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Ultrafine nanoparticles owing to their increased surface to volume ratio, coupled with the ability to tune their surface properties through molecular modification have made them ideal for their detection and remediation of broad range of environmental contaminants. Arsenic contamination has become a worldwide epidemic and remediation of this problem needs the development of technology with improved materials and systems with high efficiency. In the present study, we have demonstrated a simple and efficient method using surface functionalized ultrafine iron oxide nanoparticles for absolute removal of arsenic from arsenic treated water with low contact time period and low adsorbent dose. The efficiency of arsenic removal has been drastically improved by considering nanoparticles of size 10 nm and subsequent surface engineering of the nanoparticles resulting more adsorption sites being exposed to arsenic. The mechanism for adsorption was identified through electron microscopic and spectroscopic studies. The adsorption equilibrium data were well fitted to Freundlich isotherm.

An analysis of the equations used for modeling thermal arsenic diffusion in silicon has been carried out. It was shown that for arsenic diffusion governed by the vacancy-impurity pairs and the pairs formed due to interaction of impurity atoms with silicon self-interstitials in a neutral charge state, the doping process can be described by the Fick’s second law equation with a single effective diffusion coefficient which takes into account two impurity flows arising due to interaction of arsenic atoms with vacancies and silicon self-interstitials, respectively. Arsenic concentration profiles calculated with the use of the effective diffusivity agree well with experimental data if the maximal impurity concentration is near the intrinsic carrier concentration. On the other hand, for higher impurity concentrations a certain deviation in the local regions of arsenic distribution is observed. The difference from the experiment can occur due to the incorrect use of effective diffusivity for the description of two different impurity flows or due to the formation of nonuniform distributions of neutral vacancies and neutral self-interstitials in heavily doped silicon layers. We also suppose that the migration of nonequilibrium arsenic interstitial atoms makes a significant contribution to the formation of a low concentration region on thermal arsenic diffusion.

The Arsenic in steel commonly comes from a certain amount of iron ore but it is difficult to remove them in the iron and steelmaking process because its oxidation potential is lower than that of Iron. In this study, a certain amount of rare earth metal, Cerium and a metal with low melting point, Arsenic were closed in the barrel-shaped cylinder machine by H08 steel, heated to 1323K for 50 hours. Interaction among the cerium, arsenic and iron in the barrel-shaped cylinder were studied by X-ray diffraction, optical microscopy, and electronic probe microscopy analysis. The result shows that the ternary compound Ce12Fe57.5As41 can be developed at 1323K when the atomic ratio of Cerium to Arsenic is 1:3. The binary compound CeAs is the main product at 1323K in the Fe-As-Ce system. The eutectic compound Fe2As can be precipitated from ferrite with the temperature decreasing.