Study On Adsorption Of Phenol Saturated Activated Carbon By Dual-Frequency Ultrasound

Due to its huge specific surface area and strong adsorption capacity,activated carbon is widely used as an excellent adsorbent in the fields of micro-polluted water treatment and deep treatment.With the wide application of activated carbon,the regeneration of activated carbon has been paid more and more attention.If the saturated activated carbon is directly discarded,it will not only be a great waste of resources,but also may cause secondary pollution.Therefore,the regeneration and recovery of activated carbon has been people's attention.At present,there are many researches on the regeneration methods of activated carbon,among which the thermal regeneration method is the most widely used and the most mature one in industry.But the thermal regeneration method also has some problems,such as high energy consumption,large carbon loss and recovery of useful substances,as well as the operation process is complex.In this paper,a new process,was used to regenerate the saturated activated carbon adsorbed by phenol by ultrasonic cavitation and super-agitation.Ultrasonic wave adopts three different frequencies of 45 KHz,80KHz and 100 KHz.The power of each ultrasonic generator is 50 KW with adjustable power.In the experiment,the saturated activated carbon adsorbed by phenol was treated with ultrasonic wave of single frequency and ultrasonic wave of dual-frequencies.it was found that ultrasonic wave was effective for activated carbon regeneration.In the experiment,when using 45 KHz,80KHz and 100 KHz ultrasonic waves to regenerate saturated activated carbon adsorbed phenol at a single frequency,45 KHz had the best regeneration effect,reaching more than 60%.With the increase of frequency,the analytical rate of activated carbon decreased.It indicates that low frequency ultrasound should be used for activated carbon regeneration.When the power of ultrasound increases,the analytical rate of activated carbon increases,but it does not increase infinitely with the power.When the power reaches the optimal value,increasing the power will only increase the energy consumption,and the increase of the analytical rate of activated carbon has no practical significance.The regeneration of activated carbon was also studied by dual-frequency ultrasonic wave for the first time.The experimental results show that this method is not only feasible,but also better than single frequency ultrasonic regeneration under certain experimental conditions.In the experiment,45 KHz,80KHz and 100 KHz ultrasonic waves were combined in pairs,and ultrasound waves were emitted at different angles to act on activated carbon at the same time to regenerate it.Under the same power,the effect of dual-frequency ultrasonic regeneration ofactivated carbon is better than that of single-frequency regeneration.When the regeneration is using dual-frequency,and the two ultrasonic generators act at a certain angle,the regenerated effect is good,and the regenerated efficiency can reach more than 80%.We regard 45 KHz as the main channel that produces cavitation effect,and other frequencies as auxiliary channels,it can be concluded from the experimental results that the contributions of each auxiliary channel to the enhancement of chemical yield of the main channel are: 45KHz>80KHz>100KHz in turn.The superposition of two sound waves with the same frequency may provide enough cavitation energy again.The result of energy superposition is to promote the occurrence of cavitation and enhance the effect of cavitation regeneration.Multi-sound source,especially multi-sound source with a certain angle,is more conducive to transfer energy to the internal activated carbon,so that the deep part of the micro-pore can be recycled.Therefore,the regeneration effect is obviously better than single-frequency regeneration with the same power,or dual-frequency regeneration effect with different frequencies.For the ultrasonic regeneration of activated carbon,the analytical process mainly depends on the physical action.The cavitation effect of low frequency ultrasound is better than that of high frequency ultrasound.Under the experimental conditions,main frequency use 50KW45 KHz,auxiliary frequency use combination technology of 30°50KW45KHz,the regeneration effect is the best,regeneration efficiency can reach 86.2%.Particle size has a significant effect on ultrasonic regeneration.The preliminary results show that when the activated carbon particle size is less than 0.6mm,the ultrasonic effect is relatively stable,but when the activated carbon particle size is greater than 1.0mm,the ultrasonic regeneration effect is difficult to meet the requirements of engineering application.The carbon loss of activated carbon during regeneration was also investigated.The experimental results show that the carbon loss can be controlled within a small acceptable range.Using 50W45KHz×30 °50W45KHz dual-frequency ultrasound to act directly on the activated carbon,the carbon loss is only about 0.5%,and it is 10% ~ 17% of conventional thermal destruction.In this paper,a new method for the regeneration of saturated activated carbon is proposed,which provides a theoretical basis for the practical application of dual-frequency ultrasonic coordinated regeneration of activated carbon.