Synthesis of sulfides via reaction of aryl/alkyl halides with S8 as a sulfur-transfer reagent catalyzed by Fe3O4-magnetic-nanoparticles-supported L-Histidine-Ni(II)

One-pot synthesis of symmetrical diaryl/alkyl sulfides in high yields from the reaction between aryl/alkyl halides and S₈ can be carried out in a short period, using Fe₃O₄@SiO₂@His@Ni(II) as a reusable catalyst. The present approach offers the advantages of a clean reaction, simple methodology and high efficiency, and avoids the use of a toxic catalyst.     

Efficiency of High Gradient Magnetic Separation Applied to Micrometric Magnetic Particles

This article presents two prototypes of laboratory magnetic separators that generate high gradient magnetic fields. Such a field is created in a separation cell via steel wool. The efficiency of separators was tested on a water suspension containing weakly magnetic Fe₂O₃ nano/micro-particles, prepared in three size fractions in a size range of 60 nm – 10 μm. The separation process was evaluated via optical transmittance of the suspension before and after sequential separation processes. Repeated separations on the same sample exhibit an asymptotic trend that results in the conclusion that it is not possible to trap all solid content. According to the decrease of solid particles concentrations during cyclic separation we set the efficiency of the process. It is maximally 46% for fine fraction, 65% for medium fraction, and 40% for coarse fraction after infinity separation cycles.     

Three-dimensional g-C3N4/MgO composites as a high-performance adsorbent for removal of Pb(II) from aqueous solution

ABSTRACT

A novel, three-dimensional material of g-C₃N₄/MgO was prepared by pyrolysis method. The adsorption behavior for Pb(II) onto g-C₃N₄/MgO was systematically investigated. The adsorption experiments confirmed that the g-C₃N₄/MgO exhibited remarkable adsorption performance owing to its rough morphology and abundant active sites on the surface. The maximum adsorption capacities for Pb(II) reached to 220.3, 226.2 and 235.1 mg/g at 308 K, 318 K and 328 K, respectively. The optimum adsorbent dosage was 1.0 g/L. The adsorption kinetics and isotherm could be well described by the pseudo-second-order model and Langmuir isotherm model, respectively. The adsorption process was spontaneous and endothermic.     

Magnetic Pb(II) Ion-Imprinted Polymer Prepared by Surface Imprinting Technique and its Adsorption Properties

A novel magnetic Pb(II) ion-imprinted polymer was prepared via surface ion-imprinting technique by using magnetic Fe₃O₄@SiO₂ microspheres as supporter, Pb(II) as template ion, methacrylic acid and salicylaldoxime as monomers, and ethylene glycol dimethacrylate as crosslinker. The product was characterized by FT-IR, VSM, XRD, and SEM. The adsorption experiments showed that the imprinted polymer was employed successfully in comparison with non-imprinted polymer. When the temperature was in a range of 277 K to 291 K the maximum adsorption was about 81.83 mg/g with an optimal pH 6.0. Its relative selectivity coefficient values of Pb(II)/Cu(II), Pb(II)/Zn(II), and Pb(II)/Cd(II) were 2.60, 6.38, and 7.89 times greater than the ones of the magnetic non-imprinted polymer. The Langmuir adsorption model was more favorable for M-IIP than Freundlich or Temkin adsorption models. The Scatchard analysis suggested that M-IIP was processed with two kinds of binding sites with different affinity. Thermodynamic experiment showed that the adsorption was a spontaneous and endothermic process for Pb(II). The mechanism for Pb(II) adsorption on the imprinted polymer was also investigated.     

Efficient removal of Cr(VI) and Pb(II) from aqueous solution by magnetic nitrogen-doped carbon

The magnetic nitrogen-doped carbon (MNC) was prepared from polypyrrole by a simple high temperature calcination process in this paper. The structure and properties of MNC were analyzed by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, Brunner-Emmet-Teller, vibrating sample magnetometer, and X-ray photoelectron spectroscopy. The capacity of MNC to adsorb Cr(VI) and Pb(II) was evaluated. The effects of the initial pH, dosage, concentration and temperature on the adsorption capacity of MNC were measured. MNC had a large specific surface area and a special porous structure. Its nitrogen and carbon sources were rich, and the ratio of carbon to nitrogen was fixed. The maximum Cr(VI)-adsorption capacity and maximum Pb(II) adsorption capacity of MNC could reach 456.63 and 507.13 mg∙g⁻¹ at 318 K, respectively. The pseudo-second-order model was used to describe the adsorption kinetics of MNC, and the Freundlich model was employed to discuss its isotherms. The adsorption process was affected by the electrostatic force, the reducing reaction, pores and chelation. The results of this study suggest that MNC is a material with superior performance, and is very easily regenerated, reused, and separated in the adsorption process.     

Preparation of Low-Cost Adsorbents from Paper Industry Wastes and their Pb(II) Removal Behavior in Water

In this study, we prepare low-cost adsorbents from paper industry waste (newspaper (NP) and white paper (WP) waste) through a simple drying process and used them for Pb(II) removal. Characteristics, maximum Pb(II) removal capacities of prepared adsorbents, and Pb(II) removal mechanisms are investigated. The maximum amounts of adsorbed Pb(II) on NP and WP derived from the Langmuir isotherm are 42.4 and 18.5 mg·g^?1, respectively. This value is similar or more effective than commercial and other low-cost Pb(II) sorbents. It indicates that low-cost adsorbents prepared from paper industry waste have high potential as inexpensive and effective heavy metal adsorbents.     

Sorption of Pb(II), Cd(II) and Zn(II) by iminodiacetate chelating resins in non-competitive and competitive conditions

Two chelating resins (CRs) bearing iminodiacetate (IDA) groups derived from acrylonitrile - divinylbenzene (AN-DVB) copolymers having 10 and 15 wt.% nominal cross-linking degrees and a high mobility of the functional groups caused by the presence of a longer spacer between the matrix and the IDA groups were synthesized and tested as sorbents for heavy metal ions like: Pb(II), Cd(II) and Zn(II) from aqueous solutions by batch and column techniques. Experimental data obtained from batch equilibrium tests have been analyzed by two isotherm models: Freundlich and Langmuir. The overall adsorption tendency of CRs toward Pb(II), Cd(II) and Zn(II), under non-competitive conditions, followed the order: Cd(II) > Pb(II) > Zn(II). Selectivity studies were performed in ternary mixture of Pb(II), Cd(II) and Zn(II) to check if the synthesized CRs can be useful for selective separation of heavy metal cations. The results revealed that the CRs with IDA groups exhibited high selectivity toward Pb(II), both in batch and column techniques. Regeneration of the resins was achieved using 0.1 M HCl solution.     

Valine-Coated Magnetic Nanoparticles: Synthesis,Characterization, and Application in Removal of Cd(II) Ions from Aqueous Solution

A novel Valine coated magnetic nano-particles (MNPs-Val) has been synthesized for the removal of Cd(II) ions from aqueous solution. The MNPs-Val were developed by electrostatic attraction of valine (C₅H₁₁NO₂) on the bare surface of Fe₃O₄ nanoparticles and characterized by using FT-IR, XRD, SEM, and TEM analysis. The morphology and average particles size 15-27 nm of MNPs-Val were analyzed by SEM and TEM. The coated MNPs were applied for adsorptive removal of Cd(II) ions from aqueous solutions. Factors affecting the adsorption of Cd(II) ions on the MNPs-Val surface such as the pH, temperature, adsorbent dosage, and contact time were investigated which have significant effect on the metal ion removal. The Cd(II) ions adsorption equilibrium on the MNPs-Val could be achieved in 35 min at the optimized pH 5 and follow the pseudo-second order kinetics model. The experimental data for the adsorption of Cd(II) was followed by the Langmuir isotherm and the maximum adsorption capacity was obtained at 0.2 g L^?1 adsorbent dose at 308 K.     

Removal of Reactive Dyes using Magnetically Separable Trametes versicolor Cells as a New Composite Biosorbent

Magnetically modified Trametes versicolor cells were used for biosorption of Reactive Blue 13 (RB13), Reactive Yellow 85 (RY85) and Reactive Violet 1 (RV1). Percent biosorption values and maximum adsorption capacities of 98.30% and 135.35 mg g^?1 for RB13, 96.02% and 125 mg g^?1 for RY85, and 98.56% and 227.27 mg g^?1 for RV1 were observed under optimal conditions. The biosorption of all dyes was exothermic in nature. The biosorbent was characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and magnetic force microscopy. The Langmuir model was found to be most suitable for describing the biosorption of all dyestuffs. The experimental data fitted very well the pseudo second order kinetic model.     

Kinetic and Equilibrium Modeling of Pb(II) and Co(II) Sorption onto Rose Waste Biomass

Abstract

An attempt was made to assess the biosorption potential of rose waste biomass for the removal of Pb(II) and Co(II) ions from synthetic effluents. Biosorption of heavy metal ions (>90%) reached equilibrium in 30 min. Maximum removal of Pb(II) and Co(II) occurred at pH 5 and 6 respectively. The biosorbent dose for efficient uptake of Pb(II) and Co(II) was 0.5 g/L for both metals. The biosorbent size affected the Pb(II) and Co(II) biosorption rate and capacity. Rose waste biomass was found effective for Pb(II) and Co(II) removal from synthetic effluents in the concentration range 10–640 mg/L. Equilibrium sorption studies showed that the extent of Pb(II) and Co(II) uptake by the rose waste biomass was better described by the Langmuir isotherm in comparison to the Freundlich model. The uptake capacities of the two metal ions were 156 and 27.15 mg/g for Pb(II) and Co(II) respectively.     

Nanostructured Hypoeutectic Fe-B Alloy Prepared by a Self-propagating High Temperature Synthesis Combining a Rapid Cooling Technique

We have successfully synthesized bulk nanostructured Fe_94.3B_5.7 alloy using the one-step approach of a self-propagating high temperature synthesis (SHS) combining a rapid cooling technique. This method is convenient, low in cost, and capable of being scaled up for processing the bulk nanostructured materials. The solidification microstructure is composed of a relatively coarse, uniformly distributed dendriteto a nanostructured eutectic matrix with α-Fe(B) and t-Fe₂B phases. The fine eutectic structure is disorganized, and the precipitation Fe₂B is found in the α-Fe(B) phase of the eutectic. The dendrite phase has the t-Fe₂B structure rather than α-Fe(B) in the Fe_94.3B_5.7 alloy, because the growth velocity of t-Fe₂B is faster than that of the α-Fe with the deeply super-cooling degree. The coercivity (Hc) and saturation magnetization (Ms) values of the Fe_94.3B_5.7 alloy are 11 A/m and 1.74T, respectively. Moreover, the Fe_94.3B_5.7 alloy yields at 1430 MPa and fractures at 1710 MPa with a large ductility of 19.8% at compressive test.     

Facile Fabrication of Ultrafine Hollow Silica and Magnetic Hollow Silica Nanoparticles by a Dual-Templating Approach

The development of synthetic process for hollow silica materials is an issue of considerable topical interest. While a number of chemical routes are available and are extensively used, the diameter of hollow silica often large than 50 nm. Here, we report on a facial route to synthesis ultrafine hollow silica nanoparticles (the diameter of ca. 24 nm) with high surface area by using cetyltrimethylammmonium bromide (CTAB) and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as co-templates and subsequent annealing treatment. When the hollow magnetite nanoparticles were introduced into the reaction, the ultrafine magnetic hollow silica nanoparticles with the diameter of ca. 32 nm were obtained correspondingly. Transmission electron microscopy studies confirm that the nanoparticles are composed of amorphous silica and that the majority of them are hollow.     

磁性羟基磷灰石改性氮化硼的铅吸附特性

利用共沉淀法制备了氮化硼（BN）掺杂磁性羟基磷灰石（MP）的复合材料（MPBN），通过SEM、BET、FTIR、XRD、XPS和VSM对MPBN形貌、孔径、比表面积、元素组成、晶型、表面官能团和磁性进行表征，利用单因素吸附实验研究MPBN对Pb(II)的吸附特性。结果表明，MP成功负载在BN的层状结构中，MPBN具有超顺磁性。当Pb(II)浓度为250 mg/L，温度为25 ℃，pH=6.0，MPBN投加量为0.4 g/L时，吸附量达到460.75 mg/g，其吸附过程符合准二级动力学模型和Langmuir等温模型，表明MPBN对Pb(II)的吸附过程主要归因于单分子层的化学吸附。通过热力学模型拟合得到吸附过程的H为94.76 kJ/mol，?S为339.61 J/molK，说明该吸附过程在常温下是自发的吸热过程。同时MPBN在5次循环使用后仍然表现出优异的稳定性和良好的可回收性。     

Enhanced removal of lead and cadmium from water by Fe3O4-cross linked-O-phenylenediamine nano-composite

A method is presented for surface encapsulation of nano-Fe₃O₄ by o-phenylenediamine via cross-linking using formaldehyde and glutaraldhyde for the formation of two newly designed magnetic nano-sorbents. These have been characterized by FT-IR, TGA, and SEM and maintained the magnetic and thermal stability characters. The metal capacity values of Pb(II) and Cd(II) have been optimized in presence of different physico-chemical parameters and confirmed the superior selectivity for Pb(II). Maximum capacity values of Pb(II) (7000-10000 ± 250-675 µmol g^?1) and Cd(II) (1500-2250 ± 30-75 µmol g^?1) at optimum conditions and excellent extraction values (94.10-100.0 ± 1.2-3.5%) from industrial wastewater have been identified.     

Hexavalent chromium adsorption on superparamagnetic multi-wall carbon nanotubes and activated carbon composites

Hexavalent chromium (Cr(VI)) adsorption from aqueous solutions on magnetically modified multi-wall carbon nanotubes (M-MWCNT) and activated carbon (M-AC) was investigated. M-MWCNT and M-AC were prepared by co-precipitation method with Fe²⁺:Fe³⁺ salts as precursors. The magnetic adsorbents were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The effects of amount of adsorbents, contact time, initial pH, temperature and the initial concentration of Cr(VI) solution were determined. The adsorption equilibrium, kinetics, thermodynamics and desorption of Cr(VI) were investigated. Equilibrium data fitted well with the Langmuir isotherm for both of the adsorbents. The theoretical adsorption capacities are 14.28 mg/g of M-MWCNT and 2.84 mg/g of M-AC. Cr(VI) adsorption kinetics was modeled with pseudo-second order model, intra-particle diffusion model and Bangham model. Thermodynamic parameters were calculated and ΔG°, ΔH° and ΔS° indicate that the adsorption of Cr(VI) onto M-MWCNT and M-AC was exothermic and spontaneous in nature. Results revealed that M-MWCNT is an easily separated effective adsorbent for Cr(VI) adsorption from aqueous solution.     

An Efficient Magnetic Heterogeneous Nanocatalyst for the Synthesis of Pyrazinoporphyrazine Macrocycles

ABSTRACT

In this study, a one-pot synthesis of metallopyrazinoporphyrazines starting from simple and readily available precursors including 2,3-diaminomaleonitrile, 1,2-dicarbonyl compounds, metal salts such as CuCl₂, CoCl₂, FeCl₂, and ZnCl₂ and urea in the presence of nano-Fe₃O₄ anchored sulfuric acid as an efficient superparamagnetic heterogeneous nanocatalyst was described. The particle size of the nanocatalyst was studied by scanning electron microscopy images and chemical information about its surface functionalization was confirmed by energy-dispersive X-ray spectroscopy spectra. This new multicomponent protocol includes some important aspects such as easy work-up procedure, high atom economy, and simple and green reaction conditions for the synthesis of a new class of porphyrazine derivatives carrying six-membered pyrazine rings annulated at the periphery of the tetrapyrrolic macrocycle.     

Kinetic and equilibrium studies of Pb(II) and Cd(II) removal from aqueous solution onto colemanite ore waste

The adsorption characteristics of Pb(II) and Cd(II) onto colemanite ore waste (CW) from aqueous solution were investigated as a function of pH, adsorbent dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the adsorption isotherms. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The adsorption capacity of CW was found to be 33.6 mg/g and 29.7 mg/g for Pb(II) and Cd(II) ions, respectively. Analyte ions were desorbed from CW using both 1 M HCl and 1 M HNO₃. The recovery for both metal ions was found to be higher than 95%. The mean adsorption energies evaluated using the D-R model indicated that the adsorption of Pb(II) and Cd(II) onto CW were taken place by chemisorption. The thermodynamic parameters (ΔG^o, ΔH^o and ΔS^o) showed that the adsorption of both metal ions was feasible, spontaneous and exothermic at 20-50 °C. Adsorption mechanisms were also investigated using the pseudo-first-order and pseudo-second-order kinetic models. The kinetic results showed that the adsorption of Pb(II) and Cd(II) onto CW followed well pseudo-second order kinetics.     

Synthesis of magnetic Pb/Fe3O4/SiO2 and its catalytic activity for propylene carbonate synthesis via urea and 1,2-propylene glycol

To facilitate the recovery of Pb/SiO₂ catalyst, magnetic Pb/Fe₃O₄/SiO₂ samples were prepared separately by emulsification, sol-gel and incipient impregnation methods. The catalyst samples were characterized by means of X-ray diffraction and N₂ adsorption-desorption, and their catalytic activity was investigated in the reaction for synthesizing propylene carbonate from urea and 1,2-propylene glycol. When the gelatin was applied in the preparation of Fe₃O₄ at 60°C and the pH value was controlled at 4 in the preparation of Fe₃O₄/SiO₂, the Pb/Fe₃O₄/SiO₂ sample shows good catalytic activity and magnetism. Under the reaction conditions of a reaction temperature of 180°C, reaction time of 2 h, catalyst percentage of 1.7 wt-% and a molar ratio of urea to PG of 1:4, the yield of propylene carbonate attained was 87.7%.     

Effect of environmental conditions on the retention behaviour of Pb(II) by hematite

BACKGROUND: The retention behaviour of Pb(II) by hematite was studied as a function of various environmental parameters such as contact time, pH, ionic strength, foreign ions, humic substances and temperature under ambient conditions. RESULTS: Pb(II) sorption on hematite was rapid and the sorption could be described by a pseudo‐second‐order model very well. The sorption of Pb(II) on hematite was strongly dependent on pH and ionic strength. The presence of humic substances enhanced the sorption of Pb(II) on hematite at low pH, but reduced Pb(II) sorption at high pH. The Langmuir model fitted the sorption isotherms of Pb(II) better than the Freundlich model at three different temperatures, 293.15, 313.15 and 333.15 K. The thermodynamic parameters (ΔH°,ΔS° and ΔG°) calculated from the temperature dependent sorption isotherms indicated that the sorption process of Pb(II) on hematite was endothermic and spontaneous. CONCLUSIONS: The results indicate that hematite is a promising candidate for the treatment of heavy metal ions from large volume solution. Copyright © 2011 Society of Chemical Industry     

Fast removal of Pb(II) and Cu(II) from contaminated water by groundwater treatment waste: impact of sorbent composition

ABSTRACT

A non-hazardous groundwater treatment waste (GWTW) was examined as a low-cost sorbent for Pb(II) and Cu(II) ions. The content of the dominant elements in GWTW was as follows: 78% Fe₂O₃, 7.4% P₂O₅, 7.4% CaO and 5.2% SiO₂. The removal of Pb(II) and Cu(II) was fast, and more than 67–95% of ions were accumulated by GWTW during the first 3 min. The sorption capacity of GWTW depends on solution pH, concentration and temperature. Equilibrium data fitted well with Langmuir–Freundlich and Langmuir-partition models. The inherently formed nano-adsorbent could be utilized for the treatment of water contaminated with Pb(II) and Cu(II) ions.