Ipsita Hazra Chowdhury

Effect of anion type on the synthesis of mesoporous nanostructured MgO, and its excellent adsorption capacity for the removal of toxic heavy metal ions from water

Mesoporous MgO nanostructures of different morphologies like nanoplates, nanosheets and nanoparticle assembled microspheres were prepared by a simple hydrothermal method at 180 °C/5 h in the absence of any organic templates. The products were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR), N2 adsorption–desorption, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The role of anions of different magnesium precursors on the morphology, textural properties, and heavy metal ion (Pb(II) and Cd(II)) adsorption capacity of the products was studied. The adsorption data were interpreted with Langmuir and Freundlich models. The effect of contact time, adsorbate concentration, pH and temperature on the adsorption capacity of the products was investigated. Nanosheet-like MgO obtained from chloride and nitrate salts of magnesium having higher pore size rendered better adsorption capacity than that prepared from sulphate and carbonate sources of magnesium. The prepared MgO nanostructures showed maximum adsorption capacities up to 3900 mg g−1 and 2980 mg g−1 for Pb(II) and Cd(II) ions, respectively.

Rapid template-free synthesis of an air-stable hierarchical copper nanoassembly and its use as a reusable catalyst for 4-nitrophenol reduction

A hierarchical copper nanoassembly was synthesized by one-pot solvothermal treatment at 150 °C for 2 h in the presence of copper nitrate, formamide and water. The product exhibited phase pure hierarchical Cu microspheroids (2–7 μm) comprising a nanorod (50–100 nm) assembly. The Cu microspheroids showed excellent air-stability, antioxidative properties and catalytic reduction of p-nitrophenol.

Hexagonal sheet-like mesoporous titanium phosphate for highly efficient removal of lead ion from water

Hexagonal sheet-like mesoporous titanium phosphate was synthesized by a facile hydrothermal method at 150 °C for a shorter duration of time (2 h) in the absence of any organic templates. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis spectroscopy, thermogravimetry (TG), N2 adsorption–desorption, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The performance of the hexagonal sheet-like particles for the removal of Pb(II) ions from water was evaluated. The adsorption data was interpreted with Langmuir and Freundlich models. The effect of contact time, adsorbate concentration, pH of the solution, temperature of the solution and adsorbent concentration on the adsorption capacity of the products was investigated. The prepared hexagonal sheet-like titanium phosphate showed maximum adsorption capacities up to 1073 mg g−1, a higher value than those of previously reported phosphate compounds.

Biogenic silver nanoparticle impregnated hollow mesoporous silicalite-1: an efficient catalyst for p-nitrophenol reduction

AgNP impregnated hollow mesoporous silicalite-1 was synthesized using green carambola extract. AgNPs of 10–15 nm size were well dispersed mostly within the shell of hollow silicalite-1 which contained hierarchical porosity. The synthesized product showed enhanced catalytic efficiency for the reduction of p-nitrophenol.

Nitrogen-Doped Nanoporous Carbon Nanospheroids for Selective Dye Adsorption and Pb(II) Ion Removal from Waste Water

In the presence of melamine and block copolymers, namely, F108, F127, and P123, nitrogen-doped nanoporous carbon nanospheroids (N@CNSs) were synthesized by the hydrothermal process. The F127-modified sample (CNF127) exhibits the maximum Brunauer–Emmett–Teller (BET) surface area of 773.4 m2/g with a pore volume of 0.877 cm3/g. The microstructural study reveals that nanospheroids of size 50–200 nm were aggregated together to form a chainlike structure for all triblock copolymer-modified samples. The X-ray photoelectron spectroscopy study shows the binding energies of 398.33 and 400.7 eV attributed to sp2 (C–N=C)- and sp3 (C–N)-hybridized nitrogen-bonded carbons, respectively. The synthesized N@CNS samples showed selective adsorption of organic dye methylene blue (MB) in the presence of methyl orange (MO) as well as Pb(II) ion removal from contaminated water. The adsorptions for MB and Pb(II) ions followed pseudo-first-order and pseudo-second-order kinetic models, respectively. The sample CNF127 showed the highest adsorption of 73 and 99.82 mg/g for MB and Pb(II) adsorptions, respectively. The adsorption capacity for MB of the copolymer-modified samples follows the order CNF127 > CNP123 > CNF108, which corroborated with the mesoporosity as well as nitrogen content of the corresponding samples. The maximum % adsorption of Pb(II) follows the order CNF127 (99.82%) > CNF108 (98.74%) > CNP123 (91.82%), and this trend is attributed to the BET surface area of the corresponding samples. This study demonstrates multicomponent removal of water pollutants, both organic dyes and inorganic toxic metal ions.