Incorporating sorption/desorption of organic pollutants into river water quality model

Preliminary research was conducted about how to incorporate sorption/desorption of organic pollutants with suspended solids and sediments into single-chemical and one-dimensional water quality model of Jinghang Canal. Sedimentation-resuspension coefficient k 3 was deduced; characteristics of organic pollutants, concentrations and components of suspended solids/sediments and hydrological and hydraulic conditions were integrated into k 3 and further into river water quality model; impact of sorption/desorption of organic pollutants with suspended solids and sediments on prediction function of the model was discussed. Results demonstrated that this impact is pronounced for organic pollutants with relatively large K oc and K ow, especially when they are also conservative and f oc of river suspended solids/sediments is high, and that incorporation of sorption/ desorption of organic pollutants into river water quality model can improve its prediction accuracy.

Modeling of Adsorption of Bi(III) from Nitrate Medium by Impregnated Resin D2EHPA/XAD-1180

Di(2-ethylhexyl)phosphoric acid (D2EHPA) in acetone was supported on the Amberlite XAD-1180 polystyrene divinylbenzene copolymer resin. The use of XAD-1180 impregnated with D2EHPA for the extraction of bismuth(III) from nitrate medium was carried out using batch technique. Various parameters affecting the uptake of this metal ion were described in the previous paper (Belkhouche and Didi, 2010) and the capacity of the impregnated resin for bismuth(III) was found to be 490.7 mg/g of resin. Effect of temperature on the values of distribution equilibrium was studied to evaluate the changes in standard thermodynamic quantities. A comparison of Langmuir forms I, II and Freundlich sorption isotherms was realized and the kinetic models applied to the adsorption rate data were evaluated for Lagergren first order, the pseudo second order and Morris–Weber models. From the results, the adsorption of Bi(III) onto D2EHPA/XAD-1180 resin shown the exothermic character and followed the Langmuir form II isotherm. Thus, the capacity of monolayer adsorption of Bi(III) was equal to 769.23 mg/g of resin. Both the Lagergren pseudo first order and film-diffusion models were found to best describe the experimental rate data.

The Sorption Isosteric Heats of Rough Rice in China

Equilibrium moisture content （EMC） data for rough rice of thirteen Chinese varieties were obtained by static gravimetric method at five different temperatures （10, 20, 25, 30, and 35 ℃） and 11% to 96% equilibrium relative humidity （ERH）. Six models, i.e., Brunauer-Emmett-Teller, Guggenheim-Anderson-deBoer, Modified Chung-Pfost （MCPE）, Modified Henderson, Modified Oswin, and Strohman-Yoerger （STYE） fitted the EMC/ERH data based on the coefficient of determination, residue sum-of-squares, standard error of estimate, and mean relative percent error. The best fitted equations were MCPE and STYE, but MCPE is three-parameter, readily transformed equation and adopted in this study. The isosteric heats for both rough rice desorption and adsorption, and for both the sorption of Japonica and Indica rice, decreased rapidly with an increase in seed moisture content （m.c.） until the m.c. of 20% dry basis （d.b.） reached, and thereafter they decreased smoothly with increasing moisture content. The isosteric heats of rough rice desorption were higher than those of adsorption below the m.c. of 22.5% d.b., but thereafter, there was no significant difference found between desorption and adsorption. The sorption isosteric heats of Indica rice were slightly higher than those of Japonica rice under all moisture contents at a constant temperature. These results provide a sound basis for future work on the drying and storage of rice.

Strontium Adsorption from Sulfuric Acid Solution by Dowex 50W-X Resins

In this study,strontium adsorption from sulfuric acid solution by different Dowex 50W-X ion exchange resins was investigated.Among these resins,Dowex 50W-X8 resin showed the maximum sorption of strontium from the aqueous solutions.The effect of pH,contact time,mass of resin,temperature,and concentration of interfering ions on strontium adsorption were evaluated to determine the optimum conditions of strontium sorption process.The kinetic models of sorption were analyzed using pseudo-first and pseudo-second order models.The results indicated that the pseudo-second order kinetic model was more appropriate than the other one.Moreover,the data obtained in this study were fitted into several sorption isotherm models and it was found that the Langmuir sorption isotherm shows the best fitting to the experimental data.

Numerical simulation of PAHs sorption/desorption on soil with the influence of Tween80

In this paper, the influences of inionic surfactant Tween80 on polycyclic aromatic hydrocarbons （PAHs） sorption/desorption on artificially contaminated soil were studied, and γ model was applied to simulate the influences. Results showed that, with the use of Tween 80, the sorption behaviors of PAHs on soil altered significantly. Adsorbed Tween 80 increased the sorption amount of PAHs while the dissolved Tween80 increased the apparent solubility of PAHs. These two processes exert influences on the sorption coefficient of PAHs in soil-water system, which can be depicted by apparent sorption coefficient. The partition coefficients （the soil/water partition coefficient of PAHs and surfactants obtained fxom sorption experiments） and statistical parameters used in the amended γ model were obtained in independent experiments. With these parameters, the γ model could provide a satisfactory independent prediction of PAHs release from soil to aqueous phase at two surfactant concentrations.

Tribochemical Purification of Gases. I. The Process Model

A mathematical model of the sorption process in a tribochemical reactor with a stirrer, where monolithic granules of alkali-earth metals mutually rub in the media of the flow gas, has been built. The products of reaction of the metal with the gas impurity are continuously removed mechanically from the surface of the granules, creating new metallic regions. As a result the total area of the sorbing surface appears to be by orders of magnitude larger than that of the traditional getter materials of the same mass in the existing sorption technologies. It follows from the model that the gas purification process obeys the linear law at a constant rotation speed of the stirrer. This dependence results in a great simplification of the process control. It also makes possible replacement of a periodic mode of operation by a continuous one where the sorption capacity of the consumed chemisorbent attains theoretical limit.

Sorption Kinetic of Arsenate as Water Contaminant on Zero Valent Iron

This study investigates the sorption of arsenate from water using zero-valent iron ZVI as sorbent. Batch experiments were carried out to study the sorption kinetics of arsenate under different concentrations of arsenate varies from 0.5 to 200 mg/l. A kinetic model was considered to describe the arsenates sorption on ZVI material. The kinetics of the arsenate sorption processes were described by the Langmuir kinetic model. The sorption capacity increases with high initial concentration which obtained the maximum sorption 2.1 mg/g at 200 mg/l of arsenate initial concentration. The results show that the rapid initial sorption rates of arsenate were occurred at the beginning of experiments running time, followed by a slower removal that gradually approaches an equilibrium condition. The data from laboratory batch experiments were used to verify the simulation results of the kinetic model resulting in good agreement between measured and modeled results. The results indicate that ZVI could be employed as sorbent materials to enhance the sorption processes and increase the removal rate of arsenate from water.

Thermodynamic Model of Uranium and Arsenic Accumulation in Saline Lakes

1 Introduction The attractiveness of Shaazgai-Nuur Soda Lake(pH9.2-9.4)as an alternative metal source is explained by the high concentration of dissolved uranium(~1 mg/l)due to the location of water drainage territory within the Tsagan-

The effect of humidity on the CO_2/N_2 separation performance of copolymers based on hard polyimide segments and soft polyether chains:Experimental and modeling

In this work, we studied two copolymers formed by segments of a rubbery polyether（PPO or PEO） and of a glassy polyimide（BPDA-ODA or BKDA-ODA） suitable for gas separation and CO2 capture. Firstly, we assessed the absorption of water vapor in the materials, as a function of relative humidity（R.H.）, finding that the humidity uptake of the copolymers lies between that of the corresponding pure homopolymers values.Furthermore, we studied the effect of humidity on CO2 and N2 permeability, as well as on CO2/N2 selectivity, up to R.H. of 75%. The permeability decreases with increasing humidity, while the ideal selectivity remains approximately constant in the entire range of water activity investigated. The humidity-induced decrease of permeability in the copolymers is much smaller than the one observed in polyimides such as Matrimid? confirming the positive effect of the polyether phase on the membrane performance.Finally, we modeled the humidity-induced decrease of gas solubility, diffusivity and, consequently, permeability, using a suitable approach that considers the free volume theory for diffusion and LF model for solubility. Such model allows estimating the extent of competition that the gases undergo with water during sorption in the membranes, as a function of the relative humidity, as well as the expected reduction of free volume by means of water molecules occupation and consequent reduction of diffusivity.

分形界面吸附行为初探

煤层气吸附解吸机理研究是揭示煤层气成藏机理及高效开发煤层气的基础。已有研究表明,煤储层孔隙结构非常复杂且具有分形特征,煤层气在孔-固界面的吸附行为明显受到煤孔隙结构特征的影响。对比分析几种常用气-固界面上的吸附模型,总结这些模型的特点和适用条件,指出当前吸附模型在分形界面吸附行为的描述和应用上均未摆脱吸附选择性的平稳假设,尚未考虑吸附厚度的尺度不变特征。而分形拓扑理论可以有效标定分形对象的尺度不变属性,为分形界面的等效表征提供了理论支撑。因此,结合上述模型对气-固界面吸附行为的描述,借助分形拓扑理论提出煤储层孔-固界面上分形吸附行为的相关假设及其控制机理,构建基于吸附拓扑的单层吸附模型。在此基础上,通过设置不同的吸附拓扑参数组合获取其等温吸附曲线,分析得出,随着吸附压力的升高,吸附覆盖率表现出指数、线性和对数3种不同的增长趋势,而吸附热表现为对数减小趋势。结果显示,不同的吸附拓扑参数组合会得到不同类型的等温吸附曲线,在一定程度上弥补了Langmuir方程只能描述单一类型等温吸附线的不足。为了验证吸附模型的适用性,结合沁水盆地武乡区块富有机质泥页岩的液氮吸附实验数据,对比了实际等温吸附曲线与模拟吸附曲线的差异。结果表明,通过调整各吸附拓扑参数之间的组合关系,可以使等温吸附模拟曲线与实际吸附曲线的趋势始终保持一致。最后,探讨了吸附解吸机理的研究方向,类比电子层提出了吸附层的概念,指出发展分形动力学描述模型是解释煤层气吸附解吸规律的关键。

Sorption and desorption kinetics of phthalates and phenol on water/sediment interface

The sorption and desorption kinetics of dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and phenol on water and sediment interface were studied using two compartment model in this paper. The results showed that the sorption coefficients of DMP, DEP, DBP and phenol measured by batch equilibrium method were 16.79, 24.55, 132 and 0.65μg 1-1/n · g -1 · ml -1/n , the sorption and desorption kinetic constants of DMP, DEP, DBP, phenol were 0.0248, 0.0357, 0.0727, 0.014ml·cm -2 ·h -1 and 0.000512, 0.000754, 0.00127, 0 000899h -1 at static condition respectively; and the sorption and desorption kinetics constants of above chemicals were 0 279, 0.382, 0.496, 0.0904ml·cm -2 ·h -1 and 0.0442, 0.0031, 0.00116, 0.00247h -1 at flow water condition respectively.

Kinetics and Thermodynamic Studies: Adsorption of Pb, Cr and Ni Ions from Spent Lubrication Oil (SLO) Using Acid Modified Clay

Adsorption of Pb, Cr, and Ni ions from spent lubrication oil (SLO) by sulphuric acid modified clay (SAMC) was investigated considering the effect of contact time and temperature of the adsorption system. The removal percentage of the heavy metals was found to be temperature and contact time-dependent. Adsorption of the heavy metals increases with an increase in temperature and contact time with 95.0% - 100% adsorption recorded at the temperature of 331 K with the equilibration time of 12 hours. The thermodynamic and kinetics investigation of the adsorption process showed that the adsorption of these metals by the modified adsorbent is a spontaneous and endothermic physical adsorption process that followed the pseudo-second-order kinetic model.

3D FINITE ELEMENT ANALYSIS OF THE DAMAGE EFFECTS ON THE DENTAL COMPOSITE SUBJECT TO WATER SORPTION

The damage effects of water sorption on the mechanical properties of the hydroxyapatite particle reinforced Bis-GMA/TEGDMA copolymer （HA/Bis-GMA/TEGDMA） h-ave been predicted using 3D finite cell models. The plasticizer effect on the polymer matrix was considered as a variation of its Young＇s modulus. Three different cell models were used to determine the influence of varying particle contents, interphase strength and moisture concentration on the debonding damage. The stress distribution pattern has been examined and the stress transfer mode clarified. The Young＇s modulus and fracture strength of the Bis-GMA/TEGDMA composite were also predicted using the model with and without consideration of the damage. ine Iormer results with consideration of the debonding damage are in good agreement with existing literature experimental data. The shielding effect of our proposed model and an alternative approach were discussed. The FCC cell model has also been extended to predict the critical load for the damaged and the undamaged composite subject to the 3-point flexural test.

非平衡条件下金属氯化物-氨工质对的吸附动力学研究

金属氯化物-氨是化学吸附式制冷和储热的常用工质对,其现有的动力学模型存在复杂或动力学参数变化无规律的问题,也不能准确地独立描述多反应阶段的吸附过程。以MnCl_(2)/NH3和CaCl_(2)/NH_(3)为代表工作对,针对0.29、0.42和0.61 MPa的反应压力,进行吸附/解吸性能测试,在类比模型基础上耦合Sigmond函数,建立考虑压力势(μ)、反应速率常数(k)和反应滞后常数(n)的吸附量型动力学模型。鲁棒性测试结果表明:针对不同氯化物、不同反应阶段(Ca_(2-4-2)和Ca_(4-8-4))和不同反应方向(吸附和解吸)所建立的非平衡动力学模型的拟合曲线与实验数据点吻合度较高,拟合优度R2均高于0.97;模型参数随工况呈规律变化,同一反应压力下k与吸附温度负相关,与解吸温度正相关,|n|与解吸温度负相关。

90Sr在微风化二长花岗岩中迁移实验及模拟研究

采用加压的方式,利用动态柱实验方法,通过3H、90Sr在微风化二长花岗岩中的穿透曲线,研究了90Sr在微风化二长花岗岩中的迁移规律,获得90Sr在微风化二长花岗岩中的迁移参数。实验中控制流速为1 mL/h,3H总活度为10^(4)Bq,迁移实验进行了120 h,3H浓度峰值出现在8.0 h,活度浓度峰值为213.4 kBq/L,穿透曲线无明显拖尾现象;90Sr总活度为5×10^(4)Bq,迁移实验进行了132 d,90Sr浓度峰值出现在27.4 d,活度浓度峰值为46.26 kBq/L,浓度下降阶段呈现明显的拖尾现象。利用数值模拟方法,基于3H的穿透曲线计算得到微风化二长花岗岩的垂向弥散度为3.03 cm;对比了平衡模型、双点吸附模型、两区模型、双点吸附两区模型四种模型下90Sr在微风化二长花岗岩中的迁移拟合结果,发现四种模型拟合结果相差较大,其中双点吸附两区模型通过引入非流动区含水量、溶质交换一级速率系数、非平衡吸附一级速率系数等参数能够更好地描述核素在微风化二长花岗岩介质迁移过程中的拖尾现象。结果表明:90Sr在微风化二长花岗岩中的吸附分配系数为1.23 mL/g,溶质交换一级速率系数为0.227/d,非平衡吸附一级速率系数为0.118/d。

近海沉积物组份对有机物的吸附与吸附机理探讨

以大连近海沉积物主要组份碳酸钙、金属氧化物、腐殖酸和粘土矿物为沉积物模拟样品，测定该４种组份对硝基苯等４种毒性有机的吸附等温线，在此基础上建立了多组份吸附剂吸附等温模式。通过吸附热的测定，探付了４种沉积物组份吸附毒性有机物的机理。

溶解有机质在土壤及沉积物吸附多环芳烃类有机污染物过程中的作用研究

研究了采自官厅水库及周围水域的 6种土壤及沉积物样品对多环芳烃类有机化合物———萘、菲、芘的吸附特性 ,应用1H NMR对这 6种土壤及沉积物样品中的溶解有机质的化学组成进行了的测定 ,发现溶解有机质中芳香族和非极性脂肪族化合物的含量与Freundlich吸附容量 (K′f)之间存在着密切关系 ,Freundlich吸附指数 (n)随着溶解有机质中极性基团的增多而降低 ,但是极性芳香族成分在吸附过程中主要充当有机溶剂相 .另外 ,吸附质的化学特性对吸附也有重要影响 ,logK′f 与logKow(Kow为辛醇 水分配系数 )之间存在着线性关系 .依据溶解腐殖质的两性特征及上述结论建立了一种快速吸附模型 。

膨胀石墨的孔隙结构及其在液相吸附吸着时的变化

用氮气吸附法和压汞法测量膨胀石墨 (EG)的孔结构 ,用SEM观察EG颗粒间的孔隙结构和EG的孔隙率。实验得到 ,EG颗粒间的孔隙率占 85 %以上 ,EG颗粒开放孔的孔隙率占 13%以上 ,EG颗粒的闭合孔的孔隙率不到 1%。研究得到 ,EG颗粒的孔隙分为四级结构 ,包括颗粒片断间的V型开放孔 ,尺度数十到数百微米 ;与蠕虫状颗粒轴向垂直的几个到数十微米的柳叶状孔 ;垂直颗粒轴向的片层面上的零点几到几个微米的孔以及BET测量得到的纳米级孔。EG的比表面积 <10 0m2 g。在液相吸附 吸着作用中 ,由于EG与液相的界面张力作用 ,EG颗粒中的孔隙发生变形以及使颗粒碎裂。

非离子表面活性剂在土壤/沉积物中的吸附模型研究

采用振荡平衡法研究了非离子表面活性剂Brij35、Brij30、Tween-80、TritonX-100在土壤/沉积物上的吸附行为及Brij35、Brij30在不同处理土壤上的吸附特征。结果表明,Brij35、Tween-80、TritonX-100在土壤/沉积物上的吸附等温线呈Langmuir型,而Brij30呈S型,其达到吸附饱和时的平衡浓度分别为110、55、200、25mg·L^(-1);Brij35、TritonX-100和ween-80主要通过疏水基在土壤/沉积物有机质中的分配作用而吸附,而Brij30的吸附是亲水基团与土壤/沉积物表面的相互作用以及疏水基团之间相互作用共同作用的结果。

核素迁移的二维非平衡吸附数值模式研究

为了进一步研究核素在孔隙介质中的迁移规律，本文将水动力弥散方程与核素在孔隙介质中非平衡吸附关系式相耦合，建立了非平衡吸附数值模式，并给出了非平衡吸附数值模式中吸附解吸速率参数的获取方法．为了检验所建模式与编制的程序的正确性，利用试验场（８５）Ｓｒ迁移的野外试验资料进行了计算，并与核素迁移平衡吸附数值模式的计算结果进行了对比．结果表明，二维非平衡吸附核素迁移数值模式能够更好地描述核素迁移实际．