Preparation and application of solid ferrotitanium flocculant for treating emulsion wastewater without demulsification

Abstract

The invention belongs to the technical field of flocculants for water treatment, and particularly relates to preparation and application of a solid ferrotitanium flocculant for treating emulsion wastewater without demulsification. The flocculant is prepared by bonding organic titanate with iron ions through a sol-gel method in a specific environment, and aging and drying. The high valence state of titanium and iron in the flocculating agent greatly improves the charge neutralizing capacity of the flocculating agent, and coagulation removal of an emulsion with negative charges on the surface in water is promoted; an organic group covalently bonded into the flocculant protects an emulsion droplet surface film, ensures no demulsification in the coagulation process, and is beneficial to efficient removal of organic pollutants; the combination of the titanium salt and the iron salt can better adapt to the pH value in the water environment, and has a wider application range; the solid state of the product endows the product with better storage stability and reduces the transportation cost, and the product has good popularization and application prospects in treatment of emulsion-containing wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of flocculants for water treatment, and specifically relates to the preparation and application of a solid titanium-iron flocculant for treating emulsion wastewater without demulsification. Background Art

[0002] With the increase of world population and economic development, water pollution and water shortage are becoming increasingly prominent, posing a serious threat to the sustainable development of the whole society. It is generally believed that the resource utilization of sewage is the most effective way to deal with this challenge, which can not only provide high-quality recycled water, but also recover resources / energy. However, due to the complex and changeable composition of sewage from different sources, there are often a small amount of difficult-to-treat components, which are difficult to completely remove using existing treatment technologies or the treatment process is long and the cost is too high, which is not conducive to sustainable development. Emulsion wastewater is one of the typical difficult-to-treat wastewaters, which exists in large quantities in my country.

[0003] In emulsion-related wastewater, oil pollutants generally exist in the form of stable water-in-oil droplets (<20mm), which have the characteristics of high surfactant content, multi-component coexistence, strong system stability, and high oil content. Because the surfactant plays the role of an emulsifier, a solid interfacial film protective layer is formed around the emulsion droplets, with the hydrophilic group pointing to the water and the hydrophobic group pointing to the oil. By reducing the interfacial energy (interfacial tension) and zeta potential, the emulsion can be protected to exist stably in water for a long time, and it is difficult to effectively remove it by traditional water treatment physical methods and biological methods. Therefore, the core of emulsion wastewater treatment technology has long been demulsification. By adding demulsifiers or using physical methods (changing temperature, high voltage electric field, ultrasound, membrane filtration, etc.), the original emulsion droplets in the wastewater are destabilized, and then physical, chemical and biological methods are used to achieve oil-water separation and the removal of organic pollutants such as surfactants and various additives. Usually, several methods need to be combined. In existing research work, demulsification is considered to be the most difficult step in the treatment of emulsion wastewater, which seriously restricts the clean and efficient treatment of emulsion wastewater. Therefore, developing new methods that can simply and efficiently treat emulsion wastewater without the need for demulsification has broad application prospects.

[0004] As an indispensable water treatment technology, flocculation has attracted much attention due to its maturity, economy, practicality, relative efficiency and easy construction and upgrading. The structure and performance of flocculants in the flocculation process play a key role in the effect of wastewater treatment. At present, in wastewater treatment, there are mainly two categories: inorganic flocculants (including aluminum salts and iron salts) and organic synthetic flocculants (such as polyacrylamide and polypropylene imine and their derivatives). Among them, the advantages of inorganic coagulants are low prices, but there are also problems such as high dosage, sensitivity to pH values, and toxicity of residual metal ions (such as Al ions). Organic synthetic polymer flocculants most commonly use PAM and its derivatives, which have relatively low dosages, need to be improved in removing emulsions, and have high costs. They may also have certain biological toxicity. Flocculants destabilize colloidal particle pollutants in water and coagulate (or flocculate) to form large aggregates (flocs) through electrical neutralization, adsorption bridging and netting, and achieve sedimentation separation. However, traditional flocculants are difficult to achieve non-demulsification coagulation removal of emulsion droplets in emulsion wastewater, and cannot remove soluble organic pollutants in water. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention utilizes a special sol-gel method to dissolve an organic titanate in a proton solvent and an alcohol aqueous solution of an iron salt to undergo a cross-linking reaction and form a sol, which is further condensed to form a gel, and a solid titanium-iron flocculant is obtained after aging and drying. The flocculant can achieve non-emulsification coagulation treatment of emulsion wastewater.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification comprises the following steps:

[0008] Step 1: dissolving a stabilizer in a protic solvent, and then adding an organic titanate to obtain a solution A;

[0009] Step 2: dissolving an inorganic iron salt in a low-carbon aliphatic alcohol or a low-carbon aliphatic alcohol / water mixed solvent, adjusting the pH, and obtaining a solution B;

[0010] Step 3: Add solution B into solution A and stir evenly to form a sol;

[0011] Step 4: Aging and drying the above sol to obtain the solid titanium-iron flocculant.

[0012] Furthermore, in step 1, the stabilizer is one of acetic acid, acetylacetone, and ethyl acetoacetate; the protonic solvent is one of methanol, ethanol, isopropanol, tert-butanol, and ethylene glycol monomethyl ether; and the organic titanate is one of tetrabutyl titanate, tetraisopropyl titanate, tetrapropyl titanate, and tetraethyl titanate.

[0013] Furthermore, in step 1, the molar ratio of the stabilizer to the organic titanate is 1:1-30.

[0014] Furthermore, in step 1, the volume ratio of the stabilizer to the protic solvent is 1:10-200.

[0015] Furthermore, in step 2, the inorganic iron salt is one of FeCl2, FeCl3, Fe(NO3)2, Fe(NO3)3, FeSO4, and Fe2(SO4)3; and the low-carbon fatty alcohol is one of methanol, ethanol, isopropanol, and tert-butanol.

[0016] Furthermore, in step 2, the molar ratio of the iron salt to the organic titanate is 1:0.5-5, and the pH is 1.0-6.0.

[0017] Furthermore, the sol aging time in step 4 is 8 to 48 hours.

[0018] A solid titanium-iron flocculant prepared by the preparation method as described above is an organic-inorganic hybrid flocculant formed by Fe atoms uniformly embedded in a Ti-OR structural framework through covalent bonding.

[0019] An application of the solid titanium iron flocculant as described above is used for treating emulsion wastewater without demulsification.

[0020] Furthermore, the emulsion wastewater includes mine water containing emulsion, food processing wastewater, cutting fluid wastewater, oil field wastewater, daily chemical production enterprise wastewater, and domestic sewage containing oil-water mixed emulsion.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention adopts a special sol-gel method to prepare, and obtains a solid titanium-iron hybrid flocculant by aging and drying; (2) The flocculant of the present invention hybridizes organic titanate and iron atoms through covalent bonds, and the organic component of the organic titanate and the inorganic component of the iron salt are hydrolyzed and condensed and connected through Fe-O-Ti; (3) The titanium and iron metal ions in the flocculant molecules of the present invention are more evenly distributed, and the combination of titanium salt and iron salt can better adapt to the pH value in the water environment and has a wider range of applications; (4) The solid form of the flocculant product of the present invention overcomes the transportation and storage stability problems of traditional liquid flocculants and reduces transportation costs (5) The flocculant of the present invention has excellent capabilities such as better charge neutralization, adsorption bridging and net capture and sweeping. The high valence states of titanium and iron greatly improve the charge neutralization ability of the flocculant, and promote the coagulation and removal of emulsions with negative charges on the surface in water; the covalently hybridized organic functional groups ensure the coagulation treatment of emulsion wastewater without breaking the emulsion, and can efficiently remove water turbidity and pollutants such as organic matter, nitrogen and phosphorus; (6) Since titanium and iron elements have no obvious harm to the biosphere, and titanium is also a bio-affinity element, the flocculant of the present invention will not affect human health and the surrounding ecological environment, and is beneficial to the resource utilization of emulsion wastewater after treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Infrared spectrum of the flocculant obtained in Preparation Example 1.

[0024] Figure 2 The pollutant removal rate of the simulated wastewater treated with the flocculant obtained in Preparation Example 1 varies with the dosage.

[0025] Figure 3 The pollutant removal rate of simulated wastewater treated with commercially available PAC (polyaluminium chloride) varies with dosage.

[0026] Figure 4 Microscopic image of floccules in simulated wastewater treated with the flocculant obtained in Preparation Example 1. DETAILED DESCRIPTION

[0027] The present invention is further described below by means of specific embodiments and application examples, but the scope of protection of the present invention is not limited thereto.

[0028] Unless otherwise specified, the reagents involved in the following examples are all commercially available products and are used directly without purification before use.

[0029] Preparation Example 1

[0030] A method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification comprises the following steps:

[0031] (a) Take 0.1 mol of glacial acetic acid and dissolve it in 100 mL of anhydrous ethanol under stirring at 300 rpm (the volume ratio of glacial acetic acid to anhydrous ethanol is about 7 / 100), continue stirring for 10 min, slowly drop 0.1 mol of tetraisopropyl titanate solution under stirring, and continue stirring for 30 min to obtain a uniform mixed solution A.

[0032] (b) Dissolve 0.1 mol Fe(NO3)3 in 25 mL deionized water + 25 mL anhydrous ethanol, stir at 300 rpm for 30 min, adjust the pH to 2 with glacial acetic acid, and continue stirring for 30 min to obtain a mixed solution B.

[0033] (c) At room temperature, under stirring at 300 rpm, the mixed solution B was slowly added to the mixed solution A at a rate of 0.2 ml / min, and stirring was continued at 300 rpm for 60 min to obtain a uniform sol.

[0034] (d) The sol prepared in step (c) is placed in a glass container, aged for 8 hours, and then vacuum dried at 45° C. to a constant weight, thereby obtaining the solid titanium-iron flocculant.

[0035] The infrared spectrum of solid titanium iron flocculant is as follows Figure 1 As shown, 3300cm -1 The wide band is derived from the stretching vibration of -OH in the solid titanium-iron composite flocculant. -1 Corresponding to the bending vibration of Fe-OH, 790cm -1 The peak at 1179cm can be attributed to the stretching vibration of Ti-O-Ti bond. -1 Attributed to Fe-O-Fe vibration. Wave number 1620cm -1 The vicinity corresponds to the -OH bending vibration, 1347 cm -1 , caused by the symmetric and asymmetric stretching vibrations of Fe-O-Fe and Ti-O-Fe groups.

[0036] Preparation Example 2

[0037] A method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification comprises the following steps:

[0038] (a) Take 0.05 mol of acetylacetone and dissolve it in 200 mL of isopropanol while stirring at 100 rpm (the volume ratio of acetylacetone to isopropanol is about 5.1 / 200), continue stirring for 10 min, slowly drop 1 mol of tetrabutyl titanate solution while stirring, and continue stirring for 30 min to obtain a uniform mixed solution A.

[0039] (b) Take 0.2 mol Fe2(SO4)3 and dissolve it in 30 mL deionized water + 20 mL isopropanol, stir at 300 rpm for 30 min, adjust the pH to 4 with glacial acetic acid, and continue stirring for 30 min to obtain a mixed solution B.

[0040] (c) At room temperature, under stirring at 300 rpm, the mixed solution B was slowly added to the mixed solution A at a rate of 0.2 ml / min, and the stirring was continued at 100 rpm for 120 min to obtain a uniform sol.

[0041] (d) The sol prepared in step (c) is placed in a glass container, aged for 16 hours, and then vacuum dried at 60° C. to a constant weight, thereby obtaining the solid titanium-iron flocculant.

[0042] Preparation Example 3

[0043] A method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification comprises the following steps:

[0044] (a) Take 0.01 mol of ethyl acetoacetate and dissolve it in 200 mL of methanol under stirring at 300 rpm (the volume ratio of ethyl acetoacetate to methanol is about 1.26 / 200), continue stirring for 10 min, slowly drop 0.3 mol of tetraethyl titanate solution under stirring, and continue stirring for 30 min to obtain a uniform mixed solution A.

[0045] (b) 0.1 mol FeCl3 was dissolved in 10 mL deionized water + 30 mL methanol, stirred at 300 rpm for 30 min, adjusted to pH 6 with glacial acetic acid, and stirred for another 30 min to obtain a mixed solution B.

[0046] (c) At room temperature, under stirring at 300 rpm, the mixed solution B was slowly added to the mixed solution A at a rate of 0.2 ml / min, and stirring was continued at 300 rpm for 60 min to obtain a uniform sol.

[0047] (d) The sol prepared in step (c) is placed in a glass container, aged for 48 hours, and then vacuum dried at 45° C. to a constant weight, thereby obtaining the solid titanium-iron flocculant.

[0048] Preparation Example 4

[0049] A method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification comprises the following steps:

[0050] (a) Take 0.1 mol of acetylacetone and dissolve it in 200 mL of ethylene glycol monomethyl ether under stirring at 300 rpm (the volume ratio of acetylacetone to ethylene glycol monomethyl ether is about 10.2 / 200), continue stirring for 10 minutes, slowly drop 1 mol of tetraisopropyl titanate solution under stirring, and continue stirring for 30 minutes to obtain a uniform mixed solution A.

[0051] (b) Dissolve 2 mol Fe(NO3)2 in 5 mL deionized water + 35 mL anhydrous ethanol, stir at 300 rpm for 30 min, adjust the pH to 1 with glacial acetic acid, and continue stirring for 30 min to obtain a mixed solution B.

[0052] (c) At room temperature, under stirring at 300 rpm, the mixed solution B was slowly added to the mixed solution A at a rate of 0.2 ml / min, and stirring was continued at 300 rpm for 60 min to obtain a uniform sol.

[0053] (d) The sol prepared in step (c) is placed in a glass container, aged for 16 hours, and then vacuum dried at 45° C. to a constant weight, thereby obtaining the solid titanium-iron flocculant.

[0054] Preparation Example 5

[0055] A method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification comprises the following steps:

[0056] (a) Take 0.2 mol of glacial acetic acid and dissolve it in 300 mL of tert-butyl alcohol (the volume ratio of glacial acetic acid to anhydrous ethanol is about 14 / 300) while stirring at 300 rpm. Continue stirring for 10 min. Slowly drop 0.4 mol of tetraethyl titanate solution while stirring. Slowly drop the solution while stirring and continue stirring for 30 min to obtain a uniform mixed solution A.

[0057] (b) 0.2 mol FeSO4 was dissolved in 10 mL deionized water + 30 mL tert-butyl alcohol, stirred at 300 rpm for 30 min, adjusted to pH 2 with glacial acetic acid, and stirred for another 30 min to obtain a mixed solution B.

[0058] (c) At room temperature, under stirring at 300 rpm, the mixed solution B is slowly added to the mixed solution A at a speed of 0.2 ml / min, and the stirring is continued at 300 rpm for 60 min to obtain a uniform sol. (d) The sol prepared in step (c) is placed in a glass container, aged for 24 hours, and then vacuum dried at 45° C. to constant weight, which is the solid titanium iron flocculant.

[0059] Preparation Example 6

[0060] A method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification comprises the following steps:

[0061] (a) Take 0.2 mol of acetylacetone and dissolve it in 200 mL of anhydrous ethanol under stirring at 300 rpm (the volume ratio of acetylacetone to anhydrous ethanol is about 20.2 / 200), continue stirring for 10 minutes, slowly drop 0.5 mol of tetrabutyl titanate solution under stirring, and continue stirring for 30 minutes to obtain a uniform mixed solution A.

[0062] (b) 0.1 mol FeCl2 was dissolved in 10 mL deionized water + 25 mL anhydrous ethanol, stirred at 300 rpm for 30 min, adjusted to pH 1 with glacial acetic acid, and stirred for another 30 min to obtain a mixed solution B.

[0063] (c) At room temperature, under stirring at 300 rpm, the mixed solution B was slowly added to the mixed solution A at a rate of 0.2 ml / min, and stirring was continued at 300 rpm for 60 min to obtain a uniform sol.

[0064] (d) The sol prepared in step (c) is placed in a glass container, aged for 48 hours, and then vacuum dried at 45° C. to a constant weight, thereby obtaining the solid titanium-iron flocculant.

[0065] Application Example 1

[0066] The solid titanium iron flocculant obtained in Preparation Example 1 was applied to the coagulation treatment of simulated wastewater containing emulsion-kaolin-phosphorus-nitrogen. The treatment results are as follows: Figure 2 As shown. It can be found that under the optimized dosage of 100 mg / L, the removal rates of COD, ammonia nitrogen, nitrate nitrogen, total phosphorus, turbidity and emulsion can reach 51.3%, 24.6%, 35.9%, 90%, 93% and 59.6% respectively. In the comparative experiment, the flocculation treatment results of the same simulated emulsion by commercially available PAC (polyaluminium chloride) are as follows Figure 3 It can be seen that under the condition that the optimized dosage is 2.25 times (225 mg / L) of the solid titanium iron flocculant of the present invention, the COD is 16.5%, ammonia nitrogen is 8.4%, nitrate nitrogen is 12.6%, total phosphorus is 84%, turbidity is 88% and emulsion is 10.8%, which are all lower than the treatment results of the solid titanium iron flocculant of the present invention, and the removal rates of COD and emulsion are much lower.

[0067] The microscopic image of the flocs after being treated with the solid titanium iron flocculant of the present invention is as follows: Figure 4 As shown, it can be seen that the emulsion is aggregated together in the form of emulsion droplets, indicating that there is no emulsion breaking during the coagulation process, and the emulsion is coagulated without emulsion breaking.

[0068] Application Example 2

[0069] The solid titanium iron flocculant obtained in Preparation Example 2 was applied to the coagulation treatment of emulsion-containing mine water, and the turbidity, UV 254 The removal rates of COD, nitrate nitrogen, ammonia nitrogen and TP were 99%, 90.3%, 49.3%, 32.2%, 22.9% and 99% respectively. The corresponding removal rates of PAC were turbidity 88%, UV 254 48.9%, COD 6.8%, titanium nitrate nitrogen 3.6%, ammonia nitrogen 2.4% and TP88.1%, among which the removal rates of COD, titanium nitrate nitrogen and ammonia nitrogen are much lower than those of the solid titanium iron flocculant of the present invention.

Claims

1. A method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification, characterized in that: The following steps are involved: Step 1: dissolving a stabilizer in a protic solvent, and then adding an organic titanate to obtain a solution A; Step 2: dissolving an inorganic iron salt in a low-carbon aliphatic alcohol or a low-carbon aliphatic alcohol / water mixed solvent, adjusting the pH, and obtaining a solution B; Step 3: Add solution B into solution A and stir evenly to form a sol; Step 4: Aging and drying the above sol to obtain the solid titanium-iron flocculant.

2. The method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification according to claim 1, characterized in that: In step 1, the stabilizer is one of acetic acid, acetylacetone, and ethyl acetoacetate; the proton solvent is one of methanol, ethanol, isopropanol, tert-butanol, and ethylene glycol monomethyl ether; and the organic titanate is one of tetrabutyl titanate, tetraisopropyl titanate, tetrapropyl titanate, and tetraethyl titanate.

3. The method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification according to claim 1, characterized in that: In the step 1, the molar ratio of the stabilizer to the organic titanate is 1:1-30.

4. The method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification according to claim 1, characterized in that: In the step 1, the volume ratio of the stabilizer to the protic solvent is 1:10-200.

5. The method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification according to claim 1, characterized in that: In step 2, the inorganic iron salt is one of FeCl2, FeCl3, Fe(NO3)2, Fe(NO3)3, FeSO4, and Fe2(SO4)3; the low-carbon fatty alcohol is one of methanol, ethanol, propanol, and butanol.

6. The method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification according to claim 1, characterized in that: In step 2, the molar ratio of the iron salt to the organic titanate is 1:0.5-5, and the pH is 1.0-6.

0.

7. The method for preparing a solid titanium iron flocculant for treating emulsion wastewater without demulsification according to claim 1, characterized in that: The sol aging time in step 4 is 8 to 48 hours.

8. A solid titanium iron flocculant prepared by the preparation method according to any one of claims 1 to 7, characterized in that: It is an organic-inorganic hybrid flocculant formed by Fe atoms uniformly embedded in the Ti-OR structural framework through covalent bonding.

9. An application of the solid ferrotitanium flocculant according to claim 8, characterized in that: Used to treat emulsion wastewater without demulsification.

10. The use of the solid ferrotitanium flocculant according to claim 9, characterized in that: The emulsion wastewater includes mine water containing emulsion, food processing wastewater, cutting fluid wastewater, oil field wastewater, daily chemical production enterprise wastewater, and domestic sewage containing oil-water mixed emulsion.

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