多孔介質(zhì)中三氯乙烯的非線性吸附-對流-彌散模型(存儲版)
【正文】 eic Algorithm Toolbox[M]. Xi’an: University of Electronic Science and Technology of China Press, 2022: 16.34 生態(tài)環(huán)境 第 17 卷第 1 期（2022 年 1 月）Modeling trichloroethylene transport in porous media based on advectiondiffusion equation coupled with nonlinear adsorptionLu Jiansheng, Wu Yanqing, Ma Changwen, Sun ChengxingSchool of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 202240，ChinaAbstract: It is significant to investigate the transport of trichloroethylene (TCE) in porous media in order to evaluate its influence and predict the possible fate. Batch tests and column experiments were conducted respectively. Results from batch tests showed that the adsorption isotherms of TCE fitted the LinearLangmuirFreundlich (LLF) model very well which can reveal the mechanisms of adsorption and partition. However, after the longitudinal dispersivity was determined by utilizing the nonlinear least squares method based on the column experiments results with KCl as tracer, the adsorption parameters were inversed with generic algorithm and nonlinear adsorptionadvectiondiffusion model based on the investigation in column experiments, the results implied that Langmuir isotherm model could describe best the adsorption mechanisms of TCE in the columns. The difference made it necessary to reconsider the applicability of nonequilibrium adsorption theory carefully. The nonlinear adsorptionadvectiondiffusion model, which reveals the transport mechanisms of TCE in porous media, was established based on the experiments and the inversed parameters mentioned above, and the retardation factor in the nonlinear adsorptionadvectiondiffusion model was the nonlinear function of the solute concentration.Key words: trichloroethylene。（4）在批試驗(yàn)中 TCE 吸附的機(jī)理是表面吸附與分配作用共同作用，而在柱試驗(yàn) 中，由于受到水流運(yùn)動等因素的影響，其吸附機(jī)理 為表面吸附。同時(shí)發(fā)現(xiàn)在運(yùn)移過程中存在明 顯的拖尾現(xiàn)象，其主要原因在阻滯系數(shù)是隨溶質(zhì)質(zhì)量濃度變化而變化的。這種情況下采用模型1（Langmuir 吸附模式）的擬合結(jié)果最佳，可以理解為受到水流運(yùn)動的影響，溶質(zhì) 不易吸附到固體表面的外層，也即此時(shí)的吸附應(yīng)滿 足于單分子層吸附，溶質(zhì)間的作用力很小，這正是 Langmuir 吸附模式的前提假設(shè)。在遺傳算法中，以計(jì)算值和實(shí)驗(yàn) 數(shù)據(jù)差的平方和作為適應(yīng)度函數(shù)：2TCE01()niiif???? (16)式中 為計(jì)算值， 實(shí)驗(yàn)值 。h1，al= cm在等溫平衡吸附試驗(yàn)的基礎(chǔ)上，采用 3 種不同的等溫吸附模式來建立模型：模型 1：吸附模型方程符合方程(2)，則依據(jù)方程(7)可確定阻滯系數(shù)為： TCE2TCE()R()mllK??????? （8）模型 2：吸附模型方程符合方程(3)，則依據(jù)方程(7)可確定阻滯系數(shù)為： 1TCETCE2(1)())nmlK??????? （9）模型 3：吸附模型方程符合方程(4)，則依據(jù)方程(7)可確定阻滯系數(shù)為： 1TCETCE2(1)R())nmld????????? （10）上述 3 個(gè)模型中的吸附參數(shù) Sm、Kl、n、Kd 都是滲透速度 V 的函數(shù)，本試驗(yàn)中由于速度恒定，所以其值按常數(shù)計(jì)算。tt=, ()t。???????利用 軟件 [17]，采用非線性最小二乘法和方程（5）的解析解對實(shí)驗(yàn)數(shù)據(jù)進(jìn)行擬合，得到KCl 溶液在砂柱中遷移穿透曲 線圖，如 圖 4 所示，參數(shù)反演結(jié)果為 V= cmL)LLF圖 1 TCE 在石英砂中的等溫吸附擬合曲線Fig. 1 The isotherm adsorption and fitted curves of TCE to quartz sand表 1 TCE 分別在石英砂和 細(xì)砂中的等溫非線性吸附模型參數(shù)擬合Table 1 Fitting parameters by isotherm nonlinear adsorption models of TCE adsorbed to fine sand and quartz砂種類 Freundlich Langmuir LF LLF5 號石英砂 Kf= wm= wm= wm=n= Kl= Kl = Kl =n= n=Kd=*1015R2= R2= R2= R2=細(xì)砂 Kf= wm= wm = wm =n= Kl= Kl = Kl =n= n=Kd=R2= R2= R2= R2=ρTCE/(mgL)abC圖 3 分配作用與表面吸附作用在不同的 TCE質(zhì)量濃度時(shí)的吸附等溫曲線 Th
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