强碱性离子交换纤维吸附Cr(Ⅵ)的热力学(英文)

通过静态吸附实验,采用强碱性离子交换纤维(SAAEF)去除水溶液中的Cr(VI)。分别研究了时间、Cr(Ⅵ)的初始浓度和pH对该吸附过程的影响。SAAEF的最大饱和吸附量为187.7mg/g(pH=1)。饱和吸附量随着Cr(VI)浓度的升高而增大,在pH1的酸度范围内,随着pH值的增高而减少。采用Langmuir、Freundlich、Dubinin-Radushkevich和Temkin4种热力学模型对不同温度的等温吸附曲线进行拟合,结果表明,Langmuir等温吸附模型是描述SAAEF吸附Cr(VI)热力学过程的最佳模型;模型参数表明,SAAEF吸附Cr(VI)的过程既存在物理吸附又存在化学吸附。热力学参数ΔH、ΔG和ΔS表明,该吸附过程为一放热、熵增的自发过程。热力学参数Q(iso)不为常量,表明SAAEF表面存在能量分布不均匀的现象。     

纳米TiO_2对钼(Ⅵ)的吸附性能

研究纳米TiO_2对Mo(VI)的吸附过程,考察溶液的pH值、时间、温度等因素对吸附的影响.结果表明:在pH 1～8范围内,纳米TiO_2对Mo(VI)的吸附率均超过99%,吸附于纳米TiO_2上的Mo(VI)可用2.0 mL的0.1 mol/L NaOH溶液定量洗脱;该吸附过程符合准二级反应动力学模型,其反应的表观活化能为22.7 kJ/mol,粒子内部扩散过程是其吸附控制步骤,但液相边界层向粒子表面的扩散过程不能忽略;吸附行为服从Langmuir和D-R等温模型.在室温下,纳米TiO_2对Mo(VI)的饱和吸附容量为12.74 mg/g,平均吸附能为17.36 kJ/mol;吸附反应焓变和熵变均为正值,自由能变为负值,说明该吸附过程为自发的吸热过程.     

SQD-85树脂对水溶液中镱(Ⅲ)的吸附(英文)

用化学和红外光谱等方法研究SQD-85树脂对镱(III)的吸附和解吸行为,探讨溶液pH、镱(III)初始浓度、温度以及吸附时间对吸附量的影响。结果表明,SQD-85树脂在pH5.5的HAc-NaAc缓冲体系中对镱(III)的吸附效果最佳,测得树脂在308K时的静态饱和吸附量为347.6mg/g;等温吸附符合Langmuir模型;吸附动力学符合假二级动力学模型。热力学参数表明,SQD-85树脂吸附镱(III)是自发的吸热过程。动态实验结果符合Thomas模型。当用1.0mol/LHCl作解吸剂时,解吸率可达97.3%。因此,使用SQD-85树脂可以有效地去除和回收水溶液中的镱(III)。     

紫外-可见光催化活性的硫酸铵改性含钛高炉渣光催化剂的制备(英文)

以含钛高炉渣和硫酸铵为原料,利用高能球磨法制备硫酸盐掺杂的含钛高炉渣(STBBFS)光催化剂。利用X射线光电子能谱(XPS)、X 射线衍射(XRD)、扫描电镜(SEM)、紫外-可见吸收光谱(UV-Vis)、热重(TGA)分析以及暗态吸附 Cr(VI)废水、光催化还原 Cr(VI)废水实验对 STBBFS 催化剂的物相、表面结构、光吸收能力、吸附容量以及光催化活性进行表征。结果表明:Cr(VI)在 STBBFS 催化剂表面上的吸附遵循 Langmuir 吸附等温线模型;掺杂硫酸盐后,STBBFS 催化剂的吸附容量增大为 8.25 mg/g;在 300 °C煅烧后,STBBFS 催化剂由于存在较高的钙钛矿含量、吸附容量及表面酸性,从而具有较高的光催化活性。     

001×14.5强酸性树脂对铬(Ⅲ)的吸附性能

采用离子交换树脂法吸附铬(Ⅲ),通过树脂选型确定强酸性阳离子交换树脂001×14.5对铬(Ⅲ)吸附容量最大,用所选的001×14.5树脂研究铬(Ⅲ)的吸附性能。静态吸附实验表明:转速大于120 r/min时,对树脂吸附的影响可忽略,即外扩散基本消除,pH=7.0时,吸附最佳,铬(Ⅲ)吸附率随树脂用量的增加而增大;001×14.5树脂吸附铬(Ⅲ)的过程符合Langmuir等温曲线,且为优惠吸附;吸附过程符合拟二级动力学方程,吸附过程的表观活化能Ea=23.4 kJ/mol,颗粒内扩散为吸附速率的主要控制步骤;用1 mol/L的硫酸对吸附后的饱和树脂进行脱附再生,脱附率可达99%。     

D751螯合树脂吸附酸性溶液中钒(Ⅳ)离子的机制

用螯合树脂D751吸附酸性溶液中的钒(Ⅳ)离子,考察溶液pH、钒初始浓度、温度及杂质离子浓度对吸附效果的影响,并分析了吸附等温线及动力学和热力学过程,探讨吸附机理。结果表明：D751树脂对酸性溶液中的钒(Ⅳ)离子有较强的吸附能力(最大吸附量为78 mg/g),钒吸附率保持在80%以上,同时铁吸附率保持在20%以下,表明D751树脂适合用于酸性钒(Ⅳ)溶液的钒铁分离。酸性溶液中D751树脂吸附钒是自发吸热过程,熵增为驱动力。朗缪尔等温模型能很好地拟合实验数据,表明D751树脂吸附钒是单分子层吸附。D751树脂吸附钒的过程受内扩散与液膜扩散协同控制。根据吸附前后D751树脂红外光谱变化推测其吸附机制为：树脂表面双羧基官能团与溶液中钒酰基阳离子形成稳固的配位键,钒离子成功地被吸附在树脂上。     

双室微生物燃料电池对电解锰废水中Cr(VI)的去除及其产电性能研究

构建以F026为阳极产电菌和含Cr(VI)电解锰废水为阴极液的双室微生物燃料电池(MFC)。考察电解锰模拟废水pH、Cr(VI)初始质量浓度、MFC运行温度等因素对废水中Cr(VI)的还原率及MFC产电效果的影响规律,并对最优条件下MFC处理实际电解锰含铬废水的效果和Cr(VI)的还原产物进行研究。结果表明:当废水pH为2、MFC运行温度为303K时,MFC对含Cr(VI)废水具有最佳的处理效果。在此条件下,MFC对Cr(VI)质量浓度为124 mg/L的电解锰废水处理80 h后,92.1%的Cr(VI)可有效还原为α-Cr_2O_3,而155h处理后还原率可达100%,产电功率达到914.7 mW/cm~2,表明MFC是一种发展前景良好的含Cr(VI)电解锰废水处理工艺。     

D301树脂对铁氰溶液中Fe(Ⅲ)及CN-的吸附行为及机理

研究铁氰溶液中D301树脂对Fe(Ⅲ)及CN-的吸附性能及过程的动力学和热力学参数.结果表明:25 ℃时,D301树脂(湿树脂)对Fe(Ⅲ)及CN-的饱和吸附量分别为2.173 49 mg/mL和28.963 2 mg/mL.吸附过程符合Lagergren二级速度方程,以液膜扩散为主控步骤.树脂对Fe(Ⅲ)及CN-的吸附速率方程分别为:t/Qt=0.057 1 t+2.415和t/Qt=0.427 9 t+4.572 1,吸附速率常数分别为k2=1.35 mL/(g·min)和k2=39.9 mL/(g·min).热力学研究表明,吸附过程的焓变分别为:ΔHCN-=16.78 J/mol,ΔHFe3+=11.07 J/mol,表明吸附过程是吸热过程.     

D320树脂对Au(Ⅲ)的吸附性能研究

研究了D320树脂从酸性含金氯化溶液中吸附金的性能,考察了吸附时间、pH值、温度、氯离子浓度等因素对树脂吸附金的影响.结果表明,在pH=1时树脂的吸附效果最佳,静态饱和吸附容量可达到244.9mg/g(Au/干树脂),温度越高越有利于吸附,反应热焓△H=28.72kJ·mol-1.吸附平衡服从Freundish吸附等温式.用8%硫脲-1mol/L H2SO4混合液可以将树脂上的金完全解析.     

D113弱酸性树脂对锌(Ⅱ)的吸附性能

研究用D113弱酸性树脂吸附锌(Ⅱ)的过程.结果表明D113树脂对锌离子的吸附在pH=6.20的Hac-NaAc介质中最佳,每克树脂在298 K下静态饱和吸附容量为172 mg;用2～3 mol/L的盐酸溶液进行洗脱,一次洗脱率可达100%.不同温度下,树脂吸附锌的表观吸附速率常数分别为k288k=1.82X 10-5/s、k298K=2.34X 10-5/s、k308k=2.81×10-5/s、k313k=3.26×10-5/s;表观吸附活化能Ea=17.0 kJ/mol.测得热力学参数分别为△H=30.3 kJ/mol,△S=160J/(mol·K),△G=-17.4 kJ/mol等温吸附服从Frcundlich和Langmuir经验式.     

Adsorption of XSD-296 resin for Cr（Ⅵ）

The adsorption properties of XSD-296 for Cr（Ⅵ） were studied by using chemical analysis and infrared spectrometry. Experimental results show that XSD-296 resin has a good adsorption ability for Cr（Ⅵ） at pH=2.6 in the HAc-NaAc medium. The statically saturated adsorption capacity is 235 mg/g resin. The apparent activation energy of adsorption reaction, Ea, is 16.73 kJ/mol, and the thermodynamic parameters are △H=11.62 kJ/mol, △G298 K=-4.13 kJ/mol. The adsorption behavior of resin for Cr（Ⅵ） is in accordance with Freundlich adsorption isotherm. Cr（Ⅵ ） adsorbed on resin can be eluted by 5%NaCl-5%NaOH or 5%NH4Cl-5%NH3-H2O quantitatively. Infrared spectra and adsorption mechanism show that the functional group of resin coordinates with Cr（Ⅵ） to form co-ordination compound. The coordination molar ratio of the functional group of resin to Cr（Ⅵ） is 1：1.     

Development of hydrometallurgical process for indium recovery from waste liquid crystal display using Cyphos IL 101

The main goal of this study was to recover indium from the waste liquid crystal display (LCD) panel. In this context, an ionic liquid Cyphos IL 101 was explored. The extraction parameters such as equilibration period, acid concentration, chloride ion concentration, hydrogen ion concentration were examined on the extraction efficiency of Cyphos IL 101 towards In(III). Quantitative extraction of indium was found at 2.0 mol/L HCl using 0.005 mol/L Cyphos IL 101 and quantitative stripping with 1.0 mol/L H₂SO₄. Job's method was used to determine the extracted species and R₃R‘PInCl₄ (R=C₆H₁₃; R′=C₁₄H₂₉) was proposed. Based on the observations on multi-metal studies, Cyphos IL 101 was further employed for the removal of indium, tin and copper from the leach liquors of waste LCDs. Optimized conditions were generated for the recovery of indium from waste LCDs. McCabe−Thiele diagram analysis, counter-current extraction and selective stripping were carried out to separate the metal ions, i.e., indium, tin and copper. Two stages at O/A ratio of 1:3 were required for complete removal of tin from the feed and selective stripping of In and Sn was achieved using 0.1 mol/L H₂SO₄. A scheme for separating indium from the waste LCDs was proposed.     

用磷酸三丁酯浸渍树脂从硝酸介质中提取铈(Ⅳ)(英文)

用磷酸三丁酯(TBP)溶剂浸渍高分子交换树脂XAD-16来制备浸渍树脂。在室温下,将未稀释的磷酸三丁酯与树脂按液固比6(磷酸三丁酯体积与树脂质量比)浸渍24h得到的浸渍树脂的质量比为1.944;按液固比3.0浸渍24h,得到的浸渍树脂的质量比为1.88。将从埃及独居石矿砂得到的含37%铈、1.6%钍和40%三价稀土氧化物的氧化铈(IV)精矿浸出得到的硝酸铈溶液,用所制备的浸渍树脂从该铈溶液提取铈。在室温下,用该浸渍树脂从硝酸介质中提取Ce(IV)的效果是令人满意的。在溶液中含51.57g/L铈、2.48g/L钍、5.0mol/L游离硝酸,溶液与树脂比为10.0,浸渍时间为5.0min的条件下,该浸渍树脂对Ce(IV)的负载容量达到理论值(173g/kg(Ce/SIR))的95.6%。在其他条件不变的情况下,将铈的浓度提高到91.43g/L,浸渍树脂对Ce(Ⅳ)的负载容量达到理论值的98.75%。     

Study of hexavalent chromium ion adsorption on nano-porous anodic aluminum oxide

The present study evaluates adsorption of hexavalent chromium ion (Cr(VI)) from contaminated solution on nano-porous anodic aluminum oxide (AAO). The AAO sorbent was characterized by field emission scanning electron microscope (FE-SEM) and Fourier transform infrared (FTIR) spectroscope. Effects of the solution pH, contact time, and AAO quantity on Cr(VI) adsorption were investigated. It was shown that Cr(VI) adsorption on AAO was strongly pH dependent and Cr(VI) removal increased by decreasing of the pH, Cr(VI) displays anion-type sorption behavior on the AAO sorbent. Chromium ion removal of 82% was obtained at presence of 0.05 g/L AAO, pH of 1, and contact time of 40 min in the solution.     

Effect of acidic surface functional groups on Cr（VI） removal by activated carbon from aqueous solution

The activated carbon with high surface area was prepared by KOH activation. It was further modified by H2SO4 and HNO3 to introduce more surface functional groups. The pore structure of the activated carbons before and after modification was analyzed based on the nitrogen ad-sorption isotherms. The morphology of those activated carbons was characterized using scanning electronic microscopy (SEM). The surface functional groups were determined by Fourier transform infrared spectroscopy (FTIR). The quantity of those groups was measured by the Boehm titration method. Cr(Ⅵ) removal by the activated carbons from aqueous solution was investigated at different pH values. The results show that compared with H2SO4, HNO3 destructs the original pore of the activated carbon more seriously and induces more acidic surface functional groups on the activated carbon. The pH value of the solution plays a key role in the Cr(Ⅵ) removal. The ability of reducing Cr(Ⅵ) to Cr(Ⅲ) by the activated carbons is relative to the acidic surface functional groups. At higher pH values, the Cr(Ⅵ) removal ratio is im-proved by increasing the acidic surface functional groups of the activated carbons. At lower pH values, however, the acidic surface functional groups almost have no effect on the Cr(Ⅵ) removal by the activated carbon from aqueous solution.     

Characterization of Cr（Ⅵ） resistance and reduction by Pseudomonas aeruginosa

The experiments were conducted to evaluate the Cr(VI) resistance and reduction by Pseudomonas aeruginosa. After this bacterium tolerated 40 mg/L Cr(VI), the growth of cells was observed. The bacterial growth was obviously lower than the controls over 24 h and the binary cell fission was observed in cell morphology by scanning electron microscope. P.aeruginosa was found to be able to reduce Cr(VI) although Cr(VI) had toxic effects on the cells. The results demonstrate that Cr(VI) is reduced from 40 mg/L to about 18 mg /L in 72 h. The value of pH drops from 7.02 to around 5.65 after 72 h. A significant increase in the value of redox potential occurs during Cr(VI) reduction and Cr(VI) reduction can be observed over a range of redox potential from +3 mV to +91 mV. Both of SO₄²⁻ and NO₃⁻ have no effect on Cr(VI) reduction. The presence of Zn²⁺ has a notable inhibitory effect on Cr(VI) reduction while Cu²⁺ substantially stimulates Cr(VI) reduction. In the presence of Zn²⁺, Cr(VI) decreases from 40 mg/L to only 26–27 mg/L, whereas Cr(VI) drops to 1–2 mg/L after 48 h in the presence of Cu²⁺.     

Comparative study on biosorption of Pb（ Ⅱ ） and Cr（Ⅵ） by Synechococcus sp.

The comparative study on adsorptions of Pb（ Ⅱ ） and Cr（Ⅵ） ions by free cells and immobilized cells of Synechococcus sp. was performed, in which different aspects including Zeta potential of the cells, the influence of pH, temperature and initial concentration of metal ions, as well as adsorption kinetics and mechanism were referred. The lyophilized free cells have a surface isoelectric point at pH 3, and the correlative experiment indicates that there is an electrostatic adsorption feature of Cr（Ⅵ） and Pb（ Ⅱ ） The immobilization of the free cells by Ca-alginate does not significantly modify the adsorption features of the biosorbent. The absorption processes of Cr（Ⅵ） and Pb（Ⅱ） on both free and immobilized cells are apparently affected by pH and the initial concentration of metal ions in the bulk solution, but are much weakly affected by temperature in the test range of 10-50 ℃. The slow course of biosorption follows the first order kinetic model, the adsorption of Pb（Ⅱ） obeys both Langmuir and Freundlich isotherm models, while the adsorption of Cr（Ⅵ） obeys only Freundlich model. FT-IR results indicate that carboxylic, alcoholic, amide and amino groups are responsible for the binding of the metal ions, and reduction of Cr（Ⅵ） to Cr（Ⅲ） takes place after Cr（Ⅵ） adsorbs electrostatically onto the surface of the biosorbents.     

振荡时间、离子强度、温度和pH值对GMZ膨润土中Cr（Ⅲ解）吸特性的影响

对吸附在高庙子（GMZ）膨润土上的Cr（III）进行解吸实验，研究振荡时间、解吸溶液离子强度、温度和pH值等因素对解吸特性的影响规律。结果表明：高庙子膨润土上Cr（III）的解吸过程较易发生；Cr（III）的解吸动力学过程较吸附过程慢，实验条件下解吸过程在3 h后达到平衡；当使用0.1 mol/L HCl、1 mol/L NaCl和1 mol/L CaCl 2作为解吸液时，Cr（III）的最终解吸率分别达89.4%,56.5%和77.2%；增大解吸溶液的离子浓度能够促进解吸过程的发生；pH值对Cr（III）解吸过程有重要影响；吸附/解吸过程较符合Freundlich等温模型。GMZ膨润土在处理Cr（III）废水时具有较好的再生能力，可以多次重复利用。