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Search Results: 1 - 10 of 1945 matches for " Megh Raj Pokhrel "
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Photophysical Investigatigation of Poly [N-isopropylacrylamide-co-Acrylic Acid] Copolymers
Megh Raj Pokhrel
Journal of Nepal Chemical Society , 2011, DOI: 10.3126/jncs.v28i0.8109
Abstract: Poly[n-isopropylacrylamide], Poly[NIPAM], and Poly[n-isopropylacrylamide-co-acrylic acid], poly[NIPAM-co-AA] copolymers exhibit the interesting property of size contraction with increasing temperature. Photophysical probe, ruthenium-tris-phenanthroline has been used to monitor the above changes and the studies are correlated with independent study state fluorescence data. DOI: http://dx.doi.org/10.3126/jncs.v28i0.8109 Journal of Nepal Chemical Society Vol. 28, 2011 Page: 67-73 Uploaded Date : May 24, 2013
Assessment of Arsenic Contamination in Deep Groundwater Resources of the Kathmandu Valley, Nepal  [PDF]
Suman Man Shrestha, Kedar Rijal, Megh Raj Pokhrel
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.310013
Abstract:


This study was carried out to assess arsenic in deep groundwater resources in the Kathmandu Valley, Nepal and to predict arsenic mobilization process in relation to iron, manganese, pH and ORP. Forty-one deep groundwater samples were collected during pre monsoon and post monsoon in 2013. The depths of the wells were ranged from 84 to 304 m. In pre monsoon and post monsoon, arsenic concentration in 17% and 26% of examined groundwater wells, respectively exceeded permissible World Health Organization (WHO) guideline value of 0.010 mg/L for drinking water. The concentrations of arsenic were in the range between < 0.003 to 0.137 mg/L. The study demonstrated elevated concentrations of iron and manganese in the groundwater. Arsenic is highly correlated with iron and manganese. The strong negative correlation between arsenic and ORP indicates that arsenic mobilization occurs under reducing condition. These distinct relationships indicate that arsenic release is considered to be affected by the reductive dissolution of Fe/Mn oxides in the groundwater. Arsenic has very weak negative correlation with pH suggesting less effect of pH on arsenic mobilization. Arsenic is not significantly correlated with the season which infers similar distribution of arsenic in both seasons. Arsenic varies spatially in groundwater of the valley showing high concentrations in central groundwater district.


Assessment of Heavy Metals in Deep Groundwater Resources of the Kathmandu Valley, Nepal  [PDF]
Suman Man Shrestha, Kedar Rijal, Megh Raj Pokhrel
Journal of Environmental Protection (JEP) , 2016, DOI: 10.4236/jep.2016.74047
Abstract:

A study was carried out to address distribution of some heavy metals in deep groundwater resources of the Kathmandu Valley. Groundwater samples were analyzed for pH, ORP, EC, iron, manganese, zinc, and arsenic in 41 deep groundwater wells during pre monsoon and post monsoon seasons for two consecutive years. The study showed elevated concentrations of iron and manganese in the groundwater of the valley. The occurrence of elevated concentrations of arsenic was also exhibited and observed up to 0.160 mg/L. The spatial distribution patterns demonstrated elevated levels of EC, iron, manganese, zinc, and arsenic in central groundwater district (CGWD) of the valley. The monitored parameters except ORP are not significantly correlated with studied time series, inferring similar distribution of the metals. Correlation analysis and principal component analysis (PCA) were performed to find out relationships among examined parameters and metals. The ORP has strong negative correlations with iron, manganese, and arsenic, suggesting reductive mobilization mechanism of the metals in the groundwater. PCA results showed that iron and manganese with high positive loading factors were due to common natural source of origin of these metals in the groundwater, while negative loading factors of pH and ORP indicated that iron and manganese mobilization was favorable in low pH and reducing environment. Cluster analysis (CA) evidenced high mineralization in most of the wells in the CGWD.

Spectrophotometric Determination of Phosphate in Sugarcane Juice, Fertilizer, Detergent and Water Samples by Molybdenum Blue Method
Samjhana Pradhan,Megh Raj Pokhrel
Scientific World , 2013, DOI: 10.3126/sw.v11i11.9139
Abstract: A simple and sensitive spectrophotometric method has been developed for the determination of phosphate in mg per liter (parts per million) concentration range in sugarcane juice, water, fertilizer and detergent samples. The amount of phosphate is determined by molybdenum blue phosphorus method in conjugation with UV-visible spectrophotometer. This method is based on the formation of phosphomolybdate complex with the added molybdate followed by the reduction of the complex with hydrazine hydrate in aqueous sulphuric acid medium. The system obeys Lambert-Beer’s law at 840 nm in the concentration range 0.1-11 ppm. The colour intensity of the reduced phosphomolybdate solution is found to be proportional to the amount of phosphate present in sugarcane juice, water, fertilizer and detergent samples. The reaction conditions as well as the various experimental parameters affecting the development and stability of the coloured complex were carefully investigated and optimized for the quantitative determination of phosphate present in various samples. The optimized concentrations of various reagents used are 0.20N sulphuric acid, 0.02M hydrazine hydrate and 0.20% ammonium molybdate. The effect of time on the formation of phosphomolybdenum blue complex and addition of the order of the reagents was also studied. Scientific World, Vol. 11, No. 11, July 2013, page 58-62 DOI: http://dx.doi.org/10.3126/sw.v11i11.9139
Removal of As(III) from Aqueous Solution Using Fe(III) Loaded Pomegranate Waste
Sheela Thapa,Megh Raj Pokhrel
Journal of Nepal Chemical Society , 2012, DOI: 10.3126/jncs.v30i0.9332
Abstract: A study on As(III) removal using Fe(III) loaded pomegranate waste as an adsorbent is presented. The effects of initial metal ion concentration, contact time, adsorbent dose and pH of the solution on the removal of arsenic were investigated in a batch system. The optimum pH for As(III) adsorption using Fe(III)-loaded charred pomegranate waste [Fe-CPW] was found to be 9. The equilibrium has beenachieved in 2 hours. The maximum adsorption capacity (qmax) for the adsorption of As (III) was found tobe 50 mg/g. The experimental data fitted well with the Langmuir adsorption isotherm model. DOI: http://dx.doi.org/10.3126/jncs.v30i0.9332 Journal of Nepal Chemical Society Vol. 30, 2012 Page: ?29-36 Uploaded date : 12/16/2013 ? ?
Surface Modification of the Biowaste for Purification of Wastewater Contaminated with Toxic Heavy Metals—Lead and Cadmium  [PDF]
Bindra Shrestha, Jagjit Kour, Puspa Lal Homagai, Megh Raj Pokhrel, Kedar Nath Ghimire
Advances in Chemical Engineering and Science (ACES) , 2013, DOI: 10.4236/aces.2013.33022
Abstract:

The surface of a biowaste was modified by introduction of amino group for the purification of wastewater contaminated with heavy metals. In this study waste tea leaf was used as a biowaste which was an economic and efficient bioadsorbent. The aminated tea leaves were characterized by spectral and elemental analysis. The adsorption capacity of the surface modified biosorbent was studied as the function of solution pH, concentration of metal ions and contact time of adsorption. The applicability of Langmuir isotherm was tested. The adsorption capacities were found to be 83.04 mg/g and 57 mg/g for Pb (II) and Cd (II), respectively. The biosorbent was regenerated by desorption of the metal loaded adsorbent with 0.1 M HNO3. These results showed that the aminated tea leaves may be an attractive alternative for treatment of wastewater contaminated with heavy metals.

Removal of Chromium (VI) from Aqueous Solution using Charred Pomegranate Waste
Rajendra Prasad Gautam,Megh Raj Pokhrel
Journal of Nepal Chemical Society , 2012, DOI: 10.3126/jncs.v29i0.9256
Abstract: Removal of Cr(VI) from aqueous solution was studied using charred pomegranate fruit waste [CPW] as a new low cost biosorbent under batch method at room temperature. Its efficiency for removal of Cr(VI) was compared with raw pomegranate fruit waste[RPW]. Various sorption parameters such as contact time, initial concentration of Cr(VI) ion and effect of pH on the adsorption capacity of the biosorbent were studied. The adsorbent was effective for quantitative removal of Cr(VI) ions in highly acidic condition (pH=1) and equilibrium has been achieved in 2 hours. The adsorption isotherm data were fitted to Langmuir and Freundlich adsorption isotherm models and the model parameters were evaluated. Spectrophotometric method using diphenylcarbazide as a complexing reagent was used to analyze the chromium content in synthetic samples and the landfill site effluent collected from Kuleshwor, Kathmandu, Nepal. DOI: http://dx.doi.org/10.3126/jncs.v29i0.9256 Journal of Nepal Chemical Society Vol. 29, 2012 Page: ?81-88 Uploaded date : 12/5/2013 ?
Synthesis and Characterization of Poly(NIPAM-co-AA) Polymers Possessing Perfluorinated Side Chains and Chemically Linked Pyrene Labels
Megh Raj Pokhrel,Stefan H. Bossmann
Journal of Nepal Chemical Society , 2011, DOI: 10.3126/jncs.v27i1.6663
Abstract: The synthesis of Poly(n-isopropylacrylamide–co-acrylic acid)/-Poly(NIPAM-co-AA) polymers featuring perfluorinated side chains as well as chemically linked pyrene fluorescence labels has been reported. The resulting polymers have been characterized with the aid of UV/VIS, FTIR spectroscopy and Gel permeation chromatography.
Developing New Strategies for the Treatment of Tuberculosis Employing Ruthnium(II)Quaterpyridyl Compexes
Megh Raj Pokhrel,Pubudu Gamage,Mausam Kalita,Aibin Shi,Stefan H. Bossmann
Journal of Nepal Chemical Society , 2009, DOI: 10.3126/jncs.v23i0.2091
Abstract: A series of ruthenium(II)quaterpyridyl complexes has been synthesized as prototypes for mycobacterial channel blockers. These Ru(II)complexes show distinct changes in their luminescence spectra when bound to the porin MspA from M. smegmatis, which is a non-pathogenic relative of M. tuberculosis. By using HPLC, we have determined binding constants of the Ru(II)-complexes to MspA in phosphate buffer (0.05M, pH = 6.8) ranging from 5.2 x 109 M-1 (Ru-C2) to 1.8 x 109 M-1 (Ru-C4). Our findings indicate that channel blocking is a promising treatment strategy for mycobacterial infections. It appears to be also a viable approach towards luminescent nanostructures, because MspA features extraordinary stability.
Adoption of Goat Production Technology at the Farm Level: A Case of Krishnagandaki VDC, Shyangja District
Megh Bahadur Nepali,Sudha Sapkota,Sujaya Upreti,Bhoj Raj Pokhrel,Bimala Sharma,Hari Prasad Devkota,Sabita Mohini Amatya
Nepal Journal of Science and Technology , 2010, DOI: 10.3126/njst.v11i0.4127
Abstract: Adoption of goat production technology consists of health, breeding, nutrition, pasture and fodder and management. The study was conducted in Krishnagandaki VDC of Syangja district with the objective of exploring the existing goat production technology adoption at the farm level. The methodology of the study included household survey, participatory rural appraisal and secondary data analysis. Most of the farmers raised goats in the villages. Overall farmers reported that the average adoption of goat production technology was (42.2%). The study revealed that farmers adopted breeding technology (53.5%), health technology (34.8%), nutrition technology (36.2%), management technology (53.9%) and pasture, fodder and agro-forestry technology (32.4%). Key words: breeding; health; nutrition; pasture; management DOI: 10.3126/njst.v11i0.4127 Nepal Journal of Science and Technology 11 (2010) 79-82
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