Water quality conditioner added with improved humic acid and preparation method thereof

Abstract

The present application relates to the field of wastewater treatment, and particularly relates to a water quality conditioner added with improved humic acid and a preparation method thereof.The water quality conditioner added with improved humic acid is obtained by compounding improved humic acid and interface functionalized hematite nanocrystals; the improved humic acid is methyl methacrylic acid grafted phenol modified humic acid; the interface functionalized hematite nanocrystals are selected from one of coffee acid interface functionalized hematite nanocrystals and benzimidazole interface functionalized hematite nanocrystals.The present application does not use toxic reducing agents or noble metals; coffee acid and benzimidazole are both degradable or low-toxic small molecules, and have low residual amounts; the final product is Cr(III) hydroxide or an organic complex, which can be further precipitated or recycled, and conforms to the green water treatment concept.All reaction preparation conditions are mild, and the equipment requirements are low.The raw materials are widely sourced and low in cost, and are suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wastewater treatment, in particular to a water quality conditioner added with improved humic acid and a preparation method thereof. BACKGROUND

[0002] Chromium in natural water exists in two forms, trivalent (Cr(III)) and hexavalent (Cr(VI)). The former is an essential trace element in animal nutrition; the latter has carcinogenic, teratogenic, and mutagenic toxicity, and causes persistent environmental risk due to its easy migration. Therefore, it is urgent to remove highly toxic Cr(VI) from wastewater.

[0003] In recent years, the research and development of humic acid products have become a hot topic. Humic acid widely exists in nature and is mainly derived from lignite, peat and weathered coal. It is an organic matter accumulated through the decomposition and transformation of ancient plant residues by microorganisms and a series of geochemical processes. It contains a large number of hydroxyl, carboxyl and other groups, so it has adsorption, complexation, ion exchange and dispersion properties, and can effectively disperse metal oxides to form a relatively stable protective film on the surface of the metal, which can exhibit good corrosion inhibition, scale inhibition and scale dissolution properties. Therefore, humic acid shows a broad application prospect in the field of industrial water treatment.

[0004] Hematite nanoparticles (α-Fe2O3NPs) are a kind of inorganic nanomaterials with a particle size of 1-100 nm and a crystal structure of hematite (α-Fe2O3). Due to its high natural abundance, stable chemical properties, environmental friendliness and easy preparation, it has become an important research object in the fields of environmental science, soil chemistry and nanotechnology. It has high adsorption capacity for heavy metals such as As(Ⅲ / V), Cr(Ⅵ), Pb(Ⅱ) and organic pollutants (PCP, PHE). There is no precedent for applying hematite nanoparticle and humic acid composite materials to the treatment of hexavalent chromium wastewater. SUMMARY

[0005] To solve the problems in the prior art, the present application provides a water quality conditioner added with improved humic acid and a preparation method thereof.

[0006] The present application is realized by the following technical solutions:

[0007] A water quality conditioner added with improved humic acid, which is obtained by compounding improved humic acid and interface functionalized hematite nanocrystals.

[0008] The improved humic acid is methyl acrylate grafted phenol modified humic acid.

[0009] The interface functionalized hematite nanocrystals are selected from one of coffee acid interface functionalized hematite nanocrystals and benzimidazole interface functionalized hematite nanocrystals.

[0010] Further, the interface functionalized hematite nanocrystals are selected from coffee acid interface functionalized hematite nanocrystals.

[0011] Further, the preparation method of the coffee acid interface functionalized hematite nanocrystals is:

[0012] 1 mmol of coffee acid is dispersed in 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution A; 1 mmol of Fe(NO3)3·9H2O is added to 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution B; solution A is slowly added to solution B, and stirred for 30 min; the mixed solution is transferred into a stainless steel reaction kettle, and reacted at 100℃ for 12 h; the product is washed by centrifugation, dried at 60℃ overnight, and coffee acid interface functionalized hematite nanocrystals are obtained.

[0013] Further, the molar ratio of the coffee acid and Fe(NO3)3·9H2O is 1:1.

[0014] Further, the interface functionalized hematite nanocrystals are selected from coffee acid interface functionalized hematite nanocrystals.

[0015] Further, the preparation method of the coffee acid interface functionalized hematite nanocrystals is:

[0016] Further, the molar ratio of the coffee acid and Fe(NO3)3·9H2O is 1:1.

[0017] Further, the modified humic acid is methyl acrylate grafted phenol modified humic acid.

[0018] Further, the preparation method of the methyl methacrylic acid grafted phenol modified humic acid is as follows: 0.8g of potassium hydroxide and 50mL of distilled water are added into 2g of phenol modified humic acid, and stirred for 20min, then the pH is adjusted to 9, the temperature is raised to 75 DEG C, sodium methacrylate solution is added dropwise, and 0.2g of ammonium persulfate is added dropwise at the same time, after the dropwise addition is completed, the reaction is carried out at 75 DEG C, and after natural cooling, drying is carried out in an oven at 60 DEG C, to obtain the methyl methacrylic acid grafted phenol modified humic acid.

[0019] The sodium methacrylate solution is prepared as follows: 2g of methyl methacrylate is added into a 100mL beaker, and a saturated solution of sodium carbonate is slowly added while stirring, and the reaction is carried out until no bubbles are generated.

[0020] The preparation method of the phenol modified humic acid is as follows: 4g of humic acid powder is weighed and poured into a three-necked flask with a reflux device, and the humic acid powder is dissolved by using 25wt% KOH solution, and heated to 100 DEG C, while 1g of phenol is rapidly added, and the pH is adjusted to 11, and the reaction is carried out for 2h; then the pH is adjusted to less than 2 by using 10wt% HCl, and after standing for 24h, the precipitate is obtained by centrifugation, and dried in an oven at 60 DEG C, to obtain the phenol modified humic acid.

[0021] The application further provides a preparation method of the water quality conditioner added with the modified humic acid, which comprises the following steps: the modified humic acid and the interface functionalized hematite nanocrystal are added into deionized water, the pH is adjusted to 6, and stirring is carried out at room temperature for 24h, then centrifugation is carried out, the precipitate is washed with deionized water for 3 times, and then freeze-drying is carried out, and the product is passed through a 100mu m sieve.

[0022] Compared with the prior art, the application has the following advantages and beneficial effects:

[0023] In the application, no toxic reducing agent or noble metal is used, the caffeic acid and the benzimidazole are all small molecules which are degradable or low-toxic, and the residual amount is low, the final product is Cr(III) hydroxide or an organic complex, and can be further precipitated or recycled, which conforms to the green water treatment concept. All the reaction preparation conditions are mild, and the equipment requirement is low. The raw materials are widely available and low in cost, and are suitable for industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings described herein are used to provide further understanding of the embodiments of the application, constitute a part of the application, and do not constitute a limitation to the embodiments of the application.

[0025] Figure 1 It is a TEM diagram of the caffeic acid interface functionalized hematite nanocrystal in Example 1. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application clearer, further detailed description will be given below in combination with examples and drawings. The schematic embodiments of the present application and the description thereof are only used to explain the present application and do not limit the present application.

[0027] Example 1

[0028] A water quality conditioner added with improved humic acid, which is obtained by compounding improved humic acid and interface functionalized hematite nanocrystals.

[0029] The improved humic acid is methyl methacrylic acid grafted phenol modified humic acid, and the preparation method thereof is as follows: 0.8 g of potassium hydroxide and 50 mL of distilled water are added into 2 g of phenol modified humic acid, and then stirred for 20 min; then the pH is adjusted to 9, and the temperature is raised to 75 ℃; a sodium methacrylate solution is added dropwise, and 0.2 g of ammonium persulfate is added dropwise at the same time; after the dropwise addition is completed, the reaction is carried out at 75 ℃ with stirring; and after natural cooling, drying is carried out in an oven at 60 ℃ to obtain the methyl methacrylic acid grafted phenol modified humic acid. The sodium methacrylate solution is prepared as follows: 2 g of methyl methacrylic acid is added into a 100 mL beaker, and a saturated solution of sodium carbonate is slowly added while stirring until no bubbles are generated, and then the solution is prepared.

[0030] The preparation method of the phenol modified humic acid is as follows: 4 g of humic acid powder is weighed into a three-necked flask with a reflux device, and a 25% KOH solution is used to dissolve the humic acid powder; the temperature is raised to 100 ℃, and 1 g of phenol is quickly added while adjusting the pH to 11; the reaction is carried out for 2 h; then the pH is adjusted to less than 2 using a 10% HCl solution, and the mixture is left to stand for 24 h; then the precipitate is obtained by centrifugation, and drying is carried out in an oven at 60 ℃ to obtain the phenol modified humic acid.

[0031] The interface functionalized hematite nanocrystal is a caffeic acid interface functionalized hematite nanocrystal, and the preparation method thereof is as follows:

[0032] 1 mmol of caffeic acid is dispersed in 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution A; 1 mmol of Fe(NO3)3·9H2O is added to 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution B; solution A is slowly added to solution B, and stirring is carried out for 30 min; the mixed solution is transferred into a stainless steel reaction kettle, and the reaction is carried out at 100 ℃ for 12 h. Finally, the product is washed by centrifugation, and drying is carried out at 60 ℃ overnight to obtain the caffeic acid interface functionalized hematite nanocrystal. Figure 1 It is a TEM image of the caffeic acid interface functionalized hematite nanocrystal in Example 1.

[0033] The preparation method of the humic acid modified water quality conditioner is as follows: 1 g of methyl methacrylic acid grafted phenol modified humic acid and 5 g of coffee acid interface functionalized hematite nanocrystals are added to 250 mL of deionized water, the pH is adjusted to 6, stirring is carried out at room temperature for 24 h, then centrifugation is carried out, the precipitate is washed with deionized water for 3 times, then freeze-drying is carried out, 100 μm sieve is passed, and storage is carried out for standby use.

[0034] Example 2

[0035] A humic acid modified water quality conditioner is obtained by compounding humic acid and interface functionalized hematite nanocrystals.

[0036] The humic acid modified water quality conditioner is obtained by compounding humic acid and interface functionalized hematite nanocrystals.

[0037] The preparation method of the phenol modified humic acid is as follows: 4 g of humic acid powder is weighed into a three-necked flask with a reflux device, the humic acid powder is dissolved by using a 25% mass fraction KOH solution, heating is carried out to 100℃, 1 g of phenol is rapidly added at the same time, the pH is adjusted to 11, and reaction is carried out for 2 h; then natural cooling is carried out, a 10% mass fraction HCl is used to adjust the pH to less than 2, after standing for 24 h, centrifugation is carried out to obtain a precipitate, and drying is carried out in a 60℃ oven to obtain the phenol modified humic acid.

[0038] The interface functionalized hematite nanocrystal is a benzimidazole interface functionalized hematite nanocrystal, and the preparation method is as follows:

[0039] 1 mmol of benzimidazole is dispersed in 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution A; 1 mmol of Fe(NO3)3·9H2O is added to 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution B; solution A is slowly added to solution B, and stirring is carried out for 30 min; the mixed solution is transferred into a stainless steel reaction kettle, and reaction is carried out at 100℃ for 12 h. Finally, the product is washed by centrifugation and dried at 60℃ overnight to obtain the benzimidazole interface functionalized hematite nanocrystal.

[0040] The preparation method of the water quality conditioner added with the improved humic acid is as follows: 1 g of methacrylic acid grafted phenol modified humic acid and 5 g of benzimidazole interfacial functionalized hematite nanocrystals are added into 250 mL of deionized water, the pH is adjusted to 6, stirring is conducted at room temperature for 24 h, then centrifugation is conducted, the precipitate is washed with deionized water for 3 times, then freeze drying is conducted, 100 μm sieving is conducted, and storage is conducted for standby use.

[0041] Comparative example 1

[0042] A water quality conditioner is obtained by compounding humic acid and interfacial functionalized hematite nanocrystals.

[0043] The interfacial functionalized hematite nanocrystal is a caffeic acid interfacial functionalized hematite nanocrystal, and the preparation method thereof is as follows:

[0044] 1 mmol of caffeic acid is dispersed in 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution A; 1 mmol of Fe(NO3)3·9H2O is added into 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution B; solution A is slowly added into solution B, and stirring is conducted for 30 min; the mixed solution is transferred into a stainless steel reaction kettle, and reaction is conducted at 100 ℃ for 12 h. Finally, the product is centrifuged and washed, dried at 60 ℃ overnight, and the caffeic acid interfacial functionalized hematite nanocrystal is obtained.

[0045] The preparation method of the water quality conditioner is as follows: 1 g of humic acid and 5 g of caffeic acid interfacial functionalized hematite nanocrystals are added into 250 mL of deionized water, the pH is adjusted to 6, stirring is conducted at room temperature for 24 h, then centrifugation is conducted, the precipitate is washed with deionized water for 3 times, then freeze drying is conducted, 100 μm sieving is conducted, and storage is conducted for standby use.

[0046] Comparative example 2

[0047] A water quality conditioner is obtained by compounding humic acid and interfacial functionalized hematite nanocrystals.

[0048] The interfacial functionalized hematite nanocrystal is a benzimidazole interfacial functionalized hematite nanocrystal, and the preparation method thereof is as follows:

[0049] 1 mmol of benzimidazole is dispersed in 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution A; 1 mmol of Fe(NO3)3·9H2O is added into 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution B; solution A is slowly added into solution B, and stirring is conducted for 30 min; the mixed solution is transferred into a stainless steel reaction kettle, and reaction is conducted at 100 ℃ for 12 h. Finally, the product is centrifuged and washed, dried at 60 ℃ overnight, and the benzimidazole interfacial functionalized hematite nanocrystal is obtained.

[0050] The preparation method of the water conditioner is as follows: 1 g of humic acid and 5 g of benzimidazole interfacial functionalized hematite nanocrystals are added to 250 mL of deionized water, the pH is adjusted to 6, stirring is carried out at room temperature for 24 h, then centrifugation is carried out, the precipitate is washed with deionized water for 3 times, then freeze-drying is carried out, 100 μm sieve is passed, and storage is carried out for standby use.

[0051] Comparative Example 3

[0052] A water conditioner is compounded by humic acid and hematite nanocrystals.

[0053] The preparation method of the hematite nanocrystals is as follows:

[0054] 1 mmol of Fe(NO3)3·9H2O is added to 20 mL of DMF / H2O with a volume ratio of 1:1, and is transferred into a stainless steel reaction kettle, and is reacted at 100 ℃ for 12 h. Finally, the product is washed by centrifugation, and is dried at 60 ℃ overnight to obtain hematite nanocrystals.

[0055] The preparation method of the water conditioner is as follows: 1 g of humic acid and 5 g of hematite nanocrystals are added to 250 mL of deionized water, the pH is adjusted to 6, stirring is carried out at room temperature for 24 h, then centrifugation is carried out, the precipitate is washed with deionized water for 3 times, then freeze-drying is carried out, 100 μm sieve is passed, and storage is carried out for standby use.

[0056] Test Example

[0057] The water conditioners in each example and comparative example are added to 1 L of deionized water containing hexavalent chromium ions, and the concentration of hexavalent chromium ions is 10 mg / L, 20 mg / L, and 50 mg / L respectively. The addition amount of the water conditioner in each example and comparative example is 1 g / L. After the water conditioner is added, the solution is stirred at room temperature for 24 h, then centrifugation is carried out, and the supernatant is used to measure the concentration of hexavalent chromium ions in the supernatant by using a UV spectrophotometer.

[0058] Table 1 Performance Test

[0059] Removal rate (%, 10 mg / L) Removal rate (%, 20 mg / L) Removal rate (%, 50 mg / L) Example 1 29.4 33.5 37.8 Example 2 28.7 32.4 36.9 Comparative Example 1 22.1 24.7 27.3 Comparative Example 2 20.1 21.3 23.4 Comparative Example 3 18.7 20.1 21.1

[0060] As can be seen from Table 1, each of the embodiments and the comparative examples presents the phenomenon of "higher removal rate at higher concentration", indicating that the adsorption driving force is likely to be dominated by reduction-complexation, and high concentration promotes the redox reaction of electron donors (phenolic hydroxyl, carboxyl) with Cr(VI) or forms Cr(III)-Fe(III) coprecipitation, which intensifies with the increase of concentration. Embodiments 1-2 have better removal rate relative to the comparative examples, indicating that methacrylic acid-phenol grafting is conducive to forming multi-dentate coordination with Fe-OH on the surface of hematite, improving the stability and active site number of the complex. Embodiment 1 has better effect relative to embodiment 2, which may be that the caffeic acid contains o-diphenol structure, which can form strong bidentate chelation with Fe(III) and directly reduce Cr(VI); benzimidazole is mainly dominated by nitrogen coordination, mainly providing surface positive charge to enhance the electrostatic adsorption of Cr(VI) anions, but lacks reducing groups. The above specific embodiments further detail the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A water conditioner containing modified humic acid, characterized in that, The water conditioner containing modified humic acid is obtained by combining modified humic acid and interface-functionalized hematite nanocrystals. The modified humic acid is methacrylic acid grafted with phenol to modify humic acid. The interface-functionalized hematite nanocrystals are selected from one of caffeic acid interface-functionalized hematite nanocrystals and benzimidazole interface-functionalized hematite nanocrystals. The method for preparing the water conditioner with modified humic acid includes the following steps: adding modified humic acid and interface-functionalized hematite nanocrystals to deionized water, adjusting the pH to 6, stirring at room temperature for 24 hours, centrifuging, washing the precipitate three times with deionized water, then freeze-drying and passing it through a 100μm sieve.

2. The water conditioner containing modified humic acid as described in claim 1, characterized in that, The interface-functionalized hematite nanocrystals are selected from caffeic acid interface-functionalized hematite nanocrystals.

3. The water conditioner containing modified humic acid as described in claim 2, characterized in that, The preparation method of the caffeic acid interface-functionalized hematite nanocrystals is as follows: 1 mmol of caffeic acid is dispersed in 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution A; 1 mmol of Fe(NO3)3·9H2O is added to 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution B; solution A is slowly added to solution B and stirred for 30 min; the mixed solution is transferred to a stainless steel reactor and reacted at 100℃ for 12 h. The product was centrifuged and washed, and dried overnight at 60°C to obtain caffeic acid-functionalized hematite nanocrystals.

4. The water conditioner containing modified humic acid as described in claim 1, characterized in that, The interface-functionalized hematite nanocrystals are selected from benzimidazole interface-functionalized hematite nanocrystals.

5. The water conditioner containing modified humic acid as described in claim 4, characterized in that, The preparation method of the benzimidazole interface-functionalized hematite nanocrystals is as follows: 1 mmol of benzimidazole is dispersed in 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution A; 1 mmol of Fe(NO3)3·9H2O is added to 20 mL of DMF / H2O with a volume ratio of 1:1 to obtain solution B; solution A is slowly added to solution B and stirred for 30 min; the mixed solution is transferred to a stainless steel reactor and reacted at 100℃ for 12 h. The product was centrifuged, washed, and dried overnight at 60°C to obtain benzimidazole-functionalized hematite nanocrystals.

6. The water conditioner containing modified humic acid as described in claim 1, characterized in that, The preparation method of the methacrylic acid grafted with phenol modified humic acid is as follows: 8g of potassium hydroxide and 50mL of distilled water are added to 2g of phenol modified humic acid, stirred for 20min, then the pH is adjusted to 9, the temperature is raised to 75℃, sodium methacrylate solution is added dropwise, and 2g of ammonium persulfate is added dropwise at the same time. After the addition is completed, the temperature is kept at 75℃ for reaction, stirred, and after natural cooling, dried in an oven at 60℃ to obtain methacrylic acid grafted with phenol modified humic acid. The sodium methacrylate solution is prepared by adding 2g of methacrylic acid to a 100mL beaker, and slowly adding a saturated sodium carbonate solution while stirring, stirring until no more bubbles are released. The preparation method of the phenol-modified humic acid is as follows: Weigh 4g of humic acid powder and pour it into a three-necked flask equipped with a reflux device. Dissolve the humic acid powder with a 25% KOH solution. Heat to 100℃ and simultaneously add 1g of phenol. Adjust the pH to 11 and react for 2 hours. Then cool naturally and adjust the pH to less than 2 with a 10% HCl solution. After standing for 24 hours, centrifuge to obtain the precipitate and dry it in a 60℃ oven to obtain phenol-modified humic acid.

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