CN104229969A - The Method of Strengthening Reductive Dechlorination of Triclosan in Sewage Using Vitamin B12 - Google Patents

Abstract

The invention relates to a method for using vitamin _B12 to strengthen reduction and dechlorination of triclosan in sewage. Under the condition of pH value of 5-9, nanometer zero-valent iron and vitamins are added to the sewage containing triclosan B ₁₂ , the reaction time is 5-10 hours, and the reduction dechlorination of triclosan in sewage is carried out; wherein, the mass concentration of triclosan in sewage is 1-20 mg per liter, and the input amount of nanometer zero-valent iron is 1-20 mg per liter. 0.1-1 gram is added to 1 liter of sewage, and the input amount of vitamin _B12 is 10-100 mg per liter of sewage. Compared with the prior art, the method of the present invention requires simple reaction conditions, mild reaction, short treatment time, high removal rate of triclosan, no secondary pollution, and is suitable for treating triclosan-containing sewage and other pharmaceutical wastewater , which is conducive to the resource utilization of sewage.

Description

The Method of Strengthening Reductive Dechlorination of Triclosan in Sewage Using Vitamin B12

technical field

The invention relates to a method for treating sewage containing triclosan, in particular to a method for using vitamin _B12 to carry out enhanced reduction and dechlorination of triclosan in sewage.

Background technique

Pharmaceuticals and personal care products (PPCPs) are trace organic pollutants commonly found in water and sewage after pesticides, herbicides and endocrine disruptors, and their impact on the environment It has attracted widespread attention at home and abroad. Once PPCPs enter the human body, they will be transformed into polar and soluble metabolites and acids, and will be discharged into urban sewage along with urine and feces. Studies have shown that it is difficult to completely remove all PPCPs by traditional biological methods. Therefore, the residual PPCPs after treatment by the sewage plant will enter the surface water, groundwater or seawater along with the discharge of the tail water of the sewage plant, thereby affecting human beings and causing damage to the aquatic environment.

Over the past few decades, foreign researchers have done a lot of research on the existence and removal of PPCPs in sewage plants. Gracia-Lor et al. investigated the existence and removal of 50 target PPCPs in three sewage treatment plants in Spain. They detected 17 PPCPs residues in the effluent of the sewage treatment plants, mainly analgesics, anti-inflammatory drugs, and antibiotics. , hypolipidemic drugs, anti-allergy drugs. Previous studies have found that anti-inflammatory drugs, antibiotics, diuretics, hypolipidemic drugs, anti-allergic drugs, and stimulants are pharmaceutical pollutants that widely exist in the influent water of foreign sewage plants. Due to the differences in the selected target PPCPs and sewage Depending on the source, its concentration can range from hundreds of pg/L to hundreds of μg/L. Compared with the investigation and research on pharmaceutical pollutants, there are relatively few investigations and studies on personal hygiene care products, and only several common chlorinated organic compounds in personal hygiene care products have been studied (including triclosan and triclocarban). is the most frequently detected personal hygiene care product), because chlorinated organics are widely used in preservatives, sunscreens, fungicides, and disinfectants in personal hygiene care products. Chlorine-containing organic compounds will cause great harm to human health and the environment. Usually, chlorinated organic compounds are carcinogenic, teratogenic and mutagenic, and are difficult to be completely removed by organisms. As a broad-spectrum fungicide, triclosan is widely used in daily chemicals such as soap and toothpaste, and it is found to be ubiquitous in the influent of sewage plants in investigations and studies. Bendz et al., Yu et al., et al. and Lishman et al. investigated triclosan in sewage plants, and they found that the removal rates of triclosan in sewage plants were different, 58%, 69%, 88% and 93%, respectively. In the United States, 84% of antibacterial soaps contain triclosan, and its consumption is as high as 1,500 tons per year. Triclosan has been used in the United States as a high-volume chemical for nearly 50 years, but its hazards have received little attention until recent years.

According to previous investigations on the existence and removal of typical PPCPs in sewage plants, it was found that traditional biological methods have poor removal effects on chlorine-containing PPCPs, and their removal effects are affected by the quality of influent water and the treatment process of sewage plants. In recent years, due to its huge specific surface area and high activity, the reaction rate has been improved, and nanomaterials have been applied to contaminated soil and groundwater remediation and sewage treatment, and nano-scale zero-valent iron (nano-scale zero-valent, nZVI) research is relatively more. nZVI is an effective reducing agent for dehalogenation, which attracted people's attention as early as the 1980s. Nano-zero-valent iron can catalyze the reduction of various organic halides, such as: halogenated alkanes, halogenated olefins, halogenated aromatics and other refractory organic pollutants, and convert them into non-toxic and harmless compounds, while improving their biodegradability , can create favorable conditions for further biodegradation. When Zhang et al. used nanometer zero-valent iron to degrade trichloroacetic acid, trichloroethylene and tetrachloroethylene, they found that their removal rate could reach 99% within 24 hours. Studies by Lowry et al. have shown that the dechlorination effect of nano-sized zero-valent iron is much better than that of micron-sized zero-valent iron. Nano-sized zero-valent iron can dechlorinate polychlorinated biphenyls into less toxic chlorinated biphenyls. Although nano-zero-valent iron has many advantages, it still encounters some problems in the process of its application, such as the poor stability of nano-zero-valent iron. It has been reported that nano-zero-valent iron is easily oxidized to form iron oxides or hydroxides deposited on the surface of nano-iron, thereby causing nano-zero-valent iron to be passivated. When Song et al. used nanometer zero-valent iron to reduce tetrachloroethane, they found that with the increase of pH, the reaction rate also increased correspondingly. Become stronger. In addition, the aging effect and magnetism will also affect the activity of nano-zero-valent iron particles. In order to overcome the above shortcomings, the bimetallic catalytic reaction system (Ag, Pd, Ni, Cu, Pt and Zn) has been studied. Studies have shown that adding Pd to nZVI system can improve the removal effect of dioxin, trichlorethylene and tetrachlorethylene, but this method is too expensive and uneconomical for polluted soil or water, so some researchers use natural The catalysis of the nZVI system by transition metal coenzymes present in the environment was investigated. Their research found that transition metal coenzymes such as porphyrin and vitamin B ₁₂ existing in natural soil can catalyze the reduction reaction very well, and these metal coenzymes can be produced by anaerobic bacteria (acetogenic bacteria, methanogenic bacteria) Produced under neutral conditions. Vitamin B ₁₂ as a transition metal coenzyme consists of a corrin ring and a cobalt atom. Co ³⁺ in vitamin B ₁₂ can be reduced to Co ²⁺ (vitamin B _12r ) and Co ⁺ (vitamin B _12s ), and the reduction product of vitamin B ₁₂ will improve the electron transfer efficiency and thus have a stronger dechlorination efficiency for chlorinated organic compounds, further promoting its degradation in the bio-abiotic interaction system. Therefore, it is necessary to carry out corresponding research work.

Contents of the invention

The purpose of the present invention is exactly in order to improve the removal rate and removal effect of triclosan in sewage, and provide a kind of simple and easy reaction conditions, mild reaction, short treatment time, high removal rate of triclosan, no secondary pollution A method for enhanced reductive dechlorination of triclosan in sewage by using vitamin _B12 . The method can quickly and efficiently remove the triclosan in the sewage, reduce the harm to the environment of the triclosan-containing sewage, and is beneficial to the resource utilization of the subsequent sewage.

The purpose of the present invention can be achieved through the following technical solutions:

A method of using vitamin B ₁₂ to strengthen the reduction dechlorination of triclosan in sewage, adding nanometer zero-valent iron and vitamin B ₁₂ to the sewage containing triclosan, the reaction time is 5-10 hours, and the reaction temperature Unlimited, strengthen reductive dechlorination of triclosan in sewage. The bimetallic system formed by vitamin B ₁₂ and nano-zero-valent iron strengthens the reduction mechanism of triclosan: the nano-zero-valent iron is corroded in water to generate hydrogen gas, which is absorbed by vitamin B ₁₂ and embedded in the crystal lattice of vitamin B ₁₂ to form a strong The reducing substance vitamin B ₁₂ .H ₂ , and finally the strong reducing substance vitamin B ₁₂ .H ₂ will reductively degrade the triclosan adsorbed on the surface of vitamin B ₁₂ -nano-zero-valent iron. Triclosan is reduced to 2-hydroxy-diphenyl ether through the bimetallic system formed by vitamin B ₁₂ and nanometer zero-valent iron, its toxicity is greatly reduced, and 2-hydroxy-diphenyl ether can be greatly reduced by further conventional sewage treatment Good removal.

Further, the mass concentration of triclosan in the sewage is 1-20 mg per liter, the input amount of the nanometer zero-valent iron is 0.1-1 gram per liter of sewage, and the vitamin _B12 The input amount is 10-100 mg per liter of sewage.

Further, before adding nanometer zero-valent iron and vitamin _B12 , the pH value of the sewage is adjusted to 5-9.

Furthermore, before adding nanometer zero-valent iron and vitamin _B12 , the pH value of the sewage is adjusted to 8-9.

Furthermore, before adding nanometer zero-valent iron and vitamin _B12 , the pH value of the sewage was adjusted to 9.

Further, the particle diameter of the nano zero-valent iron is 50-70 nanometers.

The input amount of vitamin B ₁₂ is in the range of 10-100 mg per liter of sewage, the greater the amount of vitamin B ₁₂ added, the higher the removal rate of triclosan under the same operating conditions.

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

1. It has a wide range of applications and simple reaction conditions. In the present invention, vitamin _B12 and nanometer zero-valent iron are added to waste water containing triclosan, and the reaction temperature is not limited, and a good removal effect can be achieved under normal temperature and pressure.

2. The reaction rate is fast. After adding vitamin _B12 , the reductive dechlorination rate is improved, and the sewage containing triclosan with a mass concentration of 1-20 mg per liter can have a good removal effect within 5-10 hours.

3. Low processing cost. Compared with other catalytic reduction metals such as Ag, Pd, Ni, Cu, Pt and Zn, vitamin _B12 exists in the natural environment and is easy to obtain, so the cost is low and it has a good application prospect.

4. Environmental friendly. In the present invention, the vitamin _B12 is used to strengthen the reductive dechlorination and removal of triclosan, so that the toxicity of dechlorination products is significantly reduced, which is beneficial to the resource utilization of sewage.

5. It is suitable for a wide range of targets. The invention is not only applicable to the sewage containing triclosan, but also applicable to the sewage containing chlorine organic matter.

Description of drawings

Fig. 1 is the pH value of sewage and the influence of reaction time on triclosan removal rate;

Figure 2 is the effect of the concentration of vitamin B ₁₂ and reaction time on the removal rate of triclosan.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The analysis and detection of triclosan adopts Agilent7890A-5975C VL MSD gas chromatography-mass spectrometry: the chromatographic column adopts HP-5MS (30 meters × 0.25 millimeters × 0.25 microns); the inlet temperature is 270 degrees Celsius; the initial temperature is 80 degrees Celsius, Hold for 3 minutes; rise to 300°C at a rate of 20°C per minute and hold for 7 minutes; the carrier gas is helium. The carrier gas flow rate is 1 ml per minute; the split ratio is 10:1, and the injection volume is 1 microliter. Mass spectrometry conditions: ionization mode EI, ionization energy 70 electron volts, ion source temperature 280 degrees Celsius. Transfer line temperature: 250 degrees Celsius, scan range: 41-450 atomic mass units, mass spectrometer standard library: NIST library.

Example 1

First, vitamin B ₁₂ is used to strengthen the reduction dechlorination method of triclosan in sewage, and the sewage containing 10 mg per liter of triclosan is treated.

Adjust the initial pH value of the sewage to 5, and at the same time add 50 mg of vitamin B ₁₂ per liter of sewage, 0.5 grams of nano-zero-valent iron per liter of sewage, and stir evenly, wherein the particle size of nano-zero-valent iron is 50 to 70 Nano.

Example 2

The difference from Example 1 is that the initial pH value of the sewage should be adjusted to 6.

Example 3

The difference from Example 1 is that the initial pH value of the sewage should be adjusted to 7.

Example 4

The difference from Example 1 is that the initial pH value of the sewage should be adjusted to 8.

Example 5

The difference from Example 1 is that the initial pH value of the sewage should be adjusted to 9.

In Examples 1 to 5, the removal rate of triclosan in sewage should be detected at different reaction times when each embodiment is carried out, and the results are shown in Figure 1 . As can be seen from Figure 1, within 5 hours of reaction, under five pH conditions, when the pH rose from 5 to 7, the removal rate of triclosan gradually decreased; but when the pH continued to increase, the reduction of triclosan Chlorine removal rate also increased gradually, and at pH=8 and 9, the reductive dechlorination removal rate of triclosan was not much different, and at pH=9, the removal rate was greater than 99%.

Example 6

First, vitamin B ₁₂ is used to strengthen the reduction dechlorination method of triclosan in sewage, and the sewage containing 10 mg per liter of triclosan is treated.

Adjust the initial pH value of sewage to be 8, add the vitamin B ₁₂ that concentration is 10 mg per liter in the sewage containing 10 mg per liter of triclosan, the addition of nanometer zero-valent iron is 0.5 gram per liter of sewage, stir evenly, wherein , the particle diameter of the nano zero-valent iron is 50-70 nanometers.

Example 7

The difference from Example 6 is that vitamin B ₁₂ is added to the sewage at a concentration of 30 mg per liter.

Example 8

The difference from Example 6 is that vitamin B ₁₂ with a concentration of 50 mg per liter is added to the sewage.

Example 9

The difference from Example 6 is that vitamin B ₁₂ with a concentration of 70 mg per liter is added to the sewage.

Example 10

The difference from Example 6 is that vitamin B ₁₂ is added to the sewage at a concentration of 100 mg per liter.

In Examples 6-10, the removal rate of triclosan in the sewage should be detected at different reaction times during the implementation of each example, and the results are shown in Figure 2. As can be seen from Figure 2, as the concentration of vitamin B ₁₂ increases from 10 mg per liter to 50 mg per liter, the reductive dechlorination removal rate of triclosan gradually increases, but when the dosage continues to increase to 100 mg per liter liters, the final reductive dechlorination removal rate did not change much.

Example 11

A method of using vitamin _B12 to strengthen the reduction dechlorination of triclosan in sewage, adjust the pH value of sewage to 5, and add nanometer zero-valent iron to the sewage whose mass concentration of triclosan is 1 mg per liter and vitamin B ₁₂ , the input amount of nanometer zero-valent iron is 0.1 gram per liter of sewage, and the input amount of vitamin B ₁₂ is 10 mg per liter of sewage. The reaction time is 5 hours, the reaction temperature is not limited, and the triclosan in the sewage is strengthened to reduce and dechlorinate. Wherein, the particle diameter of the nanometer zero-valent iron is 50-70 nanometers.

Example 12

A method of using vitamin _B12 to strengthen the reduction dechlorination of triclosan in sewage, adjust the pH value of sewage to 9, and add nanometer zero-valent iron to the sewage whose mass concentration of triclosan is 20 mg per liter and vitamin B ₁₂ , the input amount of nanometer zero-valent iron is 1 gram per liter of sewage, and the input amount of vitamin B ₁₂ is 100 mg per liter of sewage. The reaction time is 10 hours, the reaction temperature is not limited, and the triclosan in the sewage is strengthened to reduce and dechlorinate. Wherein, the particle diameter of the nanometer zero-valent iron is 50-70 nanometers.

Claims (6)

1. one kind utilizes vitamins B ₁₂the method strengthening reduction dechlorination is carried out to triclosan in sewage, it is characterized in that, to containing in the sewage of triclosan, add nano zero valence iron and vitamins B ₁₂, reaction times 5-10 hour, carries out strengthening reduction dechlorination to the triclosan in sewage.

2. one according to claim 1 utilizes vitamins B ₁₂carry out to triclosan in sewage the method strengthening reduction dechlorination, it is characterized in that, in described sewage, the mass concentration of triclosan is 1 ~ 20 milligrams per liter, and the input amount of described nano zero valence iron is for adding 0.1 ~ 1 gram, described vitamins B in often liter of sewage ₁₂input amount for adding 10 ~ 100 milligrams in often liter of sewage.

3. one according to claim 1 utilizes vitamins B ₁₂the method strengthening reduction dechlorination is carried out to triclosan in sewage, it is characterized in that, adding nano zero valence iron and vitamins B ₁₂before, the pH value regulating sewage is 5 ~ 9.

4. one according to claim 3 utilizes vitamins B ₁₂the method strengthening reduction dechlorination is carried out to triclosan in sewage, it is characterized in that, adding nano zero valence iron and vitamins B ₁₂before, the pH value regulating sewage is 8 ~ 9.

5. one according to claim 4 utilizes vitamins B ₁₂the method strengthening reduction dechlorination is carried out to triclosan in sewage, it is characterized in that, adding nano zero valence iron and vitamins B ₁₂before, the pH value regulating sewage is 9.

6. one according to claim 1 utilizes vitamins B ₁₂carry out to triclosan in sewage the method strengthening reduction dechlorination, it is characterized in that, the grain diameter of described nano zero valence iron is 50 ~ 70 nanometers.