A method of adsorption coupling advanced oxidation technology for dye degradation

Abstract

The application discloses a method for dye degradation by using adsorption coupling advanced oxidation technology, wherein a metal-doped polyaniline adsorbent is used for enrichment and separation of dye molecules in dye wastewater, the adsorbent with the dye molecules is placed in a small volume of water to prepare a suspension solution, and then a certain amount of oxidant is added to carry out heterogeneous Fenton reaction, so that the dye molecules on the surface of the adsorbent are degraded and mineralized. The metal ions doped in the polyaniline are used as catalytic active sites, and can catalyze hydrogen peroxide, persulfate and other oxidants to produce strong oxidizing active radicals, such as hydroxyl radicals and sulfate radicals, so as to oxidize and degrade the dye molecules adsorbed by the polyaniline. The method can effectively avoid the treatment of desorption liquid after a traditional polyaniline adsorption process and the regeneration process of the adsorbent, and has great application prospect and value.

Description

TECHNICAL FIELD

[0001] The present invention belongs to the field of environmental pollution control and water treatment, and relates to a method for dye degradation by adsorption coupled with advanced oxidation technology. BACKGROUND

[0002] Water pollution is a major problem facing the ecological environment today. Among them, dye wastewater is one of the polluted water bodies that need to be solved at present due to its complex composition, high organic matter concentration, poor biodegradability, etc. Adsorption method has important application value in the treatment of dye wastewater due to its simple operation and low energy consumption. Polyaniline material, as a common adsorbent, has been used for the treatment of anionic dye wastewater [CN103861571B]. However, the polyaniline adsorption method for treating dye wastewater not only needs the process of alkali elution, acid washing regeneration to realize the recycling of adsorbent, but also cannot realize the complete removal of dye pollutants. SUMMARY

[0003] In view of the deficiencies of the prior art, the present invention aims to provide a method for dye degradation by adsorption coupled with advanced oxidation technology, which can not only remove and degrade dye molecules, but also simplify the regeneration process of the adsorbent.

[0004] The present invention is achieved by the following technical solutions:

[0005] A method for dye degradation by adsorption coupled with advanced oxidation technology uses metal-doped polyaniline as an adsorbent to enrich and separate dye molecules in wastewater, and then combines advanced oxidation technology to generate strong oxidative active free radicals around the dye molecules, realizing the degradation and mineralization of the dye molecules.

[0006] Further, the adsorption coupled with advanced oxidation technology is mainly realized by the metal-doped polyaniline adsorbent.

[0007] Further, the method comprises the following steps:

[0008] 1) uniformly dispersing the metal-doped polyaniline adsorbent in the dye wastewater, and adsorbing for a certain period of time;

[0009] 2) separating the adsorbent with adsorbed dye molecules from the wastewater;

[0010] 3) placing the adsorbent in water to prepare a suspension solution;

[0011] 4) adding a certain amount of oxidizing agent to the suspension solution, and reacting for a certain period of time to degrade and mineralize the dye molecules;

[0012] 5) solid-liquid separating the suspension solution, and the metal-doped polyaniline continues to be used for the enrichment and separation of dye molecules.

[0013] Further, the mass ratio of the metal-doped polyaniline adsorbent to the wastewater in step 1) is 1:(100-1000), and the dispersion mode includes but is not limited to ultrasonic, stirring and oscillation, and the adsorption time is 1-300 min.

[0014] Further, the mass ratio of the solid to the liquid in the suspension solution in step 3) is 1:(5-50).

[0015] Further, the oxidant used in step 4) is one or more of hydrogen peroxide, peroxymonosulfate and peroxysulfate, and the reaction time is 10-1440 min.

[0016] Further, the oxidant is added in a concentration of (0.01-10) mol·L -1 , and the adding mode includes but is not limited to one-time, batch or dropwise addition in the form of liquid or solid.

[0017] Further, the metal-doped polyaniline adsorbent is a transition metal Fe, Co or Cu-doped polyaniline adsorbent.

[0018] Compared with the existing polyaniline adsorption method for removing dye pollutants, the present application has the following beneficial technical effects:

[0019] 1. The present application can realize in-situ degradation of dye molecules on the surface of the adsorbent by coupling adsorption with advanced oxidation technology, and at the same time, release the adsorption sites. At present, the polyaniline adsorption process needs to first desorb the adsorbed dye molecules, and then treat the desorption liquid. Compared with this, the present application does not need the desorption process flow, and no high-concentration desorption liquid is generated, showing great application prospect and value.

[0020] 2. The present application uses the metal ions doped in polyaniline as catalytic active sites, can catalyze hydrogen peroxide, persulfate and other oxidants on the surface of polyaniline to produce strong oxidizing active radicals such as hydroxyl radicals and sulfate radicals, and oxidize and degrade the dye molecules adsorbed thereby, to realize the removal of pollutants and the regeneration of adsorption sites. Combining the three processes of desorption, regeneration and treatment of desorption liquid into one process, it is more convenient to operate in practical application.

[0021] 3. The present application uses advanced oxidation technology without adding additional catalysts, mainly uses the heterogeneous Fenton and Fenton-like reaction activity of the transition metal ions doped in polyaniline to realize the generation of strong oxidizing active radicals. And since the dye molecules are enriched on the surface of the adsorbent, the concentration of the oxidant can be kept at a high level by controlling the size of the reaction system, which not only increases the concentration of the active radicals, but also shortens the migration distance, thereby improving the reaction efficiency. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0023] This invention combines adsorption with advanced oxidation technology to achieve the degradation of dye molecules in wastewater.

[0024] First, a metal-doped polyaniline adsorbent is added to the wastewater to adsorb and enrich dye molecules. Then, the adsorbent containing the dye is dispersed in a small volume of purified water, and an oxidant is added to catalyze a reaction with the doped metal ions, generating highly reactive free radicals. This achieves in-situ degradation of the adsorbed pollutants and release from the adsorption sites. Taking iron-doped polyaniline adsorbent as an example, the main reaction equations are as follows:

[0025] (1) ≡Fe 2+ + H2O2→ ≡Fe 3+ + OH + OH

[0026] (2) ≡Fe 3+ + H2O2→ ≡Fe 2+ + HO2+ H +

[0027] (3) OH + ≡Organic → CO2+ H2O + ≡

[0028] Where ≡Organic represents the adsorbed pollutant, and ≡ represents the adsorption site or doping site.

[0029] Compared with the traditional polyaniline adsorption method, the dye degradation method in this invention can achieve efficient removal of dye molecules from wastewater. However, this invention can further degrade and mineralize the adsorbed dye molecules, while the traditional polyaniline adsorption method produces a high concentration of dye desorption solution, which requires further treatment.

[0030] The metal-doped polyaniline adsorbent of this invention is prepared by first alkalizing polyaniline, then impregnating it in a metal salt solution for metal doping modification, followed by washing, drying, and grinding to obtain the metal-doped polyaniline adsorbent. The metal salt solution can be ferric, ferrous, cobalt, or copper salts, with an ion concentration of 1.0 × 10⁻⁶. -6 ~ 1.0×10 1 mol·L -1 The impregnation methods include, but are not limited to, standing, ultrasonic dispersion, stirring, and oscillation, and the impregnation time is 0.01 to 24 hours.

[0031] Example 1

[0032] 1) Add 0.2 g of polyaniline powder to pure water, adjust and maintain the pH value to approximately 10, and then magnetically stir for 0.5 h. After stirring, separate the polyaniline solid and wash with deionized water until the washing solution is neutral. Further transfer the polyaniline to 20 mL of 0.1 mol·L⁻¹ water. -1 The polyaniline sample was magnetically stirred in a ferrous sulfate solution at room temperature for 1 h. Then, the polyaniline sample was separated, washed thoroughly with pure water, dried in a 60°C oven, and ground to obtain ferrous-doped polyaniline adsorbent powder.

[0033] 2) Weigh 0.1 g of the above adsorbent powder and add it to 100 mL to achieve an initial concentration of 20 mg. L -1 The acid red G dye solution was magnetically stirred for 90 min, and the dye removal rate in the solution was measured to be over 95%.

[0034] 3) Separate the adsorbent from the above solution, transfer it to 10 mL of pure water, and add 10 mmol of [agent name missing]. L -1 After adding hydrogen peroxide and magnetically stirring for 2 hours, the mixture was separated and washed to obtain an adsorbent with degraded dye molecules. Repeating step 2 with this adsorbent resulted in a dye removal rate of over 95%.

[0035] 4) Repeat step 2) to obtain an adsorbent that adsorbs Acid Red G. After washing with pure water, do not perform any other treatment and continue to repeat step 2) until the dye removal rate decreases to 75%.

[0036] Example 2

[0037] 1) Add 0.2 g of polyaniline powder to pure water, adjust and maintain the pH value to approximately 10, and then magnetically stir for 0.5 h. After stirring, separate the polyaniline solid and wash with deionized water until the washing solution is neutral. Further transfer the polyaniline to 20 mL of 0.1 mol·L⁻¹ water. -1 The polyaniline sample was magnetically stirred in a ferrous sulfate solution at room temperature for 1 h. Then, the polyaniline sample was separated, washed thoroughly with pure water, dried in a 60°C oven, and ground to obtain ferrous-doped polyaniline adsorbent powder.

[0038] 2) Weigh 0.1 g of the above adsorbent powder and add it to 100 mL to achieve an initial concentration of 20 mg. L -1 In an Acid Red G dye solution, after adjusting the pH to 4, the solution was magnetically stirred for 90 min, and the dye removal rate was measured to be over 95%.

[0039] 3) Separate the adsorbent from the above solution, transfer it to 10 mL of pure water, adjust its pH to 4, and then add 10 mmol of [a solution / concentrate]. L -1 After adding hydrogen peroxide and magnetically stirring for 90 minutes, the mixture was separated and washed to obtain an adsorbent with degraded dye molecules. Step 2) was repeated using this adsorbent, and after four cycles, the dye removal rate reached over 95%.

[0040] 4) Repeat step 2) to obtain an adsorbent that adsorbs Acid Red G. After washing with pure water, do not perform any other treatment and continue to repeat step 2). After repeating the cycle 4 times, the dye removal rate drops to 33%.

[0041] Example 3

[0042] 1) Add 0.2 g of polyaniline powder to pure water, adjust and maintain the pH value to approximately 10, and then magnetically stir for 0.5 h. After stirring, separate the polyaniline solid and wash with deionized water until the washing solution is neutral. Further transfer the polyaniline to 20 mL of 0.1 mol·L⁻¹ water. -1 The polyaniline sample was magnetically stirred in a cobalt sulfate solution at room temperature for 1 h. Then, the polyaniline sample was separated and thoroughly washed with pure water, dried in a 60°C oven, and ground to obtain cobalt-doped polyaniline adsorbent powder.

[0043] 2) Weigh 0.1 g of the above adsorbent powder and add it to 100 mL to achieve an initial concentration of 20 mg. L -1 The acid red G dye solution was magnetically stirred for 90 min, and the dye removal rate in the solution was measured to be over 95%.

[0044] 3) Separate the adsorbent from the above solution, then transfer it to 10 mL of pure water, and add 10 mmol of [agent name missing]. L -1 After being treated with potassium persulfate (KHSO5) and magnetically stirred for 2 hours, the adsorbent was separated and washed to obtain the adsorbent after the dye molecules were degraded. Repeating step 2 with this adsorbent still resulted in a dye removal rate of over 95%.

[0045] 4) Repeat step 2) to obtain an adsorbent that adsorbs Acid Red G. After washing with pure water, do not perform any other treatment and continue to repeat step 2) until the dye removal rate decreases to 75%.

[0046] Example 4

[0047] 1) Add 0.2 g of polyaniline powder to pure water, adjust and maintain the pH value to approximately 10, and then magnetically stir for 0.5 h. After stirring, separate the polyaniline solid and wash with deionized water until the washing solution is neutral. Further transfer the polyaniline to 20 mL of 0.1 mol·L⁻¹ water. -1 The polyaniline sample was magnetically stirred in a copper sulfate solution at room temperature for 1 h. Then, the polyaniline sample was separated and thoroughly washed with pure water, dried in a 60°C oven, and ground to obtain cobalt-doped polyaniline adsorbent powder.

[0048] 2) Weigh 0.1 g of the above adsorbent powder and add it to 100 mL to achieve an initial concentration of 20 mg. L -1 The acid red G dye solution was magnetically stirred for 90 min, and the dye removal rate in the solution was measured to be over 95%.

[0049] 3) Separate the adsorbent from the above solution, then transfer it to 10 mL of pure water, and add 10 mmol of [agent name missing]. L -1 After adding hydrogen peroxide and magnetically stirring for 2 hours, the mixture was separated and washed to obtain an adsorbent with degraded dye molecules. Repeating step 2 with this adsorbent still resulted in a dye removal rate of over 95%.

[0050] 4) Repeat step 2) to obtain an adsorbent that adsorbs Acid Red G. After washing with pure water, do not perform any other treatment and continue to repeat step 2) until the dye removal rate decreases to 75%.

Claims

1. A method for dye degradation using adsorption coupled with advanced oxidation technology, characterized in that: Using metal-doped polyaniline as an adsorbent, dye molecules in wastewater are enriched and separated. Then, advanced oxidation technology is combined to generate highly oxidizing free radicals around the dye molecules through the metal-doped polyaniline adsorbent, thereby achieving the degradation and mineralization of the dye molecules. Metal-doped polyaniline adsorbents are polyaniline adsorbents doped with transition metals Fe, Co, or Cu; The metal-doped polyaniline adsorbent is prepared by first alkalizing polyaniline, then impregnating it in a metal salt solution for metal doping modification, and finally washing, drying, and grinding to obtain the metal-doped polyaniline adsorbent. Includes the following steps: 1) The metal-doped polyaniline adsorbent is uniformly dispersed in the dye wastewater and adsorbed for a certain period of time; the mass ratio of the metal-doped polyaniline adsorbent to the wastewater is 1:(100-1000), the dispersion method is one of ultrasound, stirring and oscillation, and the adsorption time is 1-300 min; 2) Separate the adsorbent containing dye molecules from the wastewater; 3) Prepare a suspension solution by placing the above adsorbent in water; 4) Add a certain amount of oxidant to the above suspension and react for a certain period of time to degrade and mineralize the dye molecules; the oxidant is one or more of hydrogen peroxide, persulfate and perdisulfate, and the reaction time is 10 to 1440 min. 5) The above suspension solution is separated into solid and liquid components, and the metal-doped polyaniline is used for the enrichment and separation of dye molecules.

2. The method for dye degradation using adsorption-coupled advanced oxidation technology according to claim 1, characterized in that: In step 3), the solid-liquid mass ratio in the suspension solution is 1:(5-50).

3. The method for dye degradation using adsorption-coupled advanced oxidation technology according to claim 1, characterized in that: In step 4), the concentration of the oxidant added is (0.01–10) mol·L⁻¹. -1 The addition method can be one of adding liquid or solid form in a single batch, in batches, or dropwise.

4. The application of the adsorption-coupled advanced oxidation technology of claim 1 for dye degradation in the purification of anionic dye wastewater.