蒽在腐殖酸溶液中的增溶热力学及动力学研究

采用批平衡试验法, 研究了疏水性有机污染物蒽在腐殖酸溶液中的溶解热力学及动力学特征. 结果表明, 腐殖酸对蒽有一定的增溶性, 随着温度的升高, 增溶程度增强. 在25℃下蒽在腐殖酸溶液中的增溶行为为自发、吸热的熵增过程, ΔG~θ=-1.682 kJ/mol, ΔH~θ=11.96 kJ/mol, ΔS~θ=45.78 J/(K·mol); 在35℃、45℃下ΔG~θ分别为-2.140 kJ/mol和 -2.598 kJ/mol. 用几种溶解动力学曲线方程对腐殖酸增溶蒽的溶解动力学曲线进行了拟合, 结果表明腐殖酸增溶蒽的溶解动力学曲线更符合 Elovich 方程.     

草酸改性杨树叶对六价铬的吸附性能

利用草酸改性杨树叶为试验材料,对溶液中六价铬进行吸附去除。试验结果表明:当p H=2,吸附剂剂量为0.3 g,反应时间为120 min时,该材料对50 m L浓度为50 mg/L含铬废水的去除率达99.1%;伪二级动力学方程能较好地拟合该材料对Cr(VI)的吸附动力学过程,揭示其吸附主要是离子交换吸附;Langmuir方程能较好模拟该材料对Cr(VI)的等温吸附过程,表明其吸附主要是单分子层吸附,最大吸附量为40.91 mg/g。热力学研究表明,Cr(VI)在该材料表面的吸附是一个自发、吸热的物理吸附过程。     

大肠杆菌与水体中U(Ⅵ)的作用行为和产物研究

通过批次吸附实验及介观和谱学等表征方法,研究了大肠杆菌(E.coli)粉末对水体中U(Ⅵ)的富集行为和吸附模型,并对其作用产物进行了详细分析.结果表明:大肠杆菌对初始浓度为50mg/L U(Ⅵ)溶液(pH＝5)的吸附容量可达到276.89mg/g.Langmuir等温模型和准二级动力学方程能较好的描述其吸附过程. FTIR、SEM-EDS、XRD分析结果表明:在与水体中U(VI)作用后,大肠杆菌表面检测出UO₂²⁺的红外特征峰(876.16cm^-1)和U的能谱吸收峰(结合能=2.4~4.4keV).UO₂²⁺主要与菌体表面的烷基、氨基、羧基、分子间氢键发生作用,重点与PO₂-、P(OH)₂、PO₄^3-以及PO₃^-等含P基团进行络合配位,最终产物以CaU(PO₄)₂、Ca(UO₂)₂(PO₄)₂·xH₂O、NaUO₂(PO₃)₃等铀的磷酸盐形式存在.     

Adsorptive removal of rhodamine B from textile wastewater using water chestnut (Trapa natans L.) peel: adsorption dynamics and kinetic studies

Water chestnut peel, an agricultural bio-waste, was used as a biosorbent for removal of rhodamine B (RhB), basic textile dye, from an aqueous solution. The effects of various experimental parameters were studied. The equilibrium data correlated well with a Freundlich isotherm (R² = 0.98–0.99) followed by a Halsey isotherm model (R² = 0.98–0.99) which indicated heterogeneity of the adsorbent surface and multilayer adsorption of RhB dye onto the water chestnut peel waste (WCPW). High correlation coefficients (R² = 0.99) together with close agreement between experimental q_e (0.4–1.7 mg g^?1) and calculated q_e (0.4–2.5 mg g^?1) suggested that the adsorption process followed pseudo-second-order kinetics, with k₂ values in the range of 52–3.4 × 10^?1 g mg^?1 min^?1 at different concentrations. The overall mechanism of adsorption was controlled by both liquid-film and intra-particle diffusions. The negative values of change in Gibb's free energy (?ΔG⁰ = 19.2–29.2 kJ mol^?1) and positive values of change in enthalpy (ΔH⁰ = 30.9–117.6 kJ mol^?1) revealed the process to be spontaneous and endothermic. WCPW was found to be an effective adsorbent for removal of RhB, a cationic dye, from an aqueous solution.     

Thermodynamic and kinetic studies on Cs+- and Sr2+-exchange in natural zeolite from Akita,Japan

Thermodynamic and kinetic studies on the adsorption of Cs⁺ and Sr²⁺ by Na-exchanged clinoptilolite-rich zeolite rock from Akita (Northern Japan) were performed for the purpose of nuclear waste treatment. The thermodynamic parameters such as selectivity coefficient, thermodynamic equilibrium constant, and standard free energy of exchange were evaluated. These values indicated that the selectivity order was determined as Cs⁺ > Na⁺ > Sr²⁺. In order to discuss the adsorption mechanism of Cs⁺ and Sr²⁺ onto Na-exchanged clinoptilolite, the effective diffusion coefficients were calculated and two kinetic models, pseudo-first-order and pseudo-second-order kinetic model, were tested. For all systems studied, chemisorption seems significant in the rate-controlling step, and the pseudo-second-order kinetic model provided the best correlation of the experimental data.     

Kinetic and equilibrium study of Alizarin Red S removal by activated carbon

Activated carbon has been applied for the adsorption of Alizarin Red S (ARS) from the waste water in a batch method to obtain high removal percentage. The influence of variables such as pH, temperature, ARS concentration, mass and size of adsorbent, and contact time on ARS removal percentage was investigated. Different kinetics, thermodynamics, and isotherm models were applied for fitting the experimental data. The adsorption process follows a pseudo second-order kinetic model with R ² of 0.98 and Freundlich, Tempkin, and Dubinin-Radushkevich isotherm models with high determination coefficients (R ²) of 0.91, 0.98, and 0.98, respectively. High enthalpy (positive value), Gibbs free energy (negative value), and high entropy values shows the feasibility and the endothermic spontaneous nature of the removal process.     

腐殖酸对苯并三唑的吸附动力学及热力学研究

HA(腐殖酸)是土壤和沉积物中有机质的重要组成部分,能在很大程度上影响有机污染物的环境行为和毒理效应. 采用批量平衡法研究了BT(苯并三唑)在HA上的吸附动力学、等温吸附和吸附热力学等内容,结果表明:拟二级动力学能较好地描述BT在HA上的吸附行为,吸附过程分为快速吸附阶段和慢速吸附阶段,但主要以快速吸附为主;0~40min为快速吸附阶段,吸附总量占平衡吸附量的89.0%以上. 吸附等温线较好地符合Freundlich模型,R2均在0.9996以上. 初始ρ(BT)为300.0mg/L时,温度由288.15K升至308.15K,吸附量从15.70g/kg降至11.58g/kg,减少了26.24%. 此外,ΔH0(吸附焓变)为-30.19kJ/mol,说明吸附过程为放热反应;ΔG0(吉布斯自由能变)小于零,说明反应是自发的. 吸附反应的E_a(活化能)为19.35kJ/mol,表明吸附属于物理吸附.      

海底锰结核的热力学成因

基于同时平衡原理,采用一种新的分析方法作出了一种新的海洋环境中锰的E-pH图,根据此图,作者得出了MnO2成矿的E和pH范围,而该范围正好与海底环境的实际情况相符合,从而对海底锰结核的成因提出了一定的热力学解释。     

Combating dye pollution using cocoa pod husks: a sustainable approach

The adsorptive potential of activated carbon prepared by chemical activation of Cocoa pod husk (CPHAA) to remove Congo red (CR) dye from its aqueous solution was investigated in this study. CPHAA was characterised using Energy Dispersive X-Ray, Scanning Electron Micrograph and Fourier Transform Infrared Spectroscopy techniques. The effects of contact time, initial dye concentration, pH and solution temperature were studied. Equilibrium data were fitted to Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The equilibrium data were best represented by Langmuir isotherm model, with maximum monolayer adsorption capacity of 43.67 mg/g. The kinetic data were fitted to Pseudo-first-order, Pseudo-second-order, Elovich and Intraparticle diffusion models; the pseudo-second-order kinetic model provided the best correlation. Thermodynamic parameters such as standard enthalpy (ΔH^o), standard entropy (ΔS^o) and standard free energy (ΔG^o) were evaluated. The thermodynamic study showed that the process is endothermic, spontaneous and feasible. The mean free energy of adsorption shows that the mechanism is by physisorption. CPHAA was found to be an effective adsorbent for the removal of CR dye from aqueous solution.     

离子交换树脂D001对罗丹明B的吸附特性

采用强酸性阳离子交换树脂D001作为吸附剂吸附脱除水溶液中的罗丹明B(Rh B)。SEM和FTIR表征结果显示:D001树脂表面存在孔隙,可增加树脂的比表面积;树脂表面的磺酸基团可通过与阳离子染料Rh B络合而将其吸附。实验结果表明:Langmuir等温吸附模型能更好地描述树脂对Rh B的吸附规律,升高温度有利于树脂吸附Rh B;吸附过程符合Lagergren准一级动力学方程,初始Rh B质量浓度为20 mg/L时吸附活化能为7.06 k J/mol;树脂对Rh B的吸附是一个自发的、吸热的、熵推动的过程;颗粒扩散为吸附过程的控制步骤;树脂具有良好的重复使用性能。