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Morphology controlled facile synthesis of MnO2 adsorbents for rapid strontium removal
Umar Asim,Syed M. Husnain,Naseem Abbas,Faisal Shahzad,Abdul Rehman Khan,Tahir Ali 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-
MnO2 nanostructures with three distinct architectures, namelyflower, balk and tube-like, have beensynthesized through a single step microwave assisted hydrothermal method at different reactiontemperatures (110 C, 140 C and 180 C). The characterization of as prepared MnO2 samples wereperformed by means of Fourier transform infrared spectroscopy, X-ray diffraction, scanning electronmicroscopy, and transmission electron microscopy. The N2 adsorption–desorption isotherms revealedthe higher specific surface area and porosity of theflower like MnO2 as compared to balk and tube-likeMnO2. The adsorption behavior of as prepared adsorbents was investigated towards Sr2+ radionuclide. Because of the hierarchal structure and the high surface area (62.64 m2/g), MnO2-110 depicted the bestSr2+ adsorption performance with maximum adsorption capacity of 52 mg/g at pH 6 as compared to otherMnO2 morphologies synthesized at 140 C and 180 C. The kinetic studies revealed that the adsorption ofSr2+ onto MnO2-110 followed the pseudo-first-order model whereas the adsorption equilibrium dataobeyed the Freundlich and Sips model. Moreover, the MnO2-110 adsorbent reached the steady statequickly ( 10 min) and is capable to bind Sr2+ in slightly acidic to alkaline solutions.
Superparamagnetic Adsorbent Based on Phosphonate Grafted Mesoporous Carbon for Uranium Removal
Husnain, Syed M.,Kim, Hyun Ju,Um, Wooyong,Chang, Yoon-Young,Chang, Yoon-Seok American Chemical Society 2017 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.56 No.35
<P>A direct approach was presented to graft phosphonate groups on magnetic mesoporous carbon by an impregnation method with environmentally friendly precursors unlike the conventional methods involving a series of complicated steps and harsh conditions. Through the in situ reduction of Fe3+, magnetite particles of similar to 10 nm were successfully embedded into the mesopores, which was confirmed by HR-TEM. Surface characterization by X-ray photoelectron spectroscopy and Fourier transform infrared revealed phosphonate functional groups anchored through multidentate bonding with the surface of P-Fe-CMK-3. Due to the combined advantages of mesoporous pore size (5.5 nm), phosphonate ligands (1.42 mmol g(-1)), and magnetic sensitivity (5.20 emu g(-1)), this multifunctional adsorbent captured >85% of UO22+ within 5 min and the maximum adsorption capacity was 150 mg g(-1) at pH 4. The exceptionally high selectivity and efficiency of P-Fe-CMK-3 toward uranyl capture even in groundwater (K-d = 1 x 10(5) mL g(-1)), radioactive wastewater (K-d = 3 x 10(4) mL g(-1)), and seawater (K-d = 1 x 10(4) mL g(-1)) at V/m = 1000 mL g(-1) was better than that of the previously reported adsorbents. Importantly, the adsorbent maintained UO22+ adsorption efficiency >99% over five cycles due to the excellent chemical and structural stabilities. Above all, the adsorbent could be manipulated for UO22+ capture with help of a magnetic field in the real world, especially in case of nuclear accidents, decommissioning of nuclear power plants and/or uranium recovery from seawater.</P>