Chemistry

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

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Browsing Chemistry by Subject "Adsorption"

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    Status of arsenic contamination in the groundwater of nawalparasi west district and Remediation Using ZnCL2 Activated sugarcane bagasse as bioadsorbent
    (2024-06) Ghimire, Khag Raj; : Dr. Bhoj Raj Poudel
    Groundwater sources contaminated by arsenic represent a global threat to the environment and living organisms, including humans. Exposure to arsenic for a long period would have a severe health impact. Various conventional techniques are being applied to treat arsenic contaminated water, which are either expensive or less efficient. So, there is a need to develop cost-effective alternative technologies for the removal of arsenic. This research will investigate the possibility of using agro-waste like sugarcane bagasse as a readily available, affordable, eco-friendly bioadsorbent for remediation of toxic pollutants from water. The main target of this study is to develop a novel adsorbent from sugarcane bagasse by ZnCl2 activation. As it is reported that Nawalparasi West district in Lumbini Province has a high concentration of arsenic in ground water, the performance of bio-adsorbent will be examined by 30 different samples from arsenic contaminated area of Nawalparasi. The material which will be developed in this research from sugarcane bagasse is supposed to be efficient and selective for specified arsenic. The batch experiment will be carried out under varying experimental conditions. The kinetics of the adsorption reaction and the adsorption isotherm will be studied. The experimental results will be applied to the treatment of ground water samples from Ramgram municipality, Nawalparasi west district.
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    Studies on the Development of Natural Cation Exchanger for Heavy Metals Removal
    (Faculty of Chemistry, 2012) Homagai, Puspa Lal
    Two types of novel bioadsorbents such as charred xanthated sugarcane bagasse (CXSB) and charred aminated sugarcane bagasse (CASB)are investigated. This research work elucidates the uptake performance of biosorbent for the sequestration of heavy metal ions such as Cd ,Pb 2+ , Cu 2+ , Ni 2+ and Zn 2+ , respectively. Xanthated and aminated biosorbent prepared from sugarcane bagasse under specific experimental conditions were characterized with FT-IR,TGA/DTA, SEM, Zeta potential and Elemental analysis. Batch adsorption experiments were performed at eight different initial metal ionconcentrations (25, 50,100, 200, 400, 600, 800, 1000 mg/L), at 293 K temperature, while pH of the solutions was varied from 1 to 7. The results indicated that the uptake performance of CXSB and CASB biosorbent significantly changed with pH, concentration of metal ions and temperature. The selectivity order in the removal of heavy metals at pH around 4 follows theorder Pb> Cu > Ni > Cd >Zn for CXSB whereas the order Pb> Cd > Zn > Ni >Cu for CASB. Moreover Irwing-Williams Series support the bindings’mechanism for Cu ,Zn 2+ and Ni 2+ ions ontoboth the modified biopolymers. Adsorption of heavy metal ions onto both CXSB and CASB biosobents followed pseudo-second order kinetics with faster adsorption within 15 minutes to 40 minutes.All the obtaineddatawell followed the Langmuiradsorption isotherm.The positive value of enthalpy change (H) and negative of free energy change (G) shows the adsorption process is endothermic and spontaneous. Moreover, the obtained positive entropy changes (S) shows that an increase in randomness, is associated with the adsorption of metal ions onto the CXSB and CASB biosorbents. As in the case of plastic materials like commercial synthetic cation exchanger, the CXSB and CASB based on sugarcane bagasse developed in our laboratory revealed to be an efficientcation exchanger for removing cadmium, lead, copper, nickel and zinc ions from the aqueoussolution. Keywords:Adsorption, xanthation, amination, heavy metals, sugarcane bassage.
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    Studies on the Potential Application of Bio-Waste for Heavy Metals Removal from Aqueous Solution
    (Department of Chemistry, 2014-10) Shrestha Raghubanshi, Bindra
    An efficient and effective biosorbents were investigated by using waste tealeaves. It was prepared by amination with three different aminating reagents to introduce amino groups onto the surface of biosorbent. The biosorbent was animated by using ethylenediamine, dimethylamine and hydrazine monohydrate. They are called CATL-1, CATL-2 and CATL-3, respectively. The prepared biosorbents were characterized with elemental analysis, analysis of cellulose, hemicelluloses and lignin, SEM images, FTIR spectra, XRD analysis, TG/DTA analysis and zeta potential analysis. These aminated biosorbents were used for sequestration of heavy metals like lead, copper, cadmium and zinc. Their metal uptake performance were also elucidated by using batch experiments. The adsorption capacities of biosorbents were studied as the function of solution pH, initial concentration of metal ions and contact time of adsorption. The effect of pH on adsorption were studied by varying the solution pH from 1-7. The results indicated that the uptake performance of biosorbents significantly change with pH of solution and optimum pH for adsorption was also determined. The initial concentration of metal ions varying from 25-800 mg/L were used to calculate the optimum loading capacity of biosorbents. The optimum time for adsorption were determined by contacting the adsorbent with metal solution at different interval of time. The experimental data were found to be well fitted with langmuir isotherm model. From the isotherm plots the maximum adsorption capacities for lead was found to be highest for all of the three adsorbents while the values were lowest for zinc. Among the three biosorbents, CATL-3 is found to be having highest adsorption capacity for all metal ions used in this study. In CATL-3, the maximum adsorption capacity for Pb (II), Cu (II), Cd (II) and Zn (II) are found to be 120.8, 90.4,114.3 and 79.76 mg/g, respectively. The optimum contact time for metal ions are found to be between 120 - 150 min for all the biosorbents. The kinetic data were well fitted with pseudo - second order model. Hence the biosorbents prepared from waste tealeaves can be potentially applied for treatment of waste water contaminated with toxic heavy metals.
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    Synthesis and Characterization of Hydroxyapatite from Caprine (Goat) Bone for Microbial Adsorption and Antimicrobial Study
    (Department of Chemestry, 2021) Gautam, Bibek
    In this work, natural hydroxyapatite (HAp) was extracted from bio-waste namely caprine (goat) bone by two different methods such as thermal treatment only and chemical method followed by thermal treatment. Thus produced HAp was characterized by different scientific tools like XRD, FTIR and SEM analyses. The specific surface area of HAp was found to be 144.89 m viii 2 /g measured by using methylene blue adsorption method. Similarly, pHPZC value was calculated as 7.2 determined by using pH drift method. Adsorption study of different microorganisms on the extracted HAp as a functions of various parameters like concentration of adsorbate, contact time and adsorbent dose was studied. The maximum adsorption efficiency at pH 7 for Escherichia coli, Candida albicans, Staphylococcus aureus and Acinetobacter baumanii was found to be 32.57 × 10 5 , 37.17 × 10 5 , 6.7 × 10 5 and 43.47 × 10 cfu/mg respectively from Langmuir adsorption isotherm model. The contact time required for maximum adsorption fell within 25 mins. for all microorganisms. The experimental data was best fitted with pseudo-second order kinetics model. HAp showed the antimicrobial activity only upon Acinetobacter baumanii among the studied microorganisms. MIC and MBC values of HAp were found to be 6.25 and 100 mg/mL respectively against Acinetobacter baumanii. Thus, hydroxyapatite was synthesized from bio-waste caprine (goat) bone which can be used as an adsorbent in microbial adsorption and an antimicrobial agent. Keywords: Natural hydroxyapatite, Bio-waste, Adsorption, Microorganisms, Antimicrobial activity