CN103803695A - Method of Fenton-like photocatalytic reaction system coupled with zero-valent iron and TiO2 photocatalysis - Google Patents

Abstract

The invention provides a method of a Fenton-like photocatalytic reaction system coupled with zero-valent iron and _TiO photocatalytically, the method steps: preparing 1L of simulated dye wastewater with a concentration of 10mg/L-100mg/L and placing it in a glass container, Add 0.1g-2g Fe ⁰ to the simulated dye wastewater, adjust the pH of the simulated dye wastewater to 3 with HCl solution with a concentration of 1mol/L, and then add 1g/L TiO ₂ catalyst to the dye wastewater , turn on the ultraviolet lamp of λ=254nm, place the glass container containing the simulated dye wastewater under the ultraviolet lamp, turn on the aeration pump, and use the aeration mode at the bottom of the glass container to drive the HCl solution and the _TiO catalyst in the mixed reaction system With the simulated dye wastewater, after the reaction, turn off the UV lamp and the aeration pump, add 2-10ml of NaOH solution with a concentration of 1mol/L to the reaction system, and let it settle for 30-60min. The effect of the invention is that it can reduce the chroma and turbidity in the reaction system by 35%-50%, and the effluent water quality can meet the requirements of the first grade A standard (GB18918-2002).

Description

Method of Fenton-like photocatalytic reaction system coupled with zero-valent iron and TiO2 photocatalysis

technical field

The invention relates to an inorganic functional material and a photocatalytic wastewater treatment technology, in particular to a method of a Fenton-like photocatalytic reaction system in which zero-valent iron and _TiO2 are photocatalytically coupled.

Background technique

With the rapid development of the world economy and the rise of industry, the society's demand for water is increasing day by day, and the fresh water resources available on the earth are becoming less and less. Many countries are facing the crisis of water shortage. In recent years, water pollution has also become more and more serious. According to the environmental monitoring report in 1998, among the 176 urban river sections in the country, most of the river sections were polluted to varying degrees. And in the statistical analysis of groundwater quality monitoring data in 120 cities across the country, the groundwater in these cities is also polluted to varying degrees. Therefore, many new high-efficiency and energy-saving water treatment processes have emerged in recent years, such as photocatalysis, microwave digestion, and membrane extraction. Among many new water treatment technologies, TiO ₂ photocatalysis technology has rapidly become one of the hot topics in the field of water treatment technology research in the 21st century due to its unique advantages. With the in-depth research of TiO ₂ photocatalytic technology, it is shown that the coupling of TiO ₂ photocatalytic technology and many advanced oxidation technologies can effectively solve the defects of TiO ₂ photocatalytic oxidation technology, and the new synergistic technology will show higher catalytic activity.

Fenton technology is a relatively mature and efficient advanced oxidation technology. This technology is a waste water treatment method based on chemical oxidation of Fenton's reagent. Fenton's reagent is a kind of oxidizing agent with strong oxidizing ability mixed by H ₂ O ₂ and Fe ²⁺ . The oxidation mechanism is mainly under acidic conditions ( Generally pH<3.5), using Fe ²⁺ as a catalyst for H ₂ O ₂ to generate hydroxyl radicals (·OH) with strong oxidative electrical properties and high reactivity, and hydroxyl radicals are generated in aqueous solution with refractory organic matter Organic free radicals destroy its structure and eventually oxidize and decompose. At the same time, Fe ²⁺ is oxidized to Fe ³⁺ to produce coagulation and precipitation, and a large amount of organic matter is condensed and removed. Fenton oxidation can effectively treat wastewater containing nitrobenzene, ABS and other organic substances, and can be used for decolorization and deodorization of wastewater.

Contents of the invention

The purpose of the present invention is to provide a method for a Fenton-like photocatalytic reaction system coupled with zero-valent iron and TiO catalysis, by coupling Fe ⁰ with TiO ₂ photocatalytic technology, and combining it into a Fenton- _like photocatalytic reaction system in a certain environment. Catalytic technology can effectively improve the catalytic activity of photocatalytic technology, improve the removal efficiency of pollutants and the quality of effluent water, and reduce the generation of iron sludge in Fenton technology.

In order to achieve the above object, a kind of zero-valent iron of the present invention and TiO The method for the Fenton _- like photocatalytic reaction system of photocatalytic coupling, the method may further comprise the steps:

(1) Prepare 1L of simulated dye wastewater with a concentration of 10mg/L-100mg/L and place it in a glass container, add 0.1g-2g Fe ⁰ to the simulated dye wastewater, and adjust the The pH=3 of simulated dye waste water, then in described dye waste water, add the TiO of 1g/L _Catalyst , turn on the ultraviolet lamp of λ=254nm, the glass container that fills simulated dye waste water is placed under described ultraviolet lamp, Turn on the aeration pump, and use the aeration method at the bottom of the glass container to drive the HCl solution, TiO ₂ catalyst and simulated dye wastewater in the mixed reaction system, thereby realizing the Fenton-like photocatalytic reaction;

(2) After the above reaction is completed, add 2-10ml of NaOH solution with a concentration of 1mol/L to the reaction system, and the subsequent addition of NaOH solution not only neutralizes the H ⁺ in the reaction system, but also reacts with Fe ³⁺ in the reaction system Ferric hydroxide colloid is generated; Cl ^- and Fe ³⁺ present in the reaction system generate ferric chloride, and both ferric chloride and ferric hydroxide colloid have flocculation, which promotes the TiO ₂ catalyst, dye molecules and fine particles in the reaction system With the precipitation of particulate impurities, the effluent water quality can meet the requirements of the first-level A standard of the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002).

The pH of the reaction system is a dynamic adjustment process during the reaction process, and the reaction system is always maintained as an acidic medium with pH=3 during the reaction process. The remaining elemental iron of the zero-valent iron (Fe ⁰ ) after the reaction is finished can be directly taken out and separated from the reaction system.

Effect of the present invention is:

1. The present invention couples Fe ⁰ with TiO ₂ photocatalytic technology, and combines it into Fenton-like photocatalytic technology in a certain environment, which can effectively improve the catalytic activity of photocatalytic technology, improve the removal efficiency of pollutants and the quality of effluent water , reducing the generation of Fenton technology iron slime.

2. In the acidic system of the present invention, Fe ⁰ will release ferric ions (Fe ²⁺ ); part of Fe ²⁺ is oxidized into ferric ions (Fe ³⁺ ) under the action of oxygen. Therefore, ultraviolet light, TiO ₂ catalyst, pollutants, Fe ²⁺ and Fe ³⁺ exist in the Fenton-like photocatalytic reaction system. The Fe ²⁺ released by Fe ⁰ and the converted Fe ³⁺ are photocatalytically coupled with TiO 2 ; it can capture TiO ₂ photogenerated electrons, reduce the recombination of photogenerated electrons and holes, and enhance _the photocatalytic effect of TiO ₂ ; the photocatalytic reaction of TiO ₂ The generated hydroxyl radicals (·OH) couple with the Fe ²⁺ released from Fe ⁰ and the converted Fe ³⁺ to form a Fenton-like reaction system, which further improves the treatment efficiency of pollutants.

3. The iron ions produced in the Fe ⁰ and TiO ₂ photocatalytic synergy system and the subsequent addition of NaOH produce flocculation, which can reduce the chromaticity and turbidity in the reaction system by 35%-50%, and the effluent water quality can reach the "urban Sewage Treatment Plant Pollutant Discharge Standards" (GB18918-2002) Class A standard requirements.

The effect of the present invention is that the photocatalytic synergistic effect of zero-valent iron (Fe ⁰ ) and TiO ₂ increases the removal efficiency of pollutants by 40% compared with that of a single TiO ₂ photocatalytic effect, and the amount of iron sludge produced is compared with that of Fenton Technology reduced by 50%.

Detailed ways

The method of the Fenton-like photocatalytic reaction system coupled with the photocatalysis of zero-valent iron of the present invention and _TiO2 is illustrated in conjunction with the following examples:

The method action mechanism of the Fenton-like photocatalytic reaction system of the photocatalytic coupling of zero-valent iron and _TiO of the present invention is as follows:

TiO ₂ +hv(ultraviolet light)→e ^- +h ⁺

e ^- +O ₂ →·O ₂ ^-

·O ₂ ^- +H ⁺ →HOO·

2HOO→O ₂ +H ₂ O ₂

H ₂ O ₂ +·O ₂ ⁻ →·OH+OH ⁻ +O ₂

h ⁺ +H ₂ O→·OH+·H ⁺

h ⁺ +OH ^- → OH

Fe ⁰ +2H ⁺ →Fe ²⁺ +H ₂

Fe ²⁺ +O ₂ →Fe ³⁺

Fe ²⁺ +H ₂ O ₂ →Fe ³⁺ + OH+OH ^-

Fe ³⁺ +·H ₂ O ₂ →·OOH·+Fe ²⁺ +H ⁺

HOO·+H ₂ O ₂ ·→H ₂ O+·OH+O ₂

The method of the Fenton-like photocatalytic reaction system of the photocatalytic coupling of zero-valent iron and TiO ₂ of the present invention is to couple zero-valent iron (Fe ⁰ ) with TiO ₂ photocatalytic technology, and in an acidic system, zero-valent iron (Fe ⁰ ) will release ferric ions (Fe ²⁺ ), and part of Fe ²⁺ will be oxidized to ferric ions (Fe ³⁺ ) under the action of oxygen. Therefore, ultraviolet light, TiO ₂ catalyst, pollutants, Fe ²⁺ and Fe ³⁺ exist in the Fenton-like photocatalytic reaction system. The Fe ²⁺ released by Fe ⁰ and the converted Fe ³⁺ are photocatalytically coupled with TiO ₂ ; they can capture the photogenerated electrons of TiO ₂ , reduce the recombination of photogenerated electrons and holes, and enhance the photocatalytic effect of TiO ₂ ; the photocatalytic reaction of TiO ₂ The generated hydroxyl radicals (·OH) couple with the Fe ²⁺ released from Fe ⁰ and the converted Fe ³⁺ to form a Fenton-like reaction system, which further improves the treatment efficiency of pollutants. Moreover, the iron ions produced in the photocatalytic synergy system of Fe ⁰ and TiO ₂ can produce flocculation after adding alkali, which can reduce the chromaticity and turbidity in the reaction system by 35%-50%, and the effluent water quality can reach "urban Sewage Treatment Plant Pollutant Discharge Standards" (GB18918-2002) Class A standard requirements.

Zero-valent iron of the present invention and TiO The method for the Fenton _- like photocatalytic reaction system of photocatalytic coupling, the method comprises the following steps:

(1) Prepare 1L of simulated dye wastewater with a concentration of 10mg/L-100mg/L and place it in a glass container, add 0.1g-2g Fe ⁰ to the simulated dye wastewater, and adjust the The pH=3 of simulated dye waste water, then in described dye waste water, add the TiO of 1g/L _Catalyst , turn on the ultraviolet lamp of λ=254nm, the glass container that fills simulated dye waste water is placed under described ultraviolet lamp, Turn on the aeration pump, and use the aeration method at the bottom of the glass container to drive the HCl solution, TiO ₂ catalyst and simulated dye wastewater in the mixed reaction system, thereby realizing the Fenton-like photocatalytic reaction;

(2) After the above reaction is completed, add 2-10ml of NaOH solution with a concentration of 1mol/L to the reaction system, and the subsequent addition of NaOH solution not only neutralizes the H ⁺ in the reaction system, but also reacts with Fe ³⁺ in the reaction system Ferric hydroxide colloid is generated; Cl ^- and Fe ³⁺ present in the reaction system generate ferric chloride, and both ferric chloride and ferric hydroxide colloid have flocculation, which promotes the TiO ₂ catalyst, dye molecules and fine particles in the reaction system The precipitation of particulate impurities can reduce the chromaticity and turbidity in the reaction system by 35%-50%, and the effluent water quality can meet the requirements of the first-level A standard of the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002).

The pH of the reaction system is a dynamic adjustment process during the reaction process, and the reaction system is always maintained as an acidic medium with pH=3 during the reaction process. The remaining elemental iron of the zero-valent iron (Fe ⁰ ) after the reaction is finished can be directly taken out and separated from the reaction system.

Example 1:

(1) Prepare 1L of simulated dye wastewater with a concentration of 10mg/L and place it in a glass container with a volume V greater than 1L, add 0.1gFe ⁰ to the simulated dye wastewater, and adjust the simulated dye wastewater with a concentration of 1mol/L HCl solution pH = 3, and then add 1g/L of TiO ₂ catalyst to the dye wastewater. Turn on the ultraviolet lamp at λ=254nm, place the glass container containing the simulated dye wastewater in the ultraviolet light environment, turn on the aeration pump, and use the aeration method at the bottom of the glass container to drive the HCl solution, TiO ₂ catalyst and simulation in the mixed reaction system. Dye wastewater, thereby realizing a Fenton-like photocatalytic reaction.

(2) After the above reaction is completed, add 2ml of NaOH solution with a concentration of 1mol/L to the reaction system, and the subsequent addition of NaOH solution will not only neutralize the H ⁺ in the reaction system, but also generate hydrogen with Fe ³⁺ in the reaction system Iron oxide colloid; Cl ^- and Fe ³⁺ present in the reaction system generate ferric chloride, and both ferric chloride and ferric hydroxide colloid have flocculation, which can effectively promote TiO ₂ catalyst, dye molecules and fine particles in the reaction system The precipitation of impurities can reduce the chromaticity and turbidity in the reaction system by 35%-50%, and the effluent water quality can meet the requirements of the first-level A standard of "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002).

Example 2:

(1) Prepare 1L of simulated dye wastewater with a concentration of 50mg/L and place it in a glass container with a volume V greater than 1L, add 1g Fe ⁰ to the simulated dye wastewater, and adjust the simulated dye wastewater with a concentration of 1mol/L HCl solution pH = 3, and then add 1g/L of TiO ₂ catalyst to the dye wastewater. Turn on the ultraviolet lamp at λ=254nm, place the glass container containing the simulated dye wastewater in the ultraviolet light environment, turn on the aeration pump, and use the aeration method at the bottom of the glass container to drive the HCl solution, TiO ₂ catalyst and simulation in the mixed reaction system. Dye wastewater, thereby realizing a Fenton-like photocatalytic reaction.

(2) After the above reaction is completed, add 5ml of NaOH solution with a concentration of 1mol/L to the reaction system, and the subsequent addition of NaOH solution will not only neutralize the H ⁺ in the reaction system, but also generate hydrogen with Fe ³⁺ in the reaction system Iron oxide colloid; Cl ^- and Fe ³⁺ present in the reaction system generate ferric chloride, and both ferric chloride and ferric hydroxide colloid have flocculation, which can effectively promote TiO ₂ catalyst, dye molecules and fine particles in the reaction system Precipitation of impurities, thereby reducing the chromaticity and turbidity of the reaction system by 35%, and the quality of the effluent water can meet the requirements of the first-class A standard of the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002).

Example 3:

(1) Prepare 1L of simulated dye wastewater with a concentration of 100mg/L and place it in a glass container with a volume V greater than 1L, add 2g Fe ⁰ to the simulated dye wastewater, and adjust the simulated dye wastewater with a concentration of 1mol/L HCl solution pH = 3, and then add 1g/L of TiO ₂ catalyst to the dye wastewater. Turn on the ultraviolet lamp at λ=254nm, place the glass container containing the simulated dye wastewater in the ultraviolet light environment, turn on the aeration pump, and use the aeration method at the bottom of the glass container to drive the HCl solution, TiO ₂ catalyst and simulation in the mixed reaction system. Dye wastewater, thereby realizing a Fenton-like photocatalytic reaction.

(2) After the above reaction is completed, add 10ml of NaOH solution with a concentration of 1mol/L to the reaction system, and the subsequent addition of NaOH solution will not only neutralize the H ⁺ in the reaction system, but also generate hydrogen with Fe ³⁺ in the reaction system Iron oxide colloid; Cl ^- and Fe ³⁺ present in the reaction system generate ferric chloride, and both ferric chloride and ferric hydroxide colloid have flocculation, which can effectively promote TiO ₂ catalyst, dye molecules and fine particles in the reaction system Precipitation of impurities, thereby reducing the chromaticity and turbidity of the reaction system by 50%, and the quality of the effluent can meet the requirements of the first-level A standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB18918-2002).

Claims (3)

1. a kind of zero-valent iron and _TiO The method for the class Fenton photocatalytic reaction system of photocatalytic coupling, this method comprises the following steps: (1) Prepare 1L of simulated dye wastewater with a concentration of 10mg/L-100mg/L and place it in a glass container, add 0.1g-2g Fe ⁰ to the simulated dye wastewater, and adjust the The pH=3 of simulated dye waste water, then in described dye waste water, add the TiO of 1g/L _Catalyst , turn on the ultraviolet lamp of λ=254nm, the glass container that fills simulated dye waste water is placed under described ultraviolet lamp, Turn on the aeration pump, and use the aeration method at the bottom of the glass container to drive the HCl solution, TiO ₂ catalyst and simulated dye wastewater in the mixed reaction system, thereby realizing the Fenton-like photocatalytic reaction; (2) After the above reaction is completed, add 2-10ml of NaOH solution with a concentration of 1mol/L to the reaction system, and the subsequent addition of NaOH solution not only neutralizes the H ⁺ in the reaction system, but also reacts with Fe ³⁺ in the reaction system Ferric hydroxide colloid is generated; Cl ^- and Fe ³⁺ present in the reaction system generate ferric chloride, and both ferric chloride and ferric hydroxide colloid have flocculation, which promotes the TiO ₂ catalyst, dye molecules and fine particles in the reaction system The precipitation of particulate impurities, the effluent water quality can meet the requirements of the first-level A standard of the "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002). 2. the method for class Fenton photocatalytic reaction system according to claim 1, it is characterized in that: the pH of described reaction system is dynamic regulation process in reaction process, in reaction process, makes reaction system maintain as pH== 3 acid medium. 3 . The method of the Fenton-like photocatalytic reaction system according to claim 1 , characterized in that: after the reaction of the zero-valent iron (Fe ⁰ ), the remaining iron element can be directly taken out and separated from the reaction system.