SORPTION OF PHENOL AND P-NITROPHENOL ONTO A WEAKLY ANION EXCHANGER： XPS ANALYSIS AND MECHANISM

X-ray photoelectron spectroscopy (XPS ) was adopted to elucidate sorption mechanism of phenol and p-nitrophenol onto a weakly anion exchanger D301. The distribution of specific forms of tertiary amino group on D301 was obtained and effect of free tertiary amino group on phenol sorption onto D301 was discussed. The result indicated that the percent of the protonated tertiary amine group on polymeric matrix was much lower than the reference compound N,N-dimethylbenzylamine at an identical pH value in solution due to the much lower activity degree of hydrogen ion in inner resin phase than in the external solution. Less free amino group on D301 results in less sorption capacity of phenol and p-nitrophenol in an acidic solution. Under the experimental conditions both phenol sorption onto D301 can be explained as solid extraction and the distribution coefficient varies linearly with the content of free amino group on D301.     

氯酚在D301树脂上吸附机理的研究

研究了酸性条件下氯酚在大孔弱碱树脂D301上的吸附机理.研究表明,在一定的吸附质浓度及pH值下,D301树脂对对氯酚和邻氯酚的吸附量与溶液平衡浓度之间存在良好的线性关系,吸附过程类似于固相萃取过程,且分配系数与相应pH值下X射线光电子能谱(XPS)测得的树脂上自由叔胺基团含量呈线性关系.     

氧化叔胺树脂的合成及其对苯酚的吸附性能研究

将D301树脂的叔胺基氧化，合成了大孔交联氧化叔胺树脂．比较D301树脂与氧化叔胺树脂对正己烷溶液中和水溶液苯酚的吸附性能，发现氧化叔胺树脂对苯酚的吸附量比D301树脂的有明显的增加．为弄清吸附量增加的原因，根据氧化叔胺树脂对正己烷溶液中苯酚的吸附等温线，利用热力学函数关系计算了等量吸附焓、吸附Gibbs自由能和吸附熵，发现叔胺树脂氧化后，与苯酚的相互作用和吸附的自发倾向增强，但吸附过程仍为氢键吸附．     

D301树脂对酚类的吸附热力学研究

测定D301树脂对环己烷溶液中苯酚的吸附等温线，利用热力学函数关系计算了等量吸附焓，吸附自由能和吸附熵，等量吸附焓在30kJ/mol-35kJ/mol之间，推测吸附过程为氢键吸附。比较D301树脂对水溶液和环己烷溶液中苯酚的吸附性能，及D301树脂对环己烷溶液中苯酚和邻硝苯酚的吸附性能，进一步讨论了D301树脂对酚类物质吸附中的氢键作用。     

Isotherm analysis of phenol adsorption on polymeric adsorbents from nonaqueous solution

Macroporous poly(methyl methacrylate-co-divinylbenzene) (PMMA), interpenetrating polymer adsorbent based on poly(styrene-co-divinylbenzene) (PS) and poly(methyl methacrylate-co-divinylbenzene) (PMMA/PS), and macroporous cross-linked poly(N-p-vinylbenzyl acetylamide) (PVBA) were prepared for the adsorption of phenol from cyclohexane. The sorption isotherms of phenol on the three polymeric adsorbents were measured and fitted to Langmuir and Freundlich isotherms. It is shown that the Langmuir isotherm, which is based on a homogeneous surface model, is unsuitable to describe the sorption of phenol on the adsorbents from nonaqueous solution and the Freundlich equation fits the tested three adsorption systems well. The isosteric enthalpy was quantitatively correlated with the fractional loading for the sorption of phenol onto the three polymeric adsorbents. The surface energetic heterogeneity patterns of the adsorbents were described with functions of isosteric enthalpy. The results showed that the tested three polymeric adsorbents exhibited different surface energetic heterogeneity patterns. The initial isosteric enthalpy of phenol sorption on polymeric adsorbent has to do with the surface chemical composition and is free from the pore structure of the polymeric adsorbent matrix. Forming hydrogen bonds between phenol molecules and adsorbent is the main driving force of phenol sorption onto PVBA and PMMA adsorbent from nonaqueous solution. When phenol is adsorbed on PMMA/PS, pi-pi interaction resulting from the stacking of the benzene rings of the adsorbed phenol molecules and the pendant benzene ring of adsorbent is involved.     

Mechanism of sorption of phenols from aqueous solutions onto surfactant-modified montmorillonite

Equilibrium and kinetic studies on the sorption of phenol, m-nitrophenol (m-NP), and o-cresol from water onto montmorillonite modified with cetyltrimethylammounium bromide (CTAB) were conducted. Experiments were carried out as a function of solution pH, sorbate concentration, and temperature (25-55 degrees C). It was shown that the sorption capacity decreased in the order phenol>o-cresol>m-NP. The Langmuir, dual-mode sorption, and Redlich-Peterson models were tested to fit the sorption isotherms of single-solute systems, whereas the Langmuir competitive model was used to describe bisolute sorption equilibria. Thermodynamic parameters (DeltaH degrees and DeltaS degrees ) and the mean free energy (E) for the sorption of phenols were determined from the temperature dependence of the distribution constant and the Dubinin-Radushkevick equation, respectively. A simplified kinetic model was proposed to confirm the sorption mechanism.     

A WATER-COMPATIBLE PHENOLIC HYDROXYL MODIFIED POLYSTYRENE AS AN ADSORBENT FOR ADSORBING PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTIONS

1. INTRUDUCTION As most phenolic compounds are extremely toxic at the concentrations discharged into accepting effluents, the removal or destruction of phenolic compounds from such streams has become a significant environmental task [1]. Increasing concern for public health and environmental quality has led to the establishment of limits on the acceptable environmental levels of specific pollutants [2]. Consequently there has been a growing interest in developing and implementing various …     

Kinetics and thermodynamics of sorption of nitroaromatic compounds to as-grown and oxidized multiwalled carbon nanotubes

The sorption kinetics and thermodynamics of 1,3-dinitrobenzene (DNB), m-nitrotoluene (mNT), p-nitrophenol (pNP), and nitrobenzene (NB) on as-grown and nitric acid-oxidized multiwalled carbon nanotubes (MWCNTs) were investigated. The sorption kinetics was well described by a pseudo-second-order rate model, while both Langmuir and Freundlich models described the sorption isotherms well and the sorption thermodynamic parameters of equilibrium constant (K(0)), standard free energy (DeltaG), standard enthalpy (DeltaH), and standard entropy changes (DeltaS) were measured. The values of DeltaH and DeltaG suggested that the sorption of nitroaromatics (NACs) onto MWCNTs was exothermic and spontaneous. The structure, number, and position of nitro groups of NACs were the main factors affecting the sorption rate and capacity. Treatment of the MWCNTs with nitric acid increased both the surface area and the pore volume and introduced oxygen-containing functional groups to the MWCNTs, which depressed the sorption of NACs onto MWCNTs.     

SORPTION OF PHENOL ONTO GEL-TYPE CROSSLINKED POLYSTYRENEISOCYANURIC ACID RESIN

I INTRODUCTIONIn our previous work, three series of macroporous hydrogen-bonding adsorbents have beenstudied, which were adsorbents with hydrogen donator, adsorbents with hydrogen acceptor, andadsorbents with both hydrogen donator and acceptor if-31. If a gel-type resin with hydrogendonator and/or acceptor contacts with a compound with hydrogen acceptor and/Or donatof, canthe gel-type resin sorb the compound based on of hydrogen bonding? Here we report the sorptionof phenol onto gel-type …     

SORPTION OF PHENOL ONTO GEL—TYPE CROSSLINKED POLYSTYRENEISOCYANURIC ACID RESIN

Spherical crosslinked polystyrene-isocyanuric acid resin was synthesized by reaction of chloromethylated polystryene with isocyanuric acid.The sorption isotherms of phenol from aqueous solution and cyclohexane solution onto the resin were measured.It is of interest to notice that the resin sorbed phenol efficiently though its specific surface area was 0 and did not swell in water,and the sorption capactity from aqueous solution was close to that of phenol onto XAD-4 at the same equilibrium concentration.Sorption enthalpies calculated from the isotherms according to the Clausius-Clapeyron equation were -21-25kJ/mol and -39-41kJ/mol respectively.These values impled that the sorption processes were based on hydrogen bonding.In addition.the details of the hydrogen bonding between the active sites of the resin and phenol were suggested.     

A WATER—COMPATIBLE PHENOLIC HYDROXYL ODIFIED POLYSTYRENE AS AN ADSORBENT FOR ADSORBING PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTIONS

A water-compatible phenolic hydroxyl modified polystyrene adsorbent (AM-1) for adsorbing and removing phenolic compounds from aqueous solutions was prepared by covalent bonding of phenolic hydroxyl groups to the surface of porous polystyrene-divinylbenzene beads,this resin can be used directly without wetting process.A comparison of the sorption properites of the new resin and Amberlite XAD-4 toward four phenolic compounds,phenol,p-cresol,p-chlorophenol,and p-nitrophenol was made.The capacities of equilibrium adsorption of AM-1 for all four phenolic compounds increased around 20% over that of Amberlite XAD-4,which may be contributed to pheonl hydroxyl group on the surface and the unusual poe distribution.At their dilute solution,the equilibrium adsorption capacities of AM-1 for phenol increased aout 62% over that of Amberlite XAD-4,while equilibrium adsorption capacities of the other three phenolic compounds increased 4-35%,suggesting an advantage of AM-1 over Amberlite XAD-4 in the collection of phenol.Freundlich isotherm equations and isosteric adsorption enthalpies for the four phenolic compunds indicate a physical adsorption process on the Amberlite XAD-4 and AM-1 resins,Column studies for phenol show that AM-1 resin has excellent adsorption and desorption performance.     

一种亲水的酚羟基修饰聚苯乙烯树脂对酚类化合物的吸附热力学

在283-323K和研究的浓度范围内,苯酚、对甲苯酚、对氯苯酚和对硝基苯酚在亲水性的酚羟基修饰聚苯乙烯树脂（AM-1）与大孔吸附树脂（Amberlite XAD-4)上平衡吸附数据符合Freundlich吸附等温方程。酚类化合物在AM-1上的吸附容量比在Amberlite XAD-4上的吸附容量增加20%以上,这主要得益于AM-1表面的酚羟基入树脂的微孔结构。在较稀的溶液中AM-1对苯酚的吸附量比AmberliteXAD-4对苯酚的吸附量增加60%,表明AM-1对苯酚有特殊的选择性。Freundlich吸附等温线、相对吸附容量以及等量吸附焓表明,四种酚在两种树脂上的吸附是物理吸附过程。对酚类化合物被两种树脂吸附的吸附焓、自由能、吸附熵也作了测试,并对吸附行为作了合理的解释。     

聚(N-对乙烯基苄基二甲胺)树脂对苯酚的吸附性能

采用二甲胺为功能化试剂,化学修饰氯甲基化苯乙烯-二乙烯基苯共聚物合成了大孔交联聚(N-对乙烯基苄基二甲胺)树脂,测得树脂的氯含量由4.2mmol/g降低到0.24mmol/g,树脂的弱碱交换量为4.0mmol/g,说明氯甲基化苯乙烯-二乙烯基苯共聚物发生胺化反应完全。在水溶液中,测定了大孔交联聚(N-对乙烯基苄基二甲胺)树脂对苯酚的吸附等温线,发现吸附平衡数据符合Freundlich等温吸附方程,相关系数大于0.99。计算得到在吸附量为15、20和25mg/g时,等量吸附焓在-20.81~-30.74kJ/mol范围内,吸附自由能和吸附熵均小于0,说明吸附过程中存在氢键作用,吸附是自发、混乱度变小的过程。比较树脂对水溶液中苯酚、对硝基苯酚和对硝基甲苯的吸附性能以及树脂对水、环己烷、乙醇和乙酸乙酯溶液中苯酚的吸附性能,进一步说明大孔交联聚(N-对乙烯基苄基二甲胺)树脂对水溶液中苯酚的吸附是基于疏水作用和氢键作用协同的机理。     

Effect of lead on the sorption of phenol onto montmorillonites and organo-montmorillonites

The effect of lead (Pb) on the sorption of phenol onto montmorillonite-based sorbents was studied using a batch equilibration method when phenol and Pb were sorbed simultaneously and either Pb or phenol was previously sorbed. The sorbents were Na(+)-, Ca(2+)-, hexadecyl trimethylammonium (HDTMA)-Na(+)-, and HDTMA-Ca(2+)-montmorillonites. Pb diminished the sorption of phenol largely onto Na(+)- or Ca(2+)-montmorillonites, while phenol had little effect on the sorption of Pb onto all sorbents. Pb had no effect on the sorption of phenol onto HDTMA-Na(+)- or HDTMA-Ca(2+)-montmorillonites either. The sorption capacity of phenol followed the order HDTMA-Na(+)- > HDTMA-Ca(2+)- > Na(+)- > Ca(2+)-montmorillonites. The pseudo-second-order equation described the kinetics of phenol sorption well. Sorption isotherms of phenol followed the Freundlich equation. Phenol sorption on HDTMA-Na(+)- and HDTMA-Ca(2+)-montmorillonites was linear, while that on Na(+)- and Ca(2+)-montmorillonites was nonlinear.     

A WATER-COMPATIBLE PHENOLIC HYDROXYL MODIFIED POLYSTYRENE AS AN ADSORBENT FOR ADSORBING PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTIONS

A water-compatible phenolic hydroxyl modified polystyrene adsorbent (AM-1) foradsorbing and removing phenolic compounds from aqueous solutions was prepared by covalent bonding of phenolic hydroxyl groups to the surface of porous polystyrene-divinylbenzene beads, this resin can be used directly without wetting process. A comparison of the sorption properties of the new resin and Amberlite XAD-4 toward four phenolic compounds, phenol, p-cresol, p-chlorophenol,and p-nitrophenol was made. The capacities of equilibrium adsorption of AM-l for all four phenolic compounds increased around 20% over that of Amberlite XAD-4, which may be contributed to phenol hydroxyl group on the surface and the unusual pore distributior. At their dilute solution, the equilibrium adsorption capacities of AM-1 for phenol increased about 62% over that of Amberlite X4D-4, while equilibrium adsorption capacities of the other three phenolic compounds increased 4-35%, suggesting an advantage of AM-I over Amberlite XAD-4 in the collection of phenol.Freundlich isotherm equations and isosteric adsorption enthalpies for the four phenolic compounds indicate a physical adsorption process on the Amberlite XAD-4 and AM-I resins. Column studies for phenol show that AM-1 resin has excellent adsorption and desorption performance.     

Solubilization of p-nitrophenol in aggregates formed by hydrophobically modified polyelectrolytes

The solubilization of p-nitrophenol into the hydrophobic microdomains provided by polyelectrolytes carrying alkyl side chains of different length has been investigated in aqueous solutions of pH 5.0 and 8.0. Under these pH conditions p-nitrophenol is predominantly present in its neutral and ionic forms, respectively. Potassium salts of poly(maleic acid-co-1-olefins), PA-nK2 with n = 12, 14, 16, 18, were synthesized, and the pseudo-phase model was used to determine the distribution coefficient KS, and the standard free energy of transfer Deltamut0 of p-nitrophenol between water and polymer aggregates. The results indicate that at both pH's the solubilization of p-nitrophenol increases with increasing size of the side alkyl chain; i.e., the values of KS follow the order PA-18K2 > PA-16K2 > PA-14K2 > PA-12K2. The free energies, Deltamut0, were plotted as a function of the number of carbon atoms in the side alkyl chain and a linear relation was found. From these plots contributions of -0.324 and -0.676 kJ mol(-1) per methylene group were determined at pH 5.0 and 8.0, respectively. The effect of aggregate size on the solubility of phenol is attributed to the hydrophobic contribution per CH2 group to the free energy of transfer. The hydrophobic nature of the CH2 group is suggested to derive largely from the enthalpic contribution.     

β-环糊精接枝壳聚糖的合成及其吸附性能

采用乙二醛作为交联物合成了一种β-环糊精接枝壳聚糖,研究了其对水溶液中对硝基苯酚的吸附性能;考察了温度、pH值、吸附时间、酚溶液初始浓度等因素对其吸附性能的影响.结果表明,当吸附时间为20min,pH值为5~6,温度为25℃~35℃,酚溶液初始浓度为80 mg/L时,β-环糊精接枝壳聚糖对对硝基苯酚的吸附性能最佳.     

ADSORPTION OF PHENOL IN NON-AQUEOUS SYSTEM BASED ON HYDROGEN-BONDING

1 INTRODUCTIONHydrogen-bonding adsorbents are functional polymers for adsorption and separation via theformation of hydrogen bond between the adsorbentS and adsorbates. Because hydrogen bond is astrong intermolecular (or intramolecular) force, hydrogen-bonding adsorbents have strong potentto adsorbing adsorbates with which can form hydrogen bond. In our previous work, three seriesof hydrogen-bonding adsorbents have been studied, which were adsorbents with hydrogendonator, adsorbentS with …     

Synthesis, characterization and adsorption performance of a novel post-crosslinked adsorbent

In this paper a post-crosslinked polymeric adsorbent PDHT-2 with high specific surface area was prepared by Friedel-Crafts reaction of the pendant vinyl groups without an externally added crosslinking agent. It was obvious that both the specific surface area and the pore volume of starting copolymer PDHT-1 increased significantly after post-crosslinking. Batch adsorption runs of phenol from aqueous solution onto adsorbent PDHT-1 and PDHT-2 were researched, and commercial macroporous resin XAD-4 was chosen for comparison purpose. Experimental results showed that the adsorption isotherms could be fitted by Langmuir model and Freundlich model and the adsorption capacity onto PDHT-2 was much larger than that onto PDHT-1 and XAD-4 with respect to phenol and phenolic compound, which possibly resulted from its larger specific surface area. The adsorption process for phenol onto the three adsorbents was proved to be exothermic and spontaneous in nature. The thermodynamic parameters such as Gibb's free energy (ΔG), change in enthalpy (ΔH) and change in entropy (ΔS) had been calculated. The adsorption kinetic curves obeyed the pseudo-second order model and the intraparticle diffusion process was the rate-controlling step.     

Adsorption characteristics of poly(styrene-co-divinylbenzene) resin functionalized with methoxy and phenoxy groups for phenol

Two macroporous crosslinked poly(styrene-co-divinylbenzene) resins functionalized with methoxy and phenoxy groups, PVBME and PVBPE were prepared and their adsorption characteristics for phenol were studied in hexane as well as in aqueous solution. It was shown that the equilibrium adsorption capacity of phenol onto PVBPE was a little larger than that onto PVBME at the same temperature and equilibrium concentration. The adsorption onto PVBME in hexane can be correlated to Langmuir isotherm model, whereas the semi-empirical Freundlich isotherm model characterized the adsorption onto PVBPE better. The adsorption thermodynamic parameters were calculated and it was found that the adsorption enthalpy, adsorption free energy, and adsorption entropy were all negative, and the adsorption thermodynamic parameters onto PVBPE were more negative than the corresponding ones onto PVBME. The relationship of the adsorption capacity with the equilibrium concentration was linear in aqueous solution. The adsorption was hypersensitive to the solution pH in aqueous solution, and the optimum pH was determined to be 6.0. The adsorption dynamics of phenol onto PVBPE in aqueous solution was investigated and it was seen that the adsorption can be well fitted by the pseudo-first-order rate equation.