Search Results (2,299)

The isomerization of geraniol using natural, acid-modified minerals such as vermiculite presents a promising approach aligned with the principles of green chemistry. Vermiculite, a naturally abundant layered silicate mineral, was subjected to the acid activation and thoroughly characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). These methods allowed the evaluation of crystallinity, structural stability, and surface morphology, which are critical parameters in the heterogeneous catalysis. The catalytic performance of the modified vermiculite was examined in the transformation of geraniol under mild conditions. The study systematically investigated the influence of key process parameters—temperature, reaction time, and catalyst content—on the conversion of geraniol and products selectivities. Optimization using the response surface methodology (RSM), enabled the identification of conditions leading to high conversion of geraniol (up to 85%) and allowing us to obtain favorable selectivities toward linalool, thunbergol, and 6,11-dimethyl-2,6,10-dodecatrien-1-ol. The results indicate that the acid-treated vermiculite exhibits sufficient surface acidity to effectively catalyze isomerization and cyclization reactions, without requiring additional promoters or metal-based systems. Moreover, the use of RSM provided the efficient framework for optimization reaction conditions, reducing experimental workload, and enhancing process efficiency. This study demonstrates the viability of natural, low-cost minerals as environmentally friendly catalysts and supports their integration into sustainable and “green” chemical technologies. Full article

A phosphogypsum flotation tailings-derived zeolite (PGTZ) was synthesized from the tailings produced during the reverse flotation of phosphogypsum through alkaline fusion and hydrothermal treatment. The response surface methodology (RSM) utilizing a three-level Box–Behnken design (BBD) was used to assess the adsorption of MB by PGTZ. Polynomial regression models were developed to analyze the effects of process parameters on adsorption capacity (q_e). The maximum MB adsorption occurred under the following optimized conditions: PGTZ dosage = 5.31 g·L⁻¹; initial MB concentration = 294.59 mg·L⁻¹; pH = 7.42; and adsorption time = 187.89 min. Additionally, adsorption isotherm and kinetic models were fitted to the experimental data to determine model parameters. The Langmuir isotherm model and pseudo-second-order kinetic model incorporating intraparticle diffusion were able to effectively predict MB adsorption onto PGTZ. Thermodynamic analyses indicated that the adsorption process was spontaneous, with strong chemical interactions between MB and PGTZ. Full article

There is a need to address the limitations of wheat straw (WS) as a raw biomass fuel, promote its valorisation into a high-quality renewable solid fuel, and enable this fuel to replace fossil fuels in applications such as power plants and industrial boilers. This study focused on optimizing microwave torrefaction parameters to enhance key fuel properties. Optimal conditions were determined via the Box–Behnken design (BBD) within Response Surface Methodology (RSM) as 422.32 W of microwave power, 14.95 min of irradiation time, and a 15 g microwave absorber, resulting in a 69.12% mass yield, an 18.44 MJ/kg higher heating value (HHV) surpassing lignite at 16.76 MJ/kg, and a 25.50% Energy-Mass Co-efficiency Index (EMCI). Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis/derivative thermogravimetric analysis (TG/DTG) were conducted to gain insights about chemical composition and thermal stability variations due to torrefaction. LCA showed that electricity produced from 1 ton of torrefied WS reduces CO₂ emissions by 259.26 kg CO₂eq compared to electricity generated from bituminous coal. From an economic perspective, the usage of torrefied WS for power generation lead to a net profit of CNY 435.19/ton. This scalable technology, by valorising agricultural waste for fuel production, delivers dual environmental and economic benefits, laying the groundwork for industrial deployment. Full article

The use of recycled coarse aggregate (RCA) concrete and polypropylene fibers (PPFs) presents a sustainable alternative in concrete production. However, the non-linear and interactive effects of RCA and PPF on both fresh and hardened properties are not yet fully quantified. This study employs Response Surface Methodology (RSM) and the Random Forest (RF) algorithm with K-fold cross-validation to predict the combined effect of using recycled coarse aggregate (RCA) as a partial replacement for natural coarse aggregate and polypropylene fiber (PPF) on the engineering properties of RCA-PPF concrete, addressing the critical need for a robust, data-driven modeling framework. A dataset of 144 tested samples obtained from literature was utilized to develop and validate the prediction models. Three input variables were considered in developing the proposed prediction models, namely, RCA, PPF, and curing age (Age). The examined responses were compressive strength (CS), tensile strength (TS), ultrasonic pulse velocity (UPV), and water absorption (WA). To assess the developed models, statistical metrics were calculated, and analysis of variance (ANOVA) was employed. Afterwards, the responses were optimized using optimization in RSM. The optimal results of responses by maximizing TS, CS, and UPV and minimizing WA were achieved at a PPF of 3% by volume of concrete and an RCA of approximately 100% replacing natural coarse aggregate, highlighting optimal reuse of recycled aggregate, with an AGE of 83.6 days. The RF model demonstrated superior performance, significantly outperforming the RSM model. Feature importance analysis via SHAP values was employed to identify the most effective parameters on the predictions. The results confirm that ML techniques provide a powerful and accurate tool for optimizing sustainable concrete mixes. Full article

To address the issues of high stalk breakage rate and the mismatch between extraction force and operational speed in current horizontal shaft counter-rolling cotton stalk pullers, this study presents a novel clamping mechanism. The mechanism enables precise adjustment of the rollers’ rotational speed, inter-roller gap, and surface topography. The objective is to systematically investigate the effects of these key parameters on the peak extraction force and its timing during the stalk pulling process. Initially, pre-compressed cotton stalks were employed as test specimens. Their tensile properties post-compression were investigated by simulating the extraction forces using a universal testing machine. Subsequently, the structural design of the critical components for the test rig was created based on these experimental findings. Theoretical analysis identified the surface texture of the clamping rollers, their rotational speed, and the clamping gap as the primary experimental factors. The effects of these factors on the peak extraction force and its timing were analyzed using Response Surface Methodology (RSM). The results indicated that the optimal combination—striped surface texture for both rollers, a speed of 220 rpm, and a zero gap—yielded a time to peak force of 0.05 s and a peak force of 710.77 N, which is significantly below the measured tensile strength limit of 994.60 N for compressed stalks. This indicates that the designed clamping device for the horizontal shaft counter-rolling cotton stalk extraction machine achieves faster extraction speed while ensuring stalk integrity, and the research results can provide theoretical foundation and design guidance for the development of horizontal shaft counter-rolling cotton stalk extraction machinery. Full article

Seaweeds are increasingly valued in the food industry for their bioactive compounds, mainly hydrocolloids like carrageenan. This study investigates E. perplexum, a red seaweed, as a unique and sustainable source of carrageenan with promising functional properties. Using response surface methodology (RSM), the extraction process was optimized through alkaline extraction, identifying optimal conditions of 85 °C for 3 h with 2.58 M KOH, which yielded 77.10% carrageenan. The extracted carrageenan exhibited strong emulsifying activity (71.53 ± 2.41) and color properties comparable to commercial carrageenan, highlighting its viability for food applications. Chemical evaluation revealed a higher sulfate content (8.45 ± 0.16) and slightly reduced carbohydrate levels, which may influence its gelling and stabilizing abilities. Structural examination through ATR-FTIR spectroscopy corroborates the presence of key functional groups, including sulfate esters and galactose derivatives, inferring molecular integrity. These results emphasize the importance of RSM in optimizing extraction and underscore the ability of E. perplexum as a promising source of the derived carrageenan, which is a high-performance additive in food systems. Further research on purification, functional enhancement, and safety assessment is recommended to facilitate its integration into commercial food systems. Full article

The ultrasound-assisted extraction (UAE) method was optimized to extract bioactive compounds from Licaria armeniaca tissues. Extraction time, solid–liquid ratio (m/v), and ethanol percentage were investigated using a central composite rotational design and response surface methodology (RSM). Antioxidant activity (DPPH) and total phenolic content (TPC) served as the response variables. Most efficient extraction conditions were obtained for leaves (64.88% ethanol, 26.07 min, 6.23% m/v; R² = 0.93) and thin branches (73.81% ethanol, 31.34 min, 11% m/v; R² = 0.74). For thick branches, no significant predictive model was obtained, and optimal points were defined based on the best observed TPC and DPPH results (50% ethanol, 35 min, 11% m/v). The optimized extracts were analyzed by liquid chromatography–tandem mass spectrometry associated with molecular networking, GNPS (Global Natural Products Social Molecular Network) library searching, and machine learning tools. Metabolomic profiling indicated that leaves contained mainly alkaloids (46.34%), amino acids and peptides (19.51%), and shikimate derivatives and phenylpropanoids (12.20%). Thin branches showed predominance of alkaloids (35.97%), amino acids and peptides (20.86%), and carbohydrates (12.23%), while thick branches contained alkaloids (46.34%), amino acids and peptides (25.00%), and fatty acids (14.26%). Additionally, the extracts displayed significant cytotoxic activity against cancer cell lines of AGP-01 (malignant gastric ascites), AHOL (Human glioblastoma) and A549 (lung cancer) with IC50 values less than 50 μg/mL. Full article

This study conducted a systematic investigation of the degradation pathway and process optimization of strong acid cation exchange resins subjected to SCWO. Controlled experiments evaluated the effects of operating temperature, oxidant stoichiometry, initial organic concentration, and residence time. RSM was utilized to refine the operating parameters, and a second-order regression model (R² = 0.9951) was established to predict COD removal (R_COD), valid within experimental ranges: reaction temperature 400–500 °C, oxidant stoichiometry 80–150%, initial COD 10,000–100,000 mg·L⁻¹, and residence time 1–10 min. COD-dependent NaOH addition could enhance degradation efficiency. The R_COD was sensitive to operating temperature, oxidant stoichiometry, and residence time. Under the optimized conditions of 472 °C, oxidant stoichiometry of 137%, initial COD of 77,216 mg·L⁻¹, and residence time of 4.9 min with the addition of 1.74 wt% NaOH, the R_COD reached 99.92%, which was in close agreement with model predictions. GC-MS analysis of intermediates revealed that sulfonic groups dissociated early, followed by aromatic compounds, particularly phenol, undergoing ring-opening and oxidation to small carboxylic acids and aliphatic species, which were ultimately mineralized to CO₂ and H₂O. These findings provide mechanistic insight into resin decomposition and offer a scientific basis for the safe treatment of radioactive waste resins using SCWO. Full article

This study aimed to develop an environmentally friendly and relatively efficient method for extracting natural antioxidants from avocado by-products while investigating the antioxidant mechanisms of their core bioactive components on multiple dimensions. In vitro antioxidant assays (ABTS, FRAP, SAFR, SFR, ORAC, DPPH) demonstrated that flavonoid procyanidin was the primary antioxidant component in avocado seeds, exhibiting the strongest activity (DPPH EC₅₀ = 3.6 µg/mL). The Hill model indicated a positive synergistic effect (n = 3.1). Chemical and molecular mechanism analyses revealed that avocado seeds exert antioxidant activity predominantly through hydrogen atom transfer (HAT) and electron transfer (ET) pathways. The model predictions suggested procyanidins may stably bind to protein targets in the Keap1-Nrf2 pathway and NOX2 via hydrogen bonding, hydrophobic interactions, and π-cation interactions. Furthermore, response surface methodology (RSM) was employed to optimize the extraction process of avocado seed antioxidants in an ethanol-water system. This study underscores the considerable health benefits and antioxidant capacity of avocado by-products, supporting their promising application in functional foods formulations. Full article

The growing global demand for lithium, driven by its pivotal role in battery production, highlights the need for alternative technologies to recover this metal from low-grade and anthropogenic raw materials. This study investigates lithium extraction from aluminosilicate tailings of rare-metal production by sulfate roasting with concentrated sulfuric acid, followed by aqueous and hydrochloric acid leaching. Mineralogical analysis confirmed lithium mainly in muscovite and biotite (isomorphic substitutions) and partly as spodumene within the aluminosilicate matrix. The optimal parameters of thermochemical treatment were determined as 300 °C for 1 h at a liquid-to-solid ratio of 1:6. Subsequent aqueous leaching (90 °C, 1 h, L/S = 6:1) achieved a lithium recovery of 82.3%, while HCl proved less effective. Using response surface methodology (RSM) and a central composite design (CCD), a regression model was developed predicting up to 93.4% lithium extraction at 90 °C, a liquid-to-solid ratio of 10:1, and a leaching duration of 75 min. The calculated values showed good agreement with experimental data obtained at 90 °C, L/S = 10:1, and 30 min leaching, yielding 91.92% lithium recovery. These results confirm the efficiency of the proposed thermochemical approach and provide a scientific foundation for its further development and industrial scale-up. Full article

Adhesive wear has been identified as a significant cause of material loss, representing a substantial challenge across diverse industrial sectors. In order to address this issue, it is imperative to conduct studies with the aim of mitigating this degradation. The present study focuses on achieving a high-quality product with minimal mass loss during adhesive wear by utilizing gas nitriding treatment to optimize the wear parameters of AISI 4140 steel. The present study employed the Taguchi methodology and response surface methodology (RSM) in order to design the experiments. A comprehensive investigation was conducted into the key wear parameters, encompassing sliding speed (V), normal load (FN), and the microhardness of nitrided parts (HV). Furthermore, an artificial neural network (ANN) prediction model was developed to forecast the wear performance of 4140 Steel. The ANN model demonstrated an accuracy of approximately 99% when compared to the experimental data. In order to enhance the precision of wear estimation, prediction optimization was conducted using Bayesian and genetic algorithms. The findings demonstrated that the predicted R² values exhibited a reasonable alignment with the adjusted R² values, with a discrepancy of less than 0.2. The analysis demonstrated that the normal load is the most significant factor influencing wear, followed by hardness. In contrast, sliding speed was found to have the least significant impact. Full article

This work employed a design-of-experiments (DoE) strategy, specifically a 2³ full factorial design, to assess how suspension concentration (0.001–0.002 g/mL), substrate temperature (60–80 °C), and deposition height (10–15 cm) influence tin dioxide (SnO₂) thin films produced by ultrasonic spray pyrolysis (USP). The response variable was the net intensity of the principal diffraction peak, used as an operational metric for detecting the deposited phase. All patterns matched the SnO₂ phase cassiterite reference without impurity peaks. Statistical analyses (ANOVA, Pareto and half-normal plots, and response surface methodology, RSM) identified suspension concentration as the most influential factor, followed by significant two- and three-factor interactions. The model exhibited a high coefficient of determination (R² = 0.9908) and low standard deviation (12.53), validating its predictive capability. The optimal deposition process was achieved at the highest suspension concentration (0.002 g/mL), lowest substrate temperature (60 °C), and shortest deposition height (10 cm). These results demonstrate the utility of full factorial DoE for quantifying and controlling deposition outcomes in USP and provide a robust statistical framework to guide the synthesis of SnO₂ thin films. Full article

Pipeline anticorrosion patch spray coating is a critical process in pipeline construction and maintenance. It directly affects the adhesion between the pipe exterior and the heat-shrink sleeve and indirectly determines the quality of the coating bond. This study employs ANSYS FLUENT numerical simulations, complemented by on-site automated spray-gun experiments, to systematically investigate the influence of two key parameters—spray distance and gun traverse speed—on coating thickness distribution and uniformity. For both flat and cylindrical specimens, response surface methodology (RSM) applies to construct mathematical deposition models and to optimize process parameters. Simulation results indicate that increasing spray distance leads to edge thinning, while excessive traverse speed causes non-uniform thickness. Optimization improves coating uniformity by 18% on flat specimens and up to 15% on cylindrical specimens. Field validation demonstrates that the optimized process reduces process deviation from the target thickness to within ±10%. At the same time, the maximum relative error between simulation and experiment remains within 13.5%, and the deviation from the standard thickness is 12.25%. These findings provide solid theoretical foundations and practical guidance for automated spray-coating optimization, thereby enhancing the anticorrosion performance of pipeline joints. Full article

Biologically treated swine farm wastewater still contains high levels of refractory organics, humic substances and antibiotic residues, posing environmental risks and limiting opportunities for water reuse. Wastewater treatment by ozonation alone suffers from low mass transfer efficiency and selective oxidation. To overcome these limitations, a catalytic ozonation process (O₃/Fe²⁺/H₂O₂) was applied and optimized using Response Surface Methodology (RSM) based on single-factor experiments and Central Composite Design (CCD) for advanced swine farm wastewater treatment. The optimal conditions ([O₃] = 25.0 mg/L, [Fe²⁺] = 25.9 mg/L, [H₂O₂] = 41.1 mg/L) achieved a COD removal of 44.3%, which was 86.8% higher than that of ozonation alone, and increased TOC removal to 29.5%, indicating effective mineralization. Biodegradability (BOD₅/COD) of swine farm wastewater effluent increased from 0.01 to 0.34 after the catalytic ozonation treatment. Humic-like and fulvic-like substances were removed by 93.7% and 95.4%, respectively, and antibiotic degradation was significantly accelerated and enhanced. The synergistic process improved ozone utilization efficiency by 33.1% and removed 53.95% of total phosphorus through Fe³⁺-mediated coprecipitation. These findings demonstrate that with catalytic ozone decomposition and production of hydroxyl radicals, the O₃/Fe²⁺/H₂O₂ system effectively integrates enhanced ozone utilization efficiency, radical synergy, and simultaneous pollutant removal, providing a cost-effective and technically feasible strategy for advanced swine farm wastewater treatment and safe reuse. Full article

This study explored the optimization of green hydrogen production via seawater electrolysis powered by a hybrid photovoltaic (PV)-wind system in KwaZulu-Natal, South Africa. A Box–Behnken Design (BBD), adapted from Response Surface Methodology (RSM), was utilized to address the synergistic effect of key operational factors on the integration of renewable energy for green hydrogen production and its economic viability. Addressing critical gaps in renewable energy integration, the research evaluated the feasibility of direct seawater electrolysis and hybrid renewable systems, alongside their techno-economic viability, to support South Africa’s transition from a coal-dependent energy system. Key variables, including electrolyzer efficiency, wind and PV capacity, and financial parameters, were analyzed to optimize performance metrics such as the Levelized Cost of Hydrogen (LCOH), Net Present Cost (NPC), and annual hydrogen production. At 95% confidence level with regression coefficient (R² > 0.99) and statistical significance (p < 0.05), optimal conditions of electricity efficiency of 95%, a wind-turbine capacity of 4960 kW, a capital investment of $40,001, operational costs of $40,000 per year, a project lifetime of 29 years, a nominal discount rate of 8.9%, and a generic PV capacity of 29 kW resulted in a predictive LCOH of 0.124$/kg H₂ with a yearly production of 355,071 kg. Within the scope of this study, with the goal of minimizing the cost of production, the lowest LCOH observed can be attributed to the architecture of the power ratios (Wind/PV cells) at high energy efficiency (95%) without the cost of desalination of the seawater, energy storage and transportation. Electrolyzer efficiency emerged as the most influential factor, while financial parameters significantly affected the cost-related responses. The findings underscore the technical and economic viability of hybrid renewable-powered seawater electrolysis as a sustainable pathway for South Africa’s transition away from coal-based energy systems. Full article