Environmental Progress & Sustainable Energy最新文献

Epoxides are conventionally synthesized from petroleum-based resources, which are neither environmentally friendly nor sustainable. Sunflower oil (SO), a renewable feedstock, remains underutilized and is often considered low value. This study aims to optimize the reaction parameters for SO epoxidation via an in situ peracid mechanism, where formic acid reacts with hydrogen peroxide to form performic acid, which then epoxidizes SO in the presence of catalysts. The relative conversion to oxirane (RCO) was used to evaluate efficiency. Three catalysts were tested: sulfuric acid, amberlite IR 120, and zeolite. Kinetic modeling was conducted using the ODE45 solver based on the Runge Kutta method, showing good agreement with experimental data. Optimum catalyst loadings were 1.0 g sulfuric acid (45% RCO), 2.0 g amberlite IR 120 (75% RCO), and 1.0 g zeolite (44% RCO). The findings confirm the potential of SO as a sustainable alternative feedstock for producing bio-based epoxides.

In recent decades, China's environmental problems and rapid urbanization redirected the course of its tourism industry. Against the backdrop of increasing alarm on climate change, air quality pollution, and energy resources sustainability, it is now imperative to understand their collective impact on tourism. The adoption of green energy, environmental pollution, and tourist arrivals are interrelated in this study, centering on China's dynamic tourism environment. Spanning from 1975 to 2022, the study employs the Generalized Method of Moments (GMM) estimator for parameter estimates. The findings reveal a negative relationship between international visitor arrivals and factors such as renewable energy consumption, economic development, and transit services. Conversely, the average temperature emerges as a significant factor that positively influences the potential for international tourism. Granger causality estimates support several hypotheses, including the notion that tourism drives carbon emissions and economic development, tourism propels transport services, renewable energy fuels economic growth, emissions drive economic growth, and temperature influences emissions within a nation. The results can foster the development of environmentally conscious and economically resilient tourist sectors.

Scarcity of clean water is one of the world's most pressing challenges, particularly in remote and arid regions. Solar stills for desalination is a renewable and cost effective method of producing fresh water from sea water. This study presents a dynamic numerical analysis of a pyramid-shaped solar still integrated with phase change material (PCM), using a transient MATLAB model. The model also uses a 2D finite difference approach to simulate the heat conduction process of PCM and air zones to predict the temperature field in the domain. The latent heat effect is modeled by enthalpy method, which can help to predict the phase change behavior of the PCM. MATLAB was used to build the full numerical model, which includes the empirical correlations, the experimental parameters, and the transient input data of solar radiation and ambient temperature for an hour-by-hour basis for 24 h. This involves a one-dimensional transient heat and mass transfer analysis of the solar radiation, basin water, glass cover, ambient air, and the PCM layer. The fin enhanced PCM (FPCMs) configuration at 2 cm depth achieved the highest cumulative distillation (7.3 kg/m²), confirming the advantage of combining thermal storage and extended heat transfer surfaces. Simulation results are the time dependent temperature of water, the temperature of the glass cover and PCM, hourly efficiency, evaporative heat losses and the distillate output for a day.

The remediation of tailing water from mining operations remains a critical challenge for the oil sand industry, primarily because of the presence of toxic naphthenic acids (NAs). To explore their potential value-added utilization, new amides, alcohols, and hydroxamic derivatives of natural naphthenic acids were synthesized in the absence of catalysts and/or solvents using a microwave reactor, thereby achieving a rapid, energy-efficient, and environmentally friendly approach. The obtained compounds were evaluated for their biological activities, including plant root promotion, bacterial growth stimulation, and cytotoxicity against human carcinoma cell lines. Naphthenic alcohols showed a strong stimulatory effect on adventitious root appearance in sunflower cuttings, whereas some derivatives enhanced the proliferation of Pseudomonas sp. isolates compared with NAs and exhibited good antiproliferative activity against HT-29 cancer cells.

Keeping the operating temperature in the allowable range of the power module, under a very high heat flux, is of particular importance in the performance of the systems and their reliability. In this investigation, a new hybrid thermal heat sink consisting of phase change material with different arrangements and mass flow rates has been used for cooling an Insulated-gate bipolar transistor. As an innovation, to reduce the operating temperature of the power module at a heat flux of 100 W/cm², paraffin and metal-based PCM have been applied in the water cooling chamber and simulated simultaneously. The finite volume method and piezo algorithm were used to solve the governing equations. The melting process of the PCM was simulated by the enthalpy-porosity method in a three-dimensional domain. The comparison of local temperature distribution among four models (A–D) shows that Case D reduced the operating temperature by about 15% versus other arrangements, and at flow rates of 0.0025–0.005 kg/s achieved up to 3°C lower than pure fluid. For paraffin (k = 0.12 W/m·K, L = 255,000 J/kg), Fo·Ste. at 3600 s is 0.0904, while for the metal alloy (k = 33.2 W/m·K, L = 202,000 J/kg) it is 6.5052, indicating much faster melting. The metal-based PCM, with higher conductivity and lower latent heat, enhances heat transfer and rapid cooling, whereas paraffin, with slower melting, suits long-term energy storage.

Coffee is one of the most important agricultural commodities in Brazilian agribusiness. The processing of coffee beans generates large volumes of residues with low environmental sustainability. Converting this biomass into bioethanol is a promising alternative, which requires pretreatment and enzymatic hydrolysis. This study aimed to optimize the hydrolysis of coffee pulp pretreated with 4% sodium hydroxide for ethanol production. Initially, different biomass loadings were evaluated, and 20 g/40 mL (14% w/v, dry basis) was selected due to its significantly higher cellulose-to-glucose conversion (Tukey, p < 0.05). A central composite rotational design (CCRD) assessed the effects of cellulase (1.5–43.5 FPU/g) and β-glucosidase (0–40 CBU/g) concentrations on the release of total sugars, reducing sugars, and glucose. The optimal conditions determined by the design were 25.78 FPU/g cellulase and 28.95 CBU/g β-glucosidase, resulting in an 85% conversion of cellulose to glucose. The central point treatments of the CCRD were used for fermentation with Saccharomyces cerevisiae CAT1 and Kluyveromyces marxianus CCT 4086, yielding ethanol concentrations of 25.63 and 21.71 g/L, respectively. The results demonstrate the technical feasibility of producing fermentable sugars and ethanol from coffee pulp through integrated pretreatment, enzymatic hydrolysis, and fermentation, contributing to waste valorization and sustainable biofuel production.

Eggshell (ES) membranes are rich in proteins consisting of many disulfide bonds and are reducible by various reductants to thiol ligands if adequately treated. This study adopted factorial experiments and response surface design to verify the most critical factors and determine the optimal conditions in eggshell reduction operations. Also, isothermal and kinetic adsorption models were used to demonstrate the metal adsorptive characteristics of the non-reduced and optimally reduced eggshells that adsorbed silver, copper, and chromium in water. Analysis-wise, metals in water were treated by aqua regia digestion and analyzed through inductively coupled plasma atomic emission spectroscopy (ICP-AES). Results revealed that thioglycol (i.e., 2-mercaptoethanol) and reaction time were the two most critical eggshell-modifying factors. Results of the response surface experiments indicated that the optimal eggshell reduction conditions were at the initial reductant concentration and reaction time equal to 9.75 M and 1.9 h, respectively. As for the isothermal metal adsorption using the modified eggshells, it fit the Langmuir model the best with the maximum adsorption capacities (q_m) of silver, copper, and chromium equal to 1.35, 2.09, and 2.39 mmole/g-ES, respectively. Data revealed that the reduced eggshells could completely adsorb silver, copper, and chromium within five hours and adsorbed around 6 and 2.6 times more copper and silver than the unreduced eggshells. These results demonstrate the much better uses of the reduced eggshells than plain eggshells for water metal purification.

The performance of the multi-walled carbon nanotubes (MWCNTs)–calcined otoliths (OLT) composite (MTO) in removing tetrazine (Tatz) from aqueous solution was evaluated and compared with that of calcined otoliths (OLT) alone. To find the ideal sorption conditions for Tatz removal, the effects of key variables, including pH, contact time, adsorbent amount, initial Tatz concentration, and adsorbate temperature, were investigated through batch adsorption trials. The uptake of Tatz by OLT and MTO was dependent on the aforementioned factors of adsorption. The pseudo-second-order model provided the best fit for the kinetic data of OLT and MTO, reflecting a chemisorptive mechanism involving two molecular interactions between Tatz and the active binding sites. The Langmuir and the Freundlich models best described the equilibrium data obtained for both OLT and MTO, respectively. Therefore, MTO exhibited a higher removal efficiency for Tatz, with an adsorption capacity of 58.75 mg g⁻¹, compared to 19.53 mg g⁻¹ for OLT. Therefore, using MTO as a possible sorbent for wastewater and effluent treatment is doable and ought to be investigated further to reduce water pollution.