solution stability at rest

Modification of nano-SiO for comparison₂Stabilization of solutions with Formazin solutionsPreparing 412 NTU modified nano SiO₂The solution (No. 1) and 400NTU formalin standard solution (No. 2) are placed in a standard light source box, and the standing state of the solution at 0min, 30 min, 60min, 90 min, 120 min, 150 min and 180 min is recorded respectively, as shown in FIG. 9.

After sufficient shaking,

samples

1 and 2 were in homogeneous suspension as indicated by 0 min. After standing for 30 min, the Formazin standard solution No. 2 showed clear layering on the upper end of the solution. The solution height of the clear part of solution No. 2 became larger and larger with the passage of time, and at 120 min, the bottom of the cuvette No. 2 appeared to be settled, and the flocs were clearly seen in the upper layer of solution. When the solution is placed for 180 min, the sediment is at the bottom of the clear solution which is the upper layer of the solution 2, and the uniformly dispersed suspension is still the solution 1. Therefore, the modified nano SiO₂The standing stability of the solution is better than that of the Formazin solution.

Test 400NTU formalin standard solution and 412 NTU modified nanometer SiO separately₂The turbidity of the solution varied with standing time as shown in Table 2.

TABLE 2 modified SiO₂Turbidity change between solution and formalin standard solution

As can be seen from the data in Table 2 and FIG. 10, the turbidity of both solutions remained stable and unchanged in the first 20 min, the stability of both solutions was equivalent in the first 60min, and the turbidity of the Formazin standard solution was greatly reduced after 60min, which is identical to that shown in FIG. 9. The remaining turbidity value of the Formazin standard solution is 47.8 percent and less than 50 percent when the Formazin standard solution is stood for 100 min, the turbidity value of the Formazin standard solution is only 25.5 percent of the initial state when the Formazin standard solution is stood for 120 min, and the modified SiO is₂The haze value of the solution was 90.8% of the initial state, from which it was seen that modified SiO was present₂The solution has better standing stability.

(VII) Formazin standard substance and modified SiO₂Physicochemical property of added standard substance to water qualityInfluence of energy:

in the general water quality processor sanitary functional experiment, the labeling experiment of items such as oxygen consumption, turbidity, volatile, trichloromethane and the like can be synchronously carried out in the labeling experiment process of the filter element filtering component, so that the turbidity labeling substance is required not to influence indexes such as the pH value, the oxygen consumption, the volatile phenol, the trichloromethane and the like of water quality, and the configuration of the formalin labeling substance and the modified nano SiO₂Volatile phenol, trichloromethane and other organic matters are not introduced in the preparation process, so that the pH value and the oxygen consumption are only used as the influence factors of the added standard substances on the water quality to be measured. Separately testing tap water, formalin standard solution (25 NTU) and modified SiO₂The pH and oxygen consumption of the spiked solution (25 NTU) are shown in Table 3:

TABLE 3 Formazin standards and modified SiO₂Influence of the added standard substance on pH value and oxygen consumption of water

As can be seen from the data in Table 3, the modified SiO₂The pH value and oxygen consumption of the standard adding liquid are not obviously changed, and the formalin can be oxidized by potassium permanganate to generate oxidation reaction, so that the oxygen consumption of the standard adding water is greatly changed. Formalin labeling liquid and modified SiO₂The influence of the added standard solution on the pH value of water quality is not large. Therefore, the formalin labeling substance is not suitable for serving as the labeling substance of the water quality processor labeling experiment.

Claims

1. Modified nano SiO₂The turbidity marking substance of the water quality processor is characterized in that the SiO is₂Is spherical particles with the average particle diameter of 100-500 nm.

2. The modified nano SiO of claim 1₂The preparation method of the turbidity standard substance of the water quality processor is characterized by comprising the following steps:

(1) weighing nano SiO₂Dissolving in absolute alcohol, dissolving in absolute alcoholMagnetically stirring after sound oscillation to obtain silicon dioxide ethanol solution for later use;

(2) adding 3-chloropropyltrimethoxysilane into the dispersed nano SiO₂Performing constant-temperature water bath reaction in an ethanol solution, adding a proper amount of hydrochloric acid with the volume concentration of 3%, continuously reacting, continuously stirring in the reaction process, after the reaction is finished, performing centrifugal separation, washing for 3 times by using absolute ethyl alcohol, performing vacuum drying, and weighing a proper amount of modified nano SiO₂Adding tertiary water into the powder, and performing ultrasonic dispersion for 1h to prepare a standard solution.

3. The method according to claim 2, wherein in the step (1), the nano SiO₂The ratio of the ethanol to the absolute ethyl alcohol is 1 g: 30 mL.

4. The method according to claim 2 or 3, wherein in the step (1), the ultrasonic oscillation and the magnetic stirring are performed for 60 min.

5. The method according to claim 2, wherein in the step (2), the 3-chloropropyltrimethoxysilane and the nano SiO are mixed₂The mass ratio of (A) to (B) is 2-3: 1.

6. The preparation method according to claim 2 or 5, wherein the constant temperature water bath reaction is carried out at 85 ℃ for 0.5 h.

7. The method according to claim 1, 5 or 6, wherein the hydrochloric acid is added in an amount of 1g nano SiO₂1mL of the solution was added.

8. The preparation method according to claim 7, wherein the reaction is continued for 3.5 hours after the addition of a proper amount of 3% hydrochloric acid.

9. The method according to any one of claims 2 to 8, wherein the vacuum drying is oven drying at 55 ℃ for 8 hours.

10. Nano SiO prepared by the preparation method of any one of claims 2 to 9₂The water quality processor turbidity adding standard substance is used.