ADSORPTION OF 2,4-DICHLOROBENZOXYACETIC ACID ONTO HYPERCROSSLINKED RESIN MODIFIED BY PHENOLIC HYDROXYL GROUP (AM-1)

 An experimental comparison of the adsorption properties of hypercrosslinked resin AM-1 modified by phenolic hydroxyl group with Amberlite XAD-4 toward 2,4-dichlorobenzoxyacetic acid was performed. This paper focuses on the static equilibrium adsorption behaviors and the adsorption thermodynamics. Two isotherm models were used to explain the results. It is seen that the Langmuir equation can give a perfect fit. The adsorption capacities from the different ranges of temperature, the adsorption enthalpy change value and the comparison of desorption conditions lead to the same conclusion that the adsorption of 2,4-dichlorobenzoxyacetic acid from water onto AM-1 is a type of physical and chemical transition.     

ADSORPTION OF BENZOIC ACID AND P-NITROBENZOIC ACID ON A NEW HYPERCROSSLINKED PHENOL GROUP PST ADSORBENT

1.INTRODUCTIONThepolymericadsorbentAmberliteXAD-4isconsideredoneofthemostsuitablepolymericadsorbentsforremovingphenoliccompoundsfromwaterstreams[1,2]becauseitischemicallystable,notsolubleinsolventsandmoreselectiveforaromaticringsduetoitshydrophobicproperties.However,methanol,acetoneoracetonitrile,hastobeusedtoenhancethesurfacecontactbetweenadsorbentandthesolute.DavankovandTsyurupadescribedanewseriesofadsorbents[3,4].Thistechniqueyieldedpolystyrenesorbentsofunusualhypercrosslinkedstructu…     

ADSORPTION OF BENZOIC ACID AND P-NITROBENZOIC ACID ON A NEW HYPERCROSSLINKED PHENOL GROUP PST ADSORBENT

A comparison of the adsorption of benzoic acid and p-nitrobenzoic acid on the new hypercrosslinked polymeric adsorbent AM-I, with that by macroporous Amberlite XAD-4, including the equilibrium adsorption isotherms, the dynamic adsorption behaviors through column and the adsorption thermodynamics were studied. Results show that Freundlich equation gives a fitting adsorption isotherm. The specific surface of AM-l is only 67% of that of Amberlite XAD-4, but the adsorption capacities on AM-1 are much higher about 125%～166% than that on Amberlite XAD-4,which is contributed to the micropore mechanism and polarity. The negative values of the adsorption enthalpy are indicative of an exothermic process. Enthalpy and free energy changes of adsorption both manifest a physic-sorption process. The negative values of the adsorption entropy indicate that the adsorption is well consistent with the restricted mobilities and the configurations of the adsorbed benzoic acid molecules on the surface of studied adsorbents with superficial heterogeneity. Both adsorbents were used in mini-column experiments for adsorbing benzoic acid expecting to elucidate the higher breakthrough adsorption capacity of the new hypercrosslinked polymeric adsorbent AM-1 as compared with that of Amberlite XAD-4.     

超高交联吸附树脂吸附对硝基苯乙酮的热力学研究

比较两种超高交联聚苯乙烯吸附树脂NJ-8、AM-1与Amberlite XAD-4(以下简称XAD-4)对对硝基苯乙酮的静态吸附行为，根据吸附等温线研究了吸附热力学性质．在298～318K和研究的浓度范围内，NJ-8，AM-1、XAD-4对对硝基苯乙酮的吸附平衡数据符合Freundlich吸附等温方程．结果表明：吸附为放热过程，适当降低温度有利于吸附．计算了对硝基苯乙酮在NJ-8，AM-1、XAD-4树脂上的吸附焓变、自由能变，吸附熵变．对吸附行为作了合理的解释。     

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 …     

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.     

几种吸附树脂对硝基化合物吸附性能的研究

研究NJ－8、AM－1、Amberlite XAD-4、JX－101 4种吸附树脂对对硝基苯乙酮和对硝基苯甲酸的静态吸附行为。结果表明：江苏南大戈德环保科技有限公司研制的NJ－8和AM－1两种吸附树脂对硝基化合物的吸附效果较好。并研究NJ－8型吸附树脂的动态吸附和脱附行为，结果显示：NJ－8型吸附树脂对对硝基苯甲酸的吸附容量为128mg/g干树脂，对对硝基苯乙酮的吸附容量为383mg/g干树脂。用8%NaOH:乙醇（体积比1：1）洗脱吸附酸的树脂，用甲醇或乙醇洗脱吸附酮的树脂，体积为5BV时，温度分别为333K和313K，脱附率均接近100％。     

超高交联树脂对苯胺的吸附机理研究

在静态条件下，研究了水溶液中超高交联树脂AM－1和NJ－8及大孔吸附树脂Amberlite XAD－4吸附苯胺的热力学特性，测定了不同温度下的吸附等温线。结果表明，在稀溶液中3种树脂吸附苯胺都符合Langmuir和Freundlich模型，其中AM－1和NJ－8对苯胺的吸附是一个吸热过程；由于AM－1和NJ－8的微孔结构和表面存在酸性基团的吸附中心，对苯胺的吸附是物理吸附和化学吸附共同作用的结果。     

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.     

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。     

超高交联树脂对苯胺和对硝基苯胺的吸附行为

吸附热力学;化学吸附;超高交联树脂对苯胺和对硝基苯胺的吸附行为     

Adsorption of highly charged polyelectrolytes onto an oppositely charged porous substrate

The adsorption behavior of highly charged cationic polyelectrolytes onto porous substrates is electrostatic in nature and has been shown to be highly dependent on the polyelectrolyte properties. Copolymers of acrylamide (AM) and diallyldimethylammonium chloride (DADMAC) were synthesized to have a range of macromolecular properties (i.e., charge density and molecular mass). Traditional titration methods have been complemented by fluorescence labeling techniques that were developed to directly observe the extent that fluorescently labeled poly(AM- co-DADMAC) adsorbs into the pore structure of a cellulosic substrate. Although contributing to the electrostatic driving force, the charge density acts to limit adsorption to the outermost surface under electrolyte-free conditions. However, adsorption into the pores can occur if both the molecular mass and charge density of poly(AM- co-DADMAC) are sufficiently low. Adsorption initially increases as the electrolyte concentration is increased. However, the electrostatic persistence length of poly(AM- co-DADMAC) restricts the polyelectrolyte from entering the pores. Therefore, changes in the adsorption behavior at moderate electrolyte concentrations have been attributed to swelling of the polyelectrolyte layer at the fiber exterior. The adsorption behavior changes again at high electrolyte concentrations such that poly(AM- co-DADMAC) could adsorb into the pore structure. This occurred when the electrolyte concentration was sufficient to screen the electrostatic persistence length of poly(AM- co-DADMAC), provided that the entropic driving force for adsorption still existed. It is suggested that adsorption into the pore structure is a kinetic process that is governed by localized electrostatic interactions between poly(AM- co-DADMAC) and the charges located within the pores.     

超高交联吸附树脂对芳香有机物的吸附机理

通过3种吸附树脂AmberliteXAD-4、AM-1和JX101对芳香化合物苯胺、苯酚和苯甲酸在不同温度下的吸附特征,利用前线轨道理论进行了合理解释。结果表明,吸附剂表面进行适当的修饰,可以改变吸附剂的LUMO或HOMO,使吸附质分子与吸附剂表面的功能基产生化学作用,从而产生额外的化学吸附量,为优化设计吸附剂提供了理论指导。     

Adsorption of Pesticides on Soil Components

The adsorption of two pesticides (2,4-phenoxy acetic acid (2,4D) and thiabendazol) on silica, alumina, kaolin and montmorillonite is studied from adsorption isotherms and enthalpies. 2,4D is not adsorbed by silica, kaolinite and montmorillonite even in the presence of 0.01 mol l?1 divalent cations. On alumina, the energy of adsorption is comparable with that of the formation of an acid-base complex. Thiabendazol can be adsorbed on silica and clays from an ethanol solution. Most adsorption isotherms are of the Langmuir type and correspond to roughly constant adsorption enthalpies as a function of coverage except for kaolin where adsorption on both lateral and basal faces can be involved. Adsorption after introducing humic acids to the system was also studied for kaolin.     

ADSORPTION OF 2,4-DICHLOROPHENOL IN AQUEOUS SOLUTION ONTO ADSORPTION RESIN MODIFIED BY N-ACETYLANILINE

A hypercrosslinked adsorption resin （ZH-05） modified by N-acetylaniline in the post crosslinking process was prepared. The adsorption properties of ZH-05 toward 2,4-dichlorophenol in comparison with granular activated carbon （GAC） and Amberlite XAD-4 were observed. The present study mainly focuses on the static equilibrium adsorption behaviors, desorption profiles and the proof of chemisorption. The results show that the Langmuir equation can give a perfect fitting to experimental data, and high temperature was favorable for adsorption of 2,4-dichlorophenol on ZH-05. A related equation was used to correlate the amount of chemisorption and the suppositionai chemisorption equilibrium concentration of adsorbate in aqueous solution. The adsorption capacities from different ranges of temperature and the static desorption experiment both reveal the same conclusion, i.e., the adsorption of 2,4-dichlorophenol from water on ZH-05 is a coexistent process of physical adsorption and chemical transition as on GAC.     

Effects of linker amino acids on the potency and selectivity of dimeric antimicrobial peptides

Conformational flexibility induced by proline and aminocaproic acid can increase anticancer activity and antimicrobial activity of dimeric antimicrobial peptides with reduced hemolytic activity. This study will contribute to the design of efficient antimicrobial peptides.     

吸附树脂和络合树脂联合处理对硝基苯乙酮生产废水的研究

本文采用南京大学研制的AM－1型吸附树脂和ND－900型络合树脂联合处理对硝基苯乙酮生产废水，系统地研究了流速、温度、废水的pH值等因素对树脂吸附性能的影响，以及以NaOH为脱附剂，其流速、浓度、温度等对树脂脱附性能的影响。当废水的处理量为30BV时，其CODCr总去队达93％，表明树脂吸附性能良好。     

2,4-/2,6-二氨基甲苯在D151树脂上的吸附分离

从10种树脂中筛选出D151树脂对2,4-二氨基甲苯和2,6-二氨基甲苯的吸附分离及其热力学性质进行了研究。 测定了吸附等温线,Freundlich模型对实验的拟合度大于Langmuir模型,其相关系数大于0.99。 热力学研究结果表明,在293～313 K条件下,初始质量浓度为60～80 g/L时,2,4-二氨基甲苯的吸附焓变为-4.3490～-5.7558 kJ/mol,自由能变为-0.2911～-1.0346 kJ/mol,吸附熵变为-12.965～-16.150 J/(mol·K);而2,6-二氨基甲苯的吸附焓变为-2.9645～-3.6054 kJ/mol,自由能变为-0.1610～-0.6384 kJ/mol,吸附熵变为-7.939～-11.005 J/(mol·K)。 进一步研究了D151树脂对二氨基甲苯的动态吸附分离,可以将2,6-二氨基甲苯含量从20%提高至99.93%,将2,4-二氨基甲苯含量从80%提高至99.42%。     

ADSORPTION OF 2,4-D ON MODIFIED HYPERCROSSLINKED POLYSTYRENE （NDA-99） AND XAD-4 RESIN

The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent (NDA-99) modified by dimethylamine group as well as a nonionic macroporous adsorbent (XAD-4). The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism. It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix.Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin, which is in agreement with the IR spectroscopic results and the △E values of HOMO (the highest occupied molecular orbit) of adsorbent and LUMO (the lowest unoccupied molecular orbit) of adsorbate calculated from the MINDO/3 model.     

Removal of 2,4-dichlorophenoxyacetic acid from aqueous solutions by partially characterized organophilic sepiolite: thermodynamic and kinetic calculations

The adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) on organophilic sepiolite (dodecylammonium sepiolite, DAS) was studied as a function of solution concentration and temperature. The observed adsorption rates were found to be equal to the first-order kinetics. The rate constants were calculated for temperatures ranging between 25 and 40 degrees C at constant concentration. The adsorption energies, E, and adsorption capacity, q(m), for 2,4-D adsorption on organophilic sepiolite was estimated using the Dubinin-Radushkevic equation. Thermodynamic parameters (Deltag(a), Deltah(a), Deltas(a)) were determined by a new approximation from the isotherm of 2,4-D adsorption on DAS. Also, DeltaS(0) and DeltaH(0) values were calculated from the van't Hoff equation. These isotherms were modeled according to the Freundlich and Dubinin-Radushkevic adsorption equations. The amount of adsorption of this herbicide on organophilic sepiolite was found to be dependent on the relative energies of adsorbent-adsorbate, adsorbate-solvent, and adsorbate-adsorbate interaction.