Adsorption of rubidium ion from aqueous solution by surface ion imprinted materials

A new type of rubidium ion-imprinted polymer has been synthesized by the surface-imprinting technique using methacrylic acid as the functional monomer,the rubidium ion as the template,methanol as the solvent,and silica as a carrier.Ethylene glycol dimethacrylate and 2,2-azobisisobutyronitrile were used as acrosslinker and an initiator,respectively.In addition,based on the macrocyclic effect of crown ethers,the 18-crown-6 ligand was introduced as a ligand to fix the template ions better.Scanning electron microscopy,zeta-potential analysis,Fourier transform infrared spectroscopy,thermogravimetric analysis,and X-ray photoelectron spectroscopy were performed to characterize the ion-imprinted polymer.The effects of the preparation and adsorption conditions on the adsorption performance of the rubidium ion-imprinted polymer were investigated.The results indicated that the rubidium ion-imprinted polymer has high selectivity and faster kinetics than other adsorbents,with an equilibrium adsorption capacity of 200.19 mg·g^(-1)at 298 K within 25 min.The sorption isotherm was well described by the Freundlich isotherm model,while the adsorption kinetics fitted the pseudo-second-order kinetic model.Consecutive adsorption-desorption experiments showed that the ion-imprinted polymer had good chemical stability and reusability.

Understanding the hydroxyl adsorption behavior at Pt electrode surface in high-temperature alkaline solutions

Since the application in fuel cell,the electrochemical adsorption of hydroxyl has received considerable attention in recent years.While most research mainly focus on the room temperature,in this paper,the electrochemical adsorption of hydroxyl in alkaline solution at high temperature was investigated.An unusual oxidation peak was observed at-0.27 V,suggesting new behavior of hydroxyl adsorption occurred.As is known two kinds of cation hydrated clusters exist in alkaline solution,(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H and(H_(2)O)_xM^(+)-O_(ad)H.For K^(+)and Cs^(+),the cluster shows unstable structure due to the weak interaction between hydrated cation and OH^(-)especially at high temperature.However,For Li^(+),Na^(+)the cluster structure would be stable,as the interaction force between the hydrated cation and OH^(-)is so strong.It was revealed that the unusual oxidation peak has some relationship with the(H_(2)O)_(x-1)M^(+)-H_(2)O-O_(ad)H cluster(K^(+)and Cs^(+))absorbed at Pt electrode surface.When the temperature was raised,(H_(2)O)_(x-1)M^(+)-H_(2)O-and-O_(ad)H was disconnected,then the O_(ad)H absorbed at Pt surface got oxidated.Based on the SEM observation,it was showed the unusual electrochemical oxidation reaction would generate platinum oxides,blocking the reactive sites at Pt electrode surface,thus reducing the electrochemical reactivity of Pt electrode.Accordingly,parameters of alkaline concentration and temperature were systematically studied,it was found that increase temperature or alkaline concentration was in favor of the unusual oxidation reaction.This study provides more understanding of hydroxyl adsorption behavior at Pt electrode surface for the high temperature water solution environment.

Double open mouse-like terpyridine parts based amphiphilic ionic molecules displaying strengthened chemical adsorption for anticorrosion of copper in sulfuric acid solution

In this study,the benign target double terpyridine parts based amphiphilic ionic molecules(AIMs 1,2)and the reference single terpyridine segment included AIMs(AIMs 3,4)were synthesized through a multi-step method,and the molecular structures were fully characterized.The excellent anticorrosion of the target AIMs for copper surface in H_(2)SO_(4) solution was demonstrated by the electrochemistry analysis,which was more superior over those of the reference AIMs.The standard adsorption free energy changes of the target AIMs calculated by the adsorption isotherms were lower than -40 kJ·mol^(-1),suggesting an intensified chemical adsorption on metal surface.The molecular modeling and molecular dynamic computation of the studied AIMs were performed,demonstrating that the target AIMs exhibited lower highest occupied molecular orbital-lowest unoccupied molecular orbital energy gaps and greater adsorption energies than the reference ones.The chemical adsorption of the AIMs on metal surface was revealed by various spectroscopic methods including scanning electron microscopy,atomic force microscopy,Fourier transform infrared spectroscopy,attenuated total reflection infrared spectroscopy,Raman and X-ray diffraction.

Relation of lead adsorption on birnessites with different average oxidation states of manganese and release of Mn^(2+)/H^+/K^+

The characteristics of Pb^2＋ adsorption on the surface of birnessites with different average oxidation states （AOS） of Mn, synthesized under acidic and alkali conditions, were investigated. The results indicated that the amount of adsorbed Pb^2＋ increased with the increase of Mn AOS in birnessites. The amount of Pb〉 adsorbed positively correlated with the amount of released Mn^2＋, H^＋, and K^＋ （r = 0.9962 〉 0.6614, n = 14, ct = 0.01）. The released Mn^2＋, H^＋, and K^＋ were derived mostly from the corresponding cations adsorbed on the vacant sites. The maximum amount of adsorbed Pb^2＋ increased with the increasing vacant cation sites, leading to an increase of the total amount of released Mn^2＋, H^＋, and K^＋, and the increased likelihood for two Pb^2＋ adsorbed in the region of one side of a vacant site.

Release of Hydroxyl Ions Associated with Chloride Adsorption in Electrodialyzed Variable Charge Soils

The release of hydroxyl ions from two variable charge soils associated with the adsorption of chloride in NaClO4 solutions was examined. The complete release required about 10 minutes. The release decreased with the increase in the NaClO4 concentration at first and eventually was little affected by the latter. The adsorption of Cl- was almost linearly related with the quantity of NaCl added to the system, while the OHrelease-NaCl curve varied with the soil type and the concentration of NaClO4. The logarithm of the quantity of released OH- was linearly related with the pH. The ratio of released OH- to adsorbed Cl- was larger in dilute NaClO4 solutions than in concentrated solutions and decreased with increasing NaCl.

MSNCs and MgO-MSNCs as drug delivery systems to control the adsorption kinetics and release rate of indometacin

Mesoporous silica cocoon materials(MSNCs) and MgO doped mesoporous silica cocoons(MgO-MSNCs) with the cocoon-like hierarchical morphology and different alkalinities were synthesized as carriers for acidic drugs. Indomethacin(IMC) was selected as a model drug and loaded into carriers. All materials and the drug-loaded samples were characterized by nitrogen adsorption, FTIR spectroscopy, transmission electron microscopy(TEM), powder X-Ray diffraction(XRD) and differential scanning calorimetry(DSC). The effect of the Mg/Si molar ratio on the kinetics and equilibrium of IMC adsorption on MgO-MSNCs was thoroughly examined, and it was found that the increase in the Mg/Si molar ratio resulted in an increasing IMC adsorption rate due to the increased affinity between alkaline MgO-MSNCs and weak acid IMC. The adsorption kinetics fitted a pseudo second-order model well. The Freundlich isotherm showed a better fit, indicating that the coverage of IMC on the surface of MgO-MSNCs was heterogeneous. The maximum adsorption capacity of adsorbent was calculated by the Langmuir isotherm equation. The Temkin equation provided further support that the IMC adsorption on MgO-MSNCs was dominated by a chemisorption process. MgO-MSNCs also have the advantage of allowing an adjustment of the drug release rate of weak acid drug. The cytotoxicity assay indicated good biocompatibility of MgO-MSNCs. Our research on MgO-MSNCs carriers demonstrated their potential therapeutic benefit for safe and effective management of IMC adsorption and in vitro release.

Mathematical Modelling for the Diffusional Release of a Dispersed Solute from a Cylindrical Polymer Matrix into Finite External Volume

An exact solution has been obtained for the release kinetics of a solute from a cylindrical non-erodible polymeric matrix into a finite external volume when the initial solute loading is greater than the solubility limit in the matrix. The moving boundary solution is derived based on the combination of variable method. The formulas of the moving boundary and the fractional solute release are given. The moving boundary and the fractional solute release profiles have been calculated at various solute loading levels and different external volumes. The obtained results show that as the external fluid volume increases, the fractional release at any time and the maximum fractional release increase. In addition, for a given external volume, as initial drug loading increases, the fractional release at any time decreases.

EFFECT OF ADSORPTION ON THE VISCOSITY OF DILUTE POLYMER SOLUTION

Careful measurements of the dilute solution viscosities of polyethylene glycol and polyvinyl alcohol in water were carried out. The reduced viscosities of both polymer solutions plot upward curves at extremely dilute concentration levels similar to the phenomena observed for many polymer solutions in the early 1950's. Upon observation of the changes of the flow times of pure water in and the wall surface wettability of the viscometer after measuring solution viscosity, a view was formed that the observed viscosity abnormality at extremely dilute concentration regions is solely due to the effect of adsorption of polymer chains onto the wall surface of viscometer. A theory of adsorption effect based on the Langmuir isotherms was proposed and a mathematical; analysis for data treatment was performed. The theory could adequately describe the existing viscosity data. It seems necessary to correct the viscosity result of dilute polymer solutions measured by glass capillary viscometer by taking into account the effect of adsorption in all cases.

Trimethylamine Adsorption Mechanism on Activated Carbon and Removal in Water and Oyster Proteolytic Solution

In this study,seven coal-based activated carbons(ACs)were adopted to remove trimethylamine(TMA)in an aqueous solution as environmentally friendly and harmless adsorbents.The results showed that columnar AC(CAC)had a clear scale and honeycomb structures with few fragments and micropores,contributing to superior TMA removal capacity compared to granular AC(GAC)(71.67%for 6.0 mm CAC and 69.92%for 40–60 mesh GAC).In addition,the process of adsorption was accompanied by desorption,and the recommended absorbed time was 120–180 min.The short time to achieve equilibrium indicated that adsorption was kinetically controlled,and pseudo-second-order kinetics was more appropriate than pseudo-first-order kinetics in explaining the adsorption mechanism in both water and oyster enzymatic hydrolysate.The intraparticle diffusion model presented that the adsorption processes could be divided into three steps for GAC and two steps for CAC.The adsorption processes were consistent with the Freundlich model,indicating the existence of physisorption and chemisorption as multilayer adsorption.The results indicated that AC,especially CAC,has great potential for TMA elimination in aquatic product processing.

NH_4^+ Adsorption in a Eum-Orthic Anthrosol at Different Solution/Soil Ratios and Temperatures

Effects of NH+ concentration, solution/soil ratio and temperature on NH+ adsorption were studied in a Eum-OrthicAnthrosol. The slopes of the soil NH+ adsorption isotherms and the fitted n, the coefficient for the adsorption intensity,and k, the coefficient related to adsorption capacity, of the Freundlich equation increased with increasing solution/soilratio (SSR) and with decreasing temperature (T). For the range of experimental conditions, the value of δq/δc, the rateof change of the amount of NH+ adsorbed in the soil solid phase (q) with respect to the equilibrium concentration of NH+in soil solution (c), was 0.840, indicating that q increased with increasing c. From 2 to 45℃, δq/δSSR, the rate of changeof q with respect to SSR, decreased from 2.598 to 1.996, showing that q increased with increasing SSR, while its increasingrate decreased with temperature. From SSR 1:1 to 20:1, δq/δT, the rate of change of q with respect to T, decreasedfrom -0.095 to -0.361, indicating that q decreased with increasing temperature, and at the same time the negative effectof temperature became larger as SSR increased. Thus under the experimental conditions the order of importance indetermining the amount of NH+ adsorbed in the soil solid phase was δq/δSSR > δq/δc > ｜δq/δT｜, indicating that thegreatest effect on the amount of NH^4+ adsorbed was with the solution/soil ratio; the equilibrium concentration of NH+had a lesser effect; and temperature had the least effect.

Diffusion-controlled Adsorption Kinetics of Surfactant at Air/Solution Interface

For the diffusion-controlled adsorption,the expression of dynamic surface adsorption(t)was obtained by solving the diffusion equation.Two cases,i.e.the short and long time limits,were mainly discussed in this paper.From the measured dynamic surface tension of aqueous surfactant sodium dodecyl sulfate(SDS) solutions at25 °C,the adsorption kinetics of SDS at air/solution interface was studied.It was proved that for both of the short and long time limits,the adsorption process of SDS was controlled by diffusion.

Adsorption of Hg(Ⅱ) from aqueous solution using thiourea functionalized chelating fiber

A fast and selective adsorbent for Hg(II) from aqueous solutions using thiourea(TU) functionalized polypropylene fiber grafted acrylic acid(PP-g-AA),PP-g-AA-TU fibers,was characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.The adsorption behavior of the functionalized chelating fibers for Hg(II) was investigated by static adsorption experiments,and the effects of some essential factors on adsorption of Hg(II) were examined,such as pH,initial concentration,adsorption time,coexisting cations,and temperature.The results showed that the adsorptive equilibrium could be achieved in 10 min,and the equilibrium adsorption quantity of PP-g-AA-TU fibers was 20 times that of PP-g-AA fibers.The PP-g-AA-TU fibers showed a very high adsorption rate and a good selectivity for Hg(II) over a wide range of p H.The adsorption isotherm can be well described with Langmuir model,with the maximum adsorption capacity for Hg(II) up to52.04 mg·g^(-1)and the removal of Hg(II) more than 97%.The kinetic data indicate that the adsorption process is best-fitted into the pseudo-second-order model.

Magnesium (Ⅱ) Adsorption from Aqueous Solutions on China Clay and the Stability Constants for Complex Formation

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Adsorption Application for Removal of Hazardous Chloroform from Aqueous Solution by Nanocomposites Rectorite/Chitosan Adsorbent

A novel nanocomposite bioadsorbent rectorite/chitosan was prepared by controlling different mass ratios of chitosan to rectorite using the water phase intercalation technique. The structure of the bioadsorbent was characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM), Transmission electron microscopy (TEM), respectively. The results showed that the chitosan had been inserted into the rectorite layer successfully. The adsorption properties of the nanocomposite adsorbent toward CHCl3 from aqueous solution were investigated. Adsorption results showed that both nanocomposite adsorbents with weight ratio of rectorite to chitosan of 3:1 and 5:1 exhibited higher adsorption capacities.

ADSORPTION OF SULFOXIDES ON SOLID FROM AQUEOUS SOLUTIONS——Ⅲ.THE ADSORPTION ON CARBON BLACK

The adsorption of decylmethylsulfoxide(DEMS)onto carbon black and the effects of temperature,salt(NaCl)and acid (HCl)have been measured.Typical two plateaux type adsorption isotherms were obtained.Applying the two step model of surfactant adsorption on solid/liquld interface and the general adsorption isotherm equation[9]the experimental results were interpreted qualitatively and quantitatively.

Solution Blowing of Palygorskite-Based Nanofibers for Methylene Blue Adsorption

Palygorskite(PG)adsorbent with superior adsorption property and ion-exchange ability is highly desired in the field of dye removal.However,it generates high amounts of precipitation due to the granular form,resulting in secondary pollution after adsorption.Herein,the novel high porosity PG-based nanofibers that are easy for operating and retrieving have been fabricated using effective solution blowing and subsequent calcination.The obtained highly efficient adsorption nanofibers exhibit large specific surface area about 170.50 m^(2)/g with average diameter from 243 nm to 365 nm.Based on the abovementioned nanofibrous structure and negatively charged PG,the solution blowing of PG-based nanofibers(SBPNs)showed high adsorption capacity for methylene blue(MB)(112.36 mg/g).In addition,the adsorption of SBPNs is well described by the Langmuir isotherm model.This work provides new SBPNs forming process for the fields of dye removal,which may achieve the production of PG adsorbents at the industrial level.

Adsorption of Protein from Model Wine Solution by Different Bentonites

从模型酒的蛋白质的吸附在乙醇的不同温度， pH 价值，接触时间，和集中下面被调查，由某些火山灰成胶状黏土。结果证明乙醇分子能拓宽蛋白质分子的隧道到火山灰成胶状黏土的夹层，并且最大的蛋白质吸附数量发生在 12% 的乙醇集中下面(由卷) 并且 3.56 的 pH 值。增加的单个点 Brunauer-Emmitt-Teller (赌注) 表面区域(SBET ) 和吸附毛孔体积(VAds ) 分别地从表面建议了火山灰成胶状黏土表面和一条更宽的蛋白质隧道的大量活跃吸附地点到火山灰成胶状黏土的内部吸附地点。同时，更高的甲又蓝色测试(MBT ) 和胀大的索引(Sw ) 显示它为水的入口和蛋白质的吸收度是容易的。更高的温度被发现有利消除更多的蛋白质，到达最大的吸附带了大约 20 去 40min。

Development of controlled release formulations of thiabendazole

This study aimed to develop controlled release formulation of Thiabendazole for reduced contaminations to soil water and agricultural produces. The idea behind this work was based on changing the ionization status of Thiabendazole molecule throughout pH changes to become a cation then adsorbing it to bentonite clay surfaces. Equilibrium concentrations of Thiabendazole in the adsorption solutions were determined by HPLC. Results showed that Thiabendazole was better adsorbed in clay at the lowest pH value (pH 3). Furthermore, raising the temperature of the adsorption reaction increased the adsorbed amount of Thiabendazole. Release experiments showed that Thiabendazole is extremely slower at pH 3 than at pH 5.5 or pH 9. These promising results suggest that application of Thiabendazole clay based formulation may reduce the applied rate and that the released fraction consequently may reduce the environmental contamination. It is also advantageous to use these formulations in the acidic soil for plant disease control.