Abstract
Nanotechnology has received much attention in treating contaminated waters. In the present study, a facile co-precipitation method was employed to synthesize a novel iron and magnesium based binary metal oxide using a stoichiometrically fixed amount of FeNO3·9H2O and MgNO3·6H2O in a proportion of molar concentration 1:1 and was later evaluated in removing As (III) from contaminated waters. Characterization of the prepared nanomaterial was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX) and ultraviolet–visible spectrophotometry (UV-VIS). Experimental studies on batch scale were carried out, examining the effect of varying initial concentrations of metal, adsorbent dosage, application time and initial pH on removal efficiency. Arsenic removal increased on increasing adsorbent dosage (0.1–1 g/L) but trend reversed on increasing initial arsenic concentration attaining qmax of 263.20 mg/g. Adsorption was quite efficient in pH range 4–8. Freundlich fitted better for adsorption isotherm along with following Pseudo-2nd order kinetics. The reusability and effect of co-existing ions on arsenic adsorption, namely SO42−, CO32− and PO43− were also explored with reusability in 1st and 2nd cycles attained adsorptive removal up to 77% and 64% respectively. The prepared nano-adsorbent showed promising results in terms of high arsenic uptake (qmax of 263.20 mg/g) along with facile and cost-effective synthesis. Thus, the co-precipitation technique used in this work is a simple one step procedure without any use of any precursor as compared to most of the other procedures used for synthesis.
Highlights
X-ray diffraction (XRD) patterns were recorded in a Rigaku X-ray Diffractometer equipped with a graphite monochromator using CuKα radiation, 40 kV and 40 mA in the
The peak positions in the observed XRD pattern were well aligned with the literature data of both the metal oxides
In the XRD pattern produced, all the peaks noted were attributed to either MgO or Fe3 O4 facets, demonstrating that the diffraction pattern acquired is well compatible with the cubic lattice for both metal oxides, which establishes the lack of any other phases as impurities
Summary
Arsenic is a well known carcinogen present in water supplies all around the globe. It is prioritized as one of the top 20 hazardous substance by Agency for Toxic Substances and Disease Registry [1]. It has been reported recently in countries like China, India, Taiwan, Poland, Argentina, Japan, New Zealand, Mexico, Hungary, Canada and USA [2]. Regulatory bodies like the World Health Organization (WHO) has a directed permissible limit of arsenic as 10 ppb in drinking water [3].
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