Microwave-hydrothermal synthesis of mesoporous gamma-Al2O3 and its impregnation with AgNPs for excellent catalytic oxidation of CO

Mesoporous.-alumina was synthesized by the microwave-hydrothermal process with a shorter duration time at 150. C/2 h followed by calcination at 550. C/1 h. Ag nanoparticles (AgNPs) were impregnated into.-alumina under a reducing atmosphere at 450. C. The synthesized product was characterized by X-ray diffraction (XRD), thermogravimetric (TG)/differential thermal analysis (DTA), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption study, fieldemission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The BET surface area values of.-alumina and Ag-impregnated.-alumina were found to be 258 and 230 m2 g-1, respectively. FESEM images showed the formation of grain-like particles of 50-70 nm in size with a flake-like microstructure. The XRD, XPS and TEM studies confirmed the presence of Ag in the synthesized product. Catalytic properties of the product for CO oxidation was studied with the T50 (50% conversion) and T100 (100% conversion) values of 118 and 135. C, respectively; the enhanced values were compared with the literature reported values

Investigating the role of amides on the textural and optical properties of mesoporous-nanostructured theta-Al2O3

Mesoporous-nanostructured theta-Al2O3 was synthesized by an autoclaving technique using different amides i.e., formamide (F), dimethyl formamide (DMF) and diethyl formamide (DEF) at 150 degrees C/24 h followed by calcination at 1000 degrees C. Crystallization and structural behaviour of the as-synthesized materials were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The porosity study was carried out by N-2 adsorption-desorption (BET) technique. Microstructural features were measured by transmission electron microscopy (TEM). The amide-based solvents played a deliberate role in microstructural and textural features of theta-Al2O3. The DMF-based solvent showed an enhanced surface area of 158 m(2) g(-1). The as-prepared theta-Al2O3 rendered a nano-sheet, nano-rod and nano-flake like morphology for F, DMF and DEF derived products, respectively. From the UV-Vis spectroscopic measurement, the estimated band-gap of theta-Al2O3 was found to be 5.16-5.40eV. Photoluminescence investigation further revealed blue emission particularly for excitation at a wavelength of 252 nm. A DMF-derived sample rendered the lowest band gap due to its smaller crystallite size and higher surface area compared to that of F- and DEF-derived samples

Jute seed production as influenced by dates of sowing and topping in red and laterite zone of West Bengal

An experiment was carried out during thekharif season of two consecutive years 2014 and 2015 at Regional Research Sub-station, Raghunathpur, Bidhan Chandra Krishi Viswavidyalaya, Purulia, West Bengal with the view to maximise the jute seed yield by manipulating certain non-monetary techniques like dates of sowing and topping associated with crop production. The Capsularis variety Bidhan pat-3 was sown in three different dates (1st-25th June, 2nd-15th July and 3rd-5th August) with 3 topping (clipping of apical portion) practices at 30, 45 and 60 days after sowing (DAS) as separate treatment with no topping as control. These different agronomic practices significantly (at 5 % probability level) influenced the performance of the crop in various aspects. The 1st date of sowing showed its supremacy in terms of expression of the crop in the field in all the aspects achieving a seed yield of 709.50 kg ha-1 and 737.85 kg ha-1 during first and second year respectively, whereas, the last date of sowing showed its inferiority obtaining a seed yield of 590.10 kg ha-1 and 647.13 kg ha-1all through the first and second year respectively.1stdate of sowing also recorded higher net return(Rs. 33721.50 ha-1& Rs.35989.50 ha-1 during first and second year) and benefit: cost ratio (1.46 and 1.56 in first and second year) over the other two date of sowing. How-ever, maximum seed yield was achieved when the crop was topped on 45 DAS (728.80 kg ha-1 and 773.57 kg ha-1 during first and second year) irrespective of the date of sowing

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 BrunauerEmmettTeller (BET) surface area of 773.4 m(2)/g with a pore volume of 0.877 cm(3)/g. The microstructural study reveals that nanospheroids of size 50200 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 sp(2) (CN-)- and sp(3) (CN)-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

Perspective of Membrane Processes for the Removal of Arsenic from Water: An Overview

This article reviews different membrane processes for the removal of arsenic from groundwater. The source of arsenic and its toxic effects on human body are illustrated. Various membrane filtration processes like micro-filtration, nano-filtration, ultra-filtration and reverse osmosis are discussed. The materials used in different membrane techniques are highlighted towards the removal efficiency of arsenic from water. The influence of pH and coexisting ions on rejection efficiency towards the removal of arsenic of these different processes are studied. The constitution of membrane, rejection mechanism, merits and demerits of different membrane techniques and challenges involved therein are discussed. The future direction of research on membrane based technology is also highlighted in this review

Al-Mg-Ca-Layered Double Oxides for Efficient Removal of As(V) from Water: The Role of Amides

Al-Mg-Ca-layered double oxides (LDO) were synthesized by solvothermal process at 160 degrees C/24 h in the presence of formamide (F), dimethylformamide (DMF), and diethylformamide (DEF), followed by calcination at 500 degrees C. The role of different amides for the formation of Al-Mg-Ca LDOs in terms of their microstructural behaviors, textural properties, and surface elemental analysis toward the removal of As(V) from groundwater was investigated. Microstructural analysis shows chrysanthemum flower-like morphology (2-4 mu m) with orderly arrangement of nanorod/petal-like particles (10-15 nm). DEF-modified Al-Mg-Ca LDO exhibited the highest surface area of 251 m(2)/g, resulting in the maximum As(V) adsorption capacity of 100 mg/g. The XPS study shows peak shifting of Al-O and Mg-O to a higher binding energy after adsorption of As(V), indicating the change in chemical environment, i.e., sharing of elements with the neighboring atoms. The effects of different parameters, like contact time, dose concentration, pH, and temperature, were investigated for As(V) adsorption. The synthesized Al-Mg-Ca LDOs were used for the removal of As(V) (0.7 ppm) from the groundwater collected from the lower Indo-Gangetic plain area (Hariharpara block at Murshidabad district in West Bengal of India) down to <10 ppb