Studies on the adsorption behaviors of Pb(II) onto an acyl-thiourea resin

In this paper, an acyl-thiourea resin (PIDTR) was synthesized and its adsorption performances to Pb(II) were investigated by adsorption tests, scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses. A pH of 6.0 was found to be the optimum pH to obtain the maximum adsorption capacity in 12 hours of equilibration time. The Langmuir model was well fitted to the adsorption data with adsorption capacity of 0.756?mmol?·?g^?1. The adsorption kinetics showed that the adsorption process experienced liquid film diffusion and chemical reaction. The thermodynamic studies indicated that the adsorption for Pb(II) was spontaneous and endothermic. The results of SEM suggested that Pb(II) adsorbed on the surface of PIDTR. The FTIR and XPS analyses further confirmed Pb(II) might chemisorb onto PIDTR surfaces and N–Pb, O–Pb, and S–Pb were formed with the breakage of C?O, C?S, and N-H bonds in the PIDTR molecule.     

Acyl Thioacetamide-group Chelated Nanofiber to Adsorb Silver Ions from Aqueous Systems

The acyl thioacetamide-group chelated nanofiber was prepared from polyacrylonitrile（PAN） fiber with thioacetamide as vulcanization agent by an electrospinning process combined with chemical modification.It was found that the chelated nanofiber displays a high adsorption capacity and adsorption selectivity for Ag（Ⅰ） ions from aqueous systems.The adsorption capacity of Ag（Ⅰ） ions on chelated nanofiber increases with the increase of adsorption time.Kinetics of the Ag（Ⅰ） ions adsorption was found to follow pseudo-second-order rate equation.Based on the characterization results,a possible mechanism of Ag（Ⅰ） ions adsorbed on the acyl thioacetamide-group chelated nanofiber was proposed.The chelated nanofiber could not only chelate to Ag（Ⅰ） ions but also reduce them.This study provides a promising nanofiber material for removing heavy metal ions.     

聚酯基硫脲树脂PDTU—I对Ag（I）的吸附性能研究

测定了聚酯基硫脲树脂对银离子的吸附容量,讨论了吸附时间、溶液酸度,温度及银离子初始浓度等因素对其吸附性能的影响,并对吸附动力学和热力学进行了研究。结果表明,树脂对Ag(I)的吸附遵循G.E.Boyd液膜扩散方程和Langmuir等温式,且吸附为吸热过程。     

ADSORPTION BEHAVIORS OF Pt（IV） AND Pd（II） ON POLYMERIC ESTER THIOUREA RESIN

Polymeric ester thiourea resin （PDTU-I） is a new kind of chelating resin with functional atoms S, N and O, so it is an excellent adsorbent for noble metal ions. In batch testes, the adsorption capacities of PDTU-I for Pt（IV） and Pd（II） increase with the increase of contact time, temperature and initial concentration of metal ions. The adsorption data fit Boyd＇s diffusion equation of liquid film, Langmuir adsorption isotherm and Freundlich adsorption isotherm. The maximum adsorption capacities calculated by Langmuir equation are 2.54mmol/g for Pt（IV） and 4.88mmol/g for Pd（II）. According to FTIR and XPS results, functional groups of PDTU-I coordinate with noble metal ions in the adsorption process.     

壳聚糖对水中铝离子的吸附性能

研究了静态条件下壳聚糖对铝离子的吸附性能,探讨了壳聚糖吸附A l3+的最佳条件.结果表明,壳聚糖对水溶液中的A l3+吸附速度比较快,饱和吸附量为49.0 mg.g-1,适宜的pH为4,温度影响不大.对等温吸附平衡数据进行分析,符合Langmu ir吸附模型.对壳聚糖-铝(Ⅲ)配合物的红外光谱及电子能谱分析表明,壳聚糖分子中的氨基与A l3+发生了配位作用,吸附机理以单分子层化学吸附为主.     

Synthesis of a cellulose derivative for enhanced sorption and selectivity of uranium from phosphate rocks prior to its fluorometric determination

In this research work, the separation of Uranium from phosphate medium via adsorption prior to its fluorometric determination was carried out onto a newly synthesised adsorbent made via impregnation of urea onto cellulose (UIC). The full characterisation of the synthetic extractant (UIC) was carried out by various instrumental techniques such as elemental analysis, FTIR, TGA, XRD and SEM analysis. Various factors that may affect the quality of adsorbing U (VI) ions using synthesised Urea-impregnated cellulose had been investigated. The maximum adsorption capacity (82 mg/g) for U (VI) has been verified by the Langmuir isotherm model. The thermodynamics and kinetics of the adsorption process indicated that the uranium sorption onto synthesised Urea-impregnated cellulose was an exothermic and pseudo-second-order process. The tolerance limits for the common cations which are actually found with uranium in the phosphate solutions and may show sorption behaviour on the synthesised UIC resin were calculated and gave a high tolerance limit. Contrary to previously reported studies, several ameliorations have resulted including an elevated selectivity and adsorption capacity of uranium from phosphate medium. The optimised method was applied with good accuracy results for determination of uranium in reference and different phosphate rock types bearing uranium.     

硫脲基纳米螯合纤维对水溶液中Cd(Ⅱ)的吸附和密度泛函理论计算

以聚丙烯腈为原料, 利用静电纺丝技术和化学接枝制备得到硫脲基纳米螯合纤维, 并用于水溶液中 Cd(Ⅱ)的去除. 结合样品的表征和密度泛函(DFT)理论计算结果, 揭示了所制备纳米纤维材料对Cd(Ⅱ)的吸附机理. 借助静态吸附和动态吸附实验, 考察了硫脲基纳米螯合纤维对Cd(Ⅱ)的吸附性能. 结果表明, 纳米纤维吸附材料对Cd(Ⅱ)的最大吸附容量可达349.46 mg/g, 吸附过程在90 min以内即可达到基本平衡. 整个吸附过程符合准二级动力学模型和Langmuir等温吸附模型. 硫脲基纳米螯合纤维吸附Cd(Ⅱ)的吸附机理为表面配位络合, 增加纳米纤维表面硫脲基团的含量是提高吸附容量的重要途径. 该吸附材料经6次循环使用后, 最大动态吸附容量并未发生明显改变.     

Synthesis of ordered mesoporous carbonaceous materials and their highly efficient capture of uranium from solutions

An extremely effortless method was applied for successful synthesis of mesoporous carbonaceous materials(MCMs) using well-ordered mesoporous silica as template. Various characterizations(scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), Raman, X-ray photoelectron spectroscopy(XPS), Brunner-Emmet-Teller(BET) and Zeta potential) confirmed that MCMs had large surface area, uniform pore size distribution, and abundant oxygen-containing functional groups. The batch techniques were employed to study U(VI) adsorption on MCMs under a wide range of experiment conditions. The adsorption kinetics of U(VI) onto MCMs were well-fitted by pseudo-second-order kinetic model, indicating a chemisorption process. The excellent adsorption capacity of MCMs calculated from the Langmuir model was 293.95 mg g~(-1) at pH 4.0. The FT-IR and XPS analyses further evidenced that the binding of U(VI) onto MCMs was ascribed to the plentiful adsorption sites(–OH and –COOH groups) in the internal mesoporous structure, which could efficiently trap guest U(VI) ions. The results presented herein revealed that MCMs were ideal adsorbents in the efficient elimination of uranium or other lanthanides/actinides from aqueous solutions, which would play an important role in environmental pollution management application.     

Modified nanoporous magnetic cellulose–chitosan microspheres for efficient removal of Pb(II) and methylene blue from aqueous solution

Pyromellitic dianhydride-modified nanoporous magnetic cellulose–chitosan microspheres (PNMCMs) were designed and synthesized to introduce abundant carboxyl groups onto the basic microstructure. The novel microspheres were studied by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). Subsequently, a batch technique was applied to investigate various environmental parameters that could affect the adsorption behavior of the PNMCMs. Due to its nanoporous structure and large quantity of carboxyl groups, the cellulose/chitosan-based bioadsorbent exhibited excellent adsorption performance for removal of Pb(II) ions and methylene blue (MB) from aqueous solution, with maximum adsorption capacity of 384.6 and 833.3 mg/g, respectively. Furthermore, the adsorption kinetics and isotherms of Pb(II) ions and MB on PNMCMs obeyed the pseudo-second-order and Langmuir isotherm models, and the rate of adsorption was found to be controlled by film diffusion. Finally, the PNMCMs with adsorbed Pb(II) and MB could be easily regenerated using HCl, retaining removal capacity of almost 89% after six repeated uses.     

Enhanced adsorption of puerarin onto a novel hydrophilic and polar modified post-crosslinked resin from aqueous solution

A novel of hydrophilic and polar N-vinylpyrrolidone modified post-crosslinked resin was synthesized and the adsorption behaviors toward puerarin from aqueous solution were investigated. The post-crosslinked adsorbent PNVP-DVBpc was prepared by Friedel-Crafts reaction of residual double bonds without external crosslinking agent. The specific surface area of precursor PNVP-DVB increased obviously after post-crosslinking modification. The synthesized adsorbents were characterized by BET surface area, Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). The adsorption behaviors of puerarin from aqueous solution onto precursor PNVP-DVB and post-crosslinked adsorbent PNVP-DVBpc were thoroughly researched. Commercial polymeric adsorbents Amberlite XAD-4 and AB-8 were chosen as the comparison. Among the four media, PNVP-DVBpc presented the largest adsorption capacity of puerarin, which resulted from the synergistic effect of high specific surface area and polar groups (amide groups) onto the adsorbent matrix. Experimental results showed that equilibrium isotherms could be fitted by Freundlich model and the kinetic data could be characterized by pseudo-second order model reasonably. Column adsorption experiments indicated that the puerarin could be completely desorbed by 4.0 BV industrial alcohol. Continuous column adsorption-regeneration cycles demonstrated the PNVP-DVBpc without any significant adsorption capacity loss during operation.     

Preparation of corn stalk-based adsorbents and their specific application in metal ions adsorption

Corn stalk-based adsorbents modified from corn stalk were prepared by Cu(0)-mediated reversible-deactivation radical polymerization (Cu(0)-mediated RDRP). They were applied to remove metal ions and they exhibited good adsorption capacity, especially for Hg(II). Adsorption properties of corn stalk can be enhanced by introducing cyano, amino, amidoxime, and carboxyl groups onto its surface, which results in efficient adsorbents for different metal ions. TGA, SEM, EA, and FTIR analyses were employed to characterize the structures of corn stalk-graft-polyacrylonitrile (CS-g-PAN), corn stalk-graft-polyacrylamide (CS-g-PAM), amidoxime corn stalk-graft-polyacrylonitrile (AO CS-g-PAN) and carboxyl corn stalk-graft-poly(methyl acrylate) (CO CS-g-PMA). The maximum adsorption capacity for Hg(II) was 8.06 mmol g^?1 of AO CS-g-PAN. Kinetics of the Hg(II) adsorption on AO CS-g-PAN was found to follow the pseudo-second-order model and the adsorption isotherms were well fitted with the Freundlich isotherm model.     

Feasible fabrication of o-phenanthroline-based polymer adsorbent for selective capture of aqueous Ag(I)

Devising a desirable adsorbent for efficiently selective capture of Ag(I) from wastewater has attracted much attention but faced with huge challenges. Herein, a novel linear o-phenanthroline-based polymer l-PRL was prepared via chemical oxidative polymerization for the adsorption of Ag(I). The maximum adsorption capacity for Ag(I) by l-PRL is 325.8 mg/g at pH 0. In addition, l-PRL owes ascendant selectivity for Ag(I) from aqueous solutions containing various interfering metal ions of Pb(II), Co(II), Ni(II), Cd(II) and Fe(III). Multiple characterizations of FT-IR and XPS uncover that the N groups on l-PRL act as adsorption sites to coordinate with Ag(I). Density functional theory (DFT) calculations further evidence the mechanism that l-PRL is provided with the admirable adsorptivity and selectivity for Ag(I). It is mainly attributed to the most stable complexes of l-PRL with Ag(I), which possesses shortest Ag-N bond length compared with other heavy metal ions. Furthermore, 93.5% of initial adsorption capacity is reserved after four continuous regeneration cycles, indicating that l-PRL is equipped with superior recyclability and durability, and l-PRL is capable of removing Ag(I) in low-concentration actual Ag(I)-containing wastewater completely. This study shed light on the rational design of polymer adsorbents and in-depth insight into selective removal of aqueous Ag(I).     

A novel extractant-impregnated resin containing carminic acid for selective separation and pre-concentration of uranium(VI) and thorium(IV)

The present work proposes the use of a novel extractant-impregnated resin (EIR) as an adsorbent in trace separation and pre-concentration of U(VI) and Th(IV) ions. The new EIR was prepared by impregnating carminic acid onto Amberlite XAD-16 resin beads. The morphology of new EIR was studied by BET surface area measurements and SEM micrographs. A column packed with CA/XAD-16 was used for selective separation and pre-concentration of the metal ions. Maximum adsorption of Th(IV) and U(VI) ions occurred at pHs of 3.50–5.75 and 3.75–6.50, respectively. The adsorbed metals could be eluted sequentially using 0.55?mol?L^?1 HCl for U(VI) and 2.25?mol?L^?1 HCl for Th(IV). The dynamic capacity of EIR was found to be 0.832 and 0.814?mmol?g^?1 for Th(IV) and U(VI), respectively. The tolerance limit of some foreign ions was also studied. The proposed method showed a good performance in analyzing geological reference materials and a synthetic seawater sample. Furthermore, the above procedure was successfully employed for the analysis of natural water samples.     

Design and syntheses of functionalized copper-based MOFs and its adsorption behavior for Pb(Ⅱ)

A novel copper-based MOFs adsorbent(Cu-BTC-Th) was prepared using an one-step method by introducing a new organic ligand of 4-thioureidobenzoicacid(Th) with active groups for selectively adsorbing Pb(Ⅱ) from aqueous solutions. The chemical composition and structure of the prepared MOFs materials were characterized by scanning electron microscope(SEM), X-ray diffraction(XRD), fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), Brunner-Emmet-Teller(BET) analysis, ...     

Behaviors and mechanisms of copper adsorption on hydrolyzed polyacrylonitrile fibers

Polyacrylonitrile fiber (PANF) was hydrolyzed in a solution of sodium hydroxide and the hydrolyzed polyacrylonitrile fiber (HPANF) was used as an adsorbent to remove copper ions from aqueous solution. Scanning electron microscopy (SEM) showed that the hydrolysis process made the surface of HPANF rougher than that of PANF. Fourier transform infrared (FTIR) spectroscopy revealed that the HPANF contained conjugated imine (-Cz=Nz-) sequences. Batch adsorption results indicated that the HPANF was very effective in adsorbing copper, and the adsorption equilibrium could be reached within 10-20 min. Atomic force microscopy (AFM) showed that some aggregates formed on the surface of the HPANF after copper ion adsorption and the average surface roughness (R(a)) value of the HPANF changed from 0.363 to 3.763 nm due to copper adsorption. FTIR analysis indicated that copper adsorption caused a decrease of the light adsorption intensity of the imine (-Cz=Nz-) groups at 1573 and 1406 cm(-1) wavenumbers, and X-ray photoelectron spectroscopy (XPS) showed that the binding energy (BE) of some of the nitrogen atoms in the HPANF increased to a greater value due to copper adsorption. The FTIR and XPS results suggest that the adsorption of copper ions to the HPANF is attributed to the imine groups on the surface of the HPANF.     

以硫醚为主链的螯合树脂研究──Ⅱ．2－氨基噻唑树脂的合成及吸附性能

聚环硫丙烷和环硫氯丙烷与环氧氯丙烷共聚物，在少量二乙烯三胺存在下制得交联聚合物，将交联聚合物与２－氨基噻唑反应，制得二种侧链带有氨基噻唑的新型螯合树脂．它们对贵金属具有优良的吸附性能和高的吸附选择性．通过Ｘ－射线光电子能谱初步探讨了树脂对金属离子的螯合作用．     

接枝改性羧甲基纤维素对铜离子的吸附研究

将离子型单体丙烯酸(AA)及非离子型单体丙烯酰胺(AM)接枝在羧甲基纤维素(CMC)上,通过协同作用提高材料的吸水性及吸水速率,并研究了其对铜离子的吸附性能.通过傅里叶红外(FTIR)对材料分析表明,从及AM成功接枝在CMC上;对吸附物进行了表面分析,扫描电镜图(SEM)显示吸附物表面有大量颗粒状物质,X射线能谱(XPS)证实材料表面吸附了铜离子;在浓度为10mmol/L的铜离子溶液中,CMC-g-P(AA-co-AM)材料的吸附容量为20.30mmol/g.     

Enhanced Cu(II) and Cr(VI) biosorption capacity on poly(ethylenimine) grafted aerobic granular sludge

The biosorption characteristics of cations and anions from aqueous solution using polyethylenimine (PEI) modified aerobic granules were investigated. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis exhibit the presence of PEI on the granule surface. Compared with the raw granule, the modified aerobic granules with PEI showed a significant increase in sorption capacity for both metal ions. The monolayer biosorption capacity of granules for Cu(II) and Cr(VI) ions was found to be 71.239 and 348.125mg/g. The optimum solution pH for adsorption of Cu(II) and Cr(VI) from aqueous solutions was found to be 6 and 5.2, respectively. The biosorption data fitted better with the Redlich-Peterson isotherm model. FTIR showed chemical interactions occurred between the metal ions and the amide groups of PEI on the biomass surface. XPS results verified the presence of Cr(III) on the biomass surface, suggesting that some Cr(VI) anions were reduced to Cr(III) during the sorption.     

Dynamic Adsorption and Desorption Behaviors of Cu(II), Ag(I), and Au(III) on Silica Gel Microspheres Encapsulated by Salicylic Acid–Functionalized Polystyrene

Composite material silica gel microspheres encapsulated by salicylic acid functionalized polystyrene(SG–PS–azo–SA) have been synthesized, and the dynamic adsorption and desorption properties of this silica gel matrix inorganic–organic composite material for Cu(II), Ag(I), and Au(III) have been investigated. The results displayed that SG–PS–azo–SA had excellent adsorption for Cu(II), and the film diffusion dominated the adsorption process of SG–PS–azo–SA for Cu(II), Ag(I), and Au(III). These metal ions could be desorbed with the eluent solution of 2.5 mol/L HCl, 3% thiourea in 0.5 mol/L HCl, and 0.5% thiourea in 1 mol/L HCl, respectively. When the elution was carried out for 30 min, 30 min, and 132 min, the desorption ratio ω could reach 91.1%, 99.4%, and 60.84%, respectively. Thus, silica gel encapsulated by polystyrene coupled with salicylic acid (SG–PS–azo–SA) is favorable and useful for the removal of metal ions Cu(II), Ag(I), and Au(III), and the high adsorption capacity make it a promising candidate material for the metal ions removal.     

Performance and Mechanisms of Fluoride Removal from Groundwater by Lanthanum-aluminum-loaded Hydrothermal Palygorskite Composite

Lanthanum-aluminum loaded hydrothermal palygorskite(La-Al-HP) composite was prepared and selected as adsorbent for the fluoride removal from simulated groundwater. The adsorbent was characterized by scanning electron microscopy(SEM), Brunauer-Emmet-Teller(BET) analysis, X-ray diffraction(XRD) analysis and X-ray photoelectron spectroscopy(XPS). SEM visualization shows that the dense surface structure of raw HP appeared loose and presented micro canals after modification. The BET analysis also proved the specific surface area of La-Al-HP composite(95.58 m²/g) was higher than that of the raw HP(34.31 m²/g). Subsequently, the adsorption capacity of La-Al-HP composite was demonstrated in adsorption experiments. The kinetics of fluoride ion adsorption into La-Al-HP composite followed the pseudo-second order with a correlation coefficient of 0.997. The isotherm data was well fitted with the Langmuir model. The monolayer adsorption capacity of La-Al-HP composite was 1.30 mg/g. The XRD and XPS results reveal that the La³⁺ and Al³⁺ ions were loaded on the surface of modified HP and the fluoride ion was adsorbed onto the La-Al-HP composite. A large amount of La-Al-O composite oxide existing on the surface of La-Al-HP composite might be the immanent cause for the excellent adsorption capacity of fluoride ions.