In this study, the iron nanoparticles (Fe NPs) extract were synthesized by saffron tepal. Fe NPs were utilized for chromium (Cr) (VI) removal from the aqueous solution. Maximum adsorption efficiency Cr (VI) was achieved at pH 2, reaction time 240 min, and Fe NPs dosage 2 g/L. Under optimal conditions, more than 90% of Cr (VI) with a concentration of 100 mg/L was removed through as‐synthesized Fe NPs. The Cr (VI) adsorption trend was consistent with pseudo‐second‐order kinetics and Langmuir adsorption isotherm trend. The results confirmed the potential adsorption mechanism followed the chemisorption process such as electrostatic interactions, chemical ion exchange and chemical particle diffusion. Besides, physical adsorption may have a contribution in Cr (VI) adsorption. Generally, this study provided a new idea for the Cr (VI) removal from aqueous solution using an efficient and inexpensive adsorbent with maximum adsorption capacity of 76.34 mg/g.

Foam fracturing fluid is a prospective substitute for water‐based fracturing fluid, with the potential to effectively mitigate the adverse effects associated with unconventional reservoirs. However, the greenhouse effect caused by CO2 accumulation and CO2 utilisation represents a significant challenge, limiting the fracturing efficiency of unconventional reservoirs. The aim of this investigation is to optimise the formulation of foam fracturing fluids using CO2 fluid and analyse the fracturing capability of foam fluids. Specifically, this paper first built a fracturing model based on extended finite element and the impact of different factors on the fracturing capacity of foam fracturing fluid with CO2 fluid was analysed. In addition, the performance evaluation coupling platform is employed to elucidate the mechanism underlying the parameter changes of foam fracturing fluids. The results indicated that the foam stabilisers serve to stabilise of foam fracturing fluid, thereby reducing the CO2 fluid filtration and improving the fracturing efficiency of reservoir fractures. Furthermore, the stability, apparent viscosity and filtration of CO2 fracturing fluid are all enhanced by reservoir pressure, whereas an increase in reservoir temperature and salinity has the opposite effect. The reservoir pressure changes the apparent viscosity and filtration volume of the foam fracturing fluid by −16 and 0.42 mL, respectively, while the reservoir temperature reduces the above two parameters by 21 mPa·s and +0.23 mL. The vacuole stability and electron distribution in the diffuse double layer represent significant factors that influence the efficacy of foam fracturing fluids, and this paper could provide a basic data support for the development of foam fracturing fluids in unconventional reservoirs.

This paper presents the development of a method for the regeneration of molybdenum‐98 from spent 99Mo/99mTc generators for its reuse in the technological cycle. An optimal process for the regeneration of molybdenum from industrial waste is proposed, in which the loss rate of molybdenum is no more than 5%. Original methods and a schematic diagram of the regeneration processes are created. This study shows the possibility of using regenerated molybdenum‐98 in the manufacturing technology of technetium generators. This is confirmed by the quality of the eluate from the generator made based on the regenerated product, which, in all respects, meets the requirements of regulatory documentation. The development of molybdenum regeneration technology emphasises creating techniques that include a minimum number of stages with minimal amounts of materials used.

As part of the design of a biogas generation, purification, and compression system for Bahir Dar City’s municipal solid waste use, organic waste could be collected and treated in an anaerobic digester to produce biogas, which could then be compressed for use or storage after being purified to remove contaminants like carbon dioxide, hydrogen sulfide, moisture, and other pollutants. This approach could help the city implement a more sustainable waste management plan, produce renewable energy, and reduce waste output. Collaboration with experts in gas purification, waste management, and comprehensive Bahir Dar City station systems would be essential for the successful implementation of this design work. This project included the design and sizing of a fixed‐dome biogas digester, biogas purification, and a detailed plant schematic, as well as data on Bahir Dar’s waste potential. A locking system was not taken into consideration when developing the digesters because they were built on a wet base with a biomass‐to‐water ratio of 1:1, which maximizes biogas output in continuous mode as opposed to batch type. Various purification unit operation strategies are used to purify the undesirable gases after the digester produces biogas. In order to create fuel with a higher calorific value, biogas purification increases the amount of methane in the gas. Compressing the cleaned biogas would raise its energy density for transit and storage.

Sustainable energy production requires innovative approaches to decrease the dependence on nonrenewable resources and reduce environmental impacts. In this proof‐of‐concept study, we investigated green Santa Barbara Amorphous 15 (SBA‐15) catalysts using sugarcane bagasse ash (SCBA) as a silica source and incorporating organic acids and bases to create an eco‐friendly synthesis pathway. These catalysts were applied in the transesterification of waste sunflower oil (WSO) to produce biodiesel. Although the overall biodiesel yields were relatively low, peaking at 5.603% FAME with the L‐cysteine‐modified SBA‐15 catalyst (Lcys‐500), the main objective of this study was to establish the feasibility of employing green SBA‐15 materials as effective catalysts, rather than to optimise reaction parameters or maximise yield. Catalyst characterisation was carried out using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM–EDS), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA), confirming that the green SBA‐15 retained key structural properties of conventional SBA‐15, including ordered mesoporosity (p6mm symmetry) and spherical morphology with some variation in pore structure and thermal behaviour. Gas chromatography–mass spectrometry (GC–MS) was employed solely for biodiesel product analysis. FTIR spectra of the biodiesel confirmed successful transesterification, as indicated by characteristic C=O and C–O stretching bands. However, issues such as solidification of the CA‐500‐derived biodiesel and the low yield from the OP‐after calcination sample (0.178%) underscore the need for further refinement. Importantly, catalyst modification strategies, such as surface functionalisation or metal doping, were beyond the scope of this initial study. Overall, the results support the feasibility of producing functional mesoporous SBA‐15 catalysts from agricultural waste through green chemistry approaches. This study lays the groundwork for the development of environmentally friendly silica‐based catalysts, with future research focussed on surface functionalisation to improve catalytic performance ecologically.

Oxidative leaching is an inexpensive alternative to using chemical cyanide extraction methods for gold from low‐grade gold sulfide. Oxidation of finely ground gold‐bearing ore by Acidithiobacillus ferrooxidans was evaluated in terms of cell density, pH, and leaching efficiency of Fe and Au in shake flask experiments. The compositional and elemental analyses of the beneficiated ore were analyzed using XRD and EDXRF spectroscopy. The ore’s primary constituents are gold (4.356 mg/L), silicon, iron, and sulfur (62.456, 15.441, and 7.912 wt%, respectively). XRD spectra, the main phases of the concentrated ore, showed that the major components of the ore were quartz, syn, silicon sulfide, pyrite, and polymetallic elements such as silderenrite, gismondine, siderenikite, hematite, and syn. The experimental results, with Acidithiobacillus ferrooxidans bacteria and blank, were evaluated. The pH of the blank remained nearly constant, and the pH of the bioleached was occasionally lowered. The A. ferrooxidans strain always grew better throughout the bioleaching process. For the A. ferrooxidans strain, the cell density of cells reached a maximum of 90.00 × 106 cells/mL after the 11th week and decreased to 87.00 × 106 cells/mL after the 12th week. The decrease in cell density may be due to the presence of polymetallic elements such as Al, Cr, Ti, and Ni, leading to reduced metal tolerance of the A. ferrooxidans strain. In the A. ferrooxidans leaching process, the maximum total iron and gold extraction reached 92.16% (14.23 mg/L) and 99.97% (4.355 ppm), respectively, after the 11th week, and leaching tends to decrease up to 14 weeks, which may be due to the formation of secondary minerals. More research will be performed to optimize the procedure and leaching kinetic, examine the impact of metal content, and take into account the potential for bioleaching process pollution in addition to the amount of gold recovered.

Energy efficiency of coal‐water slurry mixing determines its application and transportation efficiency. This study compares the hydrodynamic characteristics and mixing performance of five different configurations of hydrocyclone mixers under turbulent flow conditions. Numerical calculations were used to investigate the velocity, pressure, and concentration fields of the mixer. Attempts were made to decrease the tangential inlet size and to design indentation structure to control the velocity and pressure fields inside the hydrocyclone mixer, thereby increasing the degree of mixing (DOM) and reducing mixing energy cost (MEC). The findings indicate that better mixing and dispersion can be achieved while reducing energy costs by designing the indentation structure and decreasing the size of the tangential inlet and outlet. It offers a reliable solution for uniformly mixing and dispersing coal‐water slurry with organic waste liquids and other highly concentrated fuels.

This investigation focused on assessing and enhancing ultrasound‐assisted extraction (UAE) using natural deep eutectic solvents (NADES) to extract phenolics and terpenoids from sweet basil leaves. The initial stage involved evaluating the extraction performance of twelve NADES and ethanol. A NADES comprising lactic acid and glucose with a 2 : 1 molar ratio and 20% water content (WC) obtained the highest total phenolic content (TPC) and total terpenoid content (TTC). Single‐factor experiments systematically examined the impact of liquid‐to‐solid ratio (LSR), water content in NADES (WC), ultrasound power, temperature, and exposure time on the extraction yield. Optimization using Box–Behnken Design (BBD) models for the lactic acid and glucose‐based UAE revealed the optimal conditions to be 80 ml/g LSR, 30% water, 300 W, 50°C temperature, and a 15‐minute exposure time. Under these optimized parameters, the extraction achieved the highest TPC and TTC at 69.88 mg GAE/g and 110.71 mg UA/g, respectively. This study presents an environmentally friendly and sustainable extraction protocol for the extraction of phenolic compounds and terpenoids from sweet basil leaves.

Superabsorbent polymer is a material that can swell hundreds to thousands of times after absorbing moisture. Studies that combined the use of this material in coffee bean drying have not yet been widely disclosed. In this study, a dryer assisted with superabsorbent polymer (Polydryer) was applied to improve the drying performance of coffee beans. The materials for superabsorbent polymer hydrogel (polygel) were cassava starch and acrylic acid. Based on this study, the use of polygel and heater was able to alleviate humidity while signifying the temperature inside the drying chamber. This condition certainly aided the drying process because it provided a greater driving force for free and bound water to diffuse from the inner coffee bean particle to the environment. Normal and intermittent drying modes were also carried out to compare the drying performance. The normal operation mode required 14 h to attain a product moisture content of below 12%. Meanwhile, the intermittent drying mode, where the heater operated merely in the initial stage, took 72 h to reach the maximal 12% product moisture content. Further improvement of the Polydryer was done by using three chambers arranged in series and operating in the normal mode, resulting in a more efficient drying system with a swifter process of 7 h. The results indicated that coffee bean drying using the Polydryer was effective and can be used to substitute conventional methods, especially during the night‐time and rainy season. Besides, the dried coffee beans were free of insects, rot, mold, and foreign matter and were in a specialty grade category.

The hydrogen consumption and driving range of fuel cell vehicles are key indicators for evaluating their performance. The existing testing standards mainly suffer from key issues such as cumbersome testing procedures, low testing efficiency, and incomplete calculation methods. This article proposes a rapid evaluation method for hydrogen consumption and driving range of B‐class fuel cell vehicles. This method does not require the test vehicle to be fully charged with hydrogen before the experiment but only requires the test vehicle to meet 2 cycles of pure electric driving and 7 cycles of hydrogen electric hybrid driving. Different evaluation methods were used to conduct comparative experiments on 6 vehicles. The experimental results show that after simplifying the experimental process, excluding the time and cost of preparation work before the experiment, the rapid method is only one‐third of the running method during the experimental process, and the net experimental time is significantly reduced. In addition, the rapid evaluation method has a range of 2.25% to 5.31% in hydrogen consumption per 100 km compared to the standard method, with an average increase of 3.89%. The range of variation in driving range is 7.26% to 9.51%, with an average increase of 8.65%.