D201树脂吸附硝基苯酚的热力学研究

探讨了水溶液中D201强碱阴离子交换树脂吸附硝基苯酚的等温吸附规律及吸附热力学特性,测定了不同温度下的吸附等温线。结果表明：D201树脂吸附硝基苯酚均服从Freundlich经验式,均为优惠吸附,吸附能力大小排序为：苦味酸〉2,4-二硝基苯酚〉对硝基苯酚。树脂对苦味酸的吸附为吸热、熵增的自发过程;对2,4-二硝基苯酚和对硝基苯酚的吸附为放热、熵减的自发过程。     

层析聚酰胺树脂对茶多酚的吸附热力学和吸附动力学研究

通过静态吸附实验,研究了温度对聚酰胺树脂吸附茶汤中茶多酚的影响,探讨了吸附的热力学和动力学规律.结果表明,升高温度会降低聚酰胺树脂的饱和吸附量,但会提高初始吸附速率.等温吸附规律可用Freundlich和Langmuir方程表示,吸附过程为熵驱动的放热、熵增的自发过程,属化学吸附范畴,吸附作用力主要是氢键.吸附动力学规律可用Lagergren一级速率方程表示,以颗粒内扩散为主.     

坡缕石-活性炭-壳聚糖负载环糊精对硝基苯酚的吸附性质

研究了坡缕石-活性炭-壳聚糖负载环糊精吸附剂对对硝基苯酚、邻硝基苯酚的吸附行为以及pH、温度等对吸附的影响。在pH=5.0-7.5时,自制吸附剂对对硝基苯酚,邻硝基苯酚具有较好的吸附作用。等温吸附曲线拟合结果显示,吸附剂对硝基苯酚的吸附更符合Langmu ir方程。热力学函数计算表明,吸附剂对硝基酚的吸附是自发的放热过程,对硝基苯酚的吸附热和熵变分别为-27.49 kJ/mol和-70.39 J/(mol.K),邻硝基苯酚的吸附热和熵变分别为-29.06 kJ/mol和-78.87 J/(mol.K),吸附自由能均随温度的升高而增加。     

石墨烯对4-硝基苯酚的吸附性能研究

采用氧化-还原法制备了石墨烯,研究其吸附水中4-硝基苯酚的性能。结果表明,pH为1.0时石墨烯对4-硝基苯酚的吸附量最大;4-硝基苯酚的吸附率随石墨烯用量增加而增大,随4-硝基苯酚初始浓度的增大而逐渐减小,温度的提高有利于石墨烯对4-硝基苯酚的吸附。4-硝基苯酚在石墨烯上的吸附等温线和动力学分别符合Redlich-Peterson等温吸附模型和拟二级动力学模型,该吸附过程是吸热的且为单分子层吸附。热力学参数吉布斯自由能ΔG<0证实4-硝基苯酚在石墨烯上的吸附过程可自发进行,熵变ΔS>0表明该吸附是一个熵驱动过程,焓变ΔH=75.88 kJ/mol和活化能E=51.87 kJ/mol表明该吸附是化学吸附。     

苯酚在废盐水中的吸附平衡及动力学研究

目前对含酚废水的处理是当前化工清洁生产的一大难题,在树脂吸附废盐水中苯酚的动力学少有报道。本文研究了废盐水中树脂XDA-1对苯酚的吸附平衡及吸附动力学,吸附平衡曲线显示树脂吸附符合Freundlich模型。热力学分析表明,含苯酚废盐水中树脂吸附苯酚过程的ΔG0,说明这一吸附过程是自发过程。动力学研究表明,苯酚在树脂上的吸附符合拟二级动力学方程,r/q_r=1/k_zq_a~z+(1t/q_a。     

超高交联树脂吸附酚类的热力学研究与机理探讨

合成和表征了超高交联树脂AM-1，以大孔吸附树脂Amberlite XAD-4为参照，比较研究了其在水溶液中吸附邻硝基苯酚，对硝基苯酚的吸附行为和热力学性质，测定了不同温度下的平衡吸附量，Langmuir模型和Freundlich模型均能很好拟合。利用Freundlich模型求得△H、△G、△S。     

活性碳纤维对硝基酚的吸附行为和应用研究

研究了粘胶基活性碳纤维(ACF)在水溶液中对硝基酚的吸附行为,包括ACF对硝基酚的吸附等温线、吸附容量、再生方法、吸附和再生速率、对硝基酚的吸附选择性等。结果表明:ACF对硝基酚的吸附容量达到664mg g,该吸附是一个可逆过程,吸附和解吸速率快;采用质量分数10%的NaOH作再生剂,可以恢复吸附能力,重复进行吸附-再生过程,ACF的吸附容量不变,对硝基酚的回收率均>90%。对进水硝基酚质量浓度为9790mg L的废水,吸附处理后出水浓度达到一级排放标准,同时可以回收硝基酚。     

水溶肥料中复硝酚钠的高效液相色谱分析

文章建立了水溶肥料中复硝酚钠的高效液相色谱分析方法。使用ODS反相柱和紫外可变波长检测器,以甲醇加水(用H3PO4调至pH=3.0)为流动相,外标法对对硝基酚钠、2,4-二硝基酚钠和邻硝基酚钠进行定量分析。对硝基苯酚钠在37.33～186.66μg/mL线性范围内,线性相关系数r为0.9982,2,4-二硝基苯酚钠在41.07～205.37μg/mL线性范围内,线性相关系数r为0.9974,邻硝基苯酚钠在40.04～200.19μg/mL线性范围内,线性相关系数r为0.9976;方法的偏差为6.0×10-5(对硝基苯酚钠)、3.4×10-5(2,4-二硝基苯酚钠)、1.2×10-5(邻硝基苯酚钠),变异系数分别为0.45%(对硝基苯酚钠)、0.35%(2,4-二硝基苯酚钠)、0.12%(邻硝基苯酚钠);平均回收率为99.78%(对硝基苯酚钠)、99.758%(2,4-二硝基苯酚钠)、99.158%(邻硝基苯酚钠),变异系数分别为0.34%(对硝基苯酚钠)、0.51%(2,4-二硝基苯酚钠)、0.48%(邻硝基苯酚钠)。     

花生壳生物质炭对废水中对硝基苯酚的吸附性能研究

对硝基苯酚在各个领域中都有着重要的作用,但由于其本身属于酚类,具有较强的毒性,使用不当会造成严重的污染。本研究以花生壳为原料,采用热解法在400、500、600℃下制备花生壳生物炭,研究不同操作条件下花生壳生物炭对废水中对硝基苯酚的吸附能力。研究结果表明,在不同热解温度下的花生壳生物炭对对硝基苯酚溶液的吸附能力随热解温度的升高而增强。生物质炭吸附能力随对硝基酚的投加量增加而降低,随着花生壳生物质炭的投加量的增加而增加。600℃下所制得的生物炭对浓度为10 mg/L的对硝基苯酚溶液的吸附能力最强,且在中性环境下,去除率可以达到100%。     

酚类化合物在矿化垃圾中的吸附机理研究

研究了苯酚、2-氯酚、4-氯酚、2,4-二氯酚在矿化垃圾中的吸附性能,并从动力学和热力学角度探讨了有机酚在矿化垃圾中的吸附机理。等温吸附曲线研究表明,在试验的浓度范围内,有机酚在矿化垃圾中的吸附符合Freundlich等温吸附方程。有机酚在矿化垃圾中的吸附动力学符合二级反应动力学方程,反应受孔扩散和内部扩散共同控制。在试验的温度范围内,有机酚在矿化垃圾中的吸附是一个自发过程,温度对吸附反应的自发性有着显著的影响,自由能随着温度的升高而降低,自发性增强。     

Removal of Nitrophenols by Adsorption Using β-Cyclodextrin Modified Zeolites

Removal of nitrophenols (NPs) from aqueous solutions through the adsorption process by using cationic β-cyclodextrin (CCD) modified zeolite (CCDMZ) was investigated. The effects of particle size, contact time, solution pH values and sodium chloride content in the aqueous on adsorption capacity were evaluated through a series of batch experiments. The results showed that CCDMZ had a higher adsorption capacity for removing NPs at a size fraction of 0.45-0.9 mm while adsorption of NPs on CCDMZ reached equilibrium within 60 min. The adsorption process was apparently influenced by pH values and sodium chloride content in aqueous solution. To ascertain the mechanisms of sorption, the experimental data were modeled by using the pseudo-first and pseudo-second order kinetic equations, and the results indicated that the adsorption kinetics of NPs on CCDMZ well-matched with the pseudo-second order rate expression.     

Investigation of the Polyamide 6,6 dyeing process with Acid Blue 45 dye. Part I. Thermodynamics of Acid Blue 45 adsorption

Among the many synthetic fibres, polyamides are one of the most important. Improvement in the adsorption/ absorption strength of a dye to and inside the yarns is therefore very important for their practical applications. In this study, the kinetics and thermodynamics of the sorption process of Acid Blue 45 on Polyamide 6,6 (Nylon 6,6) were investigated. The sorption was conducted at 293, 303, and 313 ± 0.1 K for 48 h from 10^-5 -10^-4 M solutions in the presence of 10^-3 M NaCl. From the kinetic experiments it was found that this time was sufficient to attain the adsorption equilibrium. The first stage of the sorption (up to 160 min) can be well described by a first-order kinetic equation by its numerical fitting to the experimental results. It is a spontaneous process in which the rate of sorption and the sorbed amount increase with increasing temperature. However, it is a relatively slow endothermic process (positive enthalpy of sorption); thus, it must be entropy-driven to produce a negative free energy of sorption. From the sorption isotherms and calculated thermodynamic functions it can be concluded that at higher temperatures (303-313 K), more polar groups of Polyamide 6,6 are accessible for the dye molecules, which may be due to a glass transition. Data on the zeta potential changes and surface free energy components of Polyamide 6,6 will be presented in Part II of this study, which may help in a better understanding of the sorption process.     

粉末活性炭静态吸附水中硝基酚的试验研究

研究了常温(20℃)条件下粉末活性炭(PAC)对水中3-硝基酚、4-硝基酚、2,6-二硝基酚和2,4-二硝基酚4种硝基酚的静态吸附规律;并对照研究了未驯化的灭活活性污泥存在时,PAC对硝基酚的吸附性能。结果表明:PAC对4种硝基酚的吸附能力远大于灭活活性污泥;当硝基酚与PAC的质量比值在0.2~1.0时,PAC对4种硝基酚的吸附在60 min内可达到平衡,且均符合Langmiur吸附模型;用Langmiur吸附模型对试验数据进行拟合,得出了PAC对4种硝基酚的饱和吸附容量和吸附系数。     

Dye‐affinity microbeads for removal of phenols and nitrophenols from aquatic systems

Alkali Blue 6B attached poly(2‐hydroxyethyl methacrylate) (PHEMA) microbeads were investigated as dye‐affinity adsorbents for the removal of phenol and nitrophenols (i.e., 2‐nitrophenol, 4‐nitrophenol, and 2,4‐dinitrophenol) from aqueous solutions. PHEMA microbeads were prepared by radical‐suspension polymerization of HEMA in the presence of azobisisobutyronitrile as the initiator. These microbeads with a swelling ratio of 55% and carrying 23.6 μmol Alkali Blue 6B/g polymer were then used in the removal of phenol and nitrophenols from aqueous media. The adsorption was fast in all cases (20‐min equilibrium time). The maximum adsorptions of phenols onto the microbeads carrying Alkali Blue 6B were 145.2 μmol/g for phenol, 87.8 μmol/g for 2,4‐dinitrophenol, 112.6 μmol/g for 4‐nitrophenol, and 104.3 μmol/g for 2‐nitrophenol. The affinity order was phenol > 4‐nitrophenol > 2‐nitrophenol > 2,4‐dinitrophenol. The adsorption of nitrophenols decreased with increasing pH. Desorption of nitrophenols was achieved using a 30% (v/v) methanol solution. The microbeads carrying Alkali Blue 6B are suitable for repeated use for more than five cycles without a noticeable loss of adsorption capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2411–2418, 2002     

Selective Solubilization of Nitrophenols and Adsorption on Ion Exchange Resins in Nonaqueous Conditions

Abstract

Separation of nitrophenols (NP) has been studied by selective solubilization in organic solvents of different polarities. o‐NP dissolves very well in heptane and toluene while intermolecular hydrogen bonding among p‐NP molecules decreases its solubilization in these solvents. Thus partial separation of o‐/p‐nitrophenols is achieved by selective solubilization of o‐NP in heptane. The trace amounts of p‐NP from the o‐NP solutions are removed by its selective sorption on basic ion exchange resins. The sorption of nitrophenols, individually and in mixtures, is experimentally determined from their solutions in heptane, toluene, and methanol by using weakly basic Indion‐850 and Duolite A‐308 resins and strongly basic Indion‐810 resin. The equilibrium adsorption studies show very selective adsorption of p‐NP from heptane with a high loading capacity on Indion‐850.     

Synthesis and Characterization of Al‐Doped ZnO as a Prospective High Adsorption Material

This work demonstrates Al‐doped ZnO adsorbents successfully synthesized by glucose‐assisted solution combustion. The addition of glucose results in nanocomposite powders with highly fluffy network, mesoporous structure, high specific surface area, and physical properties, which in turn improve the adsorption properties. The adsorption performance of the material was studied, and the influence of Al doping concentration, adsorbents and methyl orange concentration in the solution were investigated. The addition of glucose increased the adsorption capacity of methyl orange onto Al‐doped ZnO by over 2 times. The adsorption followed the Langmuir isotherm, was spontaneous and exothermic. Kinetic calculations show that the adsorption followed the pseudo‐second‐order model with a multistep diffusion process. Thermodynamic parameters indicate that the adsorption is a feasible, spontaneous, and exothermic process.     

金属离子配位作用下PA6的受限结晶

采用熔融共混法,制备了聚酰胺6/氯化钙(PA6/CaCl2)复合材料。通过差示扫描量热法(DSC)、X射线衍射法(XRD)研究了PA6基体在受限条件下的非等温结晶及晶型转变行为。结果表明:金属离子Ca2+与酰胺基团的络合配位作用使PA6/CaCl2复合材料中PA6的结晶行为和结晶度受到了限制。随着CaCl2含量的增加,PA6的结晶度、结晶峰温度、熔融峰温度逐渐降低,结晶速率减小,结晶半峰宽增大,当CaCl2的含量大于8%时,PA6变为无定形态;此外,CaCl2的引入有利于PA6中α晶的生成。     

2-吡啶甲醛功能化SBA-15介孔材料的制备及其对Cr(Ⅲ)离子的吸附

通过席夫碱反应将2-吡啶甲醛成功嫁接到氨基化的SBA-15介孔分子筛上，本文获得了一种新型功能化SBA-15吸附剂（N-SBA-15）。采用傅里叶变换红外光谱、X射线衍射、元素分析、扫描电子显微镜、透射电子显微镜、X射线光电子能谱、热重分析和氮气吸附-脱附等手段对N-SBA-15的表面官能团、形貌、孔道结构和表面化学性质进行了详细的表征分析。利用N-SBA-15对水溶液中的Cr(Ⅲ)进行了吸附实验，其最大吸附容量为84.3mg/g。动力学分析和等温吸附研究结果表明，N-SBA-15对Cr(Ⅲ)的吸附过程符合准二级动力学模型和Langmuir模型。吸附热力学分析表明，该吸附过程是自发的吸热过程（?G<0、?S>0、?H>0）。吸附机理分析表明该吸附过程主要是由N-SBA-15表面有机官能团与Cr(Ⅲ)的配位作用实现的。而且，N-SBA-15吸附剂经过5次吸附-脱附测试，仍然对Cr(Ⅲ)具有较高的吸附容量。     

非水介质中表面引发接枝聚合法制备接枝微粒PMAA/SiO2及其对阿魏酸的氢键吸附性能

以偶联剂γ-巯丙基三甲氧基硅烷(MPMS)对微米级硅胶微粒进行表面改性,制得表面键合巯基的改性微粒MPMS-SiO2. 在非水溶剂二甲基甲酰胺(DMF)中使偶氮二异丁腈(AIBN)与MPMS-SiO2表面的巯基(-SH)构成表面引发体系(-SH/AIBN),实现甲基丙烯酸(MAA)在非水介质中的表面引发接枝聚合,制得接枝度为20 g/100 g的接枝微粒PMAA/SiO2,对其进行了表征,考察了主要因素对MAA表面引发接枝聚合的影响规律,研究了PMAA/SiO2对酚酸化合物阿魏酸的氢键吸附作用. 结果表明,-SH/AIBN可顺利引发MAA在非水介质中的接枝聚合,适宜条件为75℃,AIBN用量为单体质量的1.5%. 在PMAA/SiO2与阿魏酸分子之间可产生强氢键作用,包括高强度的多位点常规氢键与p型氢键,导致PMAA/SiO2对阿魏酸有强吸附力,吸附容量达266 mg/g. 质子性溶剂甲醇中的溶剂竞争吸附作用使阿魏酸的吸附容量降低,升高温度吸附容量降低.