Journal of Water and Environmental Nanotechnology
Volume:2 Issue: 1, Winter 2017

Arsenic belongs to chemical elements, which are often found in natural waters and make it unsuitable for consumption without special treatment. Neutralization of arsenic pollutants of natural waters by converting them into insoluble form is one of the perspective methods of dearsenication. Precipitation (by iron or aluminium coagulants, lime) and adsorption (by oxides and hydroxides of iron, aluminium or manganese) are among the most popular dearsenication methods. The use of these chemicals entails the formation of poorly soluble arsenates. Since the possibility of the release of arsenic compounds into the water due to the dissolution of formed arsenates depends on its solubility under appropriate conditions, it is necessary to have information about the dependence of arsenates solubility on pH. According to the calculations the solubilities of arsenates of iron(III), aluminium, manganese(II) and calcium are highly dependent on pH. At pH<4, the solubilities of these arsenates increase in the sequence FeAsO4 – Mn3(AsO4)2 – AlAsO4 – Ca3(AsO4)2. Above рН 4 dependence changes and solubilities of these arsenates increase in the sequence FeAsO4 – AlAsO4 – Mn3(AsO4)2 – Ca3(AsO4)2.

The main objective of this work is to study the oxidation of naphthol blue black (NBB) in aqueous solution by hydrogen peroxide using a recyclable Dawson type heteropolyanion [H1.5Fe1.5P2W12Mo6O61.23H2O] as catalyst.The effects of various experimental parameters of the oxidation reaction of the dye were investigated. The mineralization of the dye was investigated by the total organic carbon (TOC) measurement in optimum conditions. The influence of the catalyst nature (Dawson- type iron -substituted heteropolyanion) and (Dawson- type copper -substituted heteropolyanion) on the oxidation process was investigated. The catalytic oxidation using a recyclable heteropolyanions as catalysts is an economically and environmentally friendly process to remove the toxicity of the recalcitrant compounds in water.

The electrochemical regeneration of methylene blue-saturated activated carbon, Nyex®1000 and sawdust has been studied and the performances in terms of capacity of adsorbent regeneration have been compared in this work. The adsorption isotherms were investigated. The results showed that the adsorption of methylene blue onto the investigated adsorbents obeyed Langmuir’s model. The electrochemical oxidation of methylene blue beforehand adsorbed was studied using a boron doped diamond anode. The electrochemical regeneration efficiencies, under the same experimental conditions, of the activated carbon and Nyex®1000 were significantly less than 100% which were much lower to that of sawdust. Indeed the electrolysis tends to activate the sawdust because all the regeneration efficiencies obtained, whatever the applied current intensity, are higher than 100 %. Increasing treatment time would also result in a better regeneration of sawdust. This study confirmed that the coupling adsorption onto sawdust and electrochemical degradation is a potential technique for the efficient elimination of low concentration organic dyes from wastewater.

Molecular dynamics simulations were carried out to study the removal of Ni2+ as a heavy metal from the water by the functionalized graphene nanosheet (GNS) and boron nitride nanosheet (BNNS). Nickel causes asthma, conjunctivitis and inflammatory reactions and nickel salts act as emetics when swallowed; therefore, removal of nickel is necessary from the aqueous solutions. The systems were comprised of a nanosheet (GNS or BNNS) with a pore in its center that it is containing an aqueous ionic solution of nickel chloride. For the removal of Ni2+ from an aqueous solution, the pores of nanosheet were functionalized by passivating each atom at the pores edge and then an external electric field was applied along the z-axis of the simulated system. To justify the passage of ions through the pores, the potential of the mean force (PMF) of ions was calculated. To evaluate the properties of the system, the ion retention time and the radial distribution functions of species were measured. Based on the findings of this study, these nanostructure membranes can be recommended as a model for removal of heavy metals.

The CO and CO2 effects are global warming, acid rain, limit visibility, decreases UV radiation; yellow/black color over cities and so on. In this study, convention of CO2 and H2O to CH4 and O2 near TiN- nanotube with Cu-nanoparticle calculated by Density Functional Theory (DFT) methods. We have studied the structural, total energy, thermodynamic properties of these systems at room temperature. All the geometry optimization structures were carried out using GAMESS program package under Linux. DFT optimized their intermediates and transient states. The results have shown a sensitivity enhancement in resistance and capacitance when CO2 and H2O are converted to CH4 and O2. TiN-nanotube used photo-catalytic reactivity for the reduction of CO2 with H2O to form CH4 and O2 at 298K. The calculations are done in state them between of three TiN-nanotubes near Cu-nanoparticle.The calculation shown which heat reaction formation (∆H) is endothermic for this reaction. This reaction needs to sun, photo active or other energy in the presence of visible light for doing.

This investigate presents the extraction-preconcentration of Lead, Cadmium, and Nickel ions from water samples using Ghezeljeh montmorillonite nanoclay or “Geleh-Sar-Shoor” (means head-washing clay) as a natural and native new adsorbent in batch single element systems. The Ghezeljeh clay is categorized by using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy-Energy Dispersive Spectrometer Operating (SEM-EDS), X-ray Diffractometry (XRD), X-ray Fluorescence (XRF), Cation Exchange Capacity (CEC) measurements, Surface property valuation (SBET) by the BET method from nitrogen adsorption isotherms and Zeta potential. According to BET theory, the specific surface area of Ghezeljeh nanoclay was computed as 19.8 m2 g-1 whereas the cation exchange capacity was determined as 150 meq (100 g-1). The results of XRD, FT-IR, XRF, zeta potential, BET surface area and CEC of the Ghezeljeh clay confirm that montmorillonite is the dominant mineral phase. Based on SEM images of clay, it can be seen that the distance between the plates is nm level. For all three ions, the limit of detection, the limit of quantification, dynamic linear range, preconcentration factor, and the adsorption capacity were obtained. The result of several interfering ions was considered. The Ghezeljeh nanoclay as a new adsorbent and experimental method were effectively used for the extraction of heavy metals (Lead, Cadmium, and Nickel) in a variety of real water samples.

Density functional theory investigations were conducted in order to study the effects of the adsorption of thiophene on the structural and electronic properties of TiO2 anatase nanoparticles. The ability of pristine and N-doped TiO2 anatase nanoparticles to recognize toxic thiophene was surveyed in detail. It was found that thiophene molecule is chemisorbed on the N-doped anatase nanoparticles in S site geometries with large adsorption energy and small distance. By including van der Waals (vdW) interactions between thiophene molecule and TiO2, we found that the adsorption on the N-doped TiO2 is energetically more favorable than the adsorption on the pristine one, suggesting that the nitrogen doping can energetically facilitate the thiophene adsorption on the N-doped nanoparticle. The order of adsorption energy is Parallel(S site)>Perpendicular(S site)>Perpendicular (H site). The interaction between thiophene and N-doped TiO2 can induce substantial variations in the HOMO/LUMO molecular orbitals of the nanoparticle, changing its electrical conductivity, which is helpful for designing the novel sensor and remover devices. Charge analysis based on Mulliken charges reveals that charge is transferred from thiophene molecule to TiO2 nanoparticle.

Twelve extracts belong to four species of edible oyster mushrooms were screened for their chemical value (viz. proteins, carbohydrates and phenols were assessed) and their capability to biosynthesize silver nanoparticles (AgNPs). In limitative conditions, dark incubation and temperature 25 °C, three modes of extracts preparation were developed. Properties of silver nanoparticles creation from extracts solution with 1 mM AgNO3 were investigated by color and UV-Visible spectroscopy to confirm silver nanoparticles formation. The bright yellow oyster mushroom (Pleurotus cornucopiae var. citrinopileatus) was finding as a potential candidate for the synthesis of AgNPs. Brown color of aqueous solution was given indication for AgNPs formation. Results showed that AgNPs absorption band was located at a peak of 440 nm for P. cornucopiae var. citrinopileatus. Although others P. ostreatus (grey & white) and P. salmoneostramineus (pink) were not form AgNPs due to no change in color of extracts with Ag ions when incubated under the same conditions, which indicative for no silver nanoparticles synthesis. Thus, AgNPs formation depended on species of oyster mushroom, method of extracting, concentration of extract and the conditions of incubation (of light and temp.), but no on content of proteins, carbohydrates and phenol in crude extract leastwise in this study