CN110835155B

CN110835155B - Method for treating water by catalyzing ozone oxidation through magnesium titanate

Info

Publication number: CN110835155B
Application number: CN201911135599.9A
Authority: CN
Inventors: 童少平; 杨强强; 鲍慧洁; 钱如意
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2019-11-19
Filing date: 2019-11-19
Publication date: 2021-12-07
Anticipated expiration: 2039-11-19
Also published as: CN110835155A

Abstract

The invention relates to the technical field of water treatment, and discloses a method for treating water by catalyzing ozone oxidation through magnesium titanate, which comprises the following steps: loading organic wastewater into a reactor, introducing ozone, and adding magnesium titanate to catalyze ozone to degrade pollutants in the organic wastewater, wherein the magnesium titanate is MgTiO₃、Mg₂TiO₄Or mixtures thereof. The method solves the problems of low ozone utilization rate and narrow pH application range of the ozone oxidation water treatment method in the prior art, and the adopted magnesium titanate induces strong ozone decomposition capacity, high water treatment efficiency and wide pH application range. Because the magnesium titanate is solid, a new pollution source is prevented from being introduced into water quality, the magnesium titanate is easy to recover and transport, can be repeatedly utilized, and saves cost.

Description

Method for treating water by catalyzing ozone oxidation through magnesium titanate

Technical Field

The invention relates to the technical field of water treatment, in particular to a method for treating water by catalyzing ozone oxidation through magnesium titanate.

Background

In recent years, the problem of industrial wastewater pollution caused by rapid development of industrialization is becoming more serious, and the pollutants are generally characterized by high concentration, high toxicity, poor biodegradability and the like. Aiming at the problem of how to treat wastewater efficiently, the mature advanced treatment technology at the present stage mainly comprises the following steps: biodegradation, adsorption technology, coagulating sedimentation technology, electrochemical technology, membrane technology, advanced oxidation technology and the like.

Wherein the biodegradation treatment speed is slow, the occupied area is large, and certain requirements are imposed on the quality of inlet water; the adsorption technology has the advantages of high efficiency and simple operation, but needs the regeneration of the adsorbent; the coagulating sedimentation technology has simple operation, low cost and small occupied area, but the sludge yield is extremely high and needs to be treated again; although the electrochemical technology has the characteristics of high efficiency, no selectivity and no secondary pollution, the cost is extremely high, and the popularization and the application are difficult; membrane technology is effective in removing most contaminants from water, but the limitations of treatment concentration and membrane fouling problems limit its application. Advanced oxidation technology is rapidly developed because of its advantages of greenness, high efficiency, wide applicability, etc.

Ozone has been used in water treatment research for a century since its discovery in 1785 as a strong oxidant, environmentally friendly and potentially useful. However, when the single ozone oxidation is adopted, the problems of incomplete oxidation, low wastewater mineralization efficiency, low ozone utilization rate and the like exist. The catalytic ozonization technology is a novel method for oxidizing organic matters which are difficult to be oxidized or degraded by ozone alone at normal temperature and normal pressure. Catalytic ozonation is classified into homogeneous catalysis and heterogeneous catalysis, and among them, heterogeneous catalytic ozonation is becoming a focus of research because a catalyst and wastewater are easily separated after a reaction. The heterogeneous catalyst mainly comprises metal oxides, metals or metal oxides loaded on a carrier, natural minerals, activated carbon and the like.

The catalytic ozonization technology utilizes a large amount of strong oxidizing free radicals (hydroxyl free radicals) generated in the reaction process to oxidize and decompose organic matters in water so as to purify the water. Currently, the following technologies are mainly used in the following forms: (1) o is₃/H₂O₂；(2)O₃/UV；(3)O₃Ultrasonic wave; (4) o is₃A metal ion; (5) o is₃Solid catalysts, etc. The hydrogen peroxide catalytic ozonization is more researched and widely applied in practice, but most of O₃/H₂O₂The oxidation technology has high removal rate under neutral or alkaline conditions.

The inventors have previously studied using hydrogen peroxide and Ti in the presence of Ti⁴⁺In CN 101717146 a, a method for catalytic ozonation water treatment is disclosed, comprising the steps of: (1) controlling the pH value of the waste water containing organic matters to be 0.5-3.5, and adding hydrogen peroxide and Ti⁴⁺Stirring and dissolving the soluble compound to obtain a mixed solution; the organic matter is selected from one or the combination of any of the following: acetic acid, acetophenone, oxalic acid, toluene; organic matter and H contained in the wastewater₂O₂、Ti⁴⁺The feeding mass ratio of (1): 0.05-2.0: 0.01 to 0.5; (2) adding the mixed solution obtained in the step (1) into an ozone reactor, and introducing ozone for degradation reaction. TheContaining Ti for use in the invention⁴⁺The soluble compound is mainly titanyl sulfate or titanium tetroxide, and can achieve better catalytic effect within the pH range of 0.5-3.5. But the applicable pH value range is narrow, the efficiency is not obviously improved, and meanwhile, Ti is adopted⁴⁺/H₂O₂Is a disposable consumable product, can not be reused, and can cause the problems of titanium ion recovery after reaction, secondary pollution to water and the like. Therefore, methods for treating water by high-efficiency catalytic ozonation still need to be continuously explored.

Disclosure of Invention

The invention aims to solve the problems of low ozone utilization rate and narrow pH application range of an ozone oxidation water treatment method in the prior art, and provides a magnesium titanate catalytic ozone oxidation water treatment method with high catalytic activity and wide pH application range.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for treating water by catalyzing ozone oxidation through magnesium titanate comprises the following steps:

and (3) loading the organic wastewater into a reactor, introducing ozone, and adding magnesium titanate to catalyze the ozone to degrade pollutants in the organic wastewater.

Different from the water treatment by catalyzing ozone and oxidizing hydrogen peroxide, in the water treatment process by catalyzing ozone and oxidizing hydrogen peroxide, the hydrogen peroxide firstly reacts with water and then catalyzes ozone, and is very easy to be influenced by the pH value of a system, and the process of catalyzing ozone by hydrogen peroxide is as follows:

O₃₊H₂O^-→·OH+O₂ ^-+O₂

in the invention, the magnesium titanate directly induces the ozone to decompose and generate hydroxyl free radicals, and the magnesium titanate is magnesium metatitanate (MgTiO)₃) Magnesium orthotitanate (Mg)₂TiO₄) Or mixtures thereof, as they all contribute to some extent to the decomposition of contaminants in water by ozone.

MgTiO₃The reaction mechanism for removing organic matters by catalyzing ozone is as follows:

MgTiO₃-^S+O₃→MgTiO₃-^SO·+O₂

MgTiO₃-^SO·+2H₂O+O₃→MgTiO₃-^S(·OH) ₂+3·OH+2O₂

OH + organics → CO₂+H₂O + degradation products

Wherein MgTiO₃-^SRefers to MgTiO₃Surface of MgTiO₃-^SO·Refers to MgTiO₃With oxygen free radicals, MgTiO₃-^S(·OH) ₂Refers to MgTiO₃The surface of the compound has hydroxyl free radicals, and the compound can also react with organic matters to play a role in degradation.

Mg₂TiO₄The reaction mechanism for removing organic matters by catalyzing ozone is as follows:

Mg₂TiO₄-^S+O₃→Mg₂TiO₄-^SO·+O₂

Mg₂TiO₄-^SO·+2H₂O+O₃→Mg₂TiO₄-^S(·OH) ₂+3·OH+2O₂

OH + organics → CO₂+H₂O + degradation products

Wherein Mg₂TiO₄-^SRefers to Mg₂TiO₄Surface of (1), Mg₂TiO₄-^SO·Refers to Mg₂TiO₄With oxygen radicals, Mg₂TiO₄-^S(·OH) ₂Refers to Mg₂TiO₄The surface of the compound has hydroxyl free radicals, and the compound can also react with organic matters to play a role in degradation.

Therefore, the magnesium titanate directly generates catalytic action on ozone, has high catalytic efficiency, can not be influenced by pH of an acceptor system, and not only can stably exist under alkaline conditions, but also has certain stability under acidic conditions. Therefore, the pH value of the organic wastewater is within the range of 3.0-9.0.

The particle size of the magnesium titanate is 10-100 nm, and the preferred particle size is 50-80 nm.

In the water treatment process, by organic waste water meter, the volume of letting in of ozone is 0.1-100 mg/L, and the ozone concentration change is great to water treatment efficiency influence, and the concentration of preferred ozone is 10-100 mg/L, and along with the increase of ozone concentration, organic pollutant degradation efficiency promotes gradually.

In the water treatment process, the input amount of the magnesium titanate is 0.1-5 g/L calculated by the organic wastewater, and the magnesium titanate promotes ozone to be converted into hydroxyl free radicals with strong oxidation capacity, so that organic pollutants in water, particularly high-stability toxic and harmful organic pollutants such as pesticides, halogenated organic matters, nitro compounds and the like, are decomposed intensively. After the magnesium titanate is added, the removal rate, the mineralization degree and the like of the pollutants are greatly improved compared with those of ozone alone.

The concentration of the ozone is 10-100 mg/L based on the amount of the organic wastewater; the input amount of the magnesium titanate is 0.5-2 g/L.

The retention time of the organic wastewater in the reactor is 5-60 min. The removal efficiency increases gradually with increasing time, after which the rate of increase slows.

The concentration of the ozone is 10-80 mg/L based on the amount of the organic wastewater; the input amount of the magnesium titanate is 0.5-2 g/L; the pH value of the organic wastewater is 3.0-9.0; the retention time of the organic wastewater in the reactor is 5-60 min. Within each range, the magnesium titanate catalyzes ozone to have highest degradation efficiency on pollutants in the organic wastewater.

In the water treatment process, inorganic acid and inorganic alkali can be used for adjusting the pH value of the organic wastewater, and sulfuric acid and sodium hydroxide are preferred.

The organic wastewater is mainly wastewater containing organic pollutants in industry, and contains at least one of acetic acid, N-dimethylformamide, acetophenone, oxalic acid and toluene.

Compared with the prior art, the invention has the following beneficial effects:

(1) the magnesium titanate adopted by the invention has strong capability of inducing ozone decomposition, improves the utilization rate of ozone and has high water treatment efficiency;

(2) the treatment method has wide pH application range, adopts magnesium titanate as a catalyst, avoids introducing a new pollution source into water quality, and is green, nontoxic and pollution-free;

(3) the catalyst magnesium titanate is solid, is easy to recover and transport, can be repeatedly utilized, and saves cost.

Drawings

FIG. 1 is a schematic representation of MgTiO used in examples 1-5₃X-ray diffraction pattern of (a).

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Those skilled in the art should understand that they can make modifications and equivalents without departing from the spirit and scope of the present invention, and all such modifications and equivalents are intended to be included within the scope of the present invention.

In the embodiment of the invention, micromolecular organic acid acetic acid which is difficult to treat is adopted as an organic pollutant, although acetic acid is a biodegradable substance, the acetic acid is often a final product of most chemical oxidation methods, the property is stable, and generally, only super-oxidative hydroxyl free radicals can oxidize and decompose the acetic acid. Generally, if acetic acid can be effectively degraded, it is considered that other organic pollutants, such as macromolecular organic substances of aliphatic group, aromatic group, etc., can be effectively and highly degraded, and the degree of mineralization is also high.

In addition, in example 5, N-dimethylacetamide was used as an organic contaminant, and the concentration change before and after the measurement treatment was carried out to show that the catalyst has a wide application range.

In the following embodiments the pH is measured using a pH precision acidimeter;

and (3) measuring the concentration of acetic acid: determined by high performance liquid chromatography UltiMate3000 (ThermoFisher Dionex UltiMate3000, USA), separation column type: c18 column (250X 4.6mm, particle size 5mm),column temperature 25 ℃, eluent 0.0134mol phosphate buffer (pH 3) mixture and methanol (950:50, V: V) at a flow rate of 1.20mL · min^-1And the ultraviolet detection wavelength is 210 nm.

Determination of N, N-dimethylacetamide concentration: determined by high performance liquid chromatography UltiMate3000 (ThermoFisher Dionex UltiMate3000, USA), separation column type: c18 column (250X 4.6mm, particle size 5mm), column temperature 40 deg.C, eluent mixture of methanol and water (850:150, V: V), flow rate of 1.00mL min^-1And the ultraviolet detection wavelength is 205 nm.

The sulfuric acid and sodium hydroxide used in the following examples were obtained from Sjogren scientific corporation, and magnesium metatitanate MgTiO was used as magnesium titanate₃From Shanghai Michelin Biochemical technology, Inc., and N, N-dimethylacetamide from Alantin Biochemical technology, Inc.

Wherein the ozone comes from a CFS-1A type ozone generator and the oxygen cylinder is used for feeding air, and the gas flow is 0-0.16 m³The ozone discharge power is 1-10.

MgTiO in the following detailed description₃Amount of addition of (A) and O₃The amount of (2) is based on the volume of the reaction solution.

FIG. 1 shows MgTiO used in examples 1 to 5₃The diffraction peak of the X-ray diffraction pattern (XRD) of (1) is related to MgTiO in the standard card₃The diffraction peaks of (a) substantially coincide.

Example 1

500mL of a reaction solution having an acetic acid concentration of 50ppm was used to simulate organic wastewater, and the pH of the reaction solution was adjusted to 7.0 with sulfuric acid and sodium hydroxide. Adding 1g/L MgTiO₃The reaction is carried out under the condition that the ozone input is 60mg/L, the experiment is started, and a sample is taken for detection after the reaction is carried out for 30 min.

As a comparison, under the same experimental conditions, O was introduced separately₃And O₂/MgTiO₃The results of the experiments in which the same concentration of acetic acid solution was removed are shown in Table 1. It was found that the concentration of acetic acid in the reaction solution was measured by O₃/MgTiO₃After treatment, the treatment efficiency is reduced from 50mg/L to 8.2mg/L, the treatment efficiency is 83.6 percent, and MgTiO is not added into the reaction liquid₃The acetic acid concentration after ozone treatment was only reduced to 34.5, the treatment efficiency is only 31 percent, and the titanium MgTiO is singly used₃Has no degradation capacity to acetic acid with oxygen, and the treatment efficiency is 0 percent.

TABLE 1

Example 2

500mL of a reaction solution having an acetic acid concentration of 50ppm was used to simulate organic wastewater, and the pH values of the reaction solution were adjusted to about 3.0, 5.0, 7.0, and 9.0 with sulfuric acid and sodium hydroxide, respectively. Adding 1g/L MgTiO₃The reaction is carried out under the condition that the ozone input is 60mg/L, the experiment is started, and a sample is taken for detection after the reaction is carried out for 30 min. The results are shown in Table 2. As can be seen, MgTiO₃The catalytic ozone degradation organic matter can be effective in the range of pH 3.0-9.0, wherein the degradation efficiency is highest when the pH of the reaction liquid is about 7.0.

TABLE 2

Example 3

500mL of a reaction solution having an acetic acid concentration of 50ppm was used to simulate organic wastewater, and the pH of the reaction solution was adjusted to 7.0 with sulfuric acid and sodium hydroxide. MgTiO 2₃The input amount distribution of (A) was 0.5g/L, 1.0g/L, 1.5g/L, 2.0g/L, the ozone introduction amount was 20mg/L, the experiment was started, a sample was taken after 30min of reaction, and the detection results are shown in Table 3. As can be seen, MgTiO₃The influence of the input amount on the degradation efficiency is not very large, and the degradation efficiency is improved along with MgTiO₃The input amount of the method is increased, the treatment efficiency is gradually improved, and the method can be adjusted and selected according to the cost in practical application.

TABLE 3

Example 4

500mL of a reaction solution containing 50ppm of acetic acidThe pH value of the reaction liquid is adjusted to 7.0 by using sulfuric acid and sodium hydroxide to simulate organic wastewater. MgTiO 2₃The amount of the ozone to be added is 1g/L, the ozone is introduced under the conditions of 10mg/L, 20mg/L, 40mg/L, 60mg/L and 80mg/L respectively in the experimental process, the sampling detection is carried out 30min after the experiment starts to react, and the detection results are shown in Table 4. It can be seen that the influence of the introduction amount of ozone on the treatment efficiency of organic pollutants is large, the higher the introduction concentration of ozone is, the higher the treatment efficiency is, and in practical application, the ozone can be automatically adjusted and selected according to the cost.

TABLE 4

Example 5

500mL of a reaction solution having an N, N-dimethylacetamide concentration of 50ppm was used to simulate organic wastewater, and the concentration change of N, N dimethylacetamide was measured to evaluate the water treatment efficiency. Adjusting the pH value of the reaction solution to 7.0 by using sulfuric acid and sodium hydroxide, and MgTiO₃The input amount of (1) is 1g/L, the ozone introduction amount is 60mg/L, the experiment is started, and the sampling detection is carried out after the reaction is carried out for 20 min. As a comparison, under the same experimental conditions, O was introduced separately₃And O₂/MgTiO₃The results of the experiment for removing the N, N-dimethylacetamide solution of the same concentration are shown in Table 5. As can be seen, MgTiO₃The catalytic ozonation water treatment can effectively degrade N, N-dimethylacetamide in organic wastewater, and MgTiO₃The input amount is 1g/L, the pH value of the reaction liquid is 7.0, and when the ozone input amount is 60mg/L, the treatment efficiency of the N, N-dimethylformamide can reach 94.4 percent after 20min of treatment.

TABLE 5

Claims

1. A method for treating water by catalyzing ozone oxidation through magnesium titanate comprises the following steps:

loading the organic wastewater into a reactor, introducing ozone, and adding magnesium titanate to catalyze ozone to degrade pollutants in the organic wastewater;

the magnesium titanate is MgTiO₃、Mg₂TiO₄Or mixtures thereof;

the concentration of the ozone is 10-100 mg/L based on the amount of the organic wastewater; the input amount of the magnesium titanate is 0.5-2 g/L;

the pH value of the organic wastewater is 3.0-9.0.

2. The method of claim 1, wherein the magnesium titanate has a particle size of 10 to 100 nm.

3. The method for treating water by catalyzing ozone oxidation through magnesium titanate according to claim 1, wherein the retention time of the organic wastewater in the reactor is 5-60 min.

4. The method for treating water by catalyzing ozone oxidation through magnesium titanate according to claim 1, wherein the concentration of ozone is 10-80 mg/L in terms of organic wastewater; the input amount of the magnesium titanate is 0.5-2 g/L; the pH value of the organic wastewater is 3.0-9.0; the retention time of the organic wastewater in the reactor is 5-60 min.

5. The method of claim 1, wherein the organic wastewater comprises at least one of acetic acid, N-dimethylformamide, acetophenone, oxalic acid, and toluene.