Adsorption and desorption properties of grafted polyethylene films modified with polyethylenimine chains

The chelating membranes for adsorption of metal ions were prepared by the bonding of linear and branched polyethylenimines (LPEI and BPEI) on the glycidyl methacrylate (GMA) photografted porous polyethylene (pPE) (pPE‐g‐PGMA) films. The adsorption and desorption properties of LPEI and BPEI‐bonded pPE‐g‐PGMA (LPEI‐(pPE‐g‐PGMA) and (BPEI‐(pPE‐g‐PGMA)) films to Cu²⁺ ions were investigated as a function of the grafted amount, amount of bonded PEI, molecular mass of PEI, pH value, and temperature. The amounts of LPEI and BPEI bonded to the pPE‐g‐PGMA films increased over the reaction time, and the bonding of LPEI and BPEI offered the water‐absorptivity to the pPE‐g‐PGMA films. The amount of adsorbed Cu²⁺ ions at pH 5.0 had the maximum value at the grafted amount of 10 mmol/g for the (LDPEI‐(pPE‐g‐PGMA) and (BPEI‐(pPE‐g‐PGMA) films with a constant amount of bonded PEI. The amount of adsorbed Cu²⁺ ions for the LPEI‐(pPE‐g‐PGMA) films was higher than that for the BPEI‐(pPE‐g‐PGMA) films. The amount of Cu²⁺ ions desorbed from the LPEI‐(pPE‐g‐PGMA) and BPEI‐(pPE‐g‐PGMA) films increased with an increase in the HCl concentration. The quantities of Cu²⁺ ions of about 100% were desorbed in the aqueous HCl solutions of more than 0.1M for the LPEI‐(pPE‐g‐PGMA) films and more than 0.05M for the BPEI‐(pPE‐g‐PGMA) films. The amounts of adsorbed Cu²⁺ ions were almost the same in each adsorption process at pH 5.0. This indicates that the LPEI‐(pPE‐g‐PGMA) and BPEI‐(pPE‐g‐PGMA) films can be applied to a repeatedly generative chelating membrane for adsorption and desorption of metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5965–5976, 2006     

Adsorption and desorption properties of expanded poly(tetrafluoroethylene) films grafted with DMAEMA and their regeneration

An investigation was undertaken on the adsorption and desorption properties of the expanded poly (tetrafluoroethylene) (ePTFE) films grafted with 2‐(dimethylamino)ethyl methacrylate (DMAEMA) to anionic dye anions with one to three sulfonic groups in response to temperature changes. The amount of adsorbed metanil yellow (MY) anions increased with the grafted amount and most of the dimethylamino groups appended to the grafted PDMAEMA chains worked as an adsorption site to MY anions for the DMAEMA‐grafted ePTFE (ePTFE‐g‐PDMAEMA) films with the grafted amounts of higher than 1.1 mmol/g. When the dye‐anion‐adsorbed ePTFE‐g‐PDMAEMA films were alternately immersed in water at two different temperatures, dye anions were desorbed from the ePTFE‐g‐PDMAEMA films at higher temperatures without any chemical agents. The amount of desorbed dye anions increased with an increase in the temperature of water from 40 to 80°C. Desorption of dye anions is caused by either deprotonation of dimethylamino groups appended to the grafted PDMAEMA chains or thermosensitive contraction of the grafted PDMAEMA chains. These results indicate that the ePTFE‐g‐PDMAEMA films can be applied as a regenerative ion‐exchange membrane for adsorption and desorption processes of anionic compounds in response to the temperature change. The thermally regenerative ion‐exchange properties of the ePTFE‐g‐PDMAEMA films was superior to that of the PE‐g‐PDMAEMA films reported in our previous article in the fact that the total degree of desorption was higher for the ePTFE‐g‐PDMAEMA films. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

螯合纤维对海水中铀的吸脱附性能研究

采用偕胺肟基螯合纤维对海水中的铀进行吸附,讨论了纤维制备条件对纤维吸附铀量的影响。结果表明:随着螯合纤维偕胺肟化时间的延长,纤维的吸附铀量增大;含偕胺肟基团的纤维经过碱水解后,纤维吸附铀量增大,适宜的碱处理时间为24 h;螯合纤维对铀的吸附量随着吸附时间的延长而逐渐增多,吸附时间超过48 h达到吸附饱和态,其饱和吸附量为2.6 mg/g。     

Synthesis and adsorption properties of magnetic resin microbeads with amine and mercaptan as chelating groups

Three magnetic chelating resins containing amino and mercapto groups were prepared by the suspended condensation polymerization of 2‐chloroethoxymethyl thiirane with diamines. The magnetic resins were microbeads whose diameter was in the range of 10 to 45 μm. The structure of the resins was characterized by XPS, IR, and elemental analysis. Their adsorption properties for Hg(II), Au(III), Pd(II), Pt(IV), Ag(I), Cu(II), Zn(II), and Pb(II) were investigated. The experimental results show the magnetic resins have high affinity for Hg(II) and noble metal ions. In the competitive adsorption, the resins predominantly adsorbed Hg(II) or Pd(II) in the coexistence of Cu(II), Zn(II), and Mg(II). Desorption of Pd(II) loaded on the resins was studied by using 2M hydrochloric acid solution containing 1% thiourea as desorbent. A high desorption ratio (up to 96.5%) was observed, and repeated adsorption/desorption operations showed the probability of repeated use of the magnetic resins. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1587–1592, 2001     

羧甲基纤维素/蒙脱土纳米复合材料对刚果红染料的吸附及解吸性能

用X 射线衍射、透射电镜和扫描电镜对羧甲基纤维素/蒙脱土纳米复合材料的结构进行表征。采用溶液插层复合法制备纳米复合材料,探讨不同羧甲基纤维素与蒙脱土质量比、反应时间和反应温度对纳米复合材料吸附刚果红染料吸附量的影响,并初步研究了纳米复合材料的解吸性能。亚微观观察表明：羧甲基纤维素通过破坏蒙脱土的晶体结构插层进入蒙脱土层间,形成插层-剥离型纳米复合材料;当羧甲基纤维素与蒙脱土质量比为1∶1,反应时间为6 h,反应温度为60℃时,纳米复合材料对刚果红染料的吸附量最大,可达50.42 mg·g-1;当解吸试剂氢氧化钠浓度为0.01 mol·L-1时,超声波解吸50 min的纳米复合材料脱附率可达80.17%。     

Studies of syntheses and adsorption properties of chelating resin from thiourea and formaldehyde

Chelating resins are useful substances in industry because of their extraordinary adsorption properties for specific metal ions. In this study, a new type of chelating resin is synthesized simply by reaction between thiourea and formaldehyde. The synthetic conditions and the structure of the product are approached and the adsorbing capacities for 11 metal ions, adsorbing rates, and selectivities investigated. The results of the experiments show that the resin has high adsorbing capacities for Ag(I): 13.1 mmol/g, and for Au(III): 6.95 mmol/g. Adsorbing rates are close to 100% in dilute solution. Isothermal adsorbing study reveals that the adsorption is monomolecular layer adsorption process. It is hopeful for the resin to be used for concentrating and retrieving Ag(I) and Au(III) ions from their dilute solutions in industry. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3127–3132, 2001     

Adsorption behavior of metal ions by amidoxime chelating resin

The adsorption properties of poly(acrylamidoxime) chelating resin for Cu(II), Cd(II), Hg(II), Zn(II), Pb(II), Cr(III), and U(VI) are investigated by the batch technique. Based on the research results of the binding capacity effect of the pH value on sorption kinetic experiments, it is shown that this resin has higher binding capacity to uranyl ions, fast kinetics, and very good selectivity from binary metal ion mixtures with Cu(II) and Pb(II). The uranyl ion sorption strongly depends on the pH value of the solution. The highest value of 99% is at pH 5, but at pH 1 there is no retention. The adsorbed UO can be eluted by sulfuric acid and sodium carbonate. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1994–1999, 2000     

Adsorption and desorption properties of cationic polyethylene film gels to organic anions and their regeneration

An investigation was undertaken on the adsorption and desorption properties of 2‐(dimethylamino)ethyl methacrylate grafted polyethylene (PE‐g‐PDMAEMA) films to anionic dye anions with one to three sulfonic groups in response to pH and temperature changes. The amounts of dye anions adsorbed on the PE‐g‐PDMAEMA films passed through the maximum values at about pH 3 because of an increase in the protonation of dimethylamino groups caused by a decrease in the pH value. The amounts of adsorbed dye anions decreased below pH 3 because the ionic strength increased with the addition of HCl to adjust the initial pH values of the aqueous dye solutions. The amounts of adsorbed dye anions decreased with an increase in the number of sulfonic groups in the dye molecules at the same pH value because electrostatic repulsion was generated between free sulfonic groups of the dye anions adsorbed onto the PE‐g‐PDMAEMA films and free dye anions in the medium. A large number of dye anions adsorbed were desorbed from the PE‐g‐PDMAEMA film with initial pH values above 11.0. The cyclic processes of adsorption at pH 3.0 and desorption at pH 11.0 were repeated without considerable fatigue. The PE‐g‐PDMAEMA films showed practically regenerative adsorption and desorption behavior in response to the pH changes. In addition, when the dye‐anion‐adsorbed PE‐g‐PDMAEMA films were alternately immersed in water at two different temperatures, dye anions were desorbed in water at higher temperatures without any chemical agents because of the deprotonation of dimethylamino groups and thermosensitive contraction of grafted PDMAEMA chains. These results indicate that PE‐g‐PDMAEMA films can be applied as regenerative ion‐exchange membranes for adsorption and desorption processes of anionic compounds in response to the pH and temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 381–391, 2006     

Adsorption properties of poly(acrylaminophosphonic-carboxyl-hydrazide)type chelating fiber for heavy metal ions

In this article, the adsorption properties of poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fibers for Cu(II), Cd(II), Co(II), Mn(II), Pb(II), Zn(II), Ni(II), and Cr(III) are investigated by a batch technique. Based on the research results of binding capacity, adsorption isotherm, effect of pH value on sorption, and adsorption kinetics experiments, it is shown that the poly(acrylaminophosphonic-carboxyl-hydrazide) chelating fibers have higher binding capacities and good adsorption kinetic properties for heavy metal ions. The sorption of the metal ions on the chelating fibers is strongly dependent on the equilibrium pH value of the solution. The adsorption isotherms of Cu(II) and Cd(II) on the chelating fiber exhibit a Langmuir-type equation. The adsorbed Cu(II), Cd(II), Zn(II), and Pb(II) could be eluted by diluted nitric acid. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 7–14, 1998     

聚丙烯酰胺在黑土上的吸附解吸特性研究

采用静态吸附法研究了聚丙烯酰胺在黑土上的吸附行为,考查了不同吸附时间对土壤吸附量的影响,得出了聚丙烯酰胺在土壤上的吸附等温线。并且研究了聚丙烯酰胺在黑土上的解吸行为,探讨了振荡时间、液固质量比、温度、pH值对黑土中聚丙烯酰胺解吸的影响。结果表明,聚丙烯酰胺在黑土上的吸附等温线符合Langmu ir吸附模式,饱和吸附质量比为1.17 mg/g,聚丙烯酰胺在土壤上有很强的吸附亲合力,在实验条件下,最大解吸量仅为总量的25%。     

阴离子交换树脂对磺基水杨酸的吸附解吸性能

用阴离子交换树脂(D201)吸附的方法研究了磺基水杨酸的富集及回收。测定了溶液的pH值、温度、吸附时间等因素对吸附的影响,探讨了吸附的热力学和动力学特性。结果表明:D201树脂在pH=2—11时,吸附能力最好,等温吸附服从Freundlich经验式,吸附动力学符合Lagergren一级速率方程,颗粒内扩散是速率控制步骤之一,膜扩散也共同影响着吸附过程。在295—313 K条件下,磺基水杨酸吸附质量分数为380—420 mg/g的吸附焓变为-13.73—-8.422 kJ/mol,自由能变为-19.89—-21.45 kJ/mol,吸附熵变为20.88—41.62 J/(K.mol),吸附速率常数为0.025 3—0.056 5 min-1,吸附活化能为34.04 kJ/mol。315 K下用质量分数10%NaCl+2%NaOH溶液可定量洗脱,洗脱率达99%。     

丙烯酸接枝改性丙纶非织造布的吸附与解吸研究

采用丙烯酸接枝改性聚丙烯非织造布(PP-g-AA)对阳离子红X-GRL染料进行吸附与解吸,探讨了PP-g-AA对染料的吸附动力学机理、解吸过程和解吸动力学机理,以及基于动态吸附的过滤分离操作,分析了PP-g-AA对染料吸附-解吸再生循环利用的可行性。结果表明:不同初始染料浓度下,PP-g-AA的吸附动力学符合Lagergren's准二级动力学模型和双指数模型;解吸液的最佳配比为表面活性剂质量分数5%,乙醇与水的体积比3∶7,解吸率随吸附量的增大呈现先增大后减小的趋势,解吸符合Lagergren's准二级动力学模型;动态吸附-解吸再生循环10次后,染料的去除率达96%以上,再生循环8次时,PP-g-AA的跨膜压力为37.1 k Pa,水通量最大达38.6 L/(m2·h)。     

Characteristics of methacrylic acid‐grafted polyethylene films prepared by photografting in the presence of polyfunctional monomers

Photografting of methacrylic acid (MAA) on low‐density polyethylene film (thickness = 30 μm), on which xanthone photoinitiator was coated earlier, in the presence of polyfunctional monomers such as N,N′‐methylenebisacrylamide, ethylene glycol dimethacrylate, and trimethylol propane triacrylate was examined at 60°C in water/acetone (3:1 v/v) mixture solvent. The photografting was retarded at the earlier stage of polymerization, and then accelerated when small amounts of the polyfunctional monomers (1–3 mol % of MAA monomer used) were added to the system. Addition of the polyfunctional monomers did not affect distribution of the grafted chains in the cross section of the resultant MAA‐grafted PE film, which was measured by electron probe microanalysis. The MAA‐grafted samples were subjected to adsorption of cupric ions at 25°C for 24 h in the system of pH = 5. The adsorption was considerably suppressed for the grafted samples prepared at the earlier stage of polymerization in the system with the polyfunctional monomers. The phenomenon was discussed in terms of the formation of crosslinked and branched structures in the MAA‐grafted chains depending on the polymerization stage in the system with polyfunctional monomers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1262–1268, 2006     

Adsorption and desorption characteristics of arsenic onto ceria nanoparticles

The rapid increase in the use of engineered nanoparticles [ENPs] has resulted in an increasing concern over the potential impacts of ENPs on the environmental and human health. ENPs tend to adsorb a large variety of toxic chemicals when they are emitted into the environment, which may enhance the toxicity of ENPs and/or adsorbed chemicals. The study was aimed to investigate the adsorption and desorption behaviors of arsenic on ceria NPs in aqueous solution using batch technique. Results show that the adsorption behavior of arsenic on ceria NPs was strongly dependent on pH and independent of ionic strength, indicating that the electrostatic effect on the adsorption of these elements was relatively not important compared to surface chemical reactions. The adsorption isotherms fitted very well to both the Langmuir and Freundlich models. The thermodynamic parameters (ΔH ⁰ , ΔS ⁰ , and ΔG ⁰ ) for the adsorption of arsenic were determined at three different temperatures of 283, 303, and 323 K. The adsorption reaction was endothermic, and the process of adsorption was favored at high temperature. The desorption data showed that desorption hysteresis occurred at the initial concentration studied. High adsorption capacity of arsenic on ceria NPs suggests that the synergistic effects of ceria NPs and arsenic on the environmental systems may exist when they are released into the environment.     

多配位基螯合纤维对Ag~+的吸附性能研究

以聚(N-乙烯基甲酰胺/丙烯腈)纤维为原料,依次与二乙烯三胺交联反应、盐酸羟胺水溶液偕胺肟化反应和氢氧化钾水溶液水解反应,制备了多配位螯合纤维,研究了纤维对Ag+的吸附性能。用红外光谱法探讨了纤维对Ag+的吸附机理。结果表明:多配位鳌合纤维具有较好的吸附动力学特性,吸附速率常数和表观吸附活化能分别为3.337×10-4s-1和3.99kJ/mol;等温吸附曲线服从Langmuir和Freundlich经验式;测得吸附热力学参数焓变、熵变、自由能变分别为0.25kJ/mol,18.39J/mol.K,-5.24kJ/mol。     

好氧颗粒污泥对钇离子的吸附/解吸性能

为实现稀土尾水中钇离子（Y3+）的回收，探究了好氧颗粒污泥（AGS）对Y3+的吸附-解吸附效果。考察了混合方式、初始Y3+浓度、pH、盐度、铅离子及粒径对AGS吸附效果的影响。相比于搅拌及振荡，曝气混合下AGS具有更好的吸附效果，80%以上的吸附在前10 min完成。当初始Y3+浓度<50 mg/L时，AGS能完全吸附废水中Y3+离子，此后吸附率随着Y3+浓度的增大而减小。H+、Na+和Pb2+会与Y3+竞争AGS上的吸附位点，导致吸附率减小。0.6～1.0 mm的AGS吸附容量最大，2.4～3.0 mm的AGS经人工破碎后吸附容量增大15%。对吸附过程进行动力学和热力学拟合。动力学符合伪二级模型（R2=0.9999），表明化学吸附起主导作用；Webber-Morris方程分析表明颗粒内扩散是影响吸附速率的主要因素。热力学符合Langmuir模型（R2=0.9849），表明吸附过程是一个单分子层吸附过程，拟合得到最大吸附量为Qmax=24.39 mg/gSS。利用XPS对吸附前后AGS进行表征，发现参与吸附官能团有酯基、羧基、氨基，同时与K+进行离子交换，钇在AGS表面的主要化学态是Y2(CO3)3。探究了硝酸及氯化铵对吸附饱和AGS的解吸效果。HNO3的单次解吸附率（99%）明显高于NH4Cl（64%），但五次吸附-解吸附循环后，HNO3组解吸附率降至10%，NH4Cl组解吸附率仍维持在50%。     

吸附二甲胺/乙二胺的胺化催化剂脱附性能研究

以自制的不同元素量比的无载体Cu、Ni(2∶1～32∶1)二元胺化催化剂作为研究对象,进行催化吸附二甲胺及乙二胺,用程序升温脱附仪在50～700℃进行脱附性能研究。用脂肪醇制叔胺的胺化反应进行了催化剂评价。结果表明,乙二胺的脱附量0.61067mL/g远大于二甲胺的脱附量0.16585mL/g,说明乙二胺对催化剂表面活性中心的吸附力远强于二甲胺,胺化反应时不能及时完全脱附,使催化剂中毒,以致胺化反应不能进行,而二甲胺可以使胺化反应顺利进行。     

螯合树脂对有机胺脱硫液中Fe2+的吸附平衡

研究了4种螯合型树脂对有机胺脱硫液中Fe2+的吸附及解吸特性,发现D751型螯合树脂具有较高的吸附选择性和良好的脱附性能,采用静态吸附实验研究了D751型螯合树脂对Fe2+的吸附平衡,并用红外光谱的方法探讨了树脂吸附Fe2+的机理。结果表明,Langmuir模型和Freundlich模型均能较好地描述D751树脂对Fe2+的吸附行为;吸附自由能变G<0,熵变S>0,吸附为自发的熵增过程,升高温度有利于吸附的进行。红外光谱表明,D751树脂通过离子交换和配位双重作用与Fe2+结合。     

Adsorption and desorption characteristics of zinc on ash particles derived from oil palm waste

Solid waste such as palm fibre and shell produced by the palm oil industry is used by palm oil mills as boiler fuel to produce steam for electricity generation. The ash produced after combustion creates a disposal problem for the palm oil industry. This study explored the potential of oil palm ash as an adsorbent material for removal and recovery of zinc ions from aqueous solutions. The equilibrium uptake of zinc was found to increase with solution pH in the range 3–6, yielding a maximum adsorption capacity of 0.163 mmol g^?1 of ash at a pH of 6. The affinity constant of oil palm ash was found to greatly exceed that of a commercial ion exchange resin, suggesting that oil palm ash may find potential application in treating dilute zinc‐containing waste streams. Four isotherm models were used to fit the constant pH equilibrium isotherms obtained at four different pH values. The entire data set was successfully simulated using two of the isotherm models: a Langmuir model with pH‐dependent parameters and an extended Langmuir–Freundlich model with pH‐independent parameters. The rates of adsorption and desorption for zinc were measured using a stirred‐batch contactor. The contact time required to reach apparent adsorption equilibrium was found to decrease with increasing adsorbent dosage. Both the rate and the extent of zinc desorption were affected by the pH of the desorbing solution. The adsorption and desorption rates were consistent with simple first‐order rate models. © 2002 Society of Chemical Industry     

吗啡啉螯合树脂对水中钨离子的吸附及解吸性能

通过制备吗啡啉螯合树脂作为吸附材料对水中钨离子进行吸附与解吸实验,考察吸附pH、共存离子、吸附温度对饱和吸附容量的影响,并对其进行了傅里叶红外光谱（FTIR）、热重分析仪（TGA）、电位分析仪（Zeta）、扫描电子显微镜（SEM）等手段的表征。结果表明PS-MPL树脂对钨离子的最佳吸附pH=4.0,308 K下饱和吸附量为349.2 mg·g^-1,平衡时间为13 h。吸附过程遵循二级动力学模型,吸附等温线与Langmuir模型较为吻合。通过2%（质量分数）NaOH溶液进行解吸,解吸率达到100%。PS-MPL树脂吸附钨离子具有高选择性、高吸附性、高洗脱率等优点。