A method for removing trichlorophenol from nitrate-containing wastewater by dechlorination
By using nitrate ions to generate free radicals in wastewater, reacting with methanol, efficient dechlorination of trichlorophenol is achieved, and the problems of unstable and costly removal of trichlorophenol in the prior art are solved, and efficient and economical dechlorination effect is achieved.
Patent Information
- Application Number
- CN202310459917.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-23
- Publication Date
- 2025-08-26
- Estimated Expiration
- 2043-04-23
AI Technical Summary
The prior art is difficult to efficiently and economically remove trichlorophenol from wastewater, and conventional biological treatment is unstable, advanced oxidation technology is costly and produces harmful by-products.
The nitrate ions in the wastewater generate free radicals under alkaline conditions, react with methanol to form reducing free radicals, and the dechlorination of trichlorophenol is achieved through medium-pressure ultraviolet lamp irradiation, and a simple reaction system and economical methanol are used as the reducing agent.
The efficient dechlorination rate of trichlorophenol is achieved up to 90%, reducing the treatment cost and avoiding the generation of harmful by-products.
Smart Images
Figure CN116425355B_ABST
Abstract
Description
(1) Technical field
[0001] The present invention relates to the fields of environmental engineering and wastewater treatment engineering, in particular to a method for treating NO3 - Treatment method for trichlorophenol in wastewater. (2) Background technology
[0002] Nitrate (NO3 - ) is one of the most common inorganic nitrogen in wastewater and the main component of total nitrogen in sewage treatment plant effluent.
[0003] Trichlorophenol is a major chemical widely used in industrial production, including dye production and pesticide manufacturing. It also occurs as a reaction byproduct in wastewater discharged from the coking industry. Certain concentrations of trichlorophenol have also been detected in natural water bodies. However, trichlorophenol has been shown to be harmful to humans, aquatic plants, and animals, exhibiting significant "three-hazard" effects. It is one of the 129 priority pollutants listed by the EPA.
[0004] Due to the toxicity of trichlorophenol to microorganisms, current conventional biological treatment technologies suffer from long processing times and low efficiency. Furthermore, they are significantly affected by water quality and the presence of toxic and hazardous substances in the water, resulting in unstable treatment results. Advanced oxidation technologies, while removing these substances, also produce more toxic metabolites. While electrochemical reduction technologies can effectively remove trichlorophenol, their electrode materials often contain precious metals, resulting in high costs. Furthermore, their low current efficiency also limits their application. (3) Summary of the invention
[0005] The present invention aims to provide a method for producing a - A method for removing trichlorophenol from wastewater by dechlorination, which utilizes NO3, the most common anion in wastewater. - , photolysis in water produces a variety of free radicals, and reacts with methanol to generate reducing free radicals, which breaks the carbon-chlorine bond in the trichlorophenol molecule and realizes the dechlorination of trichlorophenol. - The economical and efficient dechlorination of trichlorophenol in wastewater provides strong technical support for the treatment of related wastewater.
[0006] The technical solution adopted in the present invention is:
[0007] The present invention provides a method of producing a product containing NO3 - The invention discloses a method for dechlorinating and removing trichlorophenol in wastewater. The method is carried out according to the following steps: adding methanol to wastewater containing trichlorophenol and nitrate, adjusting the pH to 9-12, and irradiating the wastewater with a medium-pressure ultraviolet lamp under stirring to achieve dechlorination and removal of trichlorophenol.
[0008] Preferably, the wastewater is pretreated until light can penetrate, so that the suspended solid concentration in the wastewater is less than 10 mg / L, and the pretreatment method is one or more of biological treatment, coagulation, filtration, and sedimentation.
[0009] Preferably, trichlorophenol, NO3 - The molar concentration ratio of iodine to methanol is 1:20:10 to 1:20:80, preferably 1:20:60.
[0010] Preferably, the ultraviolet lamp is irradiated at 450W for 20-40 minutes, preferably 20 minutes.
[0011] Trichlorophenol is an important type of halogenated organic compound that is toxic to organisms. Biological treatment methods are ineffective and unstable. Advanced oxidation methods produce more harmful chlorinated oxidation byproducts. The most common anion in wastewater is NO3 - , under alkaline conditions, it will photolyze in water to produce NO·, ·NO2, O2· - These free radicals will further generate reducing free radicals with methanol. The reducing free radicals can attack the carbon-chlorine bond in the trichlorophenol molecule to break it, thereby achieving efficient dechlorination of trichlorophenol and improving the dechlorination effect of trichlorophenol.
[0012] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:
[0013] The method for treating trichlorophenol of the present invention only requires adding relatively economical methanol to trichlorophenol wastewater containing nitrate and applying ultraviolet irradiation, and the reaction system is simple and easy to operate. Different from the advanced oxidation deep treatment technology which requires adjusting the pH to a strong acid, which increases the cost significantly for the weakly alkaline biological treatment effluent with a pH usually greater than 7, the system has a good dechlorination effect under weakly alkaline and alkaline conditions, thereby reducing the cost. The present invention utilizes NO3 widely present in sewage to treat trichlorophenol wastewater. - As one of the system components, it saves reagent costs and does not produce toxic and harmful byproducts. The present invention can be applied to the deep treatment of trichlorophenol in wastewater containing nitrate, with a dechlorination rate of up to 90%. (IV) Description of the accompanying drawings
[0014] Figure 1 The figure is a bar graph showing the dechlorination rate of trichlorophenol under different raw material ratios in Example 1.
[0015] Figure 2 The figure is a bar graph showing the dechlorination rate of trichlorophenol at different pH values in Example 2.
[0016] Figure 3In Example 1, the pH was 10, the molar concentration ratio of trichlorophenol to nitrate and methanol was 1:20:60, and the reaction was carried out for 20 minutes. The ion chromatograms of the samples before (a) and after (b) the reaction were as follows: the peak at 5.2 min was Cl - peak. (V) Specific implementation methods
[0017] The present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto:
[0018] The suspended solids concentration in the wastewater used in the embodiment of the present invention is less than 10 mg / L.
[0019] Example 1
[0020] To wastewater containing nitrate concentration of 2mmol / L and 2,4,6-trichlorophenol concentration of 0.1mmol / L, different amounts of methanol were added so that the molar concentration ratio of trichlorophenol to nitrate and methanol was 1:20:0 (i.e. no methanol was added), 1:20:20, 1:20:40, 1:20:60, respectively. The pH was adjusted to 10, and the reaction was carried out under 450W ultraviolet light for 20 minutes. Samples were taken, and the chloride ion content of the system was detected by ion chromatography, and the dechlorination rate of trichlorophenol was calculated. The results are shown in Figure 2. Figure 1 The results show that when the molar concentration ratio of 2,4,6-trichlorophenol to nitrate and methanol in the system is 1:20:60, the dechlorination rate of 2,4,6-trichlorophenol within 20 minutes is increased by about 20% compared with other conditions, reaching more than 90%. The ion chromatogram when the molar concentration ratio of trichlorophenol to nitrate and methanol is 1:20:60 is shown in Figure 2. Figure 3 shown.
[0021] Ion chromatography detection conditions for chloride ions: Qingdao Puren PIC-80 ion chromatograph, 20 mM KOH eluent, flow rate 1 ml / min, analytical column AS19 (4×250 nm), guard column AG19 (4×50 nm), injection volume 100 μl.
[0022] Example 2
[0023] The pH in Example 1 was changed to 3, 7 and 10, the molar concentration ratio of trichlorophenol to nitrate and methanol was 1:20:60, and other conditions and operations were the same. The results are shown in FIG. Figure 2 The results showed that under the condition of pH 10, the dechlorination rate of 2,4,6-trichlorophenol in the system was nearly 1 times higher than that under neutral and acidic conditions.
Claims
1. A kind of NO3 - The method for removing trichlorophenol from wastewater by dechlorination is characterized by: The method is carried out as follows: adding methanol to wastewater containing trichlorophenol and nitrate, adjusting the pH to 9-12, irradiating with a medium-pressure ultraviolet lamp under stirring, and achieving dechlorination and removal of trichlorophenol; trichlorophenol, NO3 - The molar concentration ratio of methanol is 1:20:10~1:20:
80.
2. The method of claim 1 containing NO3 - The method for removing trichlorophenol from wastewater by dechlorination is characterized by: The suspended solid concentration in the wastewater is less than 10 mg / L.
3. The method of claim 1 containing NO3 - The method for removing trichlorophenol from wastewater by dechlorination is characterized by: The trichlorophenol, NO3 - The molar concentration ratio of methanol is 1:20:
60.
4. The method of claim 1 containing NO3 - The method for removing trichlorophenol from wastewater by dechlorination is characterized by: The ultraviolet lamp is irradiated at 450W for 20-40min.