Equilibrium and kinetics of adsorption of Ca(Ⅱ) ions onto KCTS and HKCTS

The adsorption of Ca(Ⅱ) ions from aqueous solution by chitosan α-ketoglutaric acid(KCTS) and hydroxamated chitosan α-ketoglutaric acid(HKCTS) was studied in a batch adsorption system.The Langmuir and Freundlich adsorption models were applied to describing the equilibrium isotherms,and isotherm constants were determined.The kinetics of the adsorption with respect to the initial Ca(Ⅱ) ions concentration,temperature and pH was investigated.The pseudo-first-order and second-order kinetic models were used to describe the kinetic data and the rate constants were evaluated.The results show that the experimental data fit well to the Langmuir isotherms with a high correlation coefficient(R2).The pseudo-second-order rate expression provides the best fitting kinetic model.The pseudo second-order kinetic model is indicated with the activation energy of 26.22 kJ/mol and 6.16 kJ/mol for KCTS and HKCTS,respectively.It is suggested that the overall rate of adsorption of Ca(Ⅱ) ions is likely to be controlled by the chemical process.     

Cadmium sorption from aqueous solutions onto Iranian sepiolite： Kinetics and isotherms

This work aims to investigate the efficiency of Fariman sepiolite from Iran as an adsorbent to remove Cd from aqueous solutions. The effects of different experimental factors such as the initial Cd concentration, contact time and the sorbent dose were investigated through a series of batch adsorption experiments. The results show that the adsorption capacity of sepiolite for Cd increases with the contact time, the initial concentration of Cd solutions and the sorbent dose. Sorption of Cd by Fariman sepiolite is rapid within the first hour of the experiment and then slowly increases until a pseudo equilibrium is approached at 8 h. The results also show that the time-dependent Cd sorption data are better described with pseudo second-order （7〉0.999） than that of pseudo first-order （r2〉0.971） kinetic model. Equilibrium isotherm studies show that the experimental data are better correlated by the Freundlich adsorption isotherm （7〉0.995） than the Langmuir （P〉0.825）. It is suggested that both adsorption and cation exchange reactions are responsible for the sorption of Cd by the sepiolite, and the mineral has a very good potential to remove Cd from aqueous solutions.     

Synthesis of 1,4-benzenedicarbonyl thiourea resins and their adsorption properties for Ag（I）

Several 1,4-benzenedicarbonyl thiourea resins (BTR) were synthesized through interfacial polymerization between 1,4-benzenedicarbonyl diisothiocyanate and polyamine. Their structures were confirmed by FT-IR. The adsorption properties (including the effect of adsorption time, pH, initial concentrations and temperature) of BTR-1, BTR-2 and BTR-3 for Ag(I) were investigated by batch tests. The results show that the adsorption equilibria of BTR-1, BTR-2, BTR-3 for Ag(I) are achieved after about 10 h. Their equilibrium adsorption capacities are 7.11, 6.75 and 6.23, respectively, and the adsorption process accords with G. E. Boyd equation and Langmuir adsorption isotherm as well. The adsorption capacities increase with the increase of pH (the highest uptake values are observed at pH being about 6–7). The thermodynamic parameters of BTR-1 were calculated. The results show that ΔH ^Θ; and ΔS ^Θ are 6 958.8 J/mol and 64.28 J/(mol·K), respectively, and ΔG ^Θ at 20, 30, 40 and 50 °C are −11.79, −12.52, −13.16 and −13.8 kJ/mol, respectively. The silver-loaded resins can be quantitatively eluted by a solution containing 6% thiourea in 1 mol/L HNO₃.     

Biosorption mechanism of Cr （Ⅳ） onto cells of Synechococcus sp.

The biosorption mechanism of Cr （Ⅳ） ions on Synechococcus sp. biosorbent was studied by analyzing the biosorption kinetics as well as speciation change and bond formation during the biosorption process. The kinetics study shows that the adsorption process of Cr （Ⅳ） consists of a very fast stage in the first several minutes, in which more than half of the saturation adsorption is attained, and a slower stage that approximately follows the first order kinetic model, basically Freundlich isotherm models were observed. Comparative studies of FT-LR spectra of K2Cr2O7, free cells of Synechococcus sp., and Cr-bound cells of Synechococcus sp show that the speciation of chromium that binds to the cells ofSynechococcus sp. is Cr （Ⅲ）, instead of Cr （Ⅳ）, and the carboxylic, alcoholic, amido and amino groups may be involved in the binding of Cr （Ⅲ）. Integrative analyses of the surface electric potential, the effect of pH value on adsorption behavior of Cr （Ⅵ）, and the results of FT-IR show that the biosorption of Cr （Ⅵ） follows two subsequent steps, biosorption of Cr2O7 ^2- by electrostatical force at the protonated active sites and reduction of Cr2O7^2- to Cr^3＋ by the reductive groups on the surface of the biosorbents.     

Fabrication and adsorption property of novel adsorbent for potential application to wastewater with Fe（Ⅲ） ions

The spherical macroporous cellulose（SMC） was fabricated using medical absorbent cotton as raw material and nano CaCO3 as porogenic agents.And then,the phenylglycine was grafted onto the SMC to obtain the novel spherical macroporous cellulose derivative adsorbent（PSMC）.FT-IR and scanning electron microscope（SEM） were employed to characterize the adsorbents and Fe3＋ ions served as model solute to evaluate the adsorption property of the adsorbents.The experimental results show that the amount of porogenic agents and the value of pH have obvious influence on adsorption capacity of the adsorbents.The data of adsorption kinetic and isotherm display that the adsorbents possess excellent equilibrium adsorption capacity（348.94 mg/g） and have a bright prospect and considerable potential in the treatment of Fe3＋ ions in wastewater.     

Removal of Cr（Ⅲ） and Cr（Ⅵ） from aqueous solution by adsorption on sugarcane pulp residue

Sugarcane pulp residue (SPR), a waste from sugar-refinery, which possesses a large surface area, can be used for removing chromium (Cr(III) and Cr(VI)) from wastewater. In this work, the kinetics, isotherms of Cr(III) and Cr(VI) adsorption and their removal by SPR were investigated. The results show that the removal percentages of Cr(VI) and Cr(III) increase with increasing SPR dosage and temperature and decrease with increasing SPR particle size and the initial concentration of chromium ions. However, the influence of pH value on the Cr(VI) removal differs from that of the Cr(III) removal. The Cr(VI) removal percentage decreases with increasing pH values, while the Cr(III) removal percentage increases with increasing pH value. The adsorption kinetics of Cr(VI) and Cr(III) well fits with pseudo-second-order model. Langmuir adsorption isotherm can well describe the adsorption phenomena of chromium ions with the maximum adsorption capacity of 0.567 mg/g for Cr(VI) and 3.446 mg/g for Cr(III). Moreover, SPR reveals higher adsorption capacity for Cr(III) than that for Cr(VI), which implies that SPR has more potential application for Cr(III)-containing wastewater treatment than that for Cr(VI)-containing wastewater treatment. Foundation item: Projects(2006AA06Z374, 2007AA021304) supported by the National High-Tech Research and Development Program of China; Project(2008SK2007) supported by the Key Program of Science and Technology of Hunan Province, China     

Rapid biosorption and reduction removal of Cr（Ⅵ） from aqueous solution by dried seaweeds

Four types of common seaweeds（Laminaria japonica,Undaria pinnatifida,Porphyra haitanensis,and Gracilaria lemaneiformis） were examined to remove Cr（Ⅵ） ions from aqueous solution.The experimental parameters that affected the biosorption process including pH,biomass dosage,contact time and temperature were investigated via batch experiments.The surface characteristics of seaweeds before and after Cr（Ⅵ） adsorption were studied with scanning electron microscopy and Fourier transform infrared spectroscopy.The results show that an initial solution with the pH of 1.0 is most favorable for Cr（Ⅵ） adsorption.Rapid adsorption is observed in the initial stage and adsorption equilibrium state is reached within 1 h.The adsorption efficiency by Porphyra haitanensis is the maximum among four types of seaweed powders,followed by Laminaria japonica and Undaria pinnatifida with biosorption efficiency up to 90%.The removal rate of Gracilaria lemaneiformis is less than 60%.The kinetic data obtained using the seaweeds are found to follow pseudo-second order kinetic model.Experimental sorption data adequately correlate with the Langmuir model.FTIR indicates that amino and carboxyl groups play an important role in the process of Cr（Ⅵ） adsorption and a large percentage of Cr（Ⅵ） ions are reduced by reductive groups on the surface of seaweeds.     

Competitive adsorption of Cu（Ⅱ） and Pb（Ⅱ） ions from aqueous solutions by Ca-alginate immobilized activated carbon and Saccharomyces cerevisiae

To establish a theoretical foundation for simultaneous removal of multi-heavy metals,the adsorption of Cu（Ⅱ） and Pb（Ⅱ） ions from their single and binary systems by Ca-alginate immobilized activated carbon and Saccharomyces cerevisiae （CAS） was investigated.The CAS beads were characterized by Scanning electron microscope （SEM） and Fourier transformed infrared spectroscopy （FTTR）.The effect of initial pH,adsorbent dosage,contact time and initial metal ions concentration on the adsorption process was systematically investigated.The experimental maximum contents of Cu（Ⅱ） and Pb（Ⅱ） uptake capacity were determined as 64.90 and 166.31 mg/g,respectively.The pseudo-second-order rate equation and Langmuir isotherm model could explain respectively the kinetic and isotherm experimental data of Cu（Ⅱ） and Pb（Ⅱ） ions in single-component systems with much satisfaction.The experimental adsorption data of Cu（Ⅱ） and Pb（Ⅱ） ions in binary system were best described by the extended Freundlich isotherm and the extended Langmuir isotherm,respectively.The removal of Cu（lⅡ） ions was more significantly influenced by the presence of the coexistent Pb（Ⅱ） species,while the Pb（Ⅱ） removal was affected slightly by varying the initial concentration of Cu（Ⅱ）.The CAS was successfully regenerated using 1 mol/L HNO3 solution.     

Synthesis of modified D401 chelating resin and its adsorption properties for Pb^2＋

A novel chelating resin with sulfonic group was synthesized by chemical modification of D401 resin with sulphonation reaction and characterized by FT-IR spectrometry. The adsorption properties of the novel chelating resin for Pb²⁺ were studied by batch adsorption, and the adsorption process was analyzed from thermodynamics and kinetics aspects. The adsorption mechanism of Pb²⁺ on the modified D401 chelating resin was discussed by FT-IR spectrometry. Experimental results show that in the Pb²⁺ concentration range of 200–400 mg/L, the adsorption capacities of the modified D401 chelating resin for Pb²⁺ increase by 77%–129%, and Langmuir isothermal adsorption model is more suitable for the equilibrium adsorption data. Adsorption is an endothermic process that runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best pH value under adsorption condition is 4–5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the adsorption capacity remains stable after five consecutive adsorption-desorption cycles. The maximal static saturated adsorption capacity of the resin is 206 mg/g at 333 K in the Pb²⁺ concentration range of 200–400 mg/L. The modified D401 chelating resin is an efficient adsorbent for the removal of Pb²⁺ from its single-metal ion solution. Foundation item: Project(708049) supported by the Important Item Cultivation Foundation of Scientific Innovation Project of Colleges and Universities of China     

硝基苯在两种不同吸附树脂上的吸附动力学研究

研究了硝基苯在HZ-816树脂和H-103树脂上的吸附动力学,结果表明,硝基苯在两种树脂上的吸附平衡时间都很短(4 h),吸附符合Lagergren一级吸附动力学方程;温度对吸附平衡影响较小,初始浓度影响较明显.静态脱附实验表明,甲醇是理想的脱附剂.     

离子交换树脂吸附稀硫酸中铁离子的热力学和动力学

采用静态实验法研究了D001树脂吸附铁离子的反应机理,在实验条件下分别用朗格缪尔(Langmiur)和弗伦德利希(Freundlich)等温吸附模型分析了D001树脂对铁离子的吸附热力学过程.结果显示:Langmuir方程有更高的相关性,能够更好地拟合树脂吸附铁离子的过程.热力学函数ΔG<0表明D001树脂吸附铁离子过程能够自发进行;ΔH>0表明离子交换过程为吸热过程,ΔS>0表明吸附过程的熵变是增大的.准二级动力学模型能够很好拟合D001树脂吸附铁离子的过程并且其相关系数在0.99以上,树脂对铁离子的吸附过程主要速率控制过程为颗粒扩散.     

丙酮酸壳聚糖的合成及其吸附性能

将壳聚糖与丙酮酸反应,用NaBH4还原制备出丙酮酸壳聚糖(PCTS),并采用红外光谱、场发射扫描电镜及元素分析仪对其结构进行表征.实验结果表明,PCTS最佳工艺条件为:反应时间4.5 h,反应体系pH值为4.5,丙酮酸与壳聚糖上氨基摩尔比为2∶1,取代度为90.6%;在pH为5.4时,1.67 g/L PCTS对30 mL质量浓度为10μg/mL的Pb2+的吸附平衡时间为1.5 h,最大吸附量为27.1 mg/g,优于壳聚糖.     

离子交换树脂吸附古龙酸的工艺

应用自行合成的阴离子树脂D02直接吸附发酵液中的2-酮基-L-古龙酸，并研究了其吸附的静态与动态过程．利用Langmuir和Freundlich吸附等温线方程对吸附等温线数据进行拟合，发现2种模型相关性都很好．测定了不同流速、温度、浓度以及pH条件下古龙酸在合成树脂柱中的穿透曲线，当上柱液pH为1．5、质量浓度为10g／L、吸附温度为309K、流速为0．35mL／min时，每g湿树脂的动态附容量为133mg．同时测定了不同洗脱剂、洗脱流速条件下的洗脱曲线．每g湿树脂的动态吸附容量达到了133mg，当温度为283K、洗脱剂为10％H2SO4 CH3OH、流速为0．2mL／min时，洗脱收率可达65．3％．     

壳聚糖改性膨润土对酸性红吸附性能的研究

探索壳聚糖与膨润土的质量比与反应介质酸度对制备壳聚糖改性膨润土的影响并以改性土为吸附剂探讨了改性土质量、吸附温度、吸附时间、介质的pH值及酸性红溶液质量浓度对酸性红吸附性能的影响．结果表明：制备的改性土随着壳聚糖质量的增加吸附量先增大后减小、随着反应介质的酸度增强,改性土的吸附能力增加;随着改性土质量的增加吸附量先增大后减小;随着反应温度上升改性土吸附能力先增大后减小;随着酸性红染料质量浓度的增加吸附能力增加;随着反应pH值的增大吸附能力先增大后减少．质量比为1：125,冰醋酸体积分数为1％为最佳制备条件,改性土质量为0．6g,温度温度为25℃,吸附时间为70min,介质pH为7左右时是最佳吸附条件．且其吸附行为满足Langmuir等温式．     

改性麦草秸秆对活性艳红的吸附动力学研究

为实现农作物秸秆资源化,解决印染废水难处理问题,将麦草秸秆经过化学改性后制备成一种有效吸附染料的吸附剂,通过静态实验,研究了吸附剂对不同质量浓度、温度和振荡速度下对活性艳红的吸附动力学特性,并考察了在不同pH值、麦草投加量下,改性麦草秸秆对活性艳红吸附效果的影响。分别用伪一级动力学方程、伪二级动力学方程、Elovich方程和颗粒内扩散方程进行拟合。结果表明:改性麦草秸秆对活性艳红的吸附动力学过程可以用伪二级动力学模型进行很好地描述,颗粒内扩散模型表明,颗粒内扩散为主要速率控制步骤。吸附活化能为17.21kJ／mol,说明该吸附过程以物理吸附为主。     

松树锯末对Pb(II)与Ni(II)的吸附研究

以松树锯末为吸附剂,研究其对水中Pb(II)和Ni(II)的吸附性能,研究了锯末用量、搅拌速度、溶液初始pH值等对吸附效果的影响及其吸附动力学和热力学性能。研究结果表明,锯末对Pb(II)和Ni(II)具有良好的吸附能力。锯末对Pb(II)和Ni(II)吸附过程均符合拟二级吸附动力学模型(R²≥0.997 7),锯末吸附Pb(II)和Ni(II)的活化能分别为9.808 7 kJ/mol和2.859 4 kJ/mol;锯末对Pb(II)和Ni(II)等温吸附符合Langmuir模型(R²≥0.999 2)。热力学研究表明,锯末对Pb(II)和Ni(II)的吸附是自发的放热过程。     

纳米磁性壳聚糖对腐殖酸和重金属离子混合吸附研究

研究了纳米磁性壳聚糖吸附剂对腐殖酸的吸附性能和重复使用性能,分析了腐殖酸存在的条件下对Cu2+、Pb2+、Cd2+三种重金属离子吸附的影响及机理.实验结果表明:该吸附剂对腐殖酸吸附的最佳pH值为11,饱和吸附量为292mg/g;吸附速度快,15min可达吸附平衡;经5次吸附后,保留了初次吸附量的60%,具有一定的可再生性和重复使用性.同时,该吸附剂吸附腐殖酸后仍可对Cu2+、Pb2+、Cd2+产生吸附作用,较单独吸附时Cu2+、Pb2+的吸附量有所降低,而Cd2+的吸附量则有大幅提高.     

壳聚糖改性膨润土的制备及其对活性嫩黄的吸附性能研究

通过对壳聚糖（CTS）改性膨润土的制备（改性土）及对活性嫩黄印染废水吸附性能研究,探讨了壳聚糖量、醋酸体积分数等因素,制得改性土以及改性土用量、染料质量浓度、介质的pH等对吸附性能的影响.结果表明：随着壳聚糖量的增加,吸附量逐渐增大,达到最大值后逐渐减小;醋酸体积分数为1％时制备的壳聚糖改性土吸附效果最好.随着改性土用量的增大,吸附量逐渐减小;吸附量随活性嫩黄染料质量浓度的增加而增加.壳聚糖量为0.089 g、醋酸体积分数1％、改性土用量0.600 g,吸附效果最好.吸附试验符合Arrhenius方程模型,并通过XRD分析结果证实了改性土的制备.     

Synthesis and adsorption properties of chitosan-crown ether resins

1　INTRODUCTIONTheeffectiveremovalorrecoveryoftoxicmetalsstillremainsamajortopicofpresentresearch .In creasedawarenessofthetoxicityofmetalshaspromptedtheimplementationofstrictregulationsforitsdisposal,causingtraditionaltreatmentprocessessuchaschemicalprecipitationtoundergochanges .Modernmetal removaltechnologiessuchasionex change ,reverseosmosis ,andmembranesystemsthatproduceeffluentsofbetterqualitymakeitpossibletorecoverandreusemetals[1,2 ] .Chitosan ,whichiseasilyderivedfromchitinbyN de…