CN105668758A - Method for degrading organic wastewater by activating persulfates with in-situ sulfur-doped activated carbon - Google Patents

Abstract

The invention relates to a method for degrading organic wastewater by activating persulfates with in-situ sulfur-doped activated carbon. The method comprises the following steps: adding persulfates into an organic wastewater solution at normal temperature (the mole ratio of the persulfates to the organic pollutants is (1-50):1), regulating the pH value of the organic wastewater solution to 2-12 with 0.1 mol/L H2SO4 or 0.1 mol/L NaOH, adding in-situ sulfur-doped activated carbon, treating the wastewater solution for 1-3 hours, and carrying out solid-liquid separation, wherein the ratio of the in-situ sulfur-doped activated carbon to the organic wastewater solution is (0.1-0.3)g:1L. The method has the advantages of high organic pollutant removal efficiency and no secondary pollution.

Description

A method for in-situ sulfur-doped activated carbon to activate persulfate to degrade organic wastewater

technical field

The invention belongs to a treatment method for degrading organic wastewater, in particular to a method for in-situ sulfur-doped activated carbon activating persulfate to degrade organic wastewater.

Background technique

In recent years, hydroxyl radical advanced oxidation technology has been widely used in the treatment of refractory organic wastewater due to its strong oxidation, low selectivity and high degradation efficiency. Due to its advantages of simple operation and strong oxidation, Fenotn (H ₂ O ₂ /Fe ²⁺ ) reagent oxidation technology has become the most widely used advanced oxidation technology. However, this technology has problems such as narrow applicable pH range, unstable H ₂ O ₂ (oxidant), and easy generation of sludge. However, persulfate with high stability and good water solubility has an O–O bond similar to H ₂ O ₂ , and can be activated to produce free sulfate radicals with a high redox potential (2.5-3.1V) and a wide pH range. base, so as to efficiently remove refractory organic pollutants. Therefore, in recent years, the persulfate advanced oxidation technology based on sulfate radicals has been widely used in the field of wastewater.

Persulfates include persulfate and persulfate, which can generate strong oxidizing sulfate radicals through thermal activation, photoactivation and transition metal ion activation (Critical Reviews in Environmental Science and Technology, 45:1756–1800, 2015) However, these methods have problems such as high energy consumption, harsh operating conditions, complex systems, and secondary pollution, which limit the application of persulfate advanced oxidation technology in wastewater treatment.

The above disadvantages can be overcome if a non-metallic heterogeneous catalyst is used to activate the persulfate. Activated carbon has been widely used in the field of heterogeneous catalysis due to its advantages such as large specific surface area, developed pore structure, high thermal stability and low production cost. In order to broaden its scope of use, many scholars have modified the surface of carbon materials by doping heteroatoms on the surface and regulating the pore structure to improve their physical and chemical properties and catalytic activity (RSCAdv., 2014, 4, 63110–63117; AppliedCatalysisB:Environmental106 (2011) 390–397). Although surface-doped heteroatom activated carbon has the advantages of strong catalytic ability and high activity, the heteroatom functional groups formed by this modification method are not uniformly embedded in the carbon skeleton, but bonded to its surface, so it will be damaged during use. Dissolution problems occur, and even the pore structure will be distorted and the pores will be blocked, resulting in a decrease in surface area and activity. If the precursor organics containing heteroatoms are directly carbonized, the above disadvantages can be overcome.

In order to solve the above problems, the present invention proposes a new method of using in-situ sulfur-doped activated carbon to activate persulfate to treat refractory organic wastewater.

At present, there is no invention related to the application of in-situ sulfur-doped activated carbon to activate persulfate to degrade organic wastewater.

Invention content:

In order to solve the problems existing in the prior art, the object of the present invention is to provide a method for degrading organic wastewater by activating persulfate in situ with sulfur-doped activated carbon with high organic pollutant removal efficiency and no secondary pollution.

In order to achieve the above-mentioned technical purpose, the method for the in-situ sulfur-doped activated carbon of the present invention to activate persulfate to degrade organic waste water comprises the following steps:

Under normal temperature conditions, add persulfate to the organic wastewater solution so that the ratio of persulfate to organic pollutants is 1-50:1, and adjust the organic waste with 0.1mol/LH ₂ SO ₄ or 0.1mol/LNaOH The pH value of the wastewater solution is 2-12, and then add in-situ sulfur-doped activated carbon to it, treat the wastewater solution for 1h-3h, and then perform solid-liquid separation; among them, in-situ sulfur-doped activated carbon: organic wastewater solution=0.1-0.3g : 1L.

The persulfates mentioned above are peroxomonosulfates or peroxodisulfates.

The above-mentioned in-situ sulfur-doped activated carbon is prepared by roasting and carbonizing the sulfur-containing precursor and adding a chemical activator to activate it during the process. The preparation process steps are:

Dissolve a certain amount of 2-thiophene methanol in acetonitrile, slowly add a certain amount _of FeCl3 into the acetonitrile solution, stir rapidly at room temperature for 15 hours, filter and wash the polythiophene precipitate several times with distilled water and acetone in turn until the filtrate is Colorless, it was dried at 105°C to obtain dry polythiophene. Mix the prepared polythiophene with KOH at a mass ratio of 1:2, and carbonize it at 600-800°C for 1h under nitrogen atmosphere. The carbonized sample was washed with 10% HCl to remove residual inorganic substances, and then washed several times with distilled water until the supernatant was neutral, and then dried at 110°C for 24 hours to obtain in-situ sulfur-doped activated carbon. For the specific preparation method, see the literature (Microporous and Mesoporous Materials 158 (2012) 318-323).

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

1. The in-situ sulfur-doped activated carbon in the present invention contains not only carbonyl, quinone and other oxygen-containing functional groups, but also a large number of thiophene sulfur and sulfone functional groups. These groups, as Lewis base active sites, can efficiently and continuously activate persulfate to generate active freedom oxidative degradation of organic pollutants in wastewater.

2. Compared with other catalysts, the method of the present invention not only improves the catalytic efficiency of the catalyst and the removal efficiency of organic pollutants, but also avoids the problem of secondary pollution caused by the stripping of active components of the catalyst.

Description of drawings:

Fig. 1 is the change figure of embodiment 1 to the removal rate of refractory organic matter;

Fig. 2 is the change graph of the removal rate of the refractory organic matter in Example 2.

detailed description:

The present invention proposes a kind of method that in-situ sulfur-doped activated carbon activates persulfate to degrade organic waste water, specifically: under normal temperature condition, add persulfate in waste water solution, make the amount of persulfate and organic pollutant substance The ratio is 1:1-50:1, use 0.1mol/LH ₂ SO ₄ or 0.1mol/LNaOH to adjust the pH value of the organic wastewater solution to 2-12, and then add raw material with a concentration of 0.1-0.3g/L Sulfur-doped activated carbon is used as a catalyst to treat water samples for 1h-3h, followed by solid-liquid separation.

A typical method for preparing in-situ sulfur-doped activated carbon is:

Dissolve 3g of 2-thiophene methanol in 20ml of acetonitrile solvent, slowly add it into 100ml of acetonitrile solution dissolved with 28.9g of FeCl ₃ , stir rapidly at room temperature for 15h, filter and wash the polythiophene precipitate several times with distilled water and acetone to the filtrate It is colorless, and it is dried at 105° C. to obtain dry polythiophene. Take three parts of dry polythiophene, mix them with KOH at a mass ratio of 1:2, and use a quartz tube to roast the mixture under a nitrogen atmosphere. The temperature is raised from room temperature to 600 °C at a rate of 3 °C/min. 700 ℃, 800 ℃, and keep the temperature and continue calcination for 1 hour, you can get in-situ sulfur-doped activated carbon calcined at different temperatures, which are respectively ACS600, ACS700, and ACS800.

The present invention will be described in detail below through specific examples.

In the embodiment of the present invention, phenol-containing wastewater is used as a typical refractory organic wastewater. Phenolic wastewater is difficult to biodegrade, which not only seriously damages aquatic ecosystems, but also seriously threatens human health. Therefore, phenolic substances are selected as target pollutants in the examples.

Example 1:

Take 200mL of untreated water samples containing coal chemical wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add potassium persulfate in this aqueous solution, make potassium persulfate and p-chlorophenol mol ratio be 24:1, then add in-situ sulfur-doped activated carbon (ACS800) 0.1g/L (wherein, the roasting temperature of ACS is 800°C), the water sample was treated for 130 minutes, and compared with the single persulfate oxidation method, the removal rate increased from 2.82% to 100%.

Figure 1 is a diagram of the removal effect of p-chlorophenol refractory organic matter in coal chemical wastewater in this example. In the figure –○ – indicates the removal rate curve of organic wastewater degraded by persulfate oxidation alone, –△ – indicates ACS800 activated persulfuric acid The removal rate curve of salt-catalyzed oxidation degradation of organic wastewater.

Example 2:

Take 200mL of untreated water samples containing coal chemical wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add potassium persulfate in this aqueous solution, make potassium persulfate and p-chlorophenol mol ratio be 24:1, then add in-situ sulfur-doped activated carbon (ACS700) 0.1g/L (wherein, the roasting temperature of ACS is 700°C), the water sample was treated for 170 minutes, and compared with the single persulfate oxidation method, the removal rate increased from 2.82% to 83.8%.

Figure 2 is a graph of the removal effect of p-chlorophenol refractory organic matter in coal chemical wastewater in this example. In the figure – ○ – indicates the removal rate curve of organic wastewater degraded by persulfate oxidation alone, – △ – indicates the activation of persulfuric acid by ACS700 The removal rate curve of salt-catalyzed oxidation degradation of organic wastewater.

Example 3:

Take 200mL of untreated water samples containing coal chemical wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add potassium persulfate in this aqueous solution, make potassium persulfate and p-chlorophenol mol ratio be 24:1, then add in-situ sulfur-doped activated carbon (ACS600) 0.1g/L (wherein, the roasting temperature of ACS is 600°C), the water sample was treated for 170 minutes, and compared with the single persulfate oxidation method, the removal rate increased from 2.82% to 52.3%.

Example 4:

Take 200mL of the untreated water sample containing pharmaceutical wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add a certain amount of potassium persulfate to the aqueous solution, so that the molar ratio of potassium persulfate to p-chlorophenol is 24:1, and then add ACS8000.15g/L to it, treat the water sample for 60min, and separate Compared with the oxidation method, the removal rate increased from 2.82% to 100%.

Example 5:

Take 200mL of the untreated water sample containing pharmaceutical wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add a certain amount of potassium persulfate to the aqueous solution, so that the molar ratio of potassium persulfate to p-chlorophenol is 3:1, and then add ACS8000.1g/L to it, and treat the water sample for 170min. Compared with the oxidation method, the removal rate increased from 0.8% to 89%.

Embodiment 6:

Take 200mL of the untreated water sample containing pharmaceutical wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add a certain amount of potassium persulfate to the aqueous solution, so that the molar ratio of potassium persulfate to p-chlorophenol is 50:1, and then add ACS8000.1g/L to it, and treat the water sample for 125min. Compared with the oxidation method, the removal rate increased from 3.1% to 100%.

Embodiment 7:

Take 200mL of the untreated water sample containing petroleum wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add a certain amount of potassium persulfate to the aqueous solution so that the molar ratio of potassium persulfate to p-chlorophenol is 24: ₁ , adjust the pH value of the wastewater solution to 2.4 with 0.1mol/ _LH2SO4 , and then add ACS8000.1g/L, treatment of water samples for 170min, compared with the single persulfate oxidation method, the removal rate increased from 2.3% to 93.8%.

Embodiment 8:

Take 200mL of the untreated water sample containing petroleum wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add a certain amount of potassium persulfate to the aqueous solution so that the molar ratio of potassium persulfate to p-chlorophenol is 24:1, adjust the pH value of the wastewater solution to 6.2 with 0.1mol/L NaOH, and then add ACS8000.1g to it /L, the water sample was treated for 170 minutes, compared with the single persulfate oxidation method, the removal rate increased from 2.1% to 98.4%.

Embodiment 9:

Take 200mL of the untreated water sample containing petroleum wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80ppm. Add a certain amount of potassium persulfate to the aqueous solution, so that the molar ratio of potassium persulfate to p-chlorophenol is 24:1, adjust the pH value of the wastewater solution to 8.4 with 0.1mol/L NaOH, and then add ACS8000.1g to it /L, the water sample was treated for 170min, compared with the single persulfate oxidation method, the removal rate increased from 2.72% to 95%.

Example 10: Take 200 mL of untreated water sample containing pulp wastewater, in which the refractory organic matter is p-chlorophenol with a concentration of 80 ppm. Add a certain amount of potassium persulfate to the aqueous solution, so that the molar ratio of potassium persulfate to p-chlorophenol is 24:1, adjust the pH value of the wastewater solution to 10.7 with 0.1mol/L NaOH, and then add ACS8000.1g to it /L, the water sample was treated for 170min, compared with the single persulfate oxidation method, the removal rate increased from 3.08% to 82.6%.

Example 11:

Take 200mL of untreated water sample containing dye wastewater, in which the refractory organic matter is phenol with a concentration of 80ppm. Add a certain amount of potassium persulfate to the aqueous solution, so that the molar ratio of potassium persulfate to phenol is 24:1, then add ACS8000.1g/L to it, treat the water sample for 150min, and compare with the single persulfate oxidation method Ratio, the removal rate increased from 2.82% to 92.2%.

Claims (3)

1. a method for in-situ sulfur-doped activated carbon activated persulfate degradation organic waste water is characterized in that comprising the steps: Under normal temperature conditions, add persulfate to the organic wastewater solution so that the ratio of persulfate to organic pollutants is 1-50:1, and adjust the organic waste with 0.1mol/LH ₂ SO ₄ or 0.1mol/LNaOH The pH value of the wastewater solution is 2-12, and then add in-situ sulfur-doped activated carbon to it, treat the wastewater solution for 1h-3h, and then perform solid-liquid separation; among them, in-situ sulfur-doped activated carbon: organic wastewater solution=0.1-0.3g : 1L. 2. The method for in-situ sulfur-doped activated carbon activated persulfate to degrade organic wastewater according to claim 1, characterized in that said persulfate is peroxomonosulfate or peroxodisulfate. 3. the method for a kind of in-situ sulfur-doped activated carbon activated persulfate degradation organic waste water as claimed in claim 1, is characterized in that comprising the steps: Dissolve a certain amount of 2-thiophene methanol in acetonitrile, slowly add a certain amount _of FeCl3 into the acetonitrile solution, stir rapidly at room temperature for 15 hours, filter and wash the polythiophene precipitate several times with distilled water and acetone in turn until the filtrate is It is colorless, dried at 105°C to obtain dry polythiophene; mix the prepared polythiophene with KOH at a mass ratio of 1:2, carbonize it at 600-800°C for 1h under nitrogen atmosphere, and use 10 % HCl to remove residual inorganic substances, and then washed several times with distilled water until the supernatant was neutral, and then dried at 110°C for 24 hours to obtain in-situ sulfur-doped activated carbon.