Chemistry

Permanent URI for this collection

https://hdl.handle.net/20.500.14540/125

Browse

Now showing 1 - 20 of 131

3d printing of biodegradable poly (butylene adipate – co – terephthalate) / hydroxyapatite nanocomposites
(Department of Chemestry, 2020) Acharya, Arun
In this work, the hydroxyapatite (HA) biomaterial from a bio-waste namely the buffalo bone was prepared in simple and environmentally friendly way. It was characterized by Fourier Transform InfraRed (FTIR), X-Ray Diffraction (XRD), Energy Dispersive X-Ray (EDX) and Scanning Electron Microscope (SEM) analyses. The average sizes of the nanoparticles were found in the range 8-41 nm as calculated by Debye-Sherrer’s formula. FTIR spectra confirmed thepresence of major functional groups (PO43- and OH-) in prepared HA samples, with small additional peaks of carbonate ion (CO32-). The SEM micrograph showed the formation of small rod-like crystals in the agglomerated particles were presented in as-dried HA powders with size ranges from 1.75 to 2.72 μm. In addition, the micrographs show morphologies for all samples with fine particles and pore size details ranges from 31.3nm to 101nm provides good agreement to be used in a biomedical application. To make the nanocomposite, HA was macroscopically uniformly distributed over poly(butylene adipate-co-terephthalate) (PBAT) by solvent casting method with the help of magnetic stirrer. By using nanocomposite, the filament for 3D printer was prepared by Noztek machine. Finally, button like structure was prepared by using 3D printer and it was investigated by water adsorption, Biodegradibility and anti-microbial test. The addition of HA brought improvements in stiffness of PBAT, due to high interactions between the carbonyl groups of the polymer matrix and the hydroxyl groups of HA. As the percentage of HA in composite increased, the water absorption percentage of nano-composite also increased. Also, degradation test showed that weight loss percentage gone to decrease with increased percentage of HA in composite. Therefore, this biomaterial has great potential for applications in regenerative medicine as a support for bone growth. Keywords: Hydroxyapatite (HA), Crystallinity, Porous, 3D Printing, Solvent Casting, Biodegradability, Water Absorption, Hydrophilicity
Adsorption Behaviour of Chromium(Vi) onto Surface Modified Sugarcane Waste
(Department of Chemistry, 2009) Wagle, Deepak
An effective chemically modified adsorbent based on sugarcane wastehas been prepared by treating with concentrated sulphuric acid in 2:1weight:volume ratio. Thus prepared adsorbent has been found to be effective in theadsorption of chromium from aqueous medium. The efficacy of the adsorbentin the removal of chromium was evaluated by batch adsorption method. Theeffect of initial concentration, contact time and pH of the solution wasinvestigated. The maximum adsorption capacity onto this adsorbent wasfound to be 195 mg/g at their optimal pH 1 at which unmodified bagasse hasonly 58 mg/g. The characterization of adsorbent was done by determiningsurface area and Boehm’s titration method. Freundlich isotherm and pseudo-second order kinetic model gave better explanation of the adsorption process.
Adsorption of Arsenic(III) Using Iron(III)-Loaded Modified Sugarcane Begasse
(Department of Chemistry, 2009) Aacharya, Sabita
Arsenic is a toxic element and may be found in natural water as well as industrial wastes. Leaching of As from industrial wastes into ground water may cause significant contamination which requires proper treatment before its use as a drinking water. The chemistry of As and its natural occurrence in some water resources combine to create a potent, widespread human health risk, requiring management and removal from drinking water. The present study describes the removal of As(III) from water. Of the available conventional techniques, adsorption is the most versatile and effective separation technique and utilizes agricultural and natural waste as adsorbent. The study mainly focuses on the removal of As(III) on Fe(III) loaded modified Sugarcane begasse in batch studies as a function of pH, dosage of adsorbent and contact time. Kinetics revealed that the uptake of As(III) ion by rapid and equilibrium time was independent of initial As(III) concentration and the adsorption process followed a pseudo second-order kinetics equation. The As(III) was strongly dependent on pH and dosage of adsorbent. The adsorption isotherm best fit the Langmuir equation as compared to Freundlich.
Adsorption of Cd (II) From Aqueous Solution by Activated Charcoal Derived from Lapsi Seeds
(Department of Chemistry, 2009) Lamsal, Nirma
The potential and effectiveness of activated carbon derived from carbonization of Lapsi (Choerospondias axillaris) seed for adsorptive removal of cadmium (II) was examined by adsorption technique. The carbon obtained from Lapsi seed was chemically modified by treating with 1:1 HNO3 at 60o C. Boehm method was used to estimate the oxygen containing acidic functional groups. The acidic functional group, specific surface area and adsorptive capacity all greatly increased with chemical treatment with nitric acid. The specific surface area of the charcoal, after chemical treatment, increased to 600 m2/g from 45 m2/g. The ash, moisture and carbon contained in modified charcoal were found to be 3.5%, 0.2 % and 96.3 % respectively. The performance of the adsorbent was in par with commercial activated charcoal. Various parameters such as contact time, adsorbent dose, pH and metal ion concentrations on adsorption were studied, optimized and applied in the present study. The maximum adsorption capacity of charcoal to adsorb Cd(II) was found to be 12.53 mg/g at optimum pH of 6 and equilibrium was attained within 150 minutes. The adsorption of cadmium followed pseudo second order kinetic model and the rate constant of the process was found to be 1.73x10-3 g mg-1 min-1. Results indicated that the Langmuir model gave a better fit to the experimental data in comparison with the Freundlich isotherm.
Adsorptive Removal of arsenic from Water by chemically modified rice HUSK
(2024) Rana, Meunka; Megh Raj Pokhrel
Available in fulltext
Adsorptive Removal of Cr(VI) and Al(III) From Aqueous Solution by Sugarcane Biomass
(Faculty of Chemistry, 2012) Mishra, Paramatma
The potential and effectiveness of activated carbon derived from carbonization of sugarcane bagasse (Saccarhum officianrum) for adsorptive removal of Cr(VI) and Al(III) was examined by adsorption technique. Activated carbon was prepared by subjecting the raw sugarcane bagasse to chemical modification using concentrated sulphuric acid in (1:2) (w/v) of ratio of adsorbent weight to volume of concentrated sulphuric acid (H2 SO4 ). Boehm method was used to estimate the oxygen containing functional groups. The acidic functional groups, specific surface area and adsorptive capacity all greatly increased with chemical modification. The batch removal of Cr(VI) and Al(III) from aqueous solution was investigated. The influence of pH, initial concentration of metal ion and contact time were also investigated. The maximum adsorption capacity of Cr(VI) was found to be 131.68 mg/g at optimum pH of 1 and the maximum adsorption capacity of Al(III) was found to be 125.89 mg/g at optimum pH of 6 at the laboratory temperature respectively. The equilibrium time for Cr(VI) and Al(III) were found to be 180 and 120 minutes respectively. Kinetics of adsorption was found to follow pseudo-second order model. Both Langmuir and Freundlich adsorption isotherm could be used to describe adsorption isotherm but the Langmuir isotherm was found to be in good agreement with experimental data.
Adsorptive Removal of Fe (II) From Aqueous Solution by Functionalized Sugarcane Bagasse
(Department of Chemistry, 2010) Acharya, Mahendra
In the present study, adsorption of Fe(II) onto different biosorbents prepared from sugarcane bagasse, i.e, raw sugarcane bagasse, charred sugarcane bagasse and phosphoric acid modified charred sugarcane bagasse has been studied by batch equilibration method under different experimental conditions. Effects of pH, Fe(II) concentration, and contact time on the adsorption of divalent iron ion were investigated. The concentration of Fe(II) ion in the test solution was determined spectrophotometrically. Maximum adsorption was observed at pH 2.5 for all the adsorbents at the optimum contact time of 9 hour, 7 hour, and 4 hour respectively for RSB, CSB and PCSB. Maximum adsorption capacity (qmax) value for the RSB, CSB and PCSB was found to be 50.5, 111.4 and 175 mg/g respectively. Adsorption of the Fe(II) ion on all the adsorbents followed Langmuir isotherm more strictly than Freundlich isotherm. The results shows that studied adsorbents may be attractive low cost alternative for the treatment of wastewater in lower concentration of iron.
ADSORPTIVE REMOVAL OF LEAD(II) USING ACTIVATED CARBONACEOUS ADSORBENT OBTAINED FROM WALLNUT SHELL(Juglans regia)
(Amrit Campus, 2023-08-17) TIMALSINA, SURESH
Presence of heavy metal ions in excess than permissible limit in aquatic environment can cause serious problems to human being and aquatic life. Adsorption is by far the most effective method for the removal of trace amounts of toxic heavy metals from wastewater. The main aim of this thesis work is to prepare a low-cost, effective, and highly efficient adsorbent from the walnut shell by chemical modification for the removal of Pb(II) ions from an aqueous solution. Charred walnut shell (CWS) and xanthated walnut shell (XWS) as adsorbents have been prepared. FTIR, XRD, and SEM characterization are used for the characterization of adsorbents. Batch experiments are performed for analysis. The effect of pH, Pb(II) concentration, and contact time have been investigated using both CWS and XWS adsorbents. The optimum working pH of 4 and optimum time of 150 min are determined for both the adsorbents. Equilibrium sorption data are best fitted for the Langmuir isotherm model and the maximum adsorption capacity of CWS and XWS are found to be 61 mg/g and 109.9 mg/g, respectively. Kinetic modeling studies revealed that the experimental data best fit to pseudo-second-order kinetic model. These results demonstrate that XWS may be an attractive alternative bio-adsorbent for the removal of Pb(II) from an aqueous solution
Adsorptive Removal of Metallic and Non- Metallic Pollutants from Water by Chemically Modified Natural ION Exchanger
(Faculty of Chemistry, 2022) Poudel, Bhoj Raj
Available with full text
ADSORPTIVE REMOVAL OF METHYLENE BLUE DYE USING ACTIVATED CARBON PREPARED FROM SEED OF TINDU (DIOSPYROS MALABARICA)
(2025-04-24) SABINA SHRESTHA; Hari Bhakta Oli
ADSORPTIVE REMOVAL OF PHOSPHATE ANION FROM AQUEOUS SOLUTION USING Al(III)- LOADED SAPONIFIED WATERMELON RIND
(2025-04-24) SIRJANA BHATTARAI; Dr. Ram Lochan Aryal
Adsorptive Separation of Heavy Metals onto Xanthated Apple Waste From Aqueous Solution
(Department of Chemistry, 2006) Bashyal, Deepak
Biosorption is potentially an attractive technology for the treatment of wastewater retaining heavy metals in aqueous solution. This study investigated the feasibility of chemically modified apple waste as a novel type of biosorbent for lead, cadmium, zinc and Iron removal from aqueous medium. Xanthated apple waste as a biosorbent was prepared by simple chemical reaction with carbon disulphide under alkaline condition. The maximum exchangeable cations of the H V + -form xanthated apple waste (XAWgel) were as high as 2.52 mol/kg. The effect of pH, sorption kinetics, effect of competitive ion and isotherm were studied by batch method. The significant effect of pH was in the range of 3 to 6. Time dependency experiments for the metal ions uptake showed the biosorption rate was fast initially for 2h, followed by slow attainment of equilibrium. Sorption isotherm test showed that equilibrium sorption data were better represented by Langmuir model than the Freundlich model, and the maximum adsorption capacity of Pb(II), Cd(II), Zn(II) and Fe(III) were found to be 250, 192.30, 123.45 and 62.89 mg/g respectively. The pseudo first-order, pseudo second-order, and secondorder models were used to analyze the kinetic data. The good correlation coefficient was obtained for pseudo second-order kinetic model. XAW-gel was found to be more efficient than the conventionally used adsorbent activated carbon and other most of the biosorbent. Based on the result, a judicious choice of modification strategy for raw apple waste precursors can produce adsorbent with active xanthated surface functional groups and appears to be a promising biosorbent for removal of heavy metals from aqueous water.
Alkaloid extract of Acacia Catechu Bark as Green inhibitor for Mild Steel Corrosion in 1 M H2so4 Solution
(Amrit Campus, 2023-08-17) Karki, Rajaram
In situ corrosion inhibition in acid cleaning processes by using green inhibitors is at the forefront in corrosion chemistry. Plant extracts, especially alkaloids, are known to be good corrosion inhibitors against mild steel corrosion. In this research, alkaloids extracted from Acacia catechu has been used as green corrosion inhibitor for mild steel corrosion in 1 M H2SO4 solution. Qualitative chemical tests and FTIR measurements have been performed to confirm alkaloids in the extract. The weight loss measurement has been adopted for the study of inhibitor concentration effect as well as variation of inhibition efficiency for time and temperature. Weight loss measurement reveals the maximum efficiency of 93.96 % at 3 hrs at 28 C. The 1000 ppm inhibitor can work up to a temperature of 48 C with 84.39 % efficiency. The inhibition efficiency of extract has been studied by using weight loss and potentiodynamic polarization methods. Electrochemical measurement results revealed that the alkaloids act as a mixed type of inhibitor. The inhibition efficiency of 98.91 % and 98.54 % in the 1000 ppm of inhibitor concentration for as-immersed and immersed conditions, respectively has been achieved. The adsorption isotherm indicated the physical adsorption of alkaloids. Also, the spontaneous and endothermic adsorption processes have been indicated by thermodynamic parameters.
ALKALOID EXTRACT OF AGERATINA ADENOPHORA STEM AS GREEN CORROSION INHIBITOR FOR MILD STEEL CORROSION IN 1M H2SO4 ACID SOLUTION
(Amrit Campus, 2025-04-23) Jamuna Thapa Magar; Hari Bhakta Oli
ALKALOID EXTRACT OF ALNUS NEPALENSIS BARK AS GREEN INHIBITOR FOR MILD STEEL CORROSION IN 1 M H2SO4 SOLUTION
(Amrit Campus, 2022-08-29) Dhakal, Kamala
Extraction of alkaloids from Alnus nepalensis bark has been successfully carried out, and used as green inhibitor for mild steel corrosion exposed to 1 M H2SO4 solutoin. Corrosion inhibition has been monitored by weight loss measurement and electrochemical methods (open circuit potential method and potentiodynamic polarization method). Alkaloids have been tested by two qualitative chemical analysis: Mayers test and FTIR spectroscpic test. Weight loss measurement was employed to study the inhibitor concentration and immersion time effect. Similarly, temperature effect on inhibition efficiency was also carried out by this method. The corrosion inhibition efficiency with concentration at the various time showed that the maximum efficiency occurs at 3 h for 1000 ppm solution is 71.94 % at 25 C. These results concluded that the inhibition efficiency was incresed with inhibitor concentration. Potentiodynamic polarization for 3 h immersed samples in the presence and absence of inhibitors has been carried out. The maximum efficiency of immersed sample is 90.00 % for 1000 ppm solution. The corrosion potential density was decreased with increase in concentration. The OCP measurement revealed that alkaloids acted as a mixed type of inhibitor. The adsorption isotherm and theromdynamic parameters are calculated and energy of activation (Ea) is found to be 74.48 kJ/mol. The positive value of enthalpy indicated that the reaction involves is endothermic in nature.
Analisys of Bioactive Phytochemicals and Study of Antimicrobial Activity From Methanolic Extract of Roots of Streptopus streptopoides
(Institute of Science & Technology, 2024-06) Subedee, Anup; Dr. Deval prasad Bhattarai
Traditional practice of using medicinal plants have been the foundation of modern medicine. Streptopus streptopoides is a plant of traditional medicinal value. This report focuses in the phytochemical analysis of root parts of Streptopus streptopoides collected from Gorkha and study of biological activity of the extract. Methanolic extract of root was used for the analysis. Herein, three hundred grams of dried powder of the root of the plant was processed to extraction using methanol. The extract of S. streptopoides root solution was subjected to primary phytochemical screening. Methanol extract method revealed the presence of various phytochemicals. Total flavonoid content (TFC) in methanol has been reported to be 1.92±0.36 mg QE/g. It indicated the prescence of very low content of flavonoid in the plant sample. The total phenolic content (TPC) in methanol extract has been quantified to be 50.37 ± 0.44 mg GAE/g. Nauplii started dying at the concentration of 50 ppm. 50% (or more) of the tested nauplli died at the highest concentration of 100 ppm. Hence, LC50 of methanol extract is at 100 ppm (100 µg/mL).
Antidiabetic activity of mahonia nepaulensis DC in neonatal Streptozatocin induced type-II Diabetic model rate
(Department of Chemistry, 2022) Basnet, Durga Bahadur
Diabetes mellitus, is a group of metabolic disorders characterized by a high blood level over a prolonged period of time. It is due to either the pancreas not producing enough insulin, or the cells of the body not responding properly to the insulin produced. Symptoms often include frequent urination, increased thirst and increased appetite. Serious long-term complication include cardiovascular disease, stroke, chronic kidney disease, foot ulcers, damage to the nerves, damage to the eyes, and cognitive impairment. Diabetes management concentrates on keeping blood sugar level as close to normal, without causing low blood sugar. This can usually be accomplished with dietary changes, excessive weight loss and use of appropriate medication (insulin, oral medication) The main aim of this research work is to evaluate the antidiabetic activity of methanolic extract from Mahonia nepaulensis bark in n-STZ induced type-II diabetic model rats. The oral glucose tolerance test was performed in normal as well as diabetic rats. Experimental rats were divided into four groups (n=6) as group-I control received normal water (10 mL/kg/bw), Group-II control received diabetic water (10 mL/kg/bw), Group-III standard received Gliclazide (20 mg/kg/5 mL/bw) and Group-IV received methanol extract (80%) of stem bark of Mahonia nepaulensis (MNB) at a dose of 1.25 g/kg/10 mL/bw. The blood was withdrawn from tail the vein at a different time intervals of 0, 30, 60, and 90 minutes again glucose levels were measured using glucose oxidaseperoxidase reactive strips and glucometer. In the oral glucose tolerance test MNB group showed significant decrease in blood glucose level. In STZ induced diabetic rats fasting blood glucose levels of the treatment group were significantly reduced by 28 days of treatment with MNB extract. The isolated compounds from M. nepaulensis include β-Sitosterol, Berberine, and 5,6Dihydro-9,10-dimethoxy benzo-1,3-benzodioxolo 5,6-quinolizinium. The crude extracts of Mahonia nepaulensis bark have potent antidiabetic activity and antilipidemic activity in streptozotocin-induced type-II diabetic rats. Keywords: Mahonia nepaulensis bark, OGTT, Gliclazide, Streptozotocin, Glucometer
Biological and Phytochemical Studies on Some Medicinal Orchids of Nepal
(Department of Chemistry, 2012) Marasini, Ramesh
Biological and phytochemical screenings of some orchid species growing in Nepal were studied. The ethanolic extracts of orchid species were tested against both gram positive and gram negative standard bacterial strains viz. Vibrio cholerae, Staphylococcusaureus, Klebsiella pneumoniae, Bacillus subtilis and Escherichia coli. All orchid extracts showed good bacterial Zone of Inhibition(ZOI) against Staphylococcus aureus. The crude extracts of Pholidota imbricata and Coelogyne cristatawere shown highest activity against Vibrio cholerae (ZOI -14 mm) and Staphylococcus aureus(ZOI –14 mm) respectively. The MIC and MBC value of the extracts of Pholidota imbricata and Coelogyne cristata were found to be 62.5 mg/ml and 31.25 mg/ml, 125 mg/ml and 250 mg/ml respectively. Only Pholidota imbricata and Pholidota articulata extracts were shown fairly good activity but all others extracts were shown very less activity or even failed to show any activity against fungal organisms viz.Candida albicans, Rhizopus stolonifer and Mucor spp. From the ethanolic extracts of orchid species, phytocon stituents detected qualitatively were Alkaloids, Terpenoides, Flavonoides, Tannins, Reducing sugars and Cynonogenicglycosides.
Biological and Phytochemical Studies on Heartwood of Acacia catechu of Nepal
(Department of Chemistry, 2011) Subedi, Yagya Prasad
Biological and Phytochemical screening of heartwood of Acacia catechu was studied. Phytocostituents found were Sterols, Flavones Aglycones, Tannins and Polyphenols. The column chromatography of diethyl ether fractions result in the isolation of β-Sitosterol (Ac1), Quercetin (Ac4), (+) Catechin (Ac6). Other four compounds Ac2, Ac3, Ac5, Ac7 whose work is on progress, were also isolated. Antibacterial screening, antifungal screening and brine shrimp bioassay of different fractions showed that hexane, chloroform, diethyl ether, ethyl acetate and methanol fraction were biologically active. In brine shrimp bioassay only diethyl ether, ethyl acetate, and methanol fraction showed activity.
Biological Studies of Some Selected Medicinal Plants from Kathmandu Valley and Isolation of Chemical Compounds
(Department of Chemestry, 2021) Kapali, Junu
The aim of this study is to investigate the phytochemical and biological properties of some selected medicinal plants from Kathmandu valley and isolation of phytoconstituents from active plant extract. The methanolic extracts of Ageratina Adenophora, Cupressus sempervirens and Lantana camara aerial parts were analyzed for their phytochemical analysis, toxicity test, antioxidant activity, total phenolic and total flavonoid content, antidiabetic properties and isolation of chemical constituents from active plant fraction and FTIR analysis. The toxicity test was studied by brine shrimp lethality test. The antioxidant potential was evaluated by DPPH radical scavenging assay. The amount of total phenolic and flavonoid was estimated with the Folin-Ciocalteu reagent and aluminium chloride method, respectively. The α amylase enzyme inhibition activity was performed to evaluate the inhibition percentage for each extract. The phytochemical analysis showed the presence of various secondary metabolites like alkaloids, flavonoids, carotenoids, coumarins, glycosides, polyphenol, carbohydrate, saponin, tannins, terpenoids, quinones, and volatile oil & fats. The methanolic extracts of Ageratina adenophora was found to be cytotoxic against brine shrimp as shown by its LC50 value of 833.68 µg/mL. The methanolic extracts of Lantana camara (106.179 ± 11.390 µg/mL) showed the strongest DPPH radical scavenging activity as its IC50 values were close to standard ascorbic acid (17.456 ± 0.822 µg/mL). Lantana camara showed the highest phenolic (10.2 ± 0.343 mg GAE/g) and flavonoid content (1.872 ± 0.16 mg QE/g) respectively. In addition, Ageratina adenophora methanolic extracts were found to inhibit enzymatic activity of α-amylase under in-vitro starch digestion bioassay with the IC50 value of 1.843 ± 0.007 mg/mL. The FTIR measurement revealed the presence of C=O, O-H and C-H stretching bands at the functional group region. Keywords: Phytochemical, antioxidant, phenolic, flavonoid, antidiabetic, αamylase.