Abstract: Advanced oxidation technology is very popular with people of concern in recent years, new wastewater treatment technology, with its handle high concentrations of refractory organic pollutants in the dyeing waste water is also widely launched. Introduces the domestic and international use of wet oxidation method, ultrasonic method, photocatalytic oxidation, supercritical oxidation and electrochemical oxidation and other advanced oxidation mechanism of dye wastewater treatment, research progress and application.
Keywords: Advanced oxidation dyeing wastewater, wastewater treatment
Printing and dyeing industry, big industrial waste water. The traditional method of dyeing wastewater treatment are: adsorption, coagulation, biochemistry methods, such as reduction of waste water treatment method, these methods because of high investment, high cost and low processing efficiency reasons, remains to be further improved. Develop cost-effective Dyeing Wastewater Treatment Technology has become Environmental protection Matter of concern among the industry. In recent years, domestic and foreign experts began to study advanced oxidation treatment of dyeing wastewater. Advanced oxidation was first proposed by Glaze, etc., refers to the oxidation process a large number of hydroxyl free radicals in-depth chemical oxidation processes, including wet air oxidation, ultrasonic oxidation, photocatalytic oxidation, supercritical water oxidation, electricity chemical oxidation, etc. The main feature are: use of a wide range of high effective, responsive, secondary pollution, recyclable energy and useful materials. It's these advantages to the intractable depth of dyeing wastewater treatment have better prospects. This will be the mechanism of these methods, research progress and application prospect to be brief.
1 Wet Oxidation The mechanism of wet oxidation
1.1 Wet air oxidation at high temperatures (125-320 ), high pressure (0.5-10MPa) under oxygen or air as the oxidant, dissolved or suspended in water oxidation state of the organic or inorganic reduced state so generated CO2 and H2O A approach. Is generally believed that wet oxidation is a free radical reaction is divided into chain initiation, chain transfer and chain development or the termination of three stages. Chain initiation stage, mainly by molecular oxygen reacts with the reactant molecules alkyl radicals (R?); Chain stage of development or transfer, free radicals and reactive molecules interact to produce ester radical (ROO?), hydroxyl radical (HO?) and alkyl radicals (R?), hydroxyl radicals are strong oxidizing go Oxidation of organic waste; chain termination phase of the collision between free radical formation and stability of the molecule, so that chain growth process interrupted, the reaction stops.
1.2 Progress of wet oxidation
Wet oxygen Chemical industry Art was originally proposed by the United States FJZimmerman first proposed in 1944, the first time in 1958 dealing with the black liquor. Joglekar that the method is mainly used for burn treatment in terms of concentration is too thin, in terms of biological treatment are too high, or have greater toxicity of organic industrial waste. After decades of research and development, the international has been successfully applied and wet oxidation, including a variety of industries including printing and dyeing wastewater effluent treatment.
80 since the 20th century in China since the beginning of the wet oxidation method studied. SU and other adsorption with carbon black - wet air oxidation of dye wastewater, the most suitable conditions, COD removal rate reached 87%, 99% color removal. Zhou Shu-day use of wet hydrogen peroxide and other technology to treat refractory biochemical degradation of methyl orange, COD and color removal rates reached 85% and 99%. Yuan Fang, and others to H2O2 as the oxidant, using wet oxidation of high concentration of dye wastewater under acidic conditions, reaction time 40-60min, COD removal efficiency greater than 80% color removal rate of greater than 90%.
1.3 prospects Along, because the wet oxidation reaction conditions more stringent equipment requirements high, so the technology subject to certain restrictions, but in recent years, cheap and efficient catalyst for the successful development of the technology to be at room temperature under pressure, effectively expanding the range of applications.
2 ultrasound oxidation The mechanism of ultrasonic oxidation
2.1
Is generally believed that the frequency range of 15kHz-1MHz ultrasound irradiation for the degradation of chemical pollutants is caused by the cavitation effect of the physical and chemical processes. Ultrasonic cavitation hot theoretical model that: a certain frequency and ultrasonic radiation pressure solution, the negative pressure phase in the acoustic solution produced under cavitation bubbles, the acoustic pressure in the subsequent phase of the effect of the rapid collapse of cavitation bubbles The whole process occurred in the ns- s time, the rapid collapse of bubbles within bubbles with a vapor phase of adiabatic compression, resulting in transient high temperature and pressure, forming the so-called "hot spots." Into the cavitation bubbles in the water vapor at high temperature and pressure of the split and the chain reaction occurs to produce? OH, HOO?,? H and other free radicals and substances such as H2O2 and H2. The way of sound chemical reactions, including high pressure and temperature pyrolysis reaction and 2 types of free radical oxidation. I am a professional writer from China Chemicals Products, which contains a great deal of information about stove solid fuel , hot plate burner, welcome to visit!
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