外文文獻(xiàn)及翻譯---在由臭氧攪拌反應(yīng)器中有機(jī)污染物的破壞模型-文庫(kù)吧
2025-04-17 12:22 本頁(yè)面
【正文】 derived enhancement factor is an implicit expression , it is inconvenient in application to simulating the degradation rates of organic pollutants in an ozonation reactor. In this paper a simple explicit expression of the enhancement factor (Cheng , 2020) relating to the Danckwerts surface renewal model in ozone absorption with a first order ozone self2deposition and a second order ozonation or a series of parallel ozonation reactions ( ajA + Bj →pj Pj , j = 1 ,2 ?n) has been applied to predict the DCP destruction rate by ozonation in a semi2batch stirred tank reactor. 1 Mathematical model 1. 1 Destruction of one single organic pollutant in aqueous solution by ozonation When ozone is bubbled into a semibatch stirred tank containing one organic pollutant solution , both gas and liquid phases can be assumed well mixed. The mass balance for ozone in the gas phase can be expressed as (Qiu , 1999) : where cA , G , cA , G,0 , cA , i and cA ,L represent the concentration of ozone in the gas bulk , in the influent stream of the reactor ,at the gas2liquid interface and in the liquid bulk respectively. H , uG , εG are the liquid height in the reactor , the velocity of gas phase and the gas holdup fraction , respectively , and t is the absorption time. kL as is the overall volumetric ozone physical mass transfer coefficient ( kL is the physical mass transfer coefficient , as is the specific interfacial area ) , E is the enhancement factor , and their product , kL as E , denotes the chemical mass transfer coefficient as discussed above. Because no dissolved ozone was detected in most experiments ( Kuo , 1982 。 Qiu , 1999) , i. e. cA ,L ≈0 , all the fast ozonation reactions can be assumed to plete within the liquid film. Then the depletion rate of the organic ponent in the liquid phase can be written as (Sotelo , 1990) : where cB ,L refers to the concentration of organic pound B in the liquid bulk , and a is the stoichiometric ratio of the ozonation reaction. In the above two equations the interfacial concentration of ozone cA , i can be expressed as cA , i = cA , G Sr. The solubility ratio of ozone Sr is 0. 21 — 0. 28 in the pH range of 5 — 9 (Qiu , 1999) and an average value 0. 24 is adopted here. A simple explicit expression of the enhancement factor in ozone absorption with ozone self2deposition and a second order ozonation reaction was derived in our previous work (Cheng , 2020) based on the surface renewal model as where DA and DB are the diffusivity of ozone and organic B respectively. k is the second order reaction constant , kd is the first order ozone self2deposition reaction constant. It should be noted that Eq. (2) is valid only if the following condition holds M = Md + M1 [1 ( E 1) /Q] 4. 1. 2 Destruction of the mixture of organic pollutants in aqueous solution by ozonation
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