Development of green technology is generating interest of researchers towards ecofriendly and low-cost methods for biosynthesis of nanoparticles (NPs). In this study, copper oxide (CuO) NPs were synthesized using a copper nitrate trihydrate precursor and Catha edulis leaves extract as a reducing and capping agent during the synthesis. The biosynthesized CuO NPs were characterized using an X-ray diffractometer (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscope (TEM), Ultraviolet visible spectroscopy (UV-Vis), and Fourier transform infrared (FTIR) spectroscopy. XRD characterization confirmed that the biosynthesized CuO NPs possessed a good crystalline nature which perfectly matched the monoclinic structure of bulk CuO. Furthermore, the results obtained from SEM and TEM showed that the biosynthesized CuO NPs were spherical in shape. EDS characterization of the biosynthesized NPs also indicated that the reaction product was composed of highly pure CuO NPs. Moreover, the antimicrobial activities of different concentrations of CuO NPs synthesized using Catha edulis extract were also tested. Accordingly, the result showed that the highest zone of inhibitions measured were for CuO NPs synthesized using 1 : 2 ratios at 40 mg/ml solution concentration and observed to be 22 ± 0.01 mm, 24 ± 0.02 mm, 32 ± 0.02 mm, and 29 ± 0.03 mm for S. aureus, S. pyogenes, E. coli, and K. pneumonia, respectively.

Currently, plant templated synthesis of magnetite iron oxide nanoparticles (Fe3O4 NPs) was emerged for multifunctional purposes. In this study, the leaf extract of the plant Thymus schimperi was utilized to synthesize Fe3O4 NPs. The synthesized NPs were characterized by using technical tools such as X-ray diffraction (XRD) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis, and ultraviolet-visible (UV-Vis) spectroscopy, and thermal analysis (TGA-DTA). The XRD result corroborated the presence of desired phase formation having pure cubic face centered phase structure with average crystallite particle size ranging from 20 nm to 30 nm. SEM micrographs confirmed microstructural homogeneities and remarkably different morphology of Fe3O4 NPs. Mercury (II) and chromium (VI) removal efficiencies of Fe3O4 NPs were found to be 90% and 86% from aqueous solution at initial concentration of 20 mg/L, respectively. Various factors which affect the metal ion removal efficiency such as metal ion initial concentrations, pH, contact time, and adsorbent dosage were also studied. The optimum pH and contact time for chromium ion adsorption were pH 5 and 60 min and that of mercury were observed to be pH 7 and 90 min, respectively. The Langmuir isotherm was best fitted for sorption of Hg(II) ion, and the Freundlich isotherm was best fitted with sorption of Cr(VI) ion onto the surface of Fe3O4 NPs. The mechanism of adsorption of both Hg(II) and Cr(VI) ions was obeyed pseudo 2nd order kinetics. The recorded percent removal efficiencies revealed that these Fe3O4 NPs synthesized through leaf extract of the plant called Thymus schimperi have demonstrated excellent potentiality in the remediation of heavy metal ions. The synthesized Fe3O4 NPs were regenerated (reused) for adsorptive removal of Hg(II) and Cr(VI) for five consecutive cycles without significant loss of removal efficiency. Fe3O4 NPs were reused with only 4.17% loss of removal efficiency against Hg(II) and only 3% loss of removal efficiency against Cr(VI) metal ions.

To design and develop integrated waste management systems, it is necessary to have information about the physical and chemical characteristics of the household's municipal solid waste (MSW). The study aims to characterize the physicochemical composition of MSW in Sawla town, Ethiopia using structured questionnaire and field observation to obtain data on the socio-economic condition and current MSW management practices of the residents. The data showed that, the town has no sanitary landfill. The per capita daily SW generation for HH range 0.21-1.02 kg/capita/day with mean value of 0.51 kg/capita/day. Regarding its chemical characteristics, the HHMSW was composed of main food and organic waste (34.81%) and ash-dust (49.45%). The remaining 6.08% of plastic, 3.87% glass, 3.51% of paper and 2.28% of metal waste. The mean percentage moisture content, volatile matter content, ash content and fixed carbon content of the MSW were 25.57%, 28.09%, 32.03%, and 14.32% respectively. The mean density, pH and fusing point of ash for the MSW were 613.22 kg/m3, 10.657 and 965 °C respectively. Using AAS, the concentration of heavy metals Cu, Pb, Zn, Co, Cd, and Cr were determined and the result was 2.59, 7.12, 293.39 and 0.125 mg/kg for Cu, Pb, Zn, and Co respectively. The concentration of Cd and Cr was not detected. In conclusion, the best ways to tackle the problems related to MSWM practices of residents are: improving the institutional structure and budget allocation of the SBD, the involvement of stakeholders in SWM practices, implementation of sustainable SWM practices through awareness creation and training and implementation of rules and regulations. The result of this study suggests that biodegradable SW constituted a lion share of the SW generated in the town. Thus, the municipality can recover this organic fraction by introducing integrated urban agriculture that might convert this waste to organic fertilizer through composting.

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In this work, the effect of DIM on the PCE and photostability of PCDTBT:PC 71 BM PSCs was investigated. DIM is an effective additive in a BHJ PCDTBT:PC 71 BM solar cell since it fulfills the requirement of a selective PC 71 BM dissolution. PCE of the device based on PCDTBT:PC 71 BM processed with DIM is higher than that of the reference device. In terms of the device stability, the PSCs processed with DIM showed poor stability at longer light exposure time. For the device without DIM especially as the light exposure time was increased, the device stability was better because the PCDTBT could be shielded from air by an aggregated PC 71 BM layer. For the PCDTBT:PC 71 BM device processed with DIM, the results obtained from J-V measurement indicates that it has a lower recombination rate. The result from IS measurement shows that for pristine PCDTBT:PC 71 BM devices with 3% DIM, the active layer resistance is lower compared to the device without DIM. However, after irradiating the device for 5 hr, the resistance of the device processed with DIM is higher and it is consistent with decreased PCE of the aged device.