http://ir.haramaya.edu.et//hru/handle/123456789/115 Thu, 23 Apr 2026 14:40:20 GMT 2026-04-23T14:40:20Z http://ir.haramaya.edu.et//hru/handle/123456789/8146 Salvia tilifolia LEAF EXTRACT-BASED SILVER NANOPARTICLES FOR COLORIMETRIC DETECTION OF Hg(II) IN SELECTED FOOD, COSMETICS, AND ENVIRONMENTAL SAMPLES Lencho Mume Ahmed; (PhD) Meseret Amde; (PhD) Deribachew Bekana In the present research, we report easy, quick, ultrasensitive, inexpensive, and eco-friendly colorimetric sensor using green synthesized silver nanoparticles (AgNPs). The AgNPs were biosynthesized utilizing Salvia tilifolia leaf extract and well characterized by various techniques, and then employed to design a colorimetric assay for Hg(II) sensing in food, cosmetics, and environmental samples. The developed colorimetric sensor found very sensitive and specific for Hg(II) detecction with limits of detection down to 5.0 nM and 0.27 nM through the naked eye and UV-vis spectrometer detection, respectively. In addition, the method showed good precision (intra- and inter-day RSD values of 2.4% and 4.9%, respectively) with linearity of R2 = 0.9984 over the 0.1–100 μM interval. Furthermore, the proposed AgNPs-based colorimetric sensors has been succesfully tested for sensing Hg(II) in a variety of real samples, including wastewater effluent, lake water, drinking water, soft drinks, mineral water, beauty cream, and canned light tuna. The percent recovery of the tested samples varied from 86.9 to 110%, demonstrating the method's real world application. In summary, the proposed method is greener, selective and highly sensitive, and recommended for detecting Hg(II) in food, cosmetics, and environmental samples 72p. Sat, 01 Jun 2024 00:00:00 GMT http://ir.haramaya.edu.et//hru/handle/123456789/8146 2024-06-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/7381 Synthesis and Characterization of Zeolite-A from Kombolcha Kaolin by Hydrothermal Method for the Removal of Mg2+and Ca2+ from Aqueous Solution Yohannes Dassie Eshete; Ephirem Taddesse (PhD); Endale Teju (PhD) Zeolite-A is one of the most important synthetic Zeolites especially in water softening with high ion exchange ability due to its low Si/Al ratio. In this study, Zeolite-A was synthesized using a hydrothermal method from Kombolcha kaolin, and its adsorptive removal efficiency for Ca2+ and Mg2+ was investigated. The material prepared as such was characterized using different instruments including XRD, SEM, FTIR, and TGA. The Powder X-ray diffraction (XRD) patterns clearly show the presence of the characteristic 2�� peaks (12.32 and 24.92°) of kaolin. X-ray diffraction measurements 2�� peaks (7.18, 10.16, 12.44, 16.12, 21.68, 24.02, 26.14, 27.16, 30.00, 32.56, and 34.22°) and scanning electron micrographs clearly show the morphology of Zeolite-A. Characteristic OH, Al-OH, Si-OH, and Si-O-Al bands were confirmed in samples with Infrared spectroscopy studies. The thermal analysis indicated that the kaolin sample undergo de-hydroxylation from 563.73℃ to about 700 ℃ and converted to metakaolin. The potential of the material to remove Ca2+ and Mg2+ ions from water sample was evaluated using EDTA titration. Batch adsorption experiments demonstrated that solution pH, the adsorbent dose, contact time, initial concentration, and temperature have significant effects on Ca2+ and Mg2+ ions removal. Using the optimized experimental parameters, removal percentages 98.27 for Ca2+ and 97.12 for Mg2+ were obtained at pH 10, contact time 30 min, initial concentration 250 mg/L, and adsorbent dose of 0.5 g. In the Freundlich isotherm model, R2 values for Ca2+ and Mg2+ adsorption were found to be 0.9992 and 0.9985, respectively. The obtained highest R2 values for the Freundlich isotherm are approximately equal to unity that confirms the experimental data is well-fitted to the model and pseudo-second-order kinetic model, which suggests that the applicability of the model to the adsorption of Ca2+ and Mg2+ by Zeolite-A. Based on this study, it can be concluded that zeolite-A was successfully synthesized from Kombolcha kaolin by using a hydrothermal method and the results obtained showed that it can be used as an effective adsorbent for the removal of Ca2+ and Mg2+ ions from aqueous solution 82 Wed, 01 Nov 2023 00:00:00 GMT http://ir.haramaya.edu.et//hru/handle/123456789/7381 2023-11-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/7380 SYNTHESIS AND CHARACTERIZATION OF ZEOLITE-A FROM KOMBOLCHA KAOLIN BY HYDROTHERMAL METHOD FOR THE REMOVAL OF Mg2+AND Ca2+ FROM AQUEOUS SOLUTION Yohannes Dassie Eshete; Ephirem Taddesse (PhD); Endale Teju (PhD) Zeolite-A is one of the most important synthetic Zeolites especially in water softening with high ion exchange ability due to its low Si/Al ratio. In this study, Zeolite-A was synthesized using a hydrothermal method from Kombolcha kaolin, and its adsorptive removal efficiency for Ca2+ and Mg2+ was investigated. The material prepared as such was characterized using different instruments including XRD, SEM, FTIR, and TGA. The Powder X-ray diffraction (XRD) patterns clearly show the presence of the characteristic 2�� peaks (12.32 and 24.92°) of kaolin. X-ray diffraction measurements 2�� peaks (7.18, 10.16, 12.44, 16.12, 21.68, 24.02, 26.14, 27.16, 30.00, 32.56, and 34.22°) and scanning electron micrographs clearly show the morphology of Zeolite-A. Characteristic OH, Al-OH, Si-OH, and Si-O-Al bands were confirmed in samples with Infrared spectroscopy studies. The thermal analysis indicated that the kaolin sample undergo de-hydroxylation from 563.73℃ to about 700 ℃ and converted to metakaolin. The potential of the material to remove Ca2+ and Mg2+ ions from water sample was evaluated using EDTA titration. Batch adsorption experiments demonstrated that solution pH, the adsorbent dose, contact time, initial concentration, and temperature have significant effects on Ca2+ and Mg2+ ions removal. Using the optimized experimental parameters, removal percentages 98.27 for Ca2+ and 97.12 for Mg2+ were obtained at pH 10, contact time 30 min, initial concentration 250 mg/L, and adsorbent dose of 0.5 g. In the Freundlich isotherm model, R2 values for Ca2+ and Mg2+ adsorption were found to be 0.9992 and 0.9985, respectively. The obtained highest R2 values for the Freundlich isotherm are approximately equal to unity that confirms the experimental data is well-fitted to the model and pseudo-second-order kinetic model, which suggests that the applicability of the model to the adsorption of Ca2+ and Mg2+ by Zeolite-A. Based on this study, it can be concluded that zeolite-A was successfully synthesized from Kombolcha kaolin by using a hydrothermal method and the results obtained showed that it can be used as an effective adsorbent for the removal of Ca2+ and Mg2+ ions from aqueous solution. 82 Wed, 01 Nov 2023 00:00:00 GMT http://ir.haramaya.edu.et//hru/handle/123456789/7380 2023-11-01T00:00:00Z http://ir.haramaya.edu.et//hru/handle/123456789/7379 SYNTHESIS, CHARACTERIZATION AND ANTIMICROBIAL ACTIVITY STUDY OF NOVEL SPIRO [INDOLINE-2, 2-PYRROLIDIN] - 3-ONES THROUGH 1, 3-DIPOLAR CYCLOADDITION Kefelegn Demissie Bekele; Muthusaravanan S. (PhD); Neelaiah Babu G. (PhD) Pyrrolidine is a heterocyclic compound which has one nitrogen atom in the five membered ring (C4H9N) with extensive applications in various medical and industrial fields. In this study two pyrrolidine derivatives P1and P2 were synthesized by using intermediate dibenzalacetone (chalcone) react with isatin and sarcosine in multicomponent reaction or dibenzalacetone react with azomethine ylide produce from isatin and sarcosine in [3+2] cycloaddition to get the target compounds namely novel Spiro [indoline-2, 2-pyrrolidin] - 3-ones. Structures of the synthesized compounds were elucidated by using IR, NMR (1H-NMR and 13C-NMR) and LC-MS. All products were assayed in vitro for their antimicrobial activities against Staphylococcus aureus and Escherichia coli bacteria and antifungal activities were also studied against fungi like Aspargillus Niger and Aspergillus versicolla using the paper disc diffusion method. Chloramphenicol and Tilt were used as a reference drug for the antibacterial and antifungal activities, respectively. The compound Spiro [indoline-2, 2’-pyrrolidine]-3-one derivatives (P1)at 75 μg/mL dose than 25 and 50 μg/mL showed a greater ability of inhibition against both tested bacteria specially Staphylococcus aureus than the other compound. In the antifungal activity, the chlorine substituted pyrrolidine derivative, Spiro [indoline-2, 2’-pyrrolidine]-3-one derivatives (P2) at 75 μg/mL dose than 25 and 50 μg/mL revealed good inhibitory activity against the tested fungal species specially Aspargillus Niger. These compounds can be identified as viable leads for further studies. 71 Wed, 01 Nov 2023 00:00:00 GMT http://ir.haramaya.edu.et//hru/handle/123456789/7379 2023-11-01T00:00:00Z