Departments of Chemistry
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Item GREEN SYNTHESIS OF CO3O4/POLYANILINE NANOCOMPOSITES USING VERNONIA AMYGDALINA LEAF EXTRACT FOR PHOTOCATALYTIC DEGRADATION OF METHYLENE BLUE AND CONGO RED UNDER SOLAR IRRADIATION(HAWASSA UNIVERSITY, 2024-11) BEZABIH KASAHUN KAYIMOPANI, Co3O4 NPs, and Co3O4/PANI nanocomposites were successfully synthesized using a green synthesis method and applied for the photocatalytic degradation of Methylene blue (MB) and Congo red (CR). The synthesized materials were characterized using analytical techniques such as XRD, FT-IR, UV-Visible, and SEM. The FT-IR spectra of VA showed that the wavenumber absorption at 3470 cm-1 represented the hydroxyl (-OH) group, while at 2931 cm-1 characterized the C-H absorption. The peak observed at 1631 and 1402 cm−1 indicates C = C stretching and O-H bending of carboxylic acid, respectively. The band at 1173 cm−1 corresponds to the C-O stretching of an aromatic ester. The prominent absorption bands at 555 cm-1 and 648 cm-1 , attributed to the stretching vibrations of the metal-oxygen bond corresponding to (Co3+ - O) and (Co2+ - O) vibrations, respectively in NPs. A peak at 1628 cm-1 and 1401 cm-1 shows C=C, and C–N stretching vibration respectively. The characteristic band formed at 3368cm -1 corresponding to N–H stretching vibration of secondary amine and for pure PANI, The peak at 1622 cm−1 , 1404cm-1 is due to the C= C stretching vibration of the quinoid rings ((N=Q=N)) and benzenoid ring (N-B-N) respectively. Band at 1118 cm−1 is due to the C−N stretching of a secondary aromatic amine. XRD patterns revealed the crystalline sizes of the materials, with average particle sizes 19.25nm, 8.24nm, 11.03 for Co3O4 NPs, PANI powder, and NCs respectively. Morphological investigations indicated unique structures for each material. UVVisible spectra provided band gap energy values for the synthesized materials (1.69 and 3.93 for Co3O4 NPs; 1.57, 3.1 and 4.12 for PANI: 3.26, 3.80 and 5.3 for NCs). The photocatalytic degradation study demonstrated that Co3O4 NPs and Co3O4/PANI NCs efficiently degraded MB and CR under natural sunlight irradiation. The degradation efficiency was influenced by catalyst dose, initial concentration, pH, and exposure time. Maximum degradation percentages were achieved under optimized conditions for both dyes (93.69% in Co3O4/PANI NCS and 90.79% in Co3O4 NPs for CR and 91.66% in Co3O4/PANI NCs and 89.60% in Co3O4 NPs for MB). Co3O4/PANI NCs exhibited higher degradation efficiency than Co3O4 NPs due to interactions between inorganic semiconductors and conducting polymers. Kinetic studies revealed that MB followed pseudo zero-order kinetics, while CR degradation followed pseudo first-order kinetics with the R2 = 0.993 and 0.992 respectivelyItem MICROBIAL FUEL CELL WITH GREEN SYNTHESIZED CuO BASED POLYANILINE COMPOSITE AS EFFICIENT BIOANODE MODIFIER CATALYST(HAWASSA UNIVERSITY, 2024-05) BETELEHEM GUTAMicrobial fuel cell is a new technology device that converts chemical energy stored in organic waste into electrical energy by using microorganisms as a catalyst with simultaneous waste water treatment. In this study, low-cost phyto-synthesized CuO nanoparticles integrate with conducting polyaniline (PANI) matrix to form CuO/PANI hybrid nanocomposite was synthesized by in situ polymerization methods and PANI was synthesized by oxidative polymerization method. The synthesized sample were characterized through UV-Vis spectroscopy, FTIR, SEM, and XRD, instruments to examine their optical properties, intermolecular bonding and the existence of functional groups, morphology and crystalline structural respectively. Four single chambered microbial fuel cells (MFCs) was constructed with bare pencil graphite anode, pencil graphite anode modified with CuO, PANI, CuO/PANI nanocomposites and PGEs cathode for all four devices. The average crystalline size for CuO NPs, PANI and CuO/PANI NCs was 28.05 nm, 3.2 nm and 20.6 nm respectively. It was found that the maximum open circuit voltage (OCV) obtained by bare PGE, CuO/ PGE,PANI/PGE and CuO/PANI/PGE was 229 ± 11.3 mV, 315 ± 35.3 mV, 485± 15.5 mV, and 630 ± 10.6 mV respectively. The maximum power density and corresponding current density obtained by CuO/PGE, and PANI/PGE have a value 265.75 mWm−2 & 2134.34 mA m−2 and 387.91 mWm−2 & 2418.06 mAm−2 respectively. A maximum of 416.01 mWm-2 , and 2429.56 mAm-2 power density at corresponding current densities was produced by CuO/PANI/PGE respectively. This was 6.3and 4-fold higher in power and current densities than unmodified PGE have values of 65.67 mWm-2 and 580.21 mAm-2 . From above results modifying anode of MFC with CuO nanoparticles based PANI composite gives a better output as compared with bare PGE in the MFC energy conversion systemItem GREEN SYNTHESIS OF COPPER OXIDE NANOPARTICLE US SOLANECIO GIGAS LEAF EXTRACT ( YESHKOKO-GOMEN) AND APPLICATION IN CATALYTIC DEGRADATION OF CRYSTAL VIOLATE(HAWASSA UNIVERSITY, 2025-03) ZEHERIYA JATORO AREBOMetal nanoparticles have enhanced much consideration in the field of organic catalysis and catalytic reactions due to the toxicological problems caused by organic dyes to the environment and human health. In the current study, CuO nanoparticle was synthesized through green method using Solanecio gigas leaf extract and, then evaluated for its catalytic degradation activity. The synthesized CuO nanoparticle was confirmed through visual inspection of colour changes and characterized by using UV-Vis, FT-IR, XRD and SEM techniques. From XRD data, the particle sizes of the synthesized CuO nanoparticle were calculated and found to be 38.91nm and appears to be more crystalline in nature. UV-vis analysis of CuO nanoparticles showed continuous absorption in the visible range. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed the presence of several functional groups, particularly hydroxyl, present in the extracts, which may be responsible for capping of nanoparticles. SEM micrographs showed a combination of different shaped and grain size CuO nanoparticle. From the catalytic degradation study, it is possible to conclude that this green route synthesized CuO nanoparticles have high efficiency to degrade Crystal violet. In the degradation of Crystal violet by CuO nanoparticle, maximum degradation efficiency was 90.57% under optimum condition (catalyst dose 0.08 gram, initial concentration 9 ppm, sodium borohydride 0.10 M, reaction time 20 min and pH of 6) The pseudo kinetic study indicates catalytic degradation of Crystal violate in the surface of CuO nanoparticle follows pseudo- zero-order kinetics. The results from this study illustrate that green synthesized CuO nanoparticles offer a cost-effective, environmentally friendly and efficient means for catalytic degradation of dyes.Item GREEN SYNTHESIS OF CO3O4/POLYANILINE NANOCOMPOSITES USING VERNONIA AMYGDALINA LEAF EXTRACT FOR PHOTOCATALYTIC DEGRADATION OF METHYLENE BLUE AND CONGO RED UNDER SOLAR IRRADIATION(Hawassa University, 2024-11) BEZABIH KASAHUN KAYIMOPANI, Co3O4 NPs, and Co3O4/PANI nanocomposites were successfully synthesized using a green synthesis method and applied for the photocatalytic degradation of Methylene blue (MB) and Congo red (CR). The synthesized materials were characterized using analytical techniques such as XRD, FT-IR, UV-Visible, and SEM. The FT-IR spectra of VA showed that the wavenumber absorption at 3470 cm-1 represented the hydroxyl (-OH) group, while at 2931 cm-1 characterized the C-H absorption. The peak observed at 1631 and 1402 cm−1 indicates C = C stretching and O-H bending of carboxylic acid, respectively. The band at 1173 cm−1 corresponds to the C-O stretching of an aromatic ester. The prominent absorption bands at 555 cm-1 and 648 cm-1, attributed to the stretching vibrations of the metal-oxygen bond corresponding to (Co3+ - O) and (Co2+- O) vibrations, respectively in NPs. A peak at 1628 cm-1 and 1401 cm-1 shows C=C, and C–N stretching vibration respectively. The characteristic band formed at 3368cm-1 corresponding to N–H stretching vibration of secondary amine and for pure PANI, The peak at 1622 cm−1 , 1404cm-1 is due to the C= C stretching vibration of the quinoid rings ((N=Q=N)) and benzenoid ring (N-B-N) respectively. Band at 1118 cm−1 is due to the C−N stretching of a secondary aromatic amine. XRD patterns revealed the crystalline sizes of the materials, with average particle sizes 19.25nm, 8.24nm, 11.03 for Co3O4 NPs, PANI powder, and NCs respectively. Morphological investigations indicated unique structures for each material. UV Visible spectra provided band gap energy values for the synthesized materials (1.69 and 3.93 for Co3O4 NPs; 1.57, 3.1 and 4.12 for PANI: 3.26, 3.80 and 5.3 for NCs). The photocatalytic degradation study demonstrated that Co3O4 NPs and Co3O4/PANI NCs efficiently degraded MB and CR under natural sunlight irradiation. The degradation efficiency was influenced by catalyst dose, initial concentration, pH, and exposure time. Maximum degradation percentages were achieved under optimized conditions for both dyes (93.69% in Co3O4/PANI NCS and 90.79% in Co3O4 NPs for CR and 91.66% in Co3O4/PANI NCs and 89.60% in Co3O4 NPs for MB). Co3O4/PANI NCs exhibited higher degradation efficiency than Co3O4 NPs due to interactions between inorganic semiconductors and conducting polymers. Kinetic studies revealed that MB followed pseudo zero-order kinetics, while CR degradation followed pseudo first-order kinetics with the R2 = 0.993 and 0.992 respectively.