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Electrospinning and galvanic displacement reaction were combined to synthesize ultra-long hollow tellurium (Te) nanofibers with controlled dimensions, morphology and crystallinity by simply tailoring the electrolyte concentration applied. Within different morphologies of nanofibers, the branched Te nanostructure shows the greatest sensing performance towards NO2 at room temperature.

A cost-effective process that combines electrospinning and a galvanic displacement reaction was utilized to synthesize ultralong hollow Pb x Se y Ni z nanofibers with controlled dimensions, morphology, composition, and crystal structure. Ni nanofibers were electrospun with an average diameter of 150 nm and were used as the sacrificial material for the galvanic displacement reaction. The composition and morphology of the Pb x Se y Ni z nanofibers were controlled during the reaction by tuning the concentration of HSeO 2 + in the electrolytes. Hollow Pb x Se y Ni z nanofibers with smooth surfaces were obtained from the low-concentration HSeO 2 + solution (i.e., 0.01 and 0.05 mM), but the hollow nanofibers synthesized from the high-concentration HSeO 2 + solution (i.e., 1 mM) have rough outer surfaces with nanocrystal protrusions. The Pb content of the nanofibers' composition was varied from 3 to 42% by adjusting the HSeO 2 + concentration. The thermoelectric properties of the nanofiber mats were characterized, and the highest Seebeck coefficient of approximately 449 μV/K at 300 K was found for the Pb 37 Se 59 Ni 4 nanofiber mat.

The removal of amaranth red dye from aqueous solution by untreated and treated pineapple peelings and coconut shells with phosphoric acid was studied in batch mode at room temperature. The study highlighted several parameters such as the contact time, the mass of the adsorbent, the pH of the solution, and the initial concentration of the dye. The results showed that the removal of dyes by the bioadsorbents depended on the pH and the initial concentration of the adsorbate. The adsorption capacity increased with increasing amaranth red dye concentration and the mass of the bioadsorbent. It was also established that maximum adsorption took place at pH = 2 for different adsorbents. The treated raw materials have greater surface area than the untreated materials. In order to deduce the adsorption mechanism, four simplified kinetic models were investigated. The kinetic data were well represented by the pseudo second order kinetic model giving high correlation coefficients R² values for all the biosorbents suggesting that chemisorption was the rate determining step. An equilibrium study of the adsorption process also showed that the Langmuir model best described the adsorption on all the biosorbents. The values of energy obtained from the Temkin isothermare also positive, this shows that the adsorption process isexothermic. These results indicate that pineapple peelings and coconut shells have a high potential as adsorbents for removing amaranth red dye from aqueous solution

1 Introduction ZnO nanomaterials are employed in a broad range of high-technology applications, including surface acoustic wave filters [1], photonic crystals [2], light emitting diodes [3], photodetectors [4], photodiodes [5], optical modulator waveguides [6], varistors [7], gas sensors [8] and solar cells [9]. This wide range of applications for ZnO stem from the materials wide band gap, 3.37 eV; large exciton binding energy, 60 meV; piezoelectric properties and its excellent chemical and thermal stability. Hydrothermal [10-20], chemical vapour [21-24], pulsed laser [25-29] and electrochemical deposition [30-32] syntheses of macroscopic, aligned, arrays of 1-dimensional ZnO nanoparticles have recently been developed. Hydrothermal routes to ZnO nanostructures have been found to be advantageous from the view point of environmental friendliness, easy upward scaling, and low production cost, especially when compared to the physical methods such as chemical vapour deposition [33] and metalorganic vapour phase epitaxy procedures [34]. In the present study, a simple, low temperature, 90 °C, preparation of zinc oxide 1-dimensional nanomaterials is employed. The reaction involves the pH driven precipitation of Zn(OH) 2 or ZnO

Olives stones and cotton cakes have been investigated as a cheap and available precursor used for the production of novel carbon using potassium hydroxide as chemical activating agent with 2:1 impregnation ratio at 1.5 M KOH. Carbonization was performed at 450°C for one hour. The activated carbons NOK and MK3 were characterized by Iodine Number, Fourier Transform Infrared (FTIR) spectroscopy, EDX Analysis, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) Analysis and Proximate Analysis (pH ZCN , pH, volatile matter, fixed carbon). The effects of initial sorbate concentration and contact time on adsorption were evaluated. Errors analysis methods were used to evaluate the experimental data: Correlation coefficient (R 2), chi-square (χ 2), average relative error (ARE), sum of absolute errors (EABS) and root mean square error (RMSE) values were tested to find the best fitting isotherm. Elovich models provide the best fit in the uptake of 2,4-dinitrophenol by activated carbons NOK and MK3. Thus, among the isotherm models studied, it appears that the Dubinin-Radushkevich and Temkin (two parameters), Sips (three parameters) and Baudu (four parameters) models describe better the adsorption data. Error analysis showed that the models with two parameters better described the adsorption of 2,4-diniphenol data compared with the three parameter and fourparameter models.

Nafion offers microporous channels of typically 1-4-nm diameter for cation exchange. Recently, it has been shown that these cation exchanger properties can be inverted to allow anion binding by pre-filling the hydrophilic channel structure. Here, prefilling is performed with hydrous iron oxide and sensitivity towards anionic phosphate and arsenate analytes is investigated. After a period of phosphate/arsenate accumulation, the voltammetric response in aqueous 1 M NaNO 3 is obtained based on the Fe(III/ II) redox process. The position of the peak at distinct potentials clearly reveals the presence of either phosphate or arsenate, presumably present in the form of FePO 4 and FeAsO 4. In the presence of mixtures of phosphate and arsenate, a competition of FePO 4 versus FeAsO 4 nucleation (within the Nafion microporous host) is suggested to result in a switch of phosphate detection at higher concentrations (ca. > 500 μM, solubility controlled) towards arsenate detection at lower concentrations (ca. < 500 μM, nucleation controlled). This phenomenon is suggested to be linked to the Ostwald step rule.