Separation and removal of Cu2+, Fe2+, and Fe3+ from environmental waste samples by N-benzoyl-n-phenylhydroxylamine.

This study was conducted to determine the optimum extraction conditions for the effective separation and removal of Cu2+, Fe2+, and Fe3+ using N-benzoyl-n-phenylhydroxylamine (BPA) as an analytical reagent. An efficient liquid-liquid extraction method was developed for the separation and removal of Cu2+, Fe2+, and Fe3+ from environmental waste samples. In this method, BPA was used as a chelating agent and the effect of different parameters- including solvents, pH, stripping agents, extraction time, and the interference of other ions- on the quantitative removal of these metals was investigated. This study demonstrates that chloroform is the most effective solvent for BPA. The maximum extraction of the selected metallic species was found between pH 3 and 5. It was demonstrated that the maximum percentage recovery of the metals can be attained using 1 M HCl as a stripping agent. Optimized conditions of different parameters could be beneficial for industry and environmental laboratories.

Synthesis and electrochemical properties of biporous alpha-Fe2O3 superstructures.

Biporous microsphere, flower and concaved cuboctahedrans like alpha-Fe2O3 superstructures have been synthesized by using a new synthetic method. Hydrothermal reaction of ferric chloride with potassium thiocyanate at 200 degrees C yields self-assembled microsphere, flower, and concaved cuboctahedrans like intermediates in ethanol, water:ethanol (1:1) mixed solvent and in water, respectively. These intermediates were further converted into corresponding alpha-Fe2O3 in a thermal decomposition process at 600 degrees C under oxygen atmospheric conditions. The influence of solvent, hydrothermal temperature, and concentration of iron precursors on the intermediate morphology was studied, and the growth mechanism has also been proposed. The synthesized intermediates and alpha-Fe2O3 were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and nitrogen adsorption analysis. The FE-SEM results indicated formation of biporous flowerlike morphology. The electrochemical properties of the flowerlike alpha-Fe2O3 electrodes in a Li-ion battery have been investigated. Plausible formation mechanisms of these intermediates were proposed.

Adsorption of Cd(II) and Pb(II) by a novel EGTA-modified chitosan material: kinetics and isotherms.

In this study, a novel adsorbent was synthesized by functionalizing chitosan with ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) ligands. The adsorption capability of EGTA-modified chitosan was investigated by the removal of Cd(II) and Pb(II) from aqueous solutions. The adsorption and regeneration studies were performed by batch techniques. The effects of pH, contact time, and initial metal concentration were studied. Metal uptake by EGTA-chitosan was 0.74 mmol g(-1) for Cd(II) and 0.50 mmol g(-1) for Pb(II). The adsorption mechanism, that the adsorbent formed octahedral chelate structures with bivalent metal ions, was proposed tentatively based on the experimental results of FTIR and the theoretically calculated data of point charges. The kinetics of Cd(II) and Pb(II) on EGTA-chitosan complied with the pseudo-second-order model and the adsorption rate was also influenced by intra-particle diffusion. BiLangmuir isotherm model was well fitted to the experimental data of one-component adsorption suggesting the surface heterogeneity of the novel adsorbent. The extended form of the BiLangmuir model was tested for the modeling of two-component adsorption equilibrium of Cd(II) and Pb(II) on EGTA-chitosan. In the two-component solution, both competitive adsorption and positive synergy of chelation between metal ions occurred and the novel adsorbent showed higher affinity toward Cd(II).

Fabrication and photocatalytic properties of self-assembled in(OH)3 and In2O3 nano/micro-cubes.

This article reports a novel fabrication method for In(OH)3 from indium oxalate by hydrothermal process. Hydrothermal decomposition of indium oxalate at 180 degrees C for 10 h results in In(OH)3. The influence of hydrothermal experimental conditions such as temperature, time on the formation of indium hydroxide was investigated. The self-assembly process was strongly influenced the experimental conditions. The thermal decomposition of In(OH)3 at 400 degrees C results In2O3. The synthesized In(OH)3 and In2O3 were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), thermal analysis (TGA and DTA), diffuse reflectance spectra (DRS), and nitrogen adsorption analysis. The XRD patterns indicated the formation of well crystallized cubic phase In(OH)3 and In2O3. The FE-SEM results indicated formation of In(OH)3 and porous In2O3 nano/micro-cubes. The photocatalytic activity of the synthesized In(OH)3 was studied under UV light irradiation and results showed that the In(OH)3 photocatalyst was efficient for dye degradation. We proposed a plausible mechanism for the formation of In(OH)3, and In2O3 self-assembly.

Quantitative response of IMS detector for mixtures containing two active components.

This study describes the relationship between the output signal of the ion mobility spectrometry (IMS) detector and the concentrations of two compounds being simultaneously introduced into the reaction section. Investigations were performed for three pairs of compounds, that is, dimethyl methylphosphonate (DMMP) and acetone, methyl tert-butyl ether (MTBE), and acetone, as well as trimethylamine (TMA) and n-nonylamine (NA). Vapors of the investigated compounds were produced in a two-channel generator with permeation sources and a dilution system based on mass-flow controllers. The generator design and the method of concentration determination are discussed in this paper. It was found that admixture can differently influence detection of an analyte. The presence of acetone does not effect the signal corresponding to dimer ions of DMMP. For pairs MTBE + acetone and TMA + NA characteristic peaks of analyte ions diminish with growing concentration of admixture, however, the detection based on the peak of the asymmetric dimer containing proton-bound molecules of both compounds is effective. For the detection of TMA in the presence of NA, the signal generated by the asymmetric dimer ions is meaningfully higher than the signals of monomer or dimer TMA ions measured without the NA admixture. The course of calibration dependencies was analyzed on the basis of a simple mathematical model of the reaction region. This model provided an estimation of the intensity of the signal for a given ionic species for definite concentration of analyte.

Membrane purification in radioactive waste management: a short review.

Radiation hazards of radionuclides arising from nuclear plant facilities are well known. Separation technologies are used to concentrate the radionuclides and prevent the spread of this hazard to the environment. The present review describes the recent advances made in radioactive waste treatment using membrane separation technology. The first part discusses the membrane methods for collective separation of radionuclides and the second part discusses the membrane methods for selective separation of individual radionuclides. For the collection separation of radionulides, methods include reverse osmosis, precipitation followed by ultrafiltration or microfiltration and membrane distillation. Individual elements have been separated using liquid supported membranes, polymer inclusion membranes, solid polymer based electrolysis, nanofiltration, electrochemical salt-splitting process and other advanced separation methods.

Degradation of chelating agents in aqueous solution using advanced oxidation process (AOP).

This article presents an overview with critical analysis of technical applicability of advanced oxidation process (AOP) in removing chelating agents from aqueous solution. Apart from the effect of metals for chelating agents as a major influencing factor, selected information such as pH, oxidant's dose, concentrations of pollutants and treatment performance is presented. The performance of individual AOP is compared. It is evident from our literature survey that photocatalysis with UV irradiation alone or coupled with TiO(2), ozonation and Fenton's oxidation are frequently applied to mineralize target pollutants. Overall, the selection of the most suitable AOP depends on the characteristics of effluents, technical applicability, discharge standard, regulatory requirements and environmental impacts.

Ion mobility spectrometry and its applications in detection of chemical warfare agents.

When fast detection of chemical warfare agents in the field is required, the ion mobility spectrometer may be the only suitable option. This article provides an essential survey of the different ion mobility spectrometry detection technologies. (To listen to a podcast about this feature, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html.).

Biological processes for treatment of landfill leachate.

This review presents an overview with critical analysis of the technical applicability of biological treatments for landfill leachate. A particular focus is given to activated sludge (AS), sequencing batch reactors (SBR), aerated lagoons (AL), and upflow anaerobic sludge blankets (UASB). Their advantages and limitations in application are evaluated. Selected information is presented such as pH, hydraulic retention time (HRT), organic loading rate (OLR), characteristics of leachate and treatment performance. It is evident from the literature survey of 188 papers (1976-2010) that none of the individual biological treatments presented is universally applicable for removing recalcitrant contaminants from leachate. Among the biological treatments reviewed, AS, SBR and UASB are the most frequently applied. These treatments are effective not only to remove over 90% of COD with a concentration ranging from 3500-26 000 mg L(-1), but also to achieve 80% of NH(3)-N removal with a concentration ranging from 100-1000 mg L(-1). A combination of physico-chemical and biological treatment into an integrated process is effective for leachate treatment. Almost complete removal of COD and NH(3)-N was reported for combined reverse osmosis (RO) and UASB with an initial COD concentration of 35 000 mg L(-1) and NH(3)-N concentration of 1600 mg L(-1). Integrated Fenton's oxidation and AS could achieve about 98% and 99% of COD and NH(3)-N removal, respectively, with initial COD and NH(3)-N concentrations of 7000 mg L(-1) and 1800 mg L(-1). Overall, the selection of the most suitable treatment for leachate depends on its characteristics, technical applicability and potential constraints, effluent limit required, cost-effectiveness, regulatory requirements and long-term environmental impacts.

Removal of Co(II) and Ni(II) ions from contaminated water using silica gel functionalized with EDTA and/or DTPA as chelating agents.

In this study, the removal of Co(II) and Ni(II) ions from contaminated water was investigated using silica gel materials functionalized with both ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA). The modified adsorbents were characterized using elemental analysis, surface area and pore size analysis, and zeta potential analysis. The adsorption and regeneration studies were conducted in batch mode. The optimum conditions for the removal of both metals at an initial concentration of 10mg/L were 2g/L of dose, pH 3, 50 rpm of agitation speed and 4h of contact time. The removal of Co(II) and Ni(II) by EDTA- and/or DTPA-modified silica gels was substantially higher than that by their unmodified form. The maximum Co(II) and Ni(II) uptakes by the EDTA-modified silica gel were 20.0 and 21.6 mg/g, comparable to their adsorption capacities by DTPA-modified silica gel (Co(II): 16.1mg/g; Ni(II): 16.7 mg/g). At the same concentration of 10mg/L, the removal of both metals by the modified adsorbents ranged from 96% to 99%. The two-site Langmuir model was representative to simulate adsorption isotherms. The kinetics of Co(II) and Ni(II) adsorption by modified silica gels followed pseudo-second-order.

Ultraviolet light emitting diodes and hydrogen peroxide in the photodegradation of aqueous phenol.

The novel system of ultraviolet (UV) light emitting diodes (LED) and hydrogen peroxide (H(2)O(2)) was studied for the degradation of phenol as a model organic pollutant in water. The effect of different viewing angles (15 and 120 degrees ), wavelengths (255, 265 and 280 nm) and phenol and H(2)O(2) concentrations were investigated in four photolytic batch reactors. Phenol degradation was observed to be most efficient with UV LEDs emitting at wavelength 280 nm, presumably due to the highest optical power. However, quantum yield for 280 nm reactor was only 0.23 compared to 0.33 of 255 nm reactor. Quantum yields for the rest of the reactors were 0.24 (265 nm, 120 degrees ) and 0.22 (265 nm, 15 degrees ). UV LEDs in combination with hydrogen peroxide are promising in wastewater treatment in degrading organic compounds, though development of both LEDs and reactor design is needed.