Analysis of the combined effect of long-term heat light soaking and KF/NaF post-deposition treatment on the open-circuit voltage loss in CIGS solar cells

Heat light soaking (HLS) has been known to impact the photovoltaic parameters of Cu(In,Ga)Se2 (CIGS) solar cells for a long time. Recently, the focus shifted to the effect of the procedure on alkali fluoride-treated CIGS. Here, we investigate the impact of long-term HLS on the open-circuit (VOC) loss in high-efficiency CIGS with potassium fluoride (KF) and sodium fluoride (NaF) post-deposition treatment (PDT). HLS is shown to increase the net doping density, however, the subsequent improvement of the VOC is lower than expected. Using an analysis based on the SQ theory, we show that HLS reduces the nonradiative recombination rate in the bulk but increases the one at the interface. We present a model to explain the increase of interface recombination. We further demonstrate that a combination of HLS and KF/NaF-PDT is necessary to enhance the positive impacts of HLS and mitigate the detrimental ones leading to high-efficiency CIGS devices (22%).

A Zero-Waste Process for the Treatment of Spent Potliner (SPL) Waste

This work presents a deep analyses of an environmentally friendly process to recover all valuable minerals contained in the spent potliner (SPL) such as graphite carbon and aluminum fluoride (AlF3) and production of sodium sulfate (Na2SO4) and gypsum (CaSO4) when H2SO4 is used as the leaching agent. The level of emission of hazardous gases such as HCN (weak acid) and HF are minimized by direct scrubbing of the HCN in aqueous AgNO3 solution to produce a stable silver cyanide (AgCN) product. The HF can be recovered as a liquid by condensation and used within the process and/or in production of metal fluorides such as the highly-soluble potassium fluoride (KF); a main source of fluoride in industry. Almost pure CO2 gas is also recovered from the process gas streams.

Investigating Source Identification and Quality of Drinking Water In Piwoyi Community of Federal Capital Territory, Abuja Nigeria.

Water is essential to sustain life, and a satisfactory supply must be readily available to promote health, prolong life expectancy and prevent diseases. This study assesses the sources and quality of drinking water in Piwoyi community of Federal Capital Territory, Abuja, Nigeria. Thirty-five (35) Boreholes and Two (2) Sachet water were identified sources of drinking water in Piwoyi Community. Six Samples (5 Boreholes and 1Sachet water) were selected at random and analyzed in the laboratory. The Physicochemical parameters examined include electrical conductivity (EC), pH, temperature, turbidity, dissolve oxygen (DO), chloride, total hardness, alkalinity, nitrate, calcium, magnesium, phosphate, phosphorous, sulphate, sodium, potassium, fluoride, bicarbonate, nitrate-nitrogen, nitrite, copper, iron and zinc; and Microbiological parameters include Coliforms, E-coli and Faecal Strep. The results of analysis shows significant concentration of physicochemical and microbiological parameters in the samples of water analyzed according to Nigerian Standard for Drinking Water Quality thereby makes the water unsafe for drinking. Drinking from these sources of water will pose serious health risk to the people of Piwoyi Community. Therefore, the study helps to identify the contaminated locations as well as assist to follow emerging remedial measures toward controlling the contamination source in the community. It also recommends continuous monitoring and enforcement of environmental violations, aggressive sensitization on water sanitation and hygiene; adequate purification of water at domestic level; and government support on potable water supply and establish reasonable management strategies for sustainable water quality protection toward protecting public health.

Synthesis of Carbide Lime Derived Strong Base Catalyst for Biodiesel Production

Carbide lime is a result of acetylene production. Carbide lime made out of calcium hydroxide with minor amount of calcium carbonate. In this study, carbide lime was used as the raw material to synthesize a new base catalyst with high base strength. A strong base catalyst was prepared through calcination and impregnation with potassium fluoride. The structure and morphology of catalyst were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) The base strength was determined by Hammett Indicator test, temperature-programmed desorption of carbon dioxide (TPD-CO2). The surface area of the catalyst was determined by Brunauer-Emmet-Teller isotherm (BET). The catalytic performance was examined through transesterification reaction. Fatty acid methyl ester (FAME) was successfully synthesized with the presence of carbide lime derived catalyst. The highest biodiesel conversion rate for sunflower oil was 95.83% with 6 wt% of catalyst loading while palm oil was 88.07% with 3 wt% of catalyst loading. The presence of the ester functional group was determined by Fourier Transform Infrared Spectroscopy (FTIR) analysis.

Low Dose of Fluoride in the Culture Medium of Cordyceps militaris Promotes Its Growth and Enhances Bioactives with Antioxidant and Anticancer Properties

Cordyceps militaris possesses several compounds with medicinal properties, and is commonly used in traditional Chinese functional food and medicine for a variety of health benefits. Because of its rare occurrence in nature, the market demand for artificial C. militaris is on the rise. Furthermore, efforts to increase its bioactive ingredients have also been considered in research. In this study, we aimed to investigate the effect of fluoride on the growth and enrichment of bioactive compounds in C. militaris. A wide range of potassium fluoride concentrations (0, 0.001, 0.01, 0.1, and 1 mM) were added to the culture media as a source of fluoride during the cultivation of C. militaris fruiting bodies. The contents of fluorine and bioactive substances of the fruiting bodies in normal (NM) and fluorine-supplemented (FM) media were measured and compared. C. militaris raised in the growth medium supplemented with 0.01 mM potassium fluoride led to a 44.86% (1.55 ± 0.14 g/bottle) increase in biomass and a 23.43% (3161.38 ± 35.71 µg/g) increase in total carotenoid content in the fruiting bodies. Furthermore, a remarkable increase in superoxide dismutase-like activity (84.75 U/mg) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (IC50 = 2.59 mg/mL) was recorded. In human cancer cell-based assays, C. militaris raised in FM caused stronger cytotoxicity, apoptosis, and cell cycle arrest in human osteosarcoma cells. These results demonstrated that a low dose of fluoride could stimulate the growth of C. militaris fruiting bodies and enhance the production of bioactive ingredients that possess useful antioxidant and anticancer activities.

Growth Peculiarities and Properties of KR3F10 (R = Y, Tb) Single Crystals

Cubic KR3F10 (R = Y, Tb) single crystals have been successfully grown using the Bridgman technique. Growth of crystals of this type is complicated due to the hygroscopicity of potassium fluoride and melt overheating. The solution to the problem of oxygen-incorporated impurities has been demonstrated through the utilization of potassium hydrofluoride as a precursor. In this study, the crystal quality, structure features, and optical, thermal and electrophysical properties of KR3F10 were examined. Data on the temperature dependences of conductivity properties of KTb3F10 crystals were obtained for the first time. These crystals indicated thermal conductivity equal to 1.54 ± 0.05 Wm−1K−1 at room temperature caused by strong phonon scattering in the Tb-based crystal lattice. Ionic conductivities of KY3F10 and KTb3F10 single crystals were 4.9 × 10−8 and 1.2 × 10−10 S/cm at 500 K, respectively, and the observed difference was determined by the activation enthalpy of F− ion migration. Comparison of the physical properties of the grown KR3F10 crystals with the closest crystalline analog from the family of Na0.5−xR0.5+xF2+2x (R = Tb, Y) cubic solid solutions is reported.