Ashu Rani

Modification in Properties of Fly Ash through Mechanical and Chemical Activation

This paper is a critical overview on chemical, structural, and morphological changes in fly ash properties with mechanical activation using high energy planetary ball mill and chemical activation by digesting with various mineral acids (HCl, HNO3, H2SO4 and HClO4) at 110oC. Mechanical activation results in increase in silica percentage, amorphous nature, specific surface area and surface roughness, as evident by analytical measurements using XRF, XRD, FT-IR, BET surface area and SEM techniques. The chemical activation of Fly ash performed by different acids results in increased silica content and surface area due to leaching of several metal ions from silico-aluminate skeleton. The surface silanol groups responsible for generating Bronsted acidity are enhanced as evident by pyridine adsorbed FT-IR. Activation with HClO4 is also evident to generate surface active Lewis acid sites due to formation of Al-OH phases on the surface. The mechano-chemical activation can generate sufficient activity on fly ash surface rendering its potential application in heterogeneous acid catalysis.

A Novel Synthesis Process for Making Nickel Oxide Nanoparticles

The main aim of this research was to prepare nanoparticles of nickel oxide through a new mixed reverse microemulsion route. Quaternary microemulsion (water/surfactant/co surfactant/oil-phase) was used to synthesize nickel oxide nanoparticles. The microemulsion was prepared by Tween-80, Aerosol-OT, n-Propanol, Cyclohexane, and Nickel Chloride. Previously nickel oxide nanoparticles were synthesized by reverse microemulsion method but the novelty of the process lies in the fact that conventionally either cationic or anionic or non ionic surfactants are used for the synthesis of nickel oxide nanoparticles.Whereas in the present developed novel process preparation of nickel oxide nanoparticleshas been carried out using a unique blend system consisting of Tween -80 and AOT. The average particle size of as synthesized nickel oxide powder, calculated by Scherrer equation, is observed to be 14 nm. The X -ray diffraction pattern confirms the p resence of pure bunsenite phase withFCC Scanning Electron Microscopy (SEM) shows that particles have spherical morphology.

Defluoridation Kinetics over Lime Stone Slurry Impregnated Fly Ash

The adsorption kinetics of the removal of fluoride (F-) from water over lime stone slurry impregnated fly ash (LSFA) catalyst using batch mode has been investigated in the present study. BET surface area, XRF, XRD, FTIR and SEM techniques were used to characterize the physico-chemical attributes (crytallinity, determination of calcium and magnesium silicate phases, morphology) of the catalyst. Adsorption data were modelled using the Freundlich and Langmuir adsorption isotherms and followed first order kinetic equation. The present research includes assessment of a new adsorbent generation, process optimization and a cost benefit process.

Acid Activated fly Ash, as a Novel Solid Acid Catalyst for Esterification of Acetic Acid

An efficient solid acid catalyst (AAFA) has been synthesized by mechanical and thermal activation of F-type fly ash (SiO2 and Al2O3>70%) followed by chemical activation using concentrated HCl at 110oC. The activation of fly ash resulted in increased silica content (79%) and surface area (5.42 m2/g) having sufficient silanol activity for esterification of n-butanol and acetic acid. The catalyst was characterized by XRD, FT-IR, and SEM techniques. The product n-butyl acetate is an important fine chemical intermediate, widely used in pharmaceutical and as flavoring agent in confectionary. The catalyst was completely recyclable without significant loss in activity up to five reaction cycles, which confers its stability during reaction. The work reports an innovative use of solid waste fly ash as an effective solid acid catalyst.

The influence of diesel—truck exhaust particles on the kinetics of the atmospheric oxidation of dissolved sulfur dioxide by oxygen

The automobile exhausts are one of the major sources of particulate matter in urban areas and these particles are known to influence the atmospheric chemistry in a variety of ways. Because of this, the oxidation of dissolved sulfur dioxide by oxygen was studied in aqueous suspensions of particulates, obtained by scraping the particles deposited inside a diesel truck exhaust pipe (DEP). A variation in pH showed the rate to increase with increase in pH from 5.22 to about ∼6.3 and to decrease thereafter becoming very slow at pH = 8.2. In acetate-buffered medium, the reaction rate was higher than the rate in unbuffered medium at the same pH. Further, the rate was found to be higher in suspension than in the leachate under otherwise identical conditions. And, the reaction rate in the blank reaction was the slowest. This appears to be due to catalysis by leached metal ions in leachate and due to catalysis by leached metal ions and particulate surface both in suspensions. The kinetics of dissolved SO2 oxidation in acetate-buffered medium as well as in unbuffered medium at pH = 5.22 were defined by rate law: kobs = k0 + kcat[DEP], where kobs and k0 are observed rate constants in the presence and the absence of DEP and kcat is the rate constant for DEP-catalyzed pathway. At pH = 8.2, the reaction rate was strongly inhibited by DEP in buffered and unbuffered media. Results suggest that the DEP would have an inhibiting effect in those areas where rainwater pH is 7 or more. These results at high pH are of particular significance to the Indian subcontinent, because of high rainwater pH. Conversely, it indicates the DEP to retard the oxidation of dissolved SO2 and control rainwater acidification.

Surface Modification of Fly Ash for Active Catalysis

Fly ash based effective solid base catalyst (KF/Al2O3/fly ash473, KF/Al2O3/fly ash673, and KF/Al2O3/fly ash873) was synthesized by loading KF over chemically and thermally activated fly ash. The chemical activation was done by treating fly ash with aluminum nitrate via precipitation method followed by thermal activation at 650°C to increase the alumina content in fly ash. The increased alumina content was confirmed by SEM-EDX analysis. The alumina enriched fly ash was then loaded with KF (10 wt%) and calcined at three different temperatures 473 K, 673 K and 873 K. The amount of loaded KF was monitored by XRD, FTIR spectroscopy, SEM-EDX, TEM and Flame Atomic Absorption Spectrophotometer. The catalytic activities of the catalysts were tested in the Claisen-Schmidt condensation of benzaldehyde and 4-methoxybenzaldehyde with 2′-hydroxyacetophenone to produce 2′-hydroxychalcone and 4-methoxy-2′-hydroxychalcone respectively. Higher conversion (83%) of benzaldehyde and (89%) of 4-methoxybenzaldehyde reveals that among these heterogeneous catalysts KF/Al2O3/fly ash673 is very active.

Assessing vulnerability in Cochabamba, Bolivia and Kota, India: how do stakeholder processes affect suggested climate adaptation interventions?

ABSTRACT In Cochabamba, the vulnerability assessment process focused on La Maica community and the agriculture sector. Community stakeholders were involved in workshops while municipal and regional actors participated through interviews. In the Kota process, the municipality was in the geographical focal point and a multi-level stakeholder group focused upon slum inhabitants. The suggested interventions and actions in both cities were dominated by systems (infrastructure and ecosystems) while identified barriers and facilitating factors to implementation revealed a greater acknowledgement of governance issues. Focus on marginalized groups and sectors is facilitated by the direct representations of those issues. While multi-stakeholder processes can be important forums for social learning adaptation planning that benefit vulnerable sectors and groups, with limited inclusion and responsibility given to representatives of marginalized sectors and groups for implementation actions, it is likely that the interests and priorities of more powerful actors will dominate and not contribute to increasing the resilience of the most vulnerable.

MODELING AND ANALYSIS OF SALT TRANSPORT IN THE SINGLE CYLINDRICAL ROOT WITH FINITE LENGTH

A mathematical model for salt transport by a cylindrical root in an infinite extent of soil is derived and solved analytically by asymptotic matching of the inner and outer solutions. By asymptotic analysis it is shown that the salt solution uptake by a single cylindrical root in the absence of competition does not influence the overall salt concentration in the soil even when the soil moisture concentration is less than full saturation.

Synthesis of Nanosized Titania by sol Gel Route

The main objective of this work was to prepare anti-pollutant and photocatalyst Titanium dioxide nanoparti- cles by simple ethylene glycol route to synthesize titanium dioxide nanoparticles at industrial level. In this work TiO2 was prepared by sol-gel route in presence of titanium n-butoxide (TNBT) as TiO2 precursor, n-butanol as dilutant and EG as solvent and chelating agent. The X-ray diffraction and scanning electron microscopy studies show that the product has anatase crystal structure with average particle size 20-50 nm. The nanoparticles thus prepared can be used for gas sensing and biological applications, also as photo-electrodes for dye-sensitized solar cells and in removing the organic chemicals which occur as pollutants in wastewater effluents from industrial and domestic sources.