阅读说明：本技术 一种基于连续变频超声波/臭氧溶液耦合作用的粉末活性炭低温热-液相原位再生方法 (Low-temperature heat-liquid phase in-situ regeneration method for powdered activated carbon based on continuous frequency conversion ultrasonic wave/ozone solution coupling effect ) 是由 杨艳玲 于瑞 李星 周志伟 于 2021-08-27 设计创作，主要内容包括：一种基于连续变频超声波/臭氧溶液耦合作用的粉末活性炭低温热-液相原位再生方法,属水处理技术领域。本发明将连续变频超声、臭氧溶液、低温热液相再生进行协同作用,粉末活性炭可原位再生及回用,降低了再生成本,克服了传统热再生法过程中存在的诸多缺陷。连续变频超声波可进一步强化臭氧溶液中臭氧分子在活性炭孔隙、孔道中的迁移和传质作用,有效避免再生过程中活性炭孔隙结构破坏,显著强化了再生效果。本发明克服了常规固定频率超声波、臭氧气泡、溶剂等再生方式的缺点,粉末活性炭再生效果得到明显改善和优化。本发明可根据粉末炭中吸附的污染物特性及再生要求再生液组成与温度、优化超声波作用参数,具有较好的适用范围。(A low-temperature heat-liquid phase in-situ regeneration method of powdered activated carbon based on continuous frequency conversion ultrasonic wave/ozone solution coupling action belongs to the technical field of water treatment. The invention carries out the synergistic action of the continuous frequency conversion ultrasound, the ozone solution and the low-temperature hydrothermal liquid phase regeneration, and the powdered activated carbon can be regenerated and recycled in situ, thereby reducing the regeneration cost and overcoming a plurality of defects in the traditional thermal regeneration process. The continuous frequency conversion ultrasonic wave can further strengthen the migration and mass transfer effects of ozone molecules in the ozone solution in active carbon pores and pore channels, effectively avoids the damage of the active carbon pore structure in the regeneration process, and obviously strengthens the regeneration effect. The invention overcomes the defects of conventional fixed frequency ultrasonic waves, ozone bubbles, solvents and other regeneration modes, and obviously improves and optimizes the regeneration effect of the powdered activated carbon. The invention can optimize the ultrasonic action parameters according to the characteristics of pollutants adsorbed in the powdered carbon and the regeneration requirement on the composition and temperature of the regeneration liquid, and has better application range.)

1. A low-temperature heat-liquid phase in-situ regeneration method of powdered activated carbon based on continuous frequency conversion ultrasonic wave/ozone solution coupling effect is characterized by comprising the following steps:

(1) directly adding a regeneration liquid with a certain concentration into the saturated powdered activated carbon precipitation concentrated solution, continuously stirring at 100-150rpm, and simultaneously heating to a certain temperature to form a low-temperature hot mixed solution of powdered activated carbon;

(2) adding an ozone solution into the low-temperature hot mixed liquid of the powdered activated carbon, and continuously stirring at 100-150rpm for 5-10min to form the low-temperature hot ozone mixed liquid of the powdered activated carbon;

(3) the low-temperature thermal ozone mixed liquid of the powdered activated carbon is subjected to continuous frequency conversion ultrasonic action for 0-60min and is continuously stirred at the speed of 100 plus 150rpm, and the regenerated powdered activated carbon is precipitated and separated, so that the regenerated powdered activated carbon can be directly recycled.

2. The method for low-temperature thermal-liquid phase in-situ regeneration of powdered activated carbon based on continuous frequency conversion ultrasonic/ozone solution coupling as claimed in claim 1, wherein the regeneration liquid in step (1) is strong acid or strong base, composite acid or composite alkali solution, the concentration of the corresponding acid or base in the low-temperature hot mixed liquid of powdered activated carbon is 0.05-0.5mM, or the regeneration liquid is organic solvent such as ethanol or methanol, and the volume ratio of the organic solvent in the precipitation concentrated liquid of saturated powdered activated carbon is 10-100%.

3. The method for low-temperature thermal-liquid phase in-situ regeneration of powdered activated carbon based on continuous frequency conversion ultrasonic wave/ozone solution coupling as claimed in claim 1, wherein the temperature of the low-temperature hot mixed liquid of the powdered activated carbon in the step (1) is 50 ℃ to 90 ℃.

4. The method for low-temperature thermal-liquid phase in-situ regeneration of powdered activated carbon based on continuous frequency conversion ultrasonic wave/ozone solution coupling as claimed in claim 1, wherein the concentration of ozone in the low-temperature thermal ozone mixed solution of the powdered activated carbon in the step (2) is 0.2-2 mg/L.

5. The low-temperature hot-liquid phase in-situ regeneration method for powdered activated carbon based on continuous frequency conversion ultrasonic wave/ozone solution coupling action as claimed in claim 1, wherein the frequency variation amplitude of the continuous frequency conversion ultrasonic wave in the step (3) is determined according to the particle size range and the pore diameter range of the powdered activated carbon; when the particle size of the powdered activated carbon is 5-300 meshes and the average pore diameter is 2-4nm, an optimal interval exists between the regeneration efficiency of the powdered activated carbon and the ultrasonic frequency; from the 0-5min time period when the ultrasonic wave starts to act, the ultrasonic wave carries out continuous frequency conversion circulation, and the frequency of each frequency conversion circulation is gradually increased in the interval of 20-40 kHz; from the 5-30min time period when the ultrasonic wave starts to act, the ultrasonic wave carries out continuous frequency conversion circulation, and the frequency of each frequency conversion circulation is gradually increased in the interval of 35-100 kHz; the ultrasonic wave is subjected to continuous frequency conversion circulation in a time period of more than 30min from the start of action of the ultrasonic wave, and the frequency of each frequency conversion circulation is gradually increased in an interval of 20-35 kHz; the cycle period of the ultrasonic continuous frequency conversion in the different action time periods is 2-5min, and the cycle period of each action time period is the same or different.

Technical Field

The invention belongs to the technical field of water treatment, and particularly relates to a method for regenerating waste powdered activated carbon for water treatment.

Background

The powdered activated carbon has a developed pore structure and stable physicochemical properties, can adsorb various pollutants in water, and is widely applied to the fields of water source water quality purification, water quality emergency treatment, advanced treatment of municipal sewage and industrial wastewater and the like. Because the activated carbon is expensive, the problems of regeneration and reuse are mostly considered in the field of water treatment. By adopting an efficient regeneration technology, the recycling of the powdered activated carbon can be realized, the amount of the waste powdered activated carbon is reduced, the use efficiency of the powdered activated carbon is improved, and the process operation cost is reduced. The thermal regeneration method is to desorb, carbonize and oxidize and decompose the adsorbate by an external heating source mode, and finally the adsorbate is changed into gas to escape. Research and development and adoption of an efficient activated carbon regeneration technology to simplify a regeneration procedure, improve the regeneration rate, reduce the carbon quality loss and reduce the regeneration cost are technical problems to be solved urgently in the field of activated carbon application.

At present, besides thermal regeneration, regeneration techniques such as ultrasonic regeneration, ozone regeneration, and solvent regeneration, which combine physical action, chemical action, and multiple actions, are also available as methods for regenerating activated carbon. The ultrasonic regeneration method is mainly suitable for physical adsorption regeneration of the activated carbon, most of the existing ultrasonic regeneration methods use ultrasonic with fixed frequency to regenerate the activated carbon, and high-speed micro jet and high-pressure shock waves generated during cavitation bubble collapse act on the aperture channel in the PAC fixed range in a concentrated manner. In order to improve the regeneration effect of the ultrasonic regeneration method, the power is required to be improved or the action time is required to be prolonged, but the pore diameter structure of the activated carbon is easy to damage due to the action of high energy and long-time ultrasonic, the secondary adsorption capacity of the activated carbon is influenced, and the energy consumption is increased. The ozone regeneration method can be carried out in situ, and has good regeneration effect. In the existing ozone regeneration method, the ozone bubbles and powdered activated carbon are often subjected to contact reaction to degrade adsorbates in the activated carbon, but the decomposition degree of the ozone bubbles in water is greatly influenced by the water quality, the reaction contact time of the ozone bubbles and the activated carbon is short, effective contact points are only limited on the surface of the activated carbon, the gas mass transfer efficiency is low, and a large amount of unreacted ozone gas is easily released into the air from a regeneration system, so that the operation efficiency is low. If the ozone solution is adopted, the problems of poor mass transfer, short contact time and incapability of entering active carbon pore passages of ozone bubbles can be effectively solved. The regenerated liquid is heated to strengthen the liquid phase mass transfer effect, and the pollutants easy to desorb can be reversibly desorbed from the powdered activated carbon, and meanwhile, the mass transfer and diffusion effects of the regenerated liquid solvent, ozone, pollutants and the like on the surface and in pore channels of the activated carbon are improved.

The ultrasonic frequency has a significant influence on the state of motion and the form of existence of cavitation bubbles. The number of cavitation bubbles increases linearly with the increase of the ultrasonic frequency, and the smaller the size of the cavitation bubbles, the smaller and denser the cavitation bubbles can impact the finer pores of the powdered activated carbon. The cavitation bubbles can fully act on the inner and outer pore passages of the powdered activated carbon with various sizes by changing the frequency, so that the regeneration efficiency is obviously improved. The pH value has great influence on the decomposition and reaction of ozone in water, and the solubility of ozone in water can be obviously changed by adjusting the pH value. The direct reaction of ozone molecules is dominant under acidic conditions, and the oxidation reaction of hydroxyl radicals (. OH) is dominant under alkaline conditions. Under the action of ultrasonic waves, ozone is decomposed to generate other free radicals with higher activity such as OH, so that the mass transfer rate constant is increased. The ultrasonic wave can increase the mixing degree and the turbulent fluctuation intensity of water, reduce the thickness of a liquid film, reduce resistance and increase the mass transfer coefficient, thereby improving the mass transfer rate of ozone. Ozone can also generate hydrogen peroxide and hydroxyl free radicals under the action of ultrasound, so that the reaction rate is improved. How to develop and establish a novel regeneration mode by utilizing the advantages and characteristics of the activated carbon regeneration technology is a new challenge in the field of activated carbon regeneration and reuse.

The invention constructs a low-temperature heat-liquid phase in-situ regeneration method of powdered activated carbon based on the coupling effect of continuous frequency conversion ultrasonic wave-ozone solution by the synergistic effect of continuous frequency conversion ultrasonic wave, ozone solution and low-temperature heat liquid phase regeneration. After the saturated powdered activated carbon is regenerated in the low-temperature thermal regeneration liquid, reversible desorption of partial pollutants is realized, the contact of ozone molecules in an ozone solution and adsorption sites of inner and outer pores of the powdered activated carbon is more sufficient, cavitation bubbles with different sizes generated by continuous frequency conversion ultrasound can catalyze and activate ozone molecules in water, so that the pollutants adsorbed by the powdered activated carbon and partial desorbed pollutants are desorbed and degraded in situ, the inner and outer pores of the powdered activated carbon are fully regenerated, the regeneration effect is obviously enhanced by coupling, the damage of the pore structure of the activated carbon in the regeneration process is effectively avoided, and a plurality of defects existing in the process of the traditional thermal regeneration method are overcome. The continuous frequency conversion ultrasonic wave can further strengthen the migration and mass transfer effects of ozone molecules in the ozone solution in pores and pore canals of the activated carbon, generate high-activity free radicals, improve the utilization rate of ozone, enhance the oxidative degradation efficiency, overcome the defects of conventional fixed frequency ultrasonic waves, ozone bubbles, solvents and other regeneration modes, and the regeneration liquid adopts the coupling effect of the continuous frequency conversion ultrasonic wave and the ozone solution to regenerate saturated powdered activated carbon, so that the regeneration efficiency of the powdered activated carbon is obviously improved and optimized.

Disclosure of Invention

The invention provides a low-temperature heat-liquid phase in-situ regeneration method of powdered activated carbon based on continuous frequency conversion ultrasonic wave/ozone solution coupling effect, which constructs the low-temperature heat-liquid phase in-situ regeneration method of powdered activated carbon based on the continuous frequency conversion ultrasonic wave/ozone solution coupling effect through the synergistic effect of the continuous frequency conversion ultrasonic wave, the ozone solution and the low-temperature heat liquid phase regeneration, and solves the problems that the regeneration process of saturated powdered activated carbon needs regeneration by professional manufacturers, the energy consumption is high, the tail gas is secondarily polluted and the like.

The scheme adopted by the invention is as follows:

a low-temperature heat-liquid phase in-situ regeneration method of powdered activated carbon based on continuous frequency conversion ultrasonic wave/ozone solution coupling effect is characterized by comprising the following steps:

(1) directly adding a regeneration liquid with a certain concentration into the saturated powdered activated carbon precipitation concentrated solution, continuously stirring at 100-150rpm, and simultaneously heating to a certain temperature to form a low-temperature hot mixed solution of powdered activated carbon;

(2) adding an ozone solution into the low-temperature hot mixed liquid of the powdered activated carbon, and continuously stirring at 100-150rpm for 5-10min to form the low-temperature hot ozone mixed liquid of the powdered activated carbon;

(3) the low-temperature thermal ozone mixed liquid of the powdered activated carbon is subjected to the action of continuous variable-frequency ultrasonic waves for 0-60min and is continuously stirred at the speed of 100-150rpm, and then the regenerated powdered activated carbon is precipitated and separated, so that the regenerated powdered activated carbon can be directly recycled.

Preferably, the regeneration liquid is strong acid or strong base, composite acid liquid or composite alkali liquid, the concentration of the corresponding acid or alkali in the low-temperature hot mixed liquid of the powdered activated carbon is 0.05-0.5mM, or the regeneration liquid is organic solvent such as ethanol or methanol, and the volume ratio of the organic solvent in the saturated powdered activated carbon precipitation concentrated liquid is 10-100%; the temperature of the low-temperature hot mixed liquid of the powdered activated carbon is 50-90 ℃;

more preferably, the concentration of ozone in the low-temperature hot ozone mixed liquid of the powdered activated carbon is 0.5-5 mg/L;

further preferably, the frequency variation amplitude of the continuous frequency conversion ultrasonic wave is determined according to the particle diameter range of the powdered activated carbon and the pore diameter range of the pore canal; when the particle size of the powdered activated carbon is 5-300 meshes and the average pore diameter is 2-4nm, an optimal interval exists between the regeneration efficiency of the powdered activated carbon and the ultrasonic frequency; from the 0-5min time period when the ultrasonic wave starts to act, the ultrasonic wave carries out continuous frequency conversion circulation, and the frequency of each frequency conversion circulation is gradually increased in the interval of 20-40 kHz; from the 5-30min time period when the ultrasonic wave starts to act, the ultrasonic wave carries out continuous frequency conversion circulation, and the frequency of each frequency conversion circulation is gradually increased in the interval of 35-100 kHz; the ultrasonic wave is subjected to continuous frequency conversion circulation in a time period of more than 30min from the start of action of the ultrasonic wave, and the frequency of each frequency conversion circulation is gradually increased in an interval of 20-35 kHz; the cycle period of the ultrasonic continuous frequency conversion in the different action time periods is 2-5min, and the cycle period of each action time period is the same or different.

The invention has the advantages that:

(1) the method regenerates saturated powdered activated carbon in situ in the liquid phase of the low-temperature thermal regeneration liquid through the synergistic effect of continuous variable frequency ultrasonic waves and an ozone solution, and the regenerated powdered activated carbon can be directly reused in a water treatment process, so that the problems of requirement of professional manufacturers, high energy consumption, large carbon loss and the like in the conventional thermal regeneration method of powdered activated carbon are solved.

(2) The continuous frequency conversion ultrasound can further strengthen the migration and mass transfer effects of ozone molecules in the ozone solution in pores and pore canals of the activated carbon, the contact efficiency of the ozone solution and adsorption sites of the powdered activated carbon is higher, the utilization efficiency of ozone oxidation is improved, and the regeneration effect of the activated carbon is obviously improved.

(3) The composition and temperature of the regeneration liquid can be adjusted according to the characteristics of pollutants adsorbed by the saturated powdered activated carbon and the regeneration requirement, the ultrasonic action parameters are optimized, and the application range is wide.

Detailed Description

The present invention is illustrated in detail by the following examples, which describe only some embodiments of the invention, but not all embodiments.

Example 1: a regeneration solution of 0.05mM sodium hydroxide was added to a saturated powdered activated carbon concentrate having a concentration of 5000mg/L adsorbing p-chlorophenol, and the mixture was stirred at 120rpm, and the regeneration solution was heated to 70 ℃ to form a low-temperature hot mixed solution. Adding an ozone solution into the low-temperature hot mixed liquid, wherein the concentration of ozone in the low-temperature hot mixed liquid is 1mg/L, and continuously stirring at 100rpm for 5min to form the low-temperature hot ozone mixed liquid of powdered activated carbon. Turning on frequency conversion ultrasound, wherein the total time of ultrasound action is 45min, wherein the continuous frequency conversion cycle interval of ultrasound in the time period of 0-5min is 20-40kHz, and the cycle period is 5 min; the ultrasonic continuous frequency conversion cycle interval of the action time period of 5-30min is 35-100kHz, and the cycle period is 5 min; the ultrasonic continuous frequency conversion cycle interval of the action time period of 30-45min is 20-35kHz, and the cycle period is 5 min. And precipitating and separating the treated powdered activated carbon, and directly recycling. Coal powder activated carbon is used as an adsorption material, the particle size of the powder activated carbon is 200 meshes, the average pore diameter is 2.24nm, the adsorption capacity of new carbon is 155.05mg/g, after regeneration treatment, the adsorption capacity of the activated carbon is restored to 147.30mg/g, and the regeneration rate reaches 95%.

Example 2: a regeneration solution of 0.05mM hydrochloric acid was added to a 2000mg/L saturated powdered activated carbon concentrate having adsorbed activated blue 81, and the mixture was stirred at 120rpm, and the regeneration solution was heated to 50 ℃ to form a low-temperature hot mixed solution. Adding an ozone solution into the low-temperature hot mixed liquid, wherein the concentration of ozone in the low-temperature hot ozone mixed liquid is 0.5mg/L, and continuously stirring at 100rpm for 5min to form the low-temperature hot ozone mixed liquid of powdered activated carbon. Turning on frequency conversion ultrasound, wherein the ultrasound action time lasts for 30min, the ultrasound continuous frequency conversion cycle interval is 20-40kHz when 0-5min, and the cycle period of the ultrasound continuous frequency conversion is 2.5 min; the ultrasonic continuous frequency conversion cycle interval is 35-100kHz when the ultrasonic continuous frequency conversion is acted for 5-30min, and the cycle period of the ultrasonic continuous frequency conversion is 5 min. And (4) separating the treated powdered activated carbon for direct recycling. The powdered activated carbon is coal, the particle size is 200 meshes, the average pore diameter is 2.99nm, the adsorption capacity of the new carbon is 397.33mg/g, after regeneration treatment, the adsorption capacity of the activated carbon is restored to 337.8mg/g, and the regeneration rate reaches 85%.

Example 3: a regeneration solution of 0.1mM sodium hydroxide was added to a saturated powdered activated carbon concentrate having a concentration of 5000mg/L and adsorbing acetone, and the mixture was stirred at 150rpm, and the regeneration solution was heated to 80 ℃ to form a low-temperature hot mixed solution. Adding an ozone solution into the low-temperature hot mixed liquid, wherein the concentration of ozone in the low-temperature hot ozone mixed liquid is 0.5mg/L, and continuously stirring at 100rpm for 5min to form the low-temperature hot ozone mixed liquid of powdered activated carbon. And (3) opening frequency conversion ultrasound, wherein the ultrasound action time lasts for 5min, the ultrasound continuous frequency conversion cycle interval of the time period of 0-5min is 20-40kHz, and the cycle period of the ultrasound continuous frequency conversion is 5 min. And (4) separating the treated powdered activated carbon for direct recycling. The adopted powdered activated carbon is wood, the particle size is 200 meshes, the average pore diameter is 3.38nm, the adsorption capacity of the new carbon is 230.96mg/g, after regeneration treatment, the adsorption capacity of the activated carbon is restored to 226.34mg/g, and the regeneration rate reaches 98%.