Fast and efficient As(III) removal from water by bifunctional nZVI@NBC.

As a notable toxic substance, metalloid arsenic (As) widely exists in water body and drinking As-contaminated water for an extended period of time can result in serious health concerns. Here, the performance of nanoscale zero-valent iron (nZVI) modified N-doped biochar (NBC) composites (nZVI@NBC) activated peroxydisulfate (PDS) for As(III) removal was investigated. The removal efficiencies of As(III) with initial concentration ranging from 50 to 1000 µg/L were above 99% (the residual total arsenic below 10 µg/L, satisfying the contaminant limit for arsenic in drinking water) within 10 min by nZVI@NBC (0.2 g/L)/PDS (100 µM). As(III) removal efficiency influenced by reaction time, PDS dosage, initial concentration, pH, co-existing ions, and natural organic matter in nZVI@NBC/PDS system were investigated. The nZVI@NBC composite is magnetic and could be conveniently collected from aqueous solutions. In practical applications, nZVI@NBC/PDS has more than 99% As(III) removal efficiency in various water bodies (such as deionized water, piped water, river water, and lake water) under optimized operation parameters. Radical quenching and EPR analysis revealed that SO4·- and ·OH play important roles in nZVI@NBC/PDS system, and the possible reaction mechanism was further proposed. These results suggest that nZVI@NBC activated peroxydisulfate may be an efficient and fast approach for the removal of water contaminated with As(III).

Conversion of Non-Optical Material to Photo-Active Nanocomposites through Non-Conventional Techniques for Water Purification by Solar Energy.

Development of optical materials has attracted strong attention from scientists across the world to obtain low band gap energy and become active in field of solar energy. This challenge, which cannot be accomplished by the usual techniques, has overcome through the current study using non-conventional techniques. This study has used explosive reactions to convert non-optical alumina to series of new optical nanocomposites with very low band gap energy for the first time. In this trend, alumina nanoparticles were prepared and modified by explosive reactions using ammonium nitrate as a solid fuel. By using methanol or ethanol as a source of carbon species, three nanocomposites were produced indicating a gradual reduction of the band gap energy of alumina from 4.34 eV to 1.60 eV. These nanocomposites were obtained by modifying alumina via two different carbon species; core-shell structure and carbon nanotubes. This modification led to sharp reduction for the band gap energy to become very sensitive in sunlight. Therefore, these nanocomposites caused fast decolorization and mineralization of green dyes after illuminating in sunlight for ten minutes. Finally, it can be concluded that reduction of the band gap energy introduces new optical materials for developing optical nano-devices and solar cells.

Shielding and dosimetry parameters for aluminum carbon steel.

Aluminum is lightweight durable, versatile, non-toxic, and corrosion-resistant surface, which makes aluminum a perfect material for improving the corrosion properties of aluminum-carbon steel which is important in the radiation domain. In this study, six carbon steel alloys doped with different aluminum concentrations were studied and compared with the standard austenite stainless steel AISI316L. Different parameters for shielding and dosimetry such as mass attenuation coefficient, tenth value layer, mean free path, equivalent effective atomic and electronic numbers were calculated using WinXCom, while the exposure absorption buildup factors, thermal and fast neutron removal cross-sections were calculated using MCNPX and the effective conductivity was calculated using Phy-X/PSD program. Regarding the radiation shielding performance, the addition of aluminum to the carbon alloys has a significant influence on the shielding parameters. The results suggest that the addition of aluminum to the carbon steel alloys would improve its shielding properties so that it is a good result to be used in the field of dosimetry and radiation shielding.

Facile one-step synthesis of 3D hierarchical flower-like magnesium peroxide for efficient and fast removal of tetracycline from aqueous solution.

Hierarchically three dimensional (3D) flower-like magnesium peroxide (MgO2) nanostructures were synthesized through a facile one-step precipitation method. The effects of magnesium salt, reaction temperature, precipitant and surfactant on the morphology and structure of MgO2 were systematically investigated. The as-obtained samples using magnesium sulfate, ammonia and trisodium citrate were composed of 3D flowers assembled by numerous nanosheets, and SO42- played a vital role in the formation of flower-like nanostructures. The 3D flower-like MgO2 possessed high active oxygen content of 24.10 wt% and large specific surface area of 385 m2/g. Ten mg of flower-like MgO2 could efficiently degrade 90 % of tetracycline (TC) within 60 min under stirring condition. ESR tests and radical quenching experiments suggested that hydroxyl radicals were crucial for TC degradation. Moreover, the column filled with flower-like MgO2 could quickly and efficiently eliminate TC with the assistance of air flow, and the degradation efficiency almost had no decrease even after twenty consecutive runs. Significantly, the concentrations of magnesium and iron ions dissolved in the filtrate from the column were far below the limits of drinking water standards. Additionally, the possible degradation pathways of TC were also proposed according to the determination of generated intermediates during the degradation process.

[GO/QPEI Nanocomposite for Fast and High-capacity Removal of M. Aeruginosa].

This work described the synthesis of graphene oxide/quanternary ammonium polyethylenimine (GO/QPEI) nanocomposite as a novel and highly efficient Microcystis aeruginosa (M. aeruginosa) removal material. From pH 4 to 10, the removal efficiency of M. aeruginosa by GO/QPEI in 2 min was over 96%. The adsorption isotherm fitted the Freundlich model better and the maximum capacity of GO/QPEI was 5.58×1011 cells·mg-1. The kinetic data supported a pseudo-second-order adsorption behavior for GO/QPEI. The enhanced removal of M. aeruginosa could be attributed to the synergistic effect of GO nanosheet and the grafted QPEI.