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Hailemariam Gebru ¹, Abi Taddesse ¹, Jyotsna Kaushal ², O. P. Yadav ³

Affiliations
1 Chemistry Department, Haramaya University, Dire Dawa, Post Box-138, ET
2 School of Applied Science, Chitkara University, Punjab, IN
3 Chemistry Department, Haramaya University, Dire Dawa, Post Box-138, IN

Abstract

Silver nanoparticles have been prepared by the reduction of silver ions using respectively castor oil (ricinus communis), khat (catha edulis) and sun flower (helianthus annuus) leaf extracts as reducing and stabilizing agents. The as-synthesized material was characterized by using spectroscopic, XRD and TEM techniques. As-synthesized silver nanoparticles are found to have face centered cubic structure with average crystallite size 28 nm. and showed antimicrobial activity against Escherichia coli and Staphylococcus aureus.

Keywords

Ag-Nanoparticles, Synthesis, Green Reducing Agents, Antimicrobial Activity.

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Kiros Guesh ¹, Abi Taddesse ¹, O. P. Yadav ¹

Affiliations
1 Chemistry Department, Haramaya University, Dire Dawa, Post Box-138, ET

Abstract

Synergetically modified nanosize TiO₂ semiconductor heterogeneous photocatalyst powder has been synthesized from TiCl₄ precursor for producing efficient photocatalyst that may work under visible radiation. The crystallite phase and size of the as-synthesized photo-catalyst were determined by X-ray diffraction (XRD) technique. As-synthesized TiO₂ was found to be nano-crystalline anatase. The absorption edge of the photo-catalyst was evaluated from the UV/ Visible diffuse absorbance spectra. The band gap energies (E_bg) of undoped-, Ag-doped-, Ndoped- and Ag-N co-doped TiO₂ semiconductor photo-catalysts were found to be 3.14, 3.02, 2.56 and 2.45 eV, respectively. Co-doping of Ag and N in TiO₂ has shown synergetic effect towards photo-catalytic degradation of methyl orange in aqueous solutions. Using Ag-N co-doped TiO₂ photo-catalyst, degradation of methyl orange under UV and visible irradiations were 79.1% and 73.5%, respectively.

Keywords

Absorbance, Degradation, Diffraction, Nanoparticles, Photo-Catalyst.

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Ashok Kumar ¹, K. Anand ¹, O. P. Yadav ¹

Affiliations
1 Department of Chemistry and Physics, CCS Haryana Agricultural University, Hisar-125 004, IN

Abstract

From the measured surface tension data, surface properties and thermodynamic quantities of micellization, adsorption at the air-liquid interface and transfer from water to mixed solvent (formamide + water) have been determined for the systems : (1) Sodium Dodecyl Sulphate + Formamide + Water; (2) Dodecyl Trimethyl Ammonium Bromide + Formamide + Water and (3) Triton X-100 + Formamide + Water. The process of micellization in the bulk solution and the adsorption of surfactants at the air-liquid interface are favoured by the enthalpy as well as the entropy effects. The results have been descirbed in terms of the intermolecular interaction of the components in the solutions.

Keywords

Micellization, Adsorption, Mixed Solvents, Thermodynamics of the Processes, Intermolecular Interaction.

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Cherinet Bekele ¹, O. P. Yadav ¹, Archana Bachheti ²

Affiliations
1 Chemistry Department, Haramaya University, Post Box : 138, Dire Dawa, ET
2 Biology Department, Haramaya University, Post Box : 138, Dire Dawa, ET

Abstract

Polyaniline (PANI)-modified glassy carbon electrode has been synthesized by electropolymerizing aniline for determining acetylsalicylic acid (ASA in pharmaceutical samples using cyclic and differential pulse voltammetric techniques. The best performance of the PANI modified glassy carbon electrode in 0.04 M Britton Robinson buffer was obtained at pH 2.0. Under these conditions single oxidation peak at a potential of 250 mV vs Ag/AgCl/sat'd KCl, characteristic of an irreversible reaction, was observed. Studies on the effects of pH, scan rate and substrate concentration revealed irreversible diffusion controlled electrode redox reaction. The PANI modified glassy carbon electrode showed higher electro-catalytic efficiency, compared to the unmodified one, for ASA determination.

Keywords

Aspirin, Electro-Catalytic Efficiency, Pharmaceutical, Polyaniline, Voltammetry.

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Marshet Getaye ¹, O. P. Yadav ¹, Abi Taddesse ¹, D. V. S. Jain ²

Affiliations
1 Department of Chemistry, College of Natural and Computational Science, Haramaya University, Dire Dawa, ET
2 Chemistry Department, Panjab University, Chandigarh - 160014, Panjab, IN

Abstract

Zinc Oxide nanoparticles and their corresponding sulphur, silver and silver (silver + sulphur) doped variants have been prepared by mechano-chemical synthesis. These have been used as photocatalysts and were characterized by XRD, TEM, FTIR and UV-Visible spectroscopic techniques. Photocatalytic degradation of malachite green (MG) dye over these photocatalysts was studied under visible as well as UV radiations. The (Ag, S) co-doped ZnO exhibited the highest photocatalytic efficiency both under UV as well as visible radiations. It is observed that doping of Ag and S in ZnO had synergetic effect in improving its photo-catalytic activity. Photocatalytic degradation of Malachite Green (MG) dye is found to follow a pseudo first order kinetics.

Keywords

Degradation, Mechano-Chemical, Nanoparticles, Photocatalyst, XRD

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A. Yugandhara Rao ¹, K. Vijay Raj ², O. P. Yadav ², L. K. Nanda ³, A. K. Rai ³, P. S. Parihar ³

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Vishakapatnam 530 007, IN
2 Atomic Minerals Directorate for Exploration and Research, Jaipur 302 033, IN
3 Atomic Minerals Directorate for Exploration and Research, Hyderabad 500 016, IN

Abstract

Magnesium-bearing calcretes of soft-gritty and hard pan varieties containing uranium concentrations from 16 to 74 ppm with <10 ppm of thorium are located along the Saraswati palaeochannel at Khemasar village, Churu district, Rajasthan. The uraniumbearing calcretes are exposed over an areal extent of 300 m × 200 m with thickness of up to 2 m in an interdunal depression. The silty sand layer occurring below the calcrete horizon suggests that it is a valley-fill calcrete, deposited along a palaeochannel. This occurrence of uraniferous Mg-calcrete in the Saraswati river palaeochannel opens up a large area for uranium exploration in the calcrete environment of Thar Desert. These calcretes are composed of 15.94% to 25.39% CaO, 7.15% to 22.39% MgO and Sr/Ba ratio up to 66.98. There is a positive correlation of U with Sr/Ba and MgO. The high Sr/Ba ratio and MgO indicate water of saline nature and high rate of evaporation. Ephemeral centripetal drainage mixing with the dissected palaeochannel waters and groundwaters, under arid climatic conditions might have resulted in the formation of this kind of uranium-bearing calcrete in fluvio-lacustrine environment.

Keywords

Fluvio-Lacustrine Environment, Khemasar, Magnesian Calcrete, Surficial Type Uranium.

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Gaim Gebrezgiabhiar ¹, O. P. Yadav ¹, Mamta Yadav ², D. V. S. Jain ³

Affiliations
1 Chemistry Department, Haramaya University, Post Box: 138, Dire Dawa, ET
2 Chemistry Department, HNB Garhwal Central University, Srinagar, Uttarakhand, IN
3 Chemistry Department, Panjab University, Chandigarh - 160014, IN

Abstract

ZnS and N-doped-ZnS nanoparticles were prepared by aqueous chemical method under optimal conditions and characterized using XRD, TEM and UV-Visible spectroscopic techniques. As-synthesized nanomaterials were used as a photo-catalysts for the degradation of Methyl Orange (MO) dye. Effects of photo-catalyst load, pH, and substrate initial concentration on degradation of the dye in aqueous solution have been investigated. Maximum degradation (76.56 %) of methyl orange was observed using optimum pH 6 and catalyst load 250 mgL^-1.

Keywords

Methyl Orange, Photo Catalysis, Nanoparticles, Rate of Degradation, XRD TEM.

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Jemal Mohammed Yasin ¹, O. P. Yadav ¹, Abi M. Taddesse ¹

Affiliations
1 Chemistry Department, Haramaya University, Post Box: 138, Dire Dawa, ET

Abstract

Nano-size Ag-N co-doped ZnO-CuO composites have been synthesized and tested for their photo-catalytic activity towards degradation of methyl orange in aqueous solution under visible as well as UV radiations. Crystal structure, surface functional groups, metallic composition and band structure of as-synthesized nano-material were investigated using XRD, FTIR, AAS and UV-Vis spectroscopic techniques, respectively. Ag-N co-doped ZnO-CuO photocatalyst showed higher photo-catalytic activity than Ag- or N-doped and undoped composite photocatalysts. The observed highest activity of Ag-N co-doped ZnO-CuO among the studied photo-catalysts, is attributed to the cumulative effects of lowering of band-gap energy and decrease of recombination rate of photo-generated electrons and holes owing to doped N and Ag, respectively. Effects of photo-catalyst load, solution pH and substrate initial concentration on the degradation of methyl orange have also been studied.

Keywords

Band-Gap, Degradation, Nanocomposite, Photocatalysts, Rate Constant, Spectroscopy.

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Sarita Yadav ¹, D. K. Tyagi ¹, O. P. Yadav ²

Affiliations
1 Department of Chemistry, D.A.V.P.G. College, Dehradun- 248001, Uttrakhand, IN
2 Chemistry Department, CCS Haryana Agricultural University, Hisar-125001, IN

Abstract

Wastewater effluents from textile, paper, tannery and beverage industries are contaminated with variety of pollutants including dyes. Dyes are skin irritant, carcinogenic and can cause allergic dermatitis and mutation. Environmental legislations are now becoming more stringent to control the release of dyes into the environment. Biological treatment of effluent requires a large land area and is constrained by toxicity of some chemicals, and less flexibility in design and operation. Chemical treatments for the removal of dyes from the polluted effluents are not cost effective. Photocatalytic dye degradation techniques suffer from their low efficiency. Adsorption method has been found to be efficient, economical, renewable and eco-friendly solution in treating effluents contaminated with dyes. An overview of the treatments of dye contaminated effluents by biological, chemical and physical methods have been presented.

Keywords

Adsorption, Biological, Chemical, Dyes, Industrial Effluents, Pollutants.

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Ram Partap ¹, Neelam Swaroop ², D. K. Tyagi ³, O. P. Yadav ⁴

Affiliations
1 Department of Chemistry, Government College, Hisar, 125001, IN
2 Jain P.G. College, Mujaffar Nagar (U.P.), 251001, IN
3 Department of Chemistry, D A V College, Dehradun, IN
4 Department of Chemistry, CCS Haryana Agricultural University, Hisar 125 004, IN

Abstract

Critical micelle concentration (CMC), maximum surface excess concentration (Γ_max), minimum area per molecule (A_min) at air-liquid interface of cetyl pyridinium chloride (CPC) in aqueous sodium chloride solutions have been, tensiometrically, determined at 288.15, 293.15 and 298.15 K. Thermodynamic parameters of micellization as well as of adsorption at air-liquid interface have been evaluated. Whereas micellization process is exothermic, adsorption of surfactant at the air-liquid interface is endothermic in nature. The latter process however becomes feasible owing to the predominant entropy gain.

Keywords

Critical Micelle Concentration, Tensiometrically, Micellization, Adsorption, Entropy.

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Sarita Yadav ¹, D. K. Tyagi ¹, O. P. Yadav ²

Affiliations
1 Department of Chemistry, D.A.V.P.G. College, Dehradun- 248001, Uttrakhand, IN
2 Chemistry Department, CCS Haryana Agricultural University, Hisar-125001, IN

Abstract

Kinetic and equilibrium studies for the adsorption of Rhodamine-B dye from aqueous solution onto activated rice husk carbon have been reported. The effect of parameters such as: contact time, dye initial concentration, temperature, adsorbent's amount and particle size on the color removing efficiency of the activated rice husk carbon has been investigated. Kinetics of adsorption of dye at adsorbent in aqueous solution was monitored spectrophotometrically. At the given initial dye concentration, its percent adsorption increases with increase in temperature as well as the adsorbate-adsorbent contact period and the equilibrium was established after 120 minutes. However, at the given temperature, % adsorption of the dye decreases with the increase in its initial concentration. The curves representing adsorption isotherms are single and continuous leading to saturation, suggesting monolayer coverage of the dye on the adsorbent surface. The observed adsorption data was analysed in the light of Langmuir and Freundlich adsorption isotherms. Dye adsorption rate constant (k_ad) follows the first order kinetics. Activation energy (Ea), intra-particle diffusion rate constant and thermodynamic quantities of dye adsorption on the rice-husk carbon have been evaluated and interpreted.

Keywords

Equilibrium, Rhodamine-B, Adsorption, Activation Energy, Thermodynamic.

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O. P. Yadav ¹, V. K. Garg ¹, Y. K. Yadav ², Eleni Daoutsali ³

Affiliations
1 Department of Environmental Science and Engineering, Guru Jambheshwar University of Science and Technology, Hisar-125001, IN
2 Department of Agricultural Processing and Energy, Haryana Agricultural University, Hisar-125001, IN
3 Institut fur Didaktik der Chemie, Fliednerstr, 21; 48149 Münster, DE

Abstract

Nano-size platinum particles were synthesized by chemical reduction of Pt⁺⁴ ions in water-in-oil microemulsion. As synthesized platinum nanoparticles have been characterized using TEM and XRD techniques. Platinum (2%)+Alumina composite was used as a catalyst for carrying out the oxidation of CO to CO₂, over 50-500°C, in a suitably designed converter comprising a vertical quartz tube connected to a quadrupole mass spectrometer. Effects of [Water]/[Surfactant] ratio and the presence of polyethylene glycol (PEG) in the microemulsion on the size and catalytic efficiency of as-synthesized platinum nanoparticles have been investigated. The size of platinum nanoparticles grows further on increasing [Water]/[Surfactant] ratio in the microemulsion composition. Whereas, using pure alumina as catalyst, conversion of CO to CO₂ occurs at 3000C, such conversion occurs at much lower temperature (225°C) using alumina+Pt (2%) as catalyst. CO to CO₂ conversion temperature is further lowered to 200°C when the platinum nanoparticles synthesized in microemulsion, stabilized by polyethylene glycol (PEG), are used in the above composite catalyst.

Keywords

Platinum, Microemulsion, Polymer, Nanoparticles, Catalyst, Mass Spectrometer, Alumina, Poly(Ethylene Glycol).

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O. P. Yadav ¹, D. V. Singh ¹, B. S. Dhillon ², T. Mohapatra ³

Affiliations
1 ICAR-Central Arid Zone Research Institute, Jodhpur 342 003, IN
2 Punjab Agricultural University, Ludhiana 141 004, IN
3 Indian Council of Agricultural Research, New Delhi 110 014, IN

Abstract

The term ‘Green Revolution’ (GR) is used to highlight an unprecedented increase in wheat production in India during 1968–72. The critics of GR allege that there is technology fatigue, especially after 1980s. The present study was undertaken to analyse the trends in productivity of major cereals and compare yield gains during the GR era and post-GR era. The period of 68 years since 1950 was divided in four phases: pre-GR era (1950–66) referred to as phase I, GR era (1967–83) as phase II, post-GR era of 1984–2000 as phase III and post-GR era of 2001–17 as phase IV. The annual rate of gain in productivity (kg/ha/yr) in each phase was estimated by linear regression. The annual gain in wheat productivity in phase III (53.1 kg/ha) was 30% higher than that in the GR era (41.0 kg/ha). In rice, the productivity gains increased consistently: annual gain in phase III (32.3 kg/ha) and phase IV (41.6 kg/ha) was 68% to 117% respectively, higher than that in the GR era (19.2 kg/ha). The rate of gain in productivity of maize and pearl millet in phases III and IV was 188–530% higher in comparison to the GR phase. The progress can largely be attributed to development and adoption of improved cultivars with higher yield potential and crop management technologies. The analysis provided conclusive evidence of India experiencing evergreen revolution in major cereals.

Keywords

Cereals, Crop Productivity, Green Revolution, Improved Cultivars.

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