Biochar from oil cakes: an efficient and economical adsorbent for the removal of acid dyes from wool dye house effluent

Clean Technologies and Environmental Policy - In the reported study, biochars were prepared from almond, coconut, and mustard oil cakes by chemical activation with phosphoric acid followed by...     

Molecular weight distributions in novolac type phenol-formaldehyde polymerizations

In the acid-catalysed condensation polymerization of phenol and formaldehyde, the ortho and para positions of the phenol ring are known to exhibit different reactivities^1,2. Along with this on polymer molecules, the internal sites have lower reactivity due to molecular shielding. To model the novolac formation, five reactive sites have been proposed³ and their reactivities are assumed to be completely determined by the site involved. To find the molecular weight distribution (MWD) of the polymer from this information, a given polymer chain has been assumed to consist of these sites in the same relative ratio as in the reaction mass. A mass balance, on polymer molecules of given size, has been made and solved numerically as a function of time. The sensitivity analysis has been carried out to show that the MWD is little affected by the variation of reactivities of the internal sites. The reactivity of para external positions and the ratio of phenol and formaldehyde, however, play a major role in determining the MWD.     

Stabilization of SnO2 nanoparticles into the nanopores of modified Montmorillonite and their antibacterial activity

Metals and metal oxide nanoparticles clay supported composites arouse much interest in recent time. In this communication, we report the insitu synthesis of SnO₂ nanoparticles by impregnation of SnCl₂.2H₂O into the nanopores of modified Montmorillonite followed by polyol reduction and aerial oxidation. The modified Montmorillonite having nanopores act as a ‘Host’ for the SnO₂ nanoparticles. The TEM study reveals that SnO₂ nanoparticles having size <10 nm are evenly distributed on the support. The XPS results show that the binding energy peaks at 490 and 498.2 eV are due to Sn3d_5/2 and Sn3d_3/2 respectively indicating the presence of Sn⁴⁺ in the SnO₂ nanoparticles. Elemental dot mapping indicate the presence of Al, Si, O and Sn on the surface of AT-Mont. supported SnO₂ nanoparticle. The synthesized SnO₂ nanoparticles show antibacterial activity against gram +ve and gram ?ve bacterial strains.     

An efficient and robust heterogeneous mesoporous montmorillonite clay catalyst for the Biginelli type reactions

Three component coupling reactions of aldehyde, β-ketoester (or β-diketone) and urea (or substituted urea) were carried out by using acid activated montmorillonite clay (AT-Mont.) catalyst having surface area about 400 m²/g for the facile synthesis of 3,4-dihydropyrimidin-2(1H)-ones via the Biginelli reactions under mild reaction conditions. The activation of montmorillonite clay was carried out with HCl under controlled conditions for generating nanopores (size 2–7 nm) into the matrix. This porous catalyst has promising feature for Biginelli reaction such as easy removal of the catalyst, short reaction time, high yield with 100% selectivity and easy workup procedure. Powder XRD, SEM-EDX, N₂ adsorption, pyridine adsorbed FT-IR and TPD analysis were carried out to characterize the solid porous AT-Mont. The catalysts can be recycled and reused several times without significant loss of their catalytic activity.     

Mesoporous aluminosilicate: efficient and reusable catalysts for esterification of <Emphasis Type="Italic">sec</Emphasis>-butanol with acetic acid

Esterification of acetic acid with sec-butanol to produce sec-butyl acetate has been systematically carried out by using mesoporous (3–9 nm size) aluminosilicate (meso-AS) catalysts (surface area 327–578 m² g^?1) derived from Na-montmorillonite by controlled HCl acid activation. High catalytic activity up to 89% conversion with nearly 100% selectivity towards sec-butyl acetate is observed. The effect of reaction temperature, mole ratio of reactants and catalyst concentration on esterification reactions were studied. The catalyst could be recycled and reused several times without significant loss of their catalytic activities. The catalysts were characterized by pyridine adsorbed FT-IR, XRD, SEM-EDX, MAS-NMR, surface area (BET) and TPD analysis.     

Exploitation of Pongamia glabra deoiled cake for alternate energy: Physico-chemical characterization and thermogravimetric studies

Utilization of agro-wastes for biofuel generation has been accepted as one of the feasible means for curbing down mankind’s dependence on conventional petro fuels. In this regard, the present investigation aims to understand the properties of Pongamia glabra deoiled cake (a byproduct of the biodiesel production process) for biofuel production. The deoiled cake was investigated for its physico-chemical characteristics by Bomb calorimetry, TG analysis (10, 20, and 40° min^–1), CHN analysis, and Fourier transform infrared spectroscopy. The proximate composition was calculated using standard ASTM methodology. The temperature characteristics, activation energy, pre-exponential factor, and reaction order for the active pyrolysis zone of the species under investigation have been provided for the respective heating rates using Arrhenius, Coats–Redfern, and Flynn–Wall–Ozawa methods. The findings suggest feasibility of liquid fuel production from Pongamia glabra deoiled cake via thermochemical conversion.     

Modelling of condensation polymerization of novolac-type phenol–formaldehyde in homogeneous,continuous-flow,stirred-tank reactors

A detailed kinetic model for the novolac-type phenol–formaldehyde polymerization has been proposed in terms of five reactive sites. These sites have been shown to have different reactivities. Mass-balance equations for homogeneous, continuous-flow, stirred tank reactors (HCSTR) for each of the species have been written, and these have been solved numerically. A comparison of the results with those for the batch reactor shows that, for a given residence time, smaller but more polydispersed and branched chains are formed.     

Flood Frequency Modeling and Prediction of Beki and Pagladia Rivers Using Deep Learning Approach

Neural Processing Letters - Flood is one of the major reasons of death and despair in the North East Indian state of Assam during the monsoon months each year. The flooding in adjacent areas...