Performance evaluation of biocoagulant for the effective removal of turbidity and microbial pathogens from drinking water.

In this study, Moringa seeds, aloe vera leaves, and cactus leaves were used as biocoagulants for the treatment of drinking water. The effects of coagulant type, coagulant dosage, and pH were studied on the quality of the treated water. Response surface methodology was used to predict and optimize the parameters. The standard Six Jar test was used to measure the performance of coagulants. Three mixing modes were used in the jar test: quick mixing at 1 min at 120 rpm, slow mixing for 19 min at 40 rpm, and 15 min settling. The characterization results showed that extracts of Moringa seeds, aloe vera leaves, and cactus leaves contain 43.95 ± 0.49, 13.9 ± 0.42, and 10.94% ± 0.37 protein, respectively. It was revealed that coagulant type, coagulant dosage, and the interaction between (coagulant type (MS-SC and AV-SC) and pH) were significant (p < 0.05) for turbidity removal. Jar test results showed a removal efficiency of turbidity 98.83%, and 98.74% and 69.83% using MS-SC, and AV-SC and Ca-SC bio, respectively. These results imply that the three coagulants can be considered as effective, low-cost, and eco-friendly resources for the treatment of drinking water in rural communities of Ethiopia where access to clean water is scarce.

Efficient H2 Evolution Coupled with Anodic Oxidation of Iodide over Defective Carbon-Supported Single-Atom Mo-N4 Electrocatalyst.

We successfully prepared nitrogen-doped defective carbon spheres (Mo-N4/d-C) with a high loading of 0.996 wt % via a designed vapor-deposition process for IOR-based hydrogen generation. The synthesized Mo-N4/d-C catalyst provides a record current density of 10 mA cm-2 at 0.77 V. Further, the Mo-N4/d-C catalyst shows a Tafel slope of 25.58 mV dec-1, exceptional stability over time in acidic media, a higher hydrogen generation rate of 0.1063 mL gcat-1 min-1, a high Faradaic efficiency of 99.8%, and a reduction of the energy consumption up to ∼50% for hydrogen evolution by anodic oxidation reaction of iodide (IOR) compared with the conventional OER-based electrolysis. Computational calculations demonstrate that the Mo-N4/d-C structure plays a vital effect on the activity of iodide oxidation, which is competitive with the Pt catalyst.

Vermicomposting as an effective approach to municipal sewage sludge management through optimization of the selected process variables.

In most developing countries, municipal sewage sludge end-use practices appear unsustainable; rather, it poses environmental concerns. This study examined the potential of vermicomposting of municipal sewage sludge and its blend with other biowaste for agricultural application. Using a response surface methodology and the Box-Behnken design in Design Expert Software (Version 10.0.7), the current study optimized the moisture content (60-90%), turning frequency (1-3 turnings/week), and substrate mixing ratios (50:50 to 80:20 wt.%) to maximize the content of nitrogen, phosphorus, and potassium. As a result, an optimal moisture content (72%), substrate mixing ratio (72.34:27.6 wt.%), and turning frequency (2 per week), producing a promising-quality vermicompost with a maximum yield of nitrogen (2.76%), phosphorus (1.80%), and potassium (1.88%) is achieved. Thus, vermicomposting can effectively turn the concerning municipal sewage sludge into useful agricultural input for its sustainable management.

Enhancing pseudocapacitive properties of cobalt oxide hierarchical nanostructures via iron doping.

Through co-precipitation and post-heat processing, nanostructured Fe-doped Co3O4 nanoparticles (NPs) were developed. Using the SEM, XRD, BET, FTIR, TGA/DTA, UV-Vis, and techniques were examined. The XRD analysis presented that Co3O4 and Co3O4 nanoparticles that had been doped with 0.25 M Fe formed single cubic phase Co3O4 NPs with average crystallite sizes of 19.37 nm and 14.09 nm, respectively. The as prepared NPs have porous architectures via SEM analyses. The BET surface areas of Co3O4 and 0.25 M Fe-doped Co3O4 NPs were 53.06 m2/g and 351.56 m2/g, respectively. Co3O4 NPs have a band gap energy of 2.96 eV and an extra sub-band gap energy of 1.95 eV. Fe-doped Co3O4 NPs were also found to have band gap energies between 2.54 and 1.46 eV. FTIR spectroscopy was used to determine whether M-O bonds (M = Co, Fe) were present. The doping impact of iron results in the doped Co3O4 samples having better thermal characteristics. The highest specific capacitance was achieved using 0.25 M Fe-doped Co3O4 NPs at 5 mV/s, which corresponding to 588.5 F/g via CV analysis. Additionally, 0.25 M Fe-doped Co3O4 NPs had energy and power densities of 9.17 W h/kg and 472.1 W/kg, correspondingly.

Binary glycerol-based deep eutectic solvents containing zinc nitrate hexahydrate salt for rechargeable zinc air batteries applications with enhanced properties.

Deep eutectic solvents (DESs) have attracted interest due to their unique and favorable electrochemical characteristics. This study reported a novel binary glycerol-zinc salt deep eutectic solvents were prepared with a combination of hydrogen bond donor (glycerol (Gly)) and hydrogen bond acceptor (Zinc nitrate hexahydrate (ZNH)) at different molar ratios of 1:2, 1:3, 1:4, 1:5, and 1:6. The various physicochemical properties including viscosity, refractivity index, conductivity, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance (EIS) were measured. The results showed that among the various combinations tested, DES 1:2 resulted in a low viscosity value of 690, 500, 310, 220, and 160 mPa (mPa s) at shear rate (S-1) values of 20, 30, 60, 100, and 200 respectively. Moreover, DES 1:2 resulted in more electrochemically stable solvents with a lower refractive index value of 1.446, and a higher conductivity (σ) of 4.41 mS/cm. The findings found disclose the features, nature and of properties of prepared DESs as a potential solvents for different electrochemical storage applications.

Biomass energy conversion in a gasifier for injera baking mitad application.

The performance of gasification for Injera baking was explored in this study, as well as the effects of moisture content, and primary and secondary airflow rates. Primary air is used in the reactor of a biomass gasifier, which creates syngas that is burned by secondary air on the mitad's bottom side. An average temperature of averaged 185 °C at the center and 170 °C away from the center was observed; the size of the cone determines the temperature distribution on the metal surface. The reactor's narrower cone diameter allowed for a greater temperature only in the center and a more variable baked Injera eye appearance. The cone diameter has been reduced to 0.15 m of the mitad diameter to improve the temperature distribution on the mitad surface. The gasifier temperature is 800 °C when the air/fuel ratio is 5.8 kg/kg and the moisture content of the wood is 16%. Gasification is improved by heating the primary air and changing the air-fuel ratio. The findings revealed that pre-heated air is more efficient for gasification and saves money on baking and fuel. Fuel efficiency (0.45) and time savings (0.12) were discovered in the new gasifier. Between gasification temperatures of 650 and 800 °C, an effective Injera baking temperature (170-185 °C) on the mitad surface was attained. Following the tests, the average specific wood fuel consumption (1.414 g/kg), char residue (317 g), and average Injera baking time were calculated. For each test of one baking cycle, this was found at the burning rate capability of both stoves, which is 6 kg/hr. Therefore, the fuel consumption and burning rate of fuel are depending on the amount of airflow rate.

Engineering nanostructured Ag doped α-MnO2 electrocatalyst for highly efficient rechargeable zinc-air batteries.

Engineering of highly active, and non-precious electrocatalysts are vital to enhance the air-electrodes of rechargeable zinc-air batteries (ZABs). We report a facile co-precipitation technique to develop Ag doped α-MnO2 nanoparticles (NPs) and investigate their application as cathode materials for ZABs. The electrochemical and physical characteristics of α-MnO2 and Ag doped α-MnO2 NPs were compared and examined via CP, CV, TGA/DTA, FT-IR, EIS, and XRD analysis. CV result displayed higher potential and current for ORR in Ag doped α-MnO2 NPs than α-MnO2; but, ORR performance decreased when the Ag doping was raised from 7.5 to10 mmol. Moreover, α-MnO2 and Ag doped α-MnO2 NPs showed 2.1 and 3.8 electron transfer pathway, respectively, showing Ag doped α-MnO2 performance to act as an active ORR electrocatalyst for ZABs. The EIS investigation exhibited that charge-transfer resistance for Ag doped α-MnO2 was extremely lower associated to the MnO2 demonstrating that the successful loading of Ag in α-MnO2. A homemade ZAB based on Ag-MnO2-7.5 showed a high open circuit potential, low ohmic resistances, and excellent discharge profile at a constant current density of 1 mA/g. Moreover, Ag-MnO2-7.5 show a specific capacity of 795 mA h g-1 with corresponding high energy density ∼875 Wh kg-1 at 1 mA cm-2 discharging conditions.

Alkaline hydrogen peroxide pretreatment of cladodes of cactus (opuntia ficus-indica) for biogas production.

The alkaline hydrogen peroxide (AHP) pretreatment of cladodes of cactus (Opuntia ficus-indica) for biogas production was evaluated based on the delignification of cladodes of cactus. The effects of alkaline hydrogen peroxide concentration (30% w/w solution) and the pretreatment time (3, 6, 9, and 12 h) were evaluated at pH 11.5, temperature of 30 °C, and 180 rpm for removal of lignin. A batch of anaerobic digestion experiments were conducted at mesophilic temperature conditions (37 ± 1 °C) with the pretreated biomass. The feed stock (cladodes of cactus) used in this study contained 12.51 ± 1.25 cellulose, 16.34 ± 2.93% hemicellulose, and 10.45 ± 2.31% lignin, and the balance were (carbohydrate, protein, lipid, and ash). After AHP pretreatment, the lignocellulosic content of the feed stock was changed to 12.50 ± 1.84%, 13.63 ± 3.23%, and 7.49 ± 3.05% for cellulose, hemicellulose, and lignin respectively. The AHP pretreatment of cladodes of cactus highly affected the lignin structure relative to cellulose and hemicellulose. The alkaline hydrogen peroxide pretreatment resulted in a higher amount of biogas produced from 877.9 ± 15.12 ml biogas/g VS to 1613.5 ± 10.76 ml biogas/g VS which is an 83.4% increment and decreased after 9 h treatment to 1398.8 ± 17.8 ml biogas/g VS. In addition, the measured methane yields range from 302.48 ± 0.33 to 602.65 ± 3.24 ml CH4/g VS. The results showed that alkaline hydrogen peroxide pretreatment of cladodes of cactus is an effective strategy for enhance biogas yield.

Engineering Co3O4/MnO2 nanocomposite materials for oxygen reduction electrocatalysis.

Stable and active electrocatalysts preparation for the oxygen reduction reaction (ORR) is essential for an energy storage and conversion materials (e.g. metal-air batteries). Herein, we prepared a highly-active MnO2 and Co3O4/MnO2 nanocomposite electrocatalysts using a facial co-precipitation approach. The electrocatalytic activity was examined in alkaline media with LSV and CV. Additionally, the physicochemical characteristics of the MnO2 and Co3O4/MnO2 composite materials were studied via SEM, XRD, BET, UV-Vis, TGA/DTA, ICP-OES and FTIR. Morphological studies indicated that a pure MnO2 has a spherical flower-like architecture, whereas Co3O4/MnO2 nanocomposites have an aggregated needle-like structure. Moreover, from the XRD investigation parameters such as the dislocation density, micro-strain, and crystallite size were analyzed. The calculated energy bandgaps for the MnO2, Co3O4/MnO2-1-5, and Co3O4/MnO2-1-1 nanocomposites were 3.07, 2.6, and 2.3 eV, correspondingly. The FTIR spectroscopy was also employed to study the presence of M-O bonds (M = Mn, Co). The thermal gravimetric investigation showed that the Co3O4/MnO2 nanocomposite materials exhibited improved thermal stability, confirming an enhanced catalytic activity of ORR for MnO2/Co3O4-1-1 composite materials for ORR. These results confirm that the prepared Co3O4/MnO2 composite materials are promising air electrode candidates for the energy storage and conversion technologies.