A method for preparing a water treatment coagulant composed of a composite inorganic polymer and an adsorbent material.

Abstract

This invention discloses a method for preparing a water treatment coagulant composed of a composite inorganic polymer and an adsorbent material, relating to the field of water treatment. The coagulant is a composite of the inorganic polymeric coagulant PATC and the adsorbent material multi-walled carbon nanotubes, wherein the multi-walled carbon nanotubes are MgCl2-modified multi-walled carbon nanotubes. This water treatment coagulant is mainly used to remove natural organic matter from water bodies, with significant effects.

Description

Technical Field

[0001] This invention relates to the field of water treatment, specifically to a method for preparing a water treatment coagulant composed of a composite inorganic polymer and an adsorption material. Background Technology

[0002] After initial treatment at drinking water plants, water undergoes disinfection at the downstream end. Disinfectants react with residual natural organic matter in the water, generating disinfection byproducts. These byproducts have teratogenic, carcinogenic, and mutagenic effects on human health, making their reduction essential. Considering economic cost, operational convenience, and feasibility, removing the precursors of disinfection byproducts—natural organic matter—is the preferred solution. Methods for removing natural organic matter from water bodies mainly include enhanced coagulation, adsorption, membrane separation, ion exchange, and ozone oxidation. Among these, enhanced coagulation can non-selectively remove natural organic matter from water bodies and is widely used in water treatment due to its large treatment capacity, simple operation, and low cost.

[0003] Conventional coagulants are mainly divided into inorganic and organic coagulants. Inorganic coagulants are primarily metal salt coagulants, such as ferric salt coagulants, aluminum salt coagulants, and titanium salt coagulants. Currently, polyaluminum chloride (PAC) is favored by many water plants due to its superior coagulation effect. In addition, polyferric chloride (PFC), polyferric sulfate (PFS), and polytitanium chloride (PTC) have been developed and applied in water treatment. Based on polymeric inorganic polymeric coagulants, bimetallic polymeric coagulants such as polyaluminum ferric chloride have been prepared using a bimetallic form. Due to their bimetallic form, they have a strong positive charge, which allows them to combine with negatively charged organic matter in water according to the principle of charge neutralization. Furthermore, these metal coagulants undergo hydrolysis in water to generate metal hydroxides, which can remove organic matter in water through adsorption bridging and net-like sweeping mechanisms. Polyaluminum chloride titanium bimetallic coagulant has improved charge neutralization capacity due to the introduction of tetravalent titanium. Studies have shown that PATC has a better ability to remove large molecular organic matter in water, but its ability to remove small molecular organic matter needs to be improved. Summary of the Invention

[0004] In view of the advantages of PATC and its existing problems, the purpose of this invention is to propose a method for preparing a water treatment coagulant that combines a composite inorganic polymer with an adsorbent material.

[0005] To achieve the above objectives, the preparation method of the present invention is as follows:

[0006] A method for preparing a water treatment coagulant composed of a composite inorganic polymer and an adsorbent material, wherein the coagulant is composed of an inorganic polymeric coagulant PATC and an adsorbent material multi-walled carbon nanotubes (MWCNTs), wherein the multi-walled carbon nanotubes are MgCl2 modified multi-walled carbon nanotubes.

[0007] Furthermore, the inorganic polymeric coagulant PATC was mixed with MgCl2-modified multi-walled carbon nanotubes by vibration.

[0008] Furthermore, the mass ratio of multi-walled carbon nanotubes to Al in the inorganic polymeric coagulant PATC in the MgCl2-modified multi-walled carbon nanotubes is 10-50%, for example, 10%, 30%, or 50%.

[0009] Furthermore, the time for ultrasonic mixing of the inorganic polymeric coagulant PATC with the MgCl2-modified multi-walled carbon nanotubes is 0.5-2 hours, for example, 0.5, 1.0, or 2.0 hours.

[0010] Furthermore, the inorganic polymeric coagulant PATC is prepared by reacting AlCl3 and TiCl4 through an ice-water bath treatment.

[0011] Furthermore, the molar ratio of Al in AlCl3 to Ti in TiCl4 is 10-30:1, for example, 10:1, 15:1, 20:1, or 30:1.

[0012] Furthermore, the AlCl3 is a 0.05-1.0 mol / L AlCl3 solution, the TiCl4 is a 98% TiCl4 solution, and the reaction time is 2-5 h; specifically, the 0.05-1.0 mol / L AlCl3 solution and the 98% TiCl4 solution are mixed and reacted in an ice-water bath for 2-5 h, and the reaction is carried out under stirring conditions at a stirring speed of 200-300 r / min.

[0013] Furthermore, TiCl4 should be added slowly, with the TiCl4 solution being added at a rate of 0.1-1 mL / min.

[0014] Furthermore, the alkalinity of the AlCl3 and TiCl4 reaction solution is adjusted with Na2CO3 (B = C(OH-) / C(Al-)). 3+ +Ti 4+ The concentration is adjusted to 1.5-1.8, for example, 1.5, 1.6, 1.7, 1.8; then stirred at 200-300 r / min for 2-5 h, and allowed to stand for 12-24 h to obtain PATC solution.

[0015] Furthermore, the Na₂CO₃ is a 0.5-1.0 mol / L Na₂CO₃ solution. The dropping rate of the Na₂CO₃ solution is 0.1-1 mL / min.

[0016] Furthermore, the MgCl2-modified multi-walled carbon nanotubes are formed by mixing multi-walled carbon nanotubes with MgCl2 through vibration and then pyrolyzing them at a high temperature of 150-400℃ (e.g., 150, 300, 350, 400℃) for 2-5 hours (e.g., 2, 3, 4, 5 hours).

[0017] Furthermore, the ratio of the multi-walled carbon nanotubes to MgCl2 is 1g:1-10mmol, preferably 1-5mmol; for example, 1g:1mmol, or 1g:3mmol, 1g:5mmol.

[0018] Furthermore, the multi-walled carbon nanotubes are soaked in anhydrous ethanol to remove impurities, and then dried for later use.

[0019] Furthermore, the time for oscillating and mixing the multi-walled carbon nanotubes with MgCl2 is 12-24 hours, for example, 12, 16, 20, or 24 hours; the oscillation and mixing speed is 200-300 r / min.

[0020] Specifically, the preparation method of the water treatment coagulant includes the following steps:

[0021] (1) Prepare a 0.05-1 mol / L AlCl3 solution, and add TiCl4 under ice-water bath conditions to make the Al / Ti ratio (n / n).

[0022] (2) After stirring the above solution at a speed of 200-300 r / min for 5-20 min, slowly add 0.5-1.0 mol / L Na2CO3 solution to adjust the alkalinity of the solution to 1.5, 1.6, 1.7, or 1.8.

[0023] (3) After the above solution is prepared, it needs to be stirred at 200-300r / min for 2-5h and then allowed to stand at room temperature for 12-24h to obtain a PATC solution of a certain concentration.

[0024] (4) Multi-walled carbon nanotubes are soaked in anhydrous ethanol to remove impurities, and then dried for later use.

[0025] (5) Multi-walled carbon nanotubes and MgCl2 were shaken at a ratio of 1g:1-10mmol, dried at a constant temperature, and then pyrolyzed at 150-400℃ for 2-5 hours before grinding for later use, so as to obtain MgCl2 modified multi-walled carbon nanotubes.

[0026] (6) The multi-walled carbon nanotubes modified by MgCl2 are ultrasonically mixed with Al in PATC solution at a mass ratio of 10%-50% for 0.5-2 hours. The above-mentioned water treatment coagulant is mainly used to remove natural organic matter from water bodies.

[0027] PATC-modified multi-walled carbon nanotube composite coagulants have the following advantages in water treatment:

[0028] 1. This invention utilizes the effective components (Al-O-Ti) and strong charge properties of bimetallic polymer coagulants to combine with metal-modified multi-walled carbon nanotubes. Under ultrasonic reaction with PATC, the effective components in PATC react with the metal compounds on the surface of the multi-walled carbon nanotubes to generate covalent bonds of three bimetallic oxides: Al-O-Mg, Al-O-Ti, and Mg-O-Ti, which can effectively enhance the ability to remove organic matter.

[0029] 2. This method was tested in actual water bodies. When the dosage was 0.20 mmol / L, the DOC removal rate reached more than 60%; the residual aluminum content was less than 0.2 mg / L.

[0030] 3. The operation method of the present invention is simple, the DOC removal rate is obvious, the coagulation effect is enhanced, the preparation method is simple, and it can be applied in practice. Attached Figure Description

[0031] Figure 1 This is a comparison chart showing the DOC removal rate of different composite coagulants prepared in Examples 1-3 of the present invention at different dosages on actual water bodies;

[0032] Figure 2 The UV index of the composite coagulant prepared in Example 2 of this invention at different dosages in actual water bodies 254 Comparison chart of residual aluminum removal status. Detailed Implementation

[0033] To further understand the purpose, technical solution, and advantages of the present invention, the technical solution of the present invention will be further described below, and the present invention will be explained in detail with reference to embodiments and accompanying drawings.

[0034] Unless otherwise specified, the pharmaceuticals mentioned in the following examples are all commercially available products.

[0035] Unless otherwise specified, the experimental methods used in the following examples are all conventional experimental methods.

[0036] This invention provides a coagulant that combines coagulation and adsorption, exhibiting excellent efficiency in organic matter removal. Polyaluminum chloride titanium is prepared via an ice-water bath and then combined with modified multi-walled carbon nanotubes under oscillating and ultrasonic conditions. This allows PATC to hydrolyze and remove macromolecular organic matter while the abundant metal functional groups on the surface of the multi-walled carbon nanotubes adsorb negatively charged organic matter, thereby improving the organic matter removal efficiency during coagulation and shortening the adsorption reaction time.

[0037] Example 1

[0038] This embodiment illustrates a method for preparing a water treatment coagulant composed of a composite inorganic polymer and an adsorbent material. The specific steps of the preparation method are as follows:

[0039] (1) Prepare a 0.1 mol / L AlCl3 solution, and add 98% TiCl4 solution dropwise under ice-water bath conditions to make the Al / Ti ratio 15:1 (n / n).

[0040] (2) After stirring the above solution at 300 r / min for 5-10 min, slowly add 1.0 mol / L Na2CO3 solution dropwise to adjust the alkalinity of the solution to 1.5.

[0041] (3) After the above solution is prepared, it needs to be stirred at 300 r / min for 4 h and then allowed to stand for 24 h to obtain a PATC solution of a certain concentration.

[0042] (4) Weigh 1g of multi-walled carbon nanotubes and add them to 1L of 5mmol / L MgCl2 solution. Shake at room temperature for 24h, centrifuge to collect the solid, dry at 60℃ for 12h, and then pyrolyze in a muffle furnace at 350℃ for 2 hours to obtain MgCl2 modified multi-walled carbon nanotubes, which are then ground for later use.

[0043] (5) Weigh 100 mL of PATC solution and add MgCl2 modified multi-walled carbon nanotubes to it. Mix the modified multi-walled carbon nanotubes with PATC at a ratio of MWCNTs / Al = 10%, and sonicate for 30 min to obtain a composite coagulant, denoted as PATC@TMgMW-10%.

[0044] Example 2

[0045] The difference between this embodiment and embodiment 1 is that in step (5), the ratio of multi-walled carbon nanotubes to PATC is MWCNTs / Al = 30%, and the mixture is sonicated for 30 minutes to obtain a composite coagulant of PATC@TMgMW-30%.

[0046] Example 3

[0047] The difference between this embodiment and embodiment 1 is that in step (5), the ratio of multi-walled carbon nanotubes to PATC is MWCNTs / Al = 50%, and the mixture is ultrasonicated for 30 minutes to obtain a composite coagulant of PATC@TMgMW-50%.

[0048] Example 4

[0049] To investigate the effects of different composite coagulants at varying concentrations on organic matter in water, the effects of the composite coagulants prepared in Examples 1-3 at dosages of 0.12 mmol / L and 0.20 mmol / L were examined. Similarly, the effects of the composite coagulant prepared in Example 2 at dosages of 0.02 mmol / L, 0.04 mmol / L, 0.08 mmol / L, 0.12 mmol / L, 0.16 mmol / L, and 0.20 mmol / L were also investigated, with no composite coagulant added as a control. The water sample used had a DOC of 56.5 mg / L and UV... 254 = 0.078 actual water volume.

[0050] A six-unit agitator was selected for the coagulation experiment.

[0051] Take 500ml of water sample into a beaker, add the composite coagulant while stirring rapidly (250rpm), stir for 2min, then stir slowly (40rpm) for 10min to promote floc formation, and finally let it settle for 30min to allow the flocs to settle to the bottom of the beaker. Take the supernatant and measure the data.

[0052] The results of DCOC removal in water by different coagulants after the coagulation experiment are shown in the figure. Figure 1 The experiment compared DOC removal at two different dosages of coagulants. At the same dosage, the DOC removal initially increased and then decreased with the increase of multi-walled carbon nanotubes (MWC). This is because an appropriate amount of MWC can effectively react with the main components in PATC, enhancing its adsorption capacity without compromising the coagulation efficiency of PATC itself, thus promoting the improved coagulation effect of the composite coagulant. However, excessive addition of MWC will cause a large amount of MWC to react with the main components in PATC, reducing the effective components in PATC and lowering its coagulation efficiency, leading to a poorer coagulation effect. Therefore, increasing the dosage of the composite coagulant, given the high DOC content of the raw water, can improve the coagulation effect.

[0053] PATC@TMgMW-30% UV at different dosages was selected. 254 Further explanation regarding the residual aluminum content is provided; experimental results are shown below. Figure 2 UV254 UV254 decreases steadily with increasing dosage and can be used as an indicator of hydrophobic organic matter content in water. 254 The reduction in concentration demonstrates the ability of the composite coagulant to remove hydrophobic organic matter. The selected composite coagulant is primarily a polymeric coagulant containing Al and Ti bimetals, with Al accounting for 85% of the composition; therefore, the residual aluminum content in the water needed to be investigated. Analysis of the results shows that with increasing dosage, the residual aluminum content initially increases and then decreases, eventually stabilizing at 40 μg / L, far below the national standard requirement of 0.2 mg / L, thus reducing the threat to human health.

[0054] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a water treatment coagulant composed of a composite inorganic polymer and an adsorbent material, characterized in that, The coagulant is composed of inorganic polymeric coagulant PATC and adsorbent multi-walled carbon nanotubes, wherein the multi-walled carbon nanotubes are MgCl2 modified multi-walled carbon nanotubes. The inorganic polymeric coagulant PATC was mixed with MgCl2-modified multi-walled carbon nanotubes by ultrasonication for 0.5-2 hours. The mass ratio of MgCl2-modified multi-walled carbon nanotubes to Al in PATC solution is 10-50%. The inorganic polymeric coagulant PATC is prepared by reacting AlCl3 and TiCl4 after ice-water bath treatment; the reaction is carried out under stirring conditions; TiCl4 is added slowly. The molar ratio of Al in AlCl3 to Ti in TiCl4 is 10-30:1; The alkalinity of the AlCl3 and TiCl4 reaction solution was adjusted to 1.5-1.8 with Na2CO3; after stirring for 2-5 hours, it was allowed to stand for 12-24 hours to mature, yielding a PATC solution; the alkalinity was C(OH)2. - ) / C(Al 3+ +Ti 4+ ); The MgCl2-modified multi-walled carbon nanotubes are formed by mixing multi-walled carbon nanotubes and MgCl2 with vibration and then pyrolyzing them at a high temperature of 150-400℃ for 2-5 hours.

2. The preparation method according to claim 1, characterized in that, The AlCl3 is a 0.05-1.0 mol / L AlCl3 solution, and the TiCl4 is a 98% TiCl4 solution.

3. The preparation method according to claim 1, characterized in that, The oscillation time is 12-24 hours.

4. The preparation method according to claim 1, characterized in that, The ratio of the multi-walled carbon nanotubes to MgCl2 is 1g:1-10mmol.

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