CN104118928A - Method for catalytic degradation of trichlorophenol organic pollutants by mixed mode - Google Patents

Abstract

The invention relates to the oxidative removal of trichlorophenol pollutants, in particular to a method for catalytic oxidation treatment of trichlorophenol organic pollutants in a mixed catalytic mode combining homogeneous and heterogeneous phases. In a reactor, in a liquid phase system, under certain temperature and pressure conditions, oxygen or air is used as an oxidant, a non-transition metal salt is used as a homogeneous catalyst, and composite metal oxide microspheres are used as a heterogeneous catalyst to oxidize Removal of trichlorophenol organic pollutants. The concentration of trichlorophenol is 10-500mg/L, the reaction temperature is 40-180°C, the reaction pressure is 0.1-5MPa, of which the oxygen partial pressure is 0.2-1.5MPa, the homogeneous catalyst concentration is 1-5000mg/L, multiphase composite The amount of the oxide catalyst is 0.1-12g/L, the reaction time is 0.5-6 hours, the removal rate of trichlorophenol reaches more than 90%, and the removal rate of TOC reaches more than 50%. The invention adopts the mixed catalytic mode of homogeneous phase and heterogeneous phase, the degradation efficiency of trichlorophenol pollutants is high, the reaction conditions are milder, the homogeneous catalyst is simple and easy to obtain, the heterogeneous catalyst can be recycled and reused, the processing cost is low, and the industrialization prospect is great .

Description

A Mixed Mode Catalytic Degradation Method of Trichlorophenol Organic Pollutants

technical field

The invention relates to the oxidative removal of trichlorophenol organic pollutants in the environment, in particular to a method for catalytic oxidation treatment of trichlorophenol organic pollutants in a mixed mode combining homogeneous phase and multiphase.

Background technique

Since the 1930s, chlorophenols (CPs) have been widely used as wood preservatives, rust inhibitors, fungicides, and herbicides, etc., and a large amount of CPs wastewater is also produced in the pulp bleaching process. It is also used for the control of schistosomiasis in Asia, Africa and South America, so the production scale of CPs in many industrialized countries is very large. At the same time, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol are all highly toxic substances, which are included in the blacklist of priority pollutants by the US EPA. The extensive use of chlorophenol compounds has caused a large number of CPs pollutants to enter the environment, causing great harm to the natural environment. Therefore, removing such compounds from the environment is a major challenge for humans.

At present, there are many methods for treating chlorophenol-containing wastewater. The commonly used methods are biodegradation, adsorption, extraction, and liquid membrane separation. However, the biological method takes a long time and is not suitable for the treatment of high-concentration chlorophenol wastewater. . In addition, the biodegradation of chlorophenol wastewater will also produce more toxic dioxin pollutants. (LGOeberg, Chemosphere, 1992). Advanced Oxidation Technology is a technology developed in the 1980s to deal with refractory organic pollutants. Its main feature is to generate hydroxyl radicals through chemical reactions, so that organic pollutants can be effectively degraded into water, carbon dioxide and inorganic ions. It mainly includes ozone oxidation, photocatalytic oxidation, wet oxidation, H ₂ O ₂ /UV, Fenton, O ₃ /UV and other methods. In the advanced oxidation method for treating chlorophenol, Meunier's catalytic oxidation system (Science1996), using hydrogen peroxide as the oxidant and iron phthalocyanine as the catalyst, treats chlorophenol organic pollutants, and the mineralization rate of carbon in trichlorophenol is 14 %, the mineralization rate of chlorine is 70%. The world patent (S.Muriel, WO0059836, 2000) invented a metal phthalocyanine catalyst, using hydrogen peroxide as an oxidant to treat trichlorophenol wastewater. In Collins' catalytic system (Science2002), tetraaminoiron macrocyclic compound was used as catalyst, hydrogen peroxide was used as catalyst, the mineralization rate of trichlorophenol was 35%, and the mineralization rate of chlorine was 83%. The existing problems are mainly that the used oxidants such as _H2O2 and _O3 are expensive, which makes the treatment cost relatively high, and in the _process of catalytic oxidation, the synthesis cost of iron phthalocyanine catalyst is also relatively high, and the catalyst is unstable , easy to deactivate, the existence of these problems makes the industrialization prospect for the treatment of chlorophenol wastewater very small.

Catalytic wet oxidation method has industrial application prospects due to the high concentration of organic matter, and has been increasingly used in the degradation research of organic pollutants in recent years (F.Luck, Catalysis Today1996; KHKim, Journal of Hazardous Material, 2011). Although the traditional homogeneous catalytic oxidation with Cu ²⁺ as the active component has a good effect, the metal ion catalyst is not recyclable and requires secondary treatment to remove it from wastewater. Therefore, more and more research has focused on heterogeneous catalysts, and the development of Oxides of noble metals, transition metals, supported Ru, Cu, Co, Mn, etc., multi-component oxide combinations such as CuO/ZnO, MnO ₂ /CeO ₂ , Fe ₂ O ₃ -CeO ₂ -TiO ₂ /γ-Al ₂ O ₃ and other composite metal oxide catalysts such as Cu-La-Ce (S. Imamura, Industrial & Engineering Chemistry Research, 1999; N. Li, Applied Catalysis B: Environmental, 2007), the main goal of which is to develop efficient and stable multi-phase catalyst while avoiding catalyst deactivation due to catalyst dissolution. This application is based on the patent (CN200510047251.6), using a self-made composite metal oxide as a heterogeneous catalyst, combined with the method described in the patent CN200510047251.6, and performing trichlorophenol in a homogeneous and multiphase mixed mode Catalytic oxidation degradation of organic pollutants, thereby improving the degradation efficiency and degradation degree.

Contents of the invention

The object of the present invention is to provide a mixed mode combining homogeneous phase and multiple phases to degrade trichlorophenol organic pollutants. A method for catalytic oxidation degradation of trichlorophenol pollutants with higher catalytic activity, better treatment effect, milder reaction conditions, recyclable heterogeneous catalysts, and great prospects for industrial application has been developed.

In order to achieve the above object, the technical scheme adopted in the present invention is:

In the stainless steel reaction kettle containing the waste liquid of trichlorophenol pollutants, in the liquid phase system, add homogeneous and composite oxide catalysts, then fill a certain amount of air or oxygen, and oxidize and remove chlorine under medium temperature and medium pressure conditions Phenolic organic pollutants. The reaction temperature is 40-180°C, the reaction pressure is 0.1-5MPa, and the oxygen partial pressure is 0.2-1.5MPa; the stirring speed is 100-1000rpm; the reaction time is 0.5-6 hours; the homogeneous catalyst is a non-transition metal K, Na, Mg, Ca, Ba, Al etc. are active cationic components, and NO ₃ ^- , NO ₂ ^- , SO ₄ ^2- , SO ₃ ^2- , CO ₃ ^2- etc. are active anion components; The concentration or total concentration of cations in the homogeneous catalyst is 0.1 to 10 times the concentration of pollutants to be removed, and the metal oxide catalyst is ZnO/TiO ₂ , Fe ₂ O ₃ /TiO ₂ , CuO/TiO ₂ , CoO/ TiO ₂ , NiO/TiO ₂ , MgO/TiO ₂ , Al ₂ O ₃ /TiO ₂ , MnO/TiO ₂ , CeO ₂ /TiO ₂ , CuO/Al ₂ O ₃ , CuO/SiO _{2 ,} etc., the amount of catalyst is 0.1 ~12g/L.

Advantages of the invention

1. High catalytic activity and mild reaction conditions. The present invention uses air or oxygen as an oxidant, a non-transition metal salt solution as a homogeneous catalyst, and a composite metal oxide as a heterogeneous catalyst to oxidize trichlorophenol organic pollutants into carbon dioxide, carbon monoxide, water and some non-toxic small molecule carboxylic acid.

2. The processing cost is local, and the industrialization prospect is great. Because the oxidizing agent and catalyst used in the present invention are cheap and easy to obtain, the treatment process is simple and convenient, and the heterogeneous catalyst can be recycled and reused, so the catalytic oxidation method of the present invention has the application prospect of industrially treating trichlorophenol pollutants.

3. Environmental friendly. The reaction system of the invention is simple, convenient and practical, the catalyst is cheap and easy to obtain, the reaction activity is high, and the pollutants can be removed thoroughly.

Detailed ways

The present invention is given further description by examples below, of course, the present invention is not limited to following examples.

Example:

Put 20ml of the wastewater solution of trichlorophenol organic pollutants with a concentration of 10mg/L to 500mg/L into a reaction kettle with a polytetrafluoroethylene liner, add homogeneous and composite oxide catalysts to the system, and then fill Enter ultra-pure oxygen or air at a certain pressure, heat up to the specified temperature while stirring, stir the reaction solution at a speed of 100-1000 rpm, and react for 1-4 hours. The removal rate of trichlorophenol after the reaction is shown in Table 1.

Carbon mineralization refers to the ratio of carbon in organic molecules to inorganic carbon, usually carbon dioxide. Common in the environmental field.

Table 1 Mixed catalytic mode treatment of trichlorophenol wastewater results table

The invention adopts the mixed catalytic mode of homogeneous phase and heterogeneous phase, the degradation efficiency of trichlorophenol pollutants is high, the reaction conditions are milder, the homogeneous catalyst is simple and easy to obtain, the heterogeneous catalyst can be recycled and reused, the processing cost is low, and the industrialization prospect is great .

Claims (7)

1. the method for a mixed mode catalyzed degradation Trichlorophenol organic pollutant, it is the method for homogeneous phase and heterogeneous mixed mode catalyzing oxidizing degrading Trichlorophenol pollutent, it is characterized in that: the waste water that contains trichlorophenol pollutent is packed in reactor, in system, add homogeneous catalyst catalyzer and composite oxides heterogeneous catalyst, taking oxygen or air as oxygenant, temperature of reaction is 30～300 DEG C, reaction pressure is 0.1～10MPa, wherein oxygen partial pressure is 0.1～5.0MPa, stirring velocity is 100～1000rpm, and the reaction times is 0.5～4h; In system, homogeneous catalysis agent concentration is 1～5000mg/L, the amount 0.1～12g/L of composite oxide catalysts.

2. it is characterized in that in accordance with the method for claim 1: described temperature of reaction is 40～180 DEG C.

3. it is characterized in that in accordance with the method for claim 1: described oxygen partial pressure is 0.2～3MPa.

4. it is characterized in that in accordance with the method for claim 1: one or two or more kinds in the soluble salt that homogeneous catalyst used is nontransition metal.

5. in accordance with the method for claim 3, it is characterized in that: homogeneous catalyst is taking one or two or more kinds in K, Na, Mg, Ca, Ba, Al as active cation component, with NO ₃ ^-, NO ₂ ^-, SO ₄ ^2-, SO ₃ ^2-, CO ₃ ^2-in one or two or more kinds be active anion component.

6. in accordance with the method for claim 1, it is characterized in that: O composite metallic oxide catalyst is micron-size spherical loaded catalyst, active ingredient is one or two or more kinds in Cu, Ni, Fe, Mg, Al, Mn, Co, Zn, Ce; Carrier is Al ₂o ₃, SiO ₂, TiO ₂in one or two or more kinds; Active ingredient mass loading amount is 0.05-3%.

7. in accordance with the method for claim 6, it is characterized in that: the preparation process of composition metal composite oxide catalysts is, be made into the activity component metal salt methyl ethyl diketone solution of 0.05M, add the ratio of 1g carrier to be mixed with mixing solutions according to every 10ml solution, then put into 140 DEG C of autoclaves aging 36 hours, filter, be dried finally calcination in retort furnace; The composite oxide catalysts granularity obtaining is 5 ~ 15 μ m, and specific surface area is 40 ~ 200m ²/ g.