A solid adsorbent for treating sewage containing solid particles and its application

Abstract

The present invention belongs to the technical field of solid adsorbents, and discloses a solid adsorbent for treating sewage containing solid particles and its application. The present invention provides a solid adsorbent for treating sewage containing solid particles, which comprises: adjusting the pH of sewage containing solid particles to 5-6, and putting a solid adsorbent therein for stirring and adsorption; the solid particle content in the sewage containing solid particles is 200 mg / L; the preparation method of the solid adsorbent comprises: crushing straw after being impregnated with ammonium formate solution, and carbonizing to form straw biochar; placing the straw biochar in a silica gel solution, and then standing and aging after microwave treatment, and drying to obtain the solid adsorbent. The present invention uses a solid adsorbent with developed pores, large specific surface area, strong adsorption effect and specific microporous structure to solve the technical problem that the treatment of sewage containing solid particles is easily blocked, resulting in a decrease in adsorption effect.

Description

Technical Field

[0001] The invention belongs to the technical field of solid adsorbents and discloses a solid adsorbent for treating sewage containing solid particles and application thereof. Background Art

[0002] Activated carbon is a type of microcrystalline carbon material made of carbon-containing materials, which has a black appearance, a developed internal pore structure, a large specific surface area, and a strong adsorption capacity. It belongs to a solid adsorbent. In terms of structure, activated carbon has the characteristics of high microporous volume and high surface area because the carbon is irregularly arranged and there are pores between the cross-connections. Activated carbon has a strong adsorption capacity for dissolved organic matter in water due to its huge specific surface area and developed pore structure, and is suitable for sewage treatment. At present, the modification treatment of activated carbon is mainly to increase the porosity and specific surface area of ​​activated carbon to improve its adsorption performance. For example, CN117088367A discloses an activated carbon for sewage treatment and a preparation method thereof, which is modified by a variety of reagents so that the activated carbon has a rich pore structure and a high specific surface area. However, these schemes ignore the problem that there are large solid particles (relative to the particles in the water) in unfiltered sewage, which leads to a decrease in the adsorption effect of activated carbon when it is used. Summary of the invention

[0003] The present invention aims to solve the problem that the presence of large solid particles in sewage causes the adsorption effect of activated carbon to decrease during use.

[0004] In order to solve the above technical problems, the present invention provides a solid adsorbent for treating wastewater containing solid particles and its application to meet the needs in the art.

[0005] In one aspect, the present invention relates to a solid adsorbent for treating wastewater containing solid particles, comprising: a method for preparing the solid adsorbent comprising: impregnating straw with an ammonium formate solution, crushing the straw, and carbonizing the straw to form straw biochar;

[0006] The straw biochar is placed in a silica gel solution, subjected to microwave treatment, allowed to stand for aging, and dried to obtain the solid adsorbent.

[0007] Furthermore, in the solid adsorbent for treating wastewater containing solid particles provided by the present invention, the pulverizing is to pulverize the straw through a 40-mesh sieve.

[0008] Furthermore, in the solid adsorbent for treating wastewater containing solid particles provided by the present invention, the concentration of the ammonium formate solution is 30-40wt%;

[0009] The immersion time is 3 to 6 hours.

[0010] Furthermore, in the solid adsorbent for treating wastewater containing solid particles provided by the present invention, the carbonization temperature is 400-500° C., and the carbonization time is 2-3 hours.

[0011] Furthermore, in the solid adsorbent for treating wastewater containing solid particles provided by the present invention, the silica gel solution comprises tetraethyl orthosilicate, ethanol and water, and the mass ratio of tetraethyl orthosilicate, ethanol and water is 2~4:5~7:20~30.

[0012] Furthermore, in the solid adsorbent for treating wastewater containing solid particles provided by the present invention, the preparation method of the silica gel solution includes: mixing tetraethyl orthosilicate, ethanol and water, adding ammonia water to adjust the pH to 8, and stirring the reaction at a constant temperature for 1 to 2 hours.

[0013] Furthermore, in the solid adsorbent for treating wastewater containing solid particles provided by the present invention, the temperature of the constant temperature stirring reaction is 20-40° C., and the rotation speed of the constant temperature stirring reaction is 400-500 rpm;

[0014] The microwave power of the microwave treatment is 500-800W, the time of the microwave treatment is 10-30min, and the microwave treatment is carried out under an inert gas environment;

[0015] Before the static aging, the pH is adjusted to 6, the static aging temperature is 60-80° C., and the static aging time is 12-24 hours.

[0016] Furthermore, in the solid adsorbent for treating wastewater containing solid particles provided by the present invention, the straw is corn straw.

[0017] On the other hand, the present invention relates to the use of the solid adsorbent for treating wastewater containing solid particles in treating wastewater containing solid particles, which comprises: adjusting the pH of the wastewater containing solid particles to 5-6, adding the solid adsorbent therein and stirring for adsorption;

[0018] The solid particle content in the solid particle-containing sewage is 200 mg / L.

[0019] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects or advantages:

[0020] The present invention provides a solid adsorbent for treating sewage containing solid particles. The straw biochar prepared by the invention adopts straw as biomass and utilizes its internal fiber morphology characteristics to have a void change that is conducive to the passage of water, which effectively solves the problem that the presence of large solid particles in sewage causes the adsorption effect of activated carbon to decrease when in use. The present invention strengthens this microstructure through ammonium formate, and utilizes the hydrophobic and lipophilic characteristics of silica gel solution, so that the dense pores created by the silica gel solution can more effectively adsorb organic matter in sewage and strengthen the skeleton of the overall material. The present invention is beneficial to the energy absorption characteristics of the silica gel solution, and generates corresponding transition metal oxides in the activated carbon voids by microwaves, which improves the adsorption effect while further avoiding the clogging problem of larger solid particles.

[0021] The present invention adopts the solid adsorbent prepared as above for treating wastewater containing solid particles, and provides a method for treating wastewater containing solid particles. The method utilizes the characteristics of the above solid adsorbent and is used for wastewater containing solid particles with a solid particle content of 200 mg / L under weak acid conditions. It can better achieve the removal of organic matter in the sewage and avoid the attenuation of adsorption performance caused by solid particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is the morphology of the solid adsorbent for treating wastewater containing solid particles prepared in Example 1. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is described below in conjunction with embodiments; however, the present invention is not limited to the following embodiments.

[0025] The experimental methods and detection methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0026] Example 1: This example provides a preparation process of a solid adsorbent for treating wastewater containing solid particles.

[0027] Step 1: Divide the corn stalks into segments of 2 to 3 cm in length, soak them in 30 wt% ammonium formate solution (prepared by weighing solid ammonium formate and dissolving it in water) for 3 hours, freeze-dry them, and then crush them through a 40-mesh sieve.

[0028] Step 2: Place the powder obtained in step 1 in a tubular furnace and carbonize it under nitrogen protection at a heating rate of 10°C / min. After reaching 400°C, keep the temperature for 2h to obtain straw biochar.

[0029] Step 3: Place the straw biochar in a silica gel solution until the straw biochar is completely immersed. After 10 min of microwave treatment at 500 W in a nitrogen atmosphere, adjust the pH to 6 with acetic acid, place in a constant temperature water bath at 60 ° C, maintain the temperature and seal for aging for 12 h, and vacuum dry at 80 ° C to obtain a solid adsorbent with a morphology as shown in FIG. Figure 1 shown.

[0030] Preparation method of silica gel solution: dissolve tetraethyl orthosilicate in an appropriate amount of ethanol, then mix the remaining ethanol and water, finally mix the two, add ammonia water to adjust the pH to 8, and stir at 400 rpm at 20°C for 1 hour to prepare silica gel solution. In the silica gel solution of this embodiment, the mass ratio of tetraethyl orthosilicate, ethanol and water is 2:5:20.

[0031] Example 2: This example provides a preparation process of a solid adsorbent for treating wastewater containing solid particles.

[0032] Step 1: Divide the corn stalks into segments of 2-3 cm in length, soak them in 35 wt% ammonium formate solution (prepared by weighing solid ammonium formate and dissolving it in water) for 4 hours, freeze-dry them, and then crush them through a 40-mesh sieve.

[0033] Step 2: Place the powder obtained in step 1 in a tubular furnace and carbonize it under nitrogen protection at a heating rate of 10°C / min. After reaching 450°C, keep the temperature for 2.5 hours to obtain straw biochar.

[0034] Step 3: Place the straw biochar in a silica gel solution until the straw biochar is completely immersed. After microwave treatment at 600 W for 20 min in a nitrogen atmosphere, adjust the pH to 6 with acetic acid, place in a constant temperature water bath at 70°C, maintain the temperature and seal for aging for 18 h, and vacuum dry at 80°C to obtain a solid adsorbent.

[0035] Preparation method of silica gel solution: dissolve tetraethyl orthosilicate in an appropriate amount of ethanol, then mix the remaining ethanol and water, finally mix the two, add ammonia water to adjust the pH to 8, and stir at 400 rpm at 30°C for 1.5 hours to prepare silica gel solution. In the silica gel solution of this embodiment, the mass ratio of tetraethyl orthosilicate, ethanol and water is 3:6:25.

[0036] Example 3: This example provides a preparation process of a solid adsorbent for treating wastewater containing solid particles.

[0037] Step 1: Divide the corn stalks into segments of 2-3 cm in length, soak them in 40 wt% ammonium formate solution (prepared by weighing solid ammonium formate and dissolving it in water) for 6 h, freeze-dry them, and then crush them through a 40-mesh sieve.

[0038] Step 2: Place the powder obtained in step 1 in a tubular furnace and carbonize it under nitrogen protection at a heating rate of 10°C / min. After reaching 500°C, keep the temperature for 3 hours to obtain straw biochar.

[0039] Step 3: Place the straw biochar in a silica gel solution until the straw biochar is completely immersed. After 800 W microwave treatment for 30 min in a nitrogen atmosphere, adjust the pH to 6 with acetic acid, place in a constant temperature water bath at 80°C, maintain the temperature and seal for aging for 24 h, and vacuum dry at 80°C to obtain a solid adsorbent.

[0040] Preparation method of silica gel solution: dissolve tetraethyl orthosilicate in an appropriate amount of ethanol, then mix the remaining ethanol and water, finally mix the two, add ammonia water to adjust the pH to 8, and stir at 500 rpm at 40°C for 2 hours to prepare silica gel solution. In the silica gel solution of this embodiment, the mass ratio of tetraethyl orthosilicate, ethanol and water is 4:7:30.

[0041] Comparative Example 1: This comparative example is the same as Example 3, except that the corn stalks are not treated by being immersed in the ammonium formate solution.

[0042] Comparative Example 2: This comparative example is the same as Example 3, except that step 3 is not performed.

[0043] Comparative Example 3: This comparative example is the same as Example 3, except that the corn stalks are replaced with fir wood chips.

[0044] Example 4: This example provides the adsorption performance of the solid adsorbents prepared in Examples 1 to 3 and Comparative Examples 1 to 3.

[0045] The solid adsorbent samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were added to a 6 mm large bulb sample tube and vacuum degassed on the instrument degassing station for 16 hours at a temperature of 473 K. A turbomolecular pump provided a vacuum environment. The degassed samples were obtained and the pore size distribution results were obtained using the Barrett-Joy-ner-Halenda (BJH) method. The volumes of total pores, micropores (<50 μm), mesopores (50-100 μm) and macropores (>100 μm) were statistically analyzed. The test results are shown in Table 1.

[0046] Table 1 Pore size distribution of solid adsorbents (volume unit: cm 3 / g)

[0047]

[0048] As can be seen from Table 1, the present invention is treated with ammonium formate and silicate gel solution, and the pore distribution is concentrated, so as to obtain a solid adsorbent with a higher proportion of mesopore volume; Comparative Example 1 has not been treated with ammonium formate solution immersion, and its macropore volume accounts for a high proportion, which is not conducive to the adsorption of organic matter in wastewater containing solid particles and is prone to clogging; Comparative Example 2 has not been treated with silicate gel solution. Although a solid adsorbent with a higher proportion of mesopore volume is obtained, it performs poorly in the flowing water test; Comparative Example 3 uses fir sawdust, and its microstructure is different from that of straw. Its pores are mainly concentrated in micropores and mesopores, which is also not conducive to the adsorption of organic matter in wastewater containing solid particles.

[0049] The adsorption performance of the solid adsorbent was tested according to the test method specified in the "Water and Wastewater Monitoring and Analysis Methods (Fourth Edition)". The test samples were from the same batch of sewage, sampled from rainwater and sewage, with a solid particulate content of 192.9~203.5mg / L, and the pH was adjusted to 5~6 with hydrochloric acid. The model of the UV-visible spectrophotometer used in the test was UV752. 1 removal: add the solid adsorbent to the sewage, the addition amount is 15g / L, stir and adsorb for 15 minutes. 10 removals: add the solid adsorbent to the sewage, the addition amount is 15g / L, stir and adsorb for 15 minutes, filter out the solid adsorbent and re-add it to the sewage (not treated with the solid adsorbent), and repeat the adsorption for a total of 10 times. The COD removal rate and ammonia nitrogen removal rate of the treated sewage were measured, and the test results are shown in Table 2.

[0050] Table 2 COD removal rate and ammonia nitrogen removal rate

[0051]

[0052] As can be seen from Table 2, Comparative Example 1 was not treated with ammonium formate solution immersion, and its adsorption performance was significantly reduced compared with Example 3. This may be because the microstructure that was not strengthened with ammonium formate caused greater structural damage to the corn straw during the carbonization process, affecting the further compounding of silica gel and its improvement effect; Comparative Example 2 was not treated with silica gel solution, which resulted in a decrease in the adsorption performance of the activated carbon; Comparative Example 3 used fir wood chips, whose microstructure was different from that of the straw, resulting in a significant decrease in adsorption performance after repeated use.

[0053] As described above, the basic principle, main features and advantages of the present invention are well described. The above embodiments and descriptions are only descriptions of the preferred embodiments of the present invention, and the present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, various changes and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the protection scope determined by the present invention.

Claims

1. A solid adsorbent for treating wastewater containing solid particles, characterized in that: The preparation method of the solid adsorbent comprises: soaking straw in ammonium formate solution, crushing the straw, and carbonizing the straw to prepare straw biochar; The straw biochar is placed in a silica gel solution, subjected to microwave treatment, allowed to stand for aging, and dried to obtain the solid adsorbent; The concentration of the ammonium formate solution is 30-40wt%; The immersion time is 3 to 6 hours; The silicic acid gel solution comprises tetraethyl orthosilicate, ethanol and water, and the mass ratio of tetraethyl orthosilicate, ethanol and water is 2-4:5-7:20-30; The preparation method of the silica gel solution comprises: mixing tetraethyl orthosilicate, ethanol and water, adding ammonia water to adjust the pH to 8, and stirring at a constant temperature for 1 to 2 hours; The microwave power of the microwave treatment is 500-800W, the time of the microwave treatment is 10-30min, and the microwave treatment is carried out under an inert gas environment; Before the static aging, the pH is adjusted to 6, the static aging temperature is 60-80° C., and the static aging time is 12-24 hours; The carbonization temperature is 400-500°C, and the carbonization time is 2-3h; The straw is corn straw.

2. The solid adsorbent for treating wastewater containing solid particles according to claim 1, characterized in that: The crushing is to crush the straw through a 40-mesh sieve.

3. The solid adsorbent for treating wastewater containing solid particles according to claim 1, characterized in that: The temperature of the constant temperature stirring reaction is 20-40° C., and the rotation speed of the constant temperature stirring reaction is 400-500 rpm.

4. Use of the solid adsorbent for treating wastewater containing solid particles according to any one of claims 1 to 3 in treating wastewater containing solid particles, characterized in that: include: The pH of the wastewater containing solid particles is adjusted to 5-6, and the solid adsorbent is added therein for stirring and adsorption; The solid particle content in the solid particle-containing sewage is 200 mg / L.

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