Chemistry

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

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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
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 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.
CORROSION INHIBITION BY ALKALOIDS OF SOLANUM XANTHOCARPUM STEM FOR MILD STEEL IN 1 M H2SO4 SOLUTION
(Amrit Campus, 2023-08-17) THAPA, ONISHA
Alkaloids from Solanum xanthocarpum stem were successfully extracted. Extracted alkaloids were characterized by qualitative chemical tests and spectroscopic measurements. The effectiveness of the inhibitor was determined by weight loss and electrochemical measurement methods. From the weight loss measurement, maximum inhibition efficiency of 93.14% was achieved. The temperature effect study reveals that the inhibitor can work up to a temperature of 58 C. Electrochemical measurement reveals that alkaloids could inhibit effectively up to 98.14% and serve as a mixed type of inhibitor. A study on kinetic parameters reflects that the inhibitor forms a potential barrier to protecting the MS. The values obtained from the thermodynamic parameters study reflect that the process is a spontaneous endothermic process.
CORROSION INHIBITION BY SHOREA ROBUSTA (SAAL) BARK EXTRACT FOR MILD STEEL CORROSION IN 1 M H2SO4 SOLUTION
(Amrit Campus, 2023-08-17) BAJGAI, AJAY KUMAR
A novel corrosion inhibitor for mild steel (MS) corrosion has been extracted in methanol solvent from Shorea robusta bark. Qualitative chemical tests, VU, and FTIR measurements were carried out to confirm phytochemicals in the extract. The inhibition efficiency of extract has been studied by using weight loss and potentiodynamic polarization methods. 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 71.47% at ½ hours immersion time in 1000 ppm inhibitor concentration at 18 oC. The 1000 ppm inhibitor can work up to a temperature of 55 oC with 50% efficiency. The open-circuit potential (OCP) measurement reveals the extract as a mixed type of inhibitor. From the potentiodynamic polarization measurement results, the inhibition efficiency of the extract for MS was 93.73% and 75% in the 1000 ppm of inhibitor concentration for as-immersed and immersed conditions respectively. The adsorption isotherm and thermodynamic parameters support that the process is spontaneous and endothermic.
EVALUATION OF CHEMICAL CONSTITUENTS AND BIOLOGICAL PROPERTIES OF EXTRACTS OF LEAVES OF Kalanchoe pinnata (LAM.) PERS FROM RUPANDEHI DISTRICT OF NEPAL
(Amrit Campus, 2023-08-17) BHUSAL, DAKSHINA
The Crassulaceae family includes Kalanchoe pinnata (synonym: Bryophyllum pinnatum), also known as "Pattharchatta" in Nepali. The plant's therapeutic and medical properties contain wound-healing, antioxidant, antiproliferative, antimicrobial, anti allergic, analgesic, nephroprotective, gastroprotective, antidiabetic, antidepressant, sedative, antilithiatic, chemoprotective, antihypertensive and immunosuppressant activities. The current study examined phytochemical screening, GC-MS, UV, FT-IR, total phenolic and flavonoid content. Extracts of K. pinnata were also analyzed for antimicrobial, antioxidant, antidiabetic, cytotoxicity, thin-layer, and column chromatography. The air dried powder of K. pinnata were extracted using seven different solvents: hexane, DCM, chloroform, ethyl acetate, acetone, methanol, and water. The aqueous extract outperformed the other six, yielding 14.50 g, whereas ethyl acetate produced only 0.21 g. Phytochemical screening discovered the presence of flavonoids, phenolic chemicals, terpenoids, tannins, steroids, and carbohydrates. The antioxidant activity was assessed by DPPH free radical scavenging method. The 3,5- dinitrosalicylic acid (DNSA) technique revealed a range of α-amylase inhibition properties. Antimicrobial susceptibility tests were tested against Bacillus subtilis, Escherichia coli, and Candida albicans. All the extracts showed better antimicrobial properties. The quantitative analysis of phytochemicals revealed that the TPC and TFC of the ethyl acetate is higher as comparison to the methanol extract The IC50 values of chloroform, ethyl acetate and methanol extracts were 2219.41 µg/mL, 365.22 µg/mL, and 293.53 µg/mL, respectively, in the antioxidant assay. The IC50 values of acetone, ethyl acetate and methanol extracts were 285.71 µg/mL, 504.21 µg/mL, and 195.39 µg/mL, respectively, in the α-amylase inhibition assay. The LC50 values of chloroform, acetone and methanol extracts were 0.181 mg/mL, 0.175 mg/mL, and 0.29 mg/mL respectively. The best TLC was shown by methanol extract in the Acetone: Hexane solvent system. From the column chromatography, single spot is obtained at 1% Ac: Hex and 5% Ac: Hex. The existence of multiple bonds, aromaticity, conjugation, and unsaturated organic molecules were confirmed through UV-visible spectrophotometer's results. The presence of O-H, C-H, C=O, -CH2, -NO2 and C-O were verified by FT-IR findings.
GC-MS, ANTIBACTERIAL, CYTOTOXICITY AND ESSENTIAL OIL OF (SPRENG. PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE MASTER OF SCIENCE DEGREE IN CHEMISTRY T.U. REGISTRATION NO.: DEPARTMENT OF CHEMISTRY INSTITUTE OF MS, ANTIBACTERIAL, ANTIOXIDANT, TPC, TFC TOXICITY AND FTIR ANALYSIS OF EXTRACTS AND ESSENTIAL OIL OF AGERATINA ADENOPHORA SPRENG.) R.M. KING & H. ROB. FROM PALPA DISTRICT OF NEPAL
(Amrit Campus, 2022-07-10) Thapa, Arjun
Ageratina adenophora (Spreng.) R.M. King & H. Rob. is an important perennial medicinal herb that belongs to the family Asteraceae. It has scented leaves that have historically been used as a medicine. The plants of A. adenophora were collected from the Palpa district and were air-dried. The goal of this study was to look into GC-MS analysis, phytochemical screening, total phenolic content, total flavonoid content, antibacterial and antifungal activity, toxicity, Thin layer chromatography, and column chromatography of A. adenophora extracts and essential oil. Clevenger-type hydro distillation apparatus was used to extract the essential oil. The air-dried powdered plant materials of A. adenophora were extracted with methanol, hexane, chloroform, and ethyl acetate solvents for the extract. Qualitative phytochemical analysis of methanol, hexane, chloroform, and ethyl acetate extracts of A. adenophora plants showed the presence of alkaloids, flavonoids, phenols, steroids, quinones, saponins, tannins, cardiac glycosides, carbohydrate, terpenoids, proteins, and amino acids. The GC-MS study of chloroform extract revealed ten different possible compounds, whereas essential oil revealed fourteen. 1-naphthalenol (24.33%) and α–bisabolol (18.01%) were the most numerous components in the chloroform extract, and 1-napthalenol (24.56%) and α-bisabolol (14.74%) were the most abundant components in the essential oil of A. adenophora. Free radical scavenging activity was evaluated using (DPPH) free radical. The antioxidant activity of essential oil was determined to be 50.24 % at 15 mg/mL of sample solution, while the antioxidant activity of chloroform extract was 62.84 % at 2 mg/mL of sample solution. The IC50 value of essential oil was found to be 17.21 mg/mL whereas that of chloroform extract was found to be 1.46 mg/mL. The TPC content of the essential oil and extract was found to be 53.42 mg gallic acid/g of equivalent and 89.75 mg gallic acid/g of equivalent. The TFC content in essential oil and chloroform extract was found to be 3.372 mg quercetin equivalent/g of dry extract and 49.252 mg quercetin equivalent/g of dry extract respectively. The essential oil, as well as chloroform extract, also showed LC50 values of 64.56 µg/mL and 174.78 µg/mL respectively. Antibacterial activity was shown to E. coli, Proteus vulgaris, and Staphylococcus subsp. aureus in both chloroform extract and essential oil of A. adenophora. There was no evidence of antifungal action. In FTIR analysis of chloroform leaf extracts of A. adenophora studies revealed the presence of these functional groups: 1° amine (N-H), the carboxylic acid (-COOH), alkane (C-H), aldehyde (-CHO). A single spot was seen in the solvent system of ethyl acetate and hexane (5:95), (10:90), (20:80) by the use of column chromatography.
GREEN SYNTHESIS OF BIMETALLIC Cu-Zn NANOFLAKES FROM LEAF EXTRACT OF Magnolia champaca AND STUDY OF ITS ANTI MICROBIAL PROPERTIES
(Amrit Campus, 2023-08-17) PANTHI, GRISHMA
Nanotechnology has created huge impact in modern day pharmaceutical application. With such applicability, research on nanotechnology must be done with new creativity and ideas. Development in field is possible when number of research is carried out. So, this research is focused on green synthesis of nanoflakes both mono (CuO and ZnO) and bi (Cu-Zn alloy) metallic nanflakes using plant extract of Magnolia champaca (leaf) as reducing and capping agents, which inhibits aggregation and coagulation of metal nanoflakes. The formed bimetallic nanoflakes (CuZn) were light green in colour where as CuO was black and ZnO were white in colour. Synthesized nanoflakes were characterized using FTIR, UV, XRD, FESEM. Simultaneously, compared their anti-bacterial and antifungal properties to expand knowledge regarding which of them are more effective. Cu-Zn alloy nanoflakes shows high resistivity toward gram +ve bacteria while CuO nanoflakes shows resistivity against gram –ve and fungus and among them ZnO has lower resistivity. Phytochemical screening of Magnolia champaca leaf is done to know the biomolecules which involved in reduction.
GREEN SYNTHESIS OF SILVER/ZINC OXIDE NANOCOMPOSITES USING LEAF EXTRACT OF DESMOSTACHYA BIPINNATA (KUSH) AND STUDY OF ITS PHOTOCATALYTIC ACTIVITIES
(Amrit Campus, 2024-10-28) Anita Bhattarai; Ramesh
Removing organic pollutants including textile waste solution and dyes has become an essential requirement for maintaining a secure and healthy environment. Therefore, the present study deals with the synthesis of ZnO and Ag/ZnO nanocomposites using the leaf extract of Desmostachya bipinnata. The leaf extract of Desmostachya bipinnata contained a different bio-active compound that serves the dual purpose of acting as stabilizing and reducing agents. Out of various methods, green synthesis has been extensively employed for its simplicity, low-cost, and eco-friendly nature. The characterization of the as-synthesized ZnO and Ag/ZnO nanocomposties were subjected to ultra violet visible (UV-vis) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD). XRD pattern revealed the crystalline nature of nanoparticles. The crystallite size of Ag/ZnO was found to be 12-14 nm, according to Debye Scherer formula. The synthesized NPs and NCs were used for the catalytic photodegradation of Methylene blue (MB). The MB was degraded at room temperature under exposure to UV light. The degradation efficiency of ZnO, and 25 % Ag/ZnO were found to be 79 % and 85 %, respectively. Therefore, it was found that Ag/ZnO nanocomposites have potential to degrade MB as organic dye, and can be used for wastewater treatment.
PHYTOCHEMICAL SCREENING, GC-MS ANALYSIS, ANTIBACTERIAL, ANTIOXIDANT, TPC, TFC, AND CYTOTOXICITY ANALYSIS OF EXTRACTS AND ESSENTIAL OIL OF AEGLE MARMELOS (L.) CORREA
(Amrit Campus, 2022-07-17) Karki, Homa
Aegle marmelos (L.) Correa (Rutaceae family), also known as the Bel fruit tree, is a widely distributed plant and is found in Nepal, Bangladesh, India, China, Sri Lanka, Myanmar, Pakistan, etc. The objective of the present study is to evaluate the phytochemicals and bio-activities of extracts and essential oil of A. marmelos. The A. marmelos leaves were successively extracted using methanol, hexane, and chloroform organic solvents. Qualitative phytochemical analysis of methanol and chloroform extracts of A. marmelosleaves confirmed the presence of alkaloids, saponins, glycosides, phenols, flavonoids, protein, and tannin. GC MS analysis of crude chloroform extract showed 9 different major compounds among which Limonene dioxide (27.78 %) and Germacrene B (20.65 %) were the most abundant. The IC50 value of the chloroform extract against DPPH was found to be 308.21 μg/mL. The result showed that the total phenolic and flavonoid content in A. marmelos leaves with the value 58.36 mg gallic acid equivalent and 142.29 mg quercetin equivalent/g of dry extract respectively. The extract also exhibited higher toxicity against brine shrimp with the LC50 value of 157.50 μg/mL. The essential oil by hydrodistillation was analyzed by GC-MS for its composition and exhibited the presence of 12 different compounds. The most abundant were Limonene (25.06 %) and Germacrene B (18.63 %). Antibacterial activity was performed against six bacterial species and Bacillus subtilis was susceptible to the essential oil showing zone of inhibition (ZOI) 7 mm. The IC50 value of the essential oil against DPPH was found to be 13.63 mg/mL. The total phenolic content and flavonoid content in the essential oil of A. marmelos leaves were found to be 10.65 mg gallic acid equivalent and 3.27 mg quercetin equivalent/g of essential oil respectively. The toxicity of essential oil of A. marmelos tested by brine shrimp lethality (LC50) was found to be 58.17 μg/mL.
PREPARATION AND CHARACTERIZATION OF Shorea robusta (SAAL) BARK BASED ACTIVATED CARBON AND STUDY OF ITS ELECTROCHEMICAL PERFORMANCE
(Amrit Campus, 2023-08-17) JOSHI, KULDIP
In this work, activated carbon (AC) was prepared in the laboratory using Shorea robusta (Saal) bark by charring with conc. sulphuric acid followed by phosphoric acid activation with different ratios of precursor to an activating agent at a different temperature on a fixed time. As-prepared activated carbon was characterized by methylene blue number (MBN) and Iodine number (IN) method. The methylene blue number was found to be 193.8802 mg/g whereas iodine number was found to be 2108.2 mg/g. AC-15 at 600 °C for 3 hours had the highest value of methylene blue number which indicated the presence of micropore as well as mesopore in the prepared material. The phase state of the sample was determined by X-ray diffraction (XRD) technique which indicates a predominantly amorphous nature of the prepared material. The surface functionality of the sample was examined by Fourier Transform Infrared Spectroscopy (FTIR) which showed the presence of O-H, aromatic C C, C-O, and aromatic compounds. Further electrochemical characterization of prepared materials AC-400 and AC-500 were carried out by cyclic voltammetry at a scan rate of 3 mV/s. Specific capacitance of the as-synthesized material was calculated from the measurement of absolute area of cyclic voltammetry curve. The specific capacitance recorded in this work is 76.67 Farad/g. This value shows that AC-500 could be used for electrical double-layer capacitor (EDLC) applications.
PREPARATION AND CHARACTERIZATION OF SHOREA ROBUSTA BARK BASED BIOSORBENT FOR THE REMOVAL OF Cr(VI) IN DRINKING WATER
(Amrit Campus, 2023-08-17) REGMI, POOJA
Activated carbons have been used in the removal of heavy metal. High surface area and porosity of activated carbon materials support in the removal of heavy metal ions. In this work, biochar has been synthesized from Shorea robusta bark. Excellent removal efficiency from methylene blue and iodine number can be seen in S. robusta treated with Zinc chloride. Due to the pHzpc of activated carbon and biochar having 6.16 and 4.62, respectively, this sorbent may effectively remove cationic Cr(VI) contaminants from alkaline aqueous solutions. Using the batch adsorption approach, the adsorption of Cr(VI) ions on biochar and chemically modified biochar of S. robusta has been examined in this study. The outcome demonstrates that all the factors that affected the removal of Cr(VI) by adsorption were discovered at pH 2, starting concentration of 50 ppm, equilibrium period of 120 minutes, and adsorbent dose of 50 mg. Kinetic data are presented after the pseudo second order kinetic model. By using FTIR and XRD, sample characteristics was examined. The experimental findings suggest that S. robusta can be used as a low-cost commercial alternative adsorbent to remove Cr(VI) from wastewater
SYNTHESIS, CHARACTERIZATION AND EVALUATION OF ANTIMICROBIAL ACTIVITIES AND CYTOTOXICITY OF SOME NEW 1,2,4-TRIAZOLE DERIVATIVES CONTAINING 2-SUBSTITUTED BENZIMIDAZOLE
(Amrit Campus, 2023-08-17) ARYAL, PRATEEK
The development of a potent new drug with high biological activity is a challenge in drug design and is of strategic importance. Due to the increasing resistance of pathogens on the existing drugs there is always a need for the development of a potent drug with high biological activity. The pharmacological effects are seen in compounds with the presence of different moieties of pharmaceutical importance such as triazole, Schiff’s base, benzimidazole as described in the chemical literature. By applying different synthetic reactions in a convergent pattern, two new compounds have been prepared with three pharmacophores viz. triazole, benzimidazole and Schiff base incorporated in a single compound. The structure of the prepared compounds was confirmed by different spectroscopic techniques like, FT-IR, UV-VIS, 1H-NMR, and 13C-NMR. The progress of the reaction was monitored by TLC and determination of melting point. All compounds exhibited moderate antibacterial activity against Staphylococcus aureus (ATCC 6538P) and Staphylococcus epidermidis (ATCC 1228). Antioxidant activity was carried out by DPPH radical scavenging test and among the tested five compounds, the IC50 value of 4-amino-2- (2-hydroxyphenyl)-1H-1,2,4-triazole-5-thione was found to be 32.364 μgmL-1 which is closer to the ascorbic acid sample that was found to be 28.546 μgmL-1. All tested compounds were toxic against brine shrimp where 5-((1H-benzo[d]imidazol-2-yl)thio)-4-((4- chlorobenzylidene) amino)-4H-1,2,4-triazol-3-yl) (2-hydroxyphenyl) methanone was comparatively more toxic (LC50= 26.827 μgmL-1)
SYNTHESIS, CHARACTERIZATION AND EVALUATION OF ANTIMICROBIAL ACTIVITY...................
(Amrit Campus, 2023-08-17) Joshi, Madhav Prasad
SYNTHESIS, CHARACTERIZATION AND STUDY OF BIOLOGICAL ACTIVITIES OF MANNICH BASES DERIVED FROM 4-(FURAN-2-YL-METHYLENEAMINO)-3-(2- HYDROXYPHENYL)-1H-1,2,4-TRIAZOLE-5-THIONE
(Amrit Campus, 2022-07-15) Deo, Prem Shankar
Triazole nucleus has been studied a lot since the last decade because of its various potent biological activities. The pharmacological application of triazoles has been widely recognized and well documented. Allocating various biological activities of triazole derivative in one place has been the milestone for new research towards this moiety. Triazole derivatives such as Schiff bases have been introduced as the potent bioactive compound. They possess various biological activities and are mostly derived from the triazole nucleus via condensation of primary amino compounds with aldehyde or ketone. However, there is not much documentation about the Mannich bases as their study has begun lately. Mannich bases are the β−aminoketone which are generally formed when amine, aldehyde and carbon acid reacts. Mannich bases have shown multiple biological activities such as antibacterial, antifungal, antiviral, anticancer, etc. Schiff base (4) was converted into thione based Mannich bases (5a and 5b) by reaction with diphenylamine/piperazine in presence of formaldehyde in ethanol. These newly synthesized thione based Mannich bases were characterized by elemental analysis such as UV, FT-IR, 1 H-NMR and 13C-NMR. These Mannich bases were also tested against several bacterial and fungal strains. Mannich bases containing Piperazine moiety (5b) showed better antifungal property than Mannich bases with diphenylamine moiety (5a) whereas 5a showed better antibacterial activity than 5b.

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