Green Chemical Engineering最新文献

In the contemporary context, tetracycline is widely utilized as a prevalent antibiotic in various facets of life. However, the excessive use of antibiotics has caused visible environmental consequences. Henceforth, the scientific community has increasingly focused on developing catalysts that exhibit exceptional efficacy in the proficient degradation of tetracycline. In this study, a novel nanomaterial was developed to encapsulate CdTe quantum dots (QDs) with a SiO₂ shell. The distinct synthesis approach generated a composite material that showed heterogeneity and considerably increased the contact area with contaminants. Consequently, the transfer of photoelectron to the SiO₂ spheres was significantly improved, leading to a more efficient separation during the catalytic process. The study investigated how different factors, such as the loading of the catalyst, the initial concentration of tetracycline, pH levels, and the wight ratio of CdTe QDs (SiO₂ + CdTe QDs) affected the effectiveness of photocatalytic tetracycline degradation. The findings indicated that the optimal degradation efficiency was observed at a catalyst concentration of 0.25 g/L and a solution pH of 9, leading to an impressive degradation rate of 96% within a mere 2 h timeframe.

The separation of He/H₂ using membrane technology has gained significant interest in the field of He extraction from natural gas. One of the greatest challenges associated with this process is the extremely close kinetic diameters of the two gas molecules, resulting in low membrane selectivity. In this study, we investigated the structure-performance relationship of metal-organic framework (MOF) membranes for He/H₂ separation through molecular simulations and machine learning approaches. By conducting molecular simulations, we identified the potential MOF membranes with high separation performance from the Computation-Ready Experimental (CoRE) MOF database, and the diffusion-dominated mechanism was further elucidated. Moreover, random forest (RF)-based machine learning models were established to identify the crucial factors influencing the He/H₂ separation performance of MOF membranes. The pore limiting diameter (PLD) and void fraction (φ), are revealed as the most important physical features for determining the membrane selectivity and He permeability, respectively. Additionally, density functional theory (DFT) calculations were carried out to validate the molecular simulation results and suggested that the electronegative atoms on the pore surfaces can enhance the diffusion-based separation of He/H₂, which is critical for improving the membrane selectivities of He/H₂. This study offers useful insights for designing and developing novel MOF membranes for the separation of He/H₂ at the molecular level.

The development of green route for preparing propylene oxide (PO) with molecular oxygen is of significance both in academic and industrial. In this work, propylene epoxidation coupled with furfural oxidation catalyzed by platinum meso-tetraphenylporphyrin (Pt (II)TPP) has been developed. Propylene conversion and PO selectivity reached up to 56% and 83%, respectively. Meanwhile, furfural was almost completely converted to furoic acid. Based on operando characterizations and electron paramagnetic resonance (EPR) tests, a mechanism involved high-valent Pt species was proposed. This work is expected to provide a potential application prospects for producing PO and furoic acid simultaneously in chemical industry.

To overcome the limitations of geography, climate, and ore characteristics on the ore beneficiation process, bio-oxidation studies on low-grade arsenic-bearing refractory gold ore by pool leaching were carried out, as well as process fitting analysis. The gold particles are encapsulated by pyrite and arsenopyrite. After 60 days of bio-oxidation, the oxidation rates of arsenic, sulfur, and gold were 39%∼69%, 24%∼41%, and 49%∼83%, respectively. The inoculated Acidithiobacillus ferrooxidans, Ferroplasma acidiphilum, and Leptospirillum ferrodiazotrophum could all mediate the initial pyrite/arsenopyrite oxidation and the Fe²⁺ oxidation reaction, but only the former could mediate the subsequent sulfur compound oxidation. When compared to daily bacterial circulation and bacterial replacement every ten days, aeration improved the gold leaching rate by 14%∼22%. The Boltzmann model could fit both the arsenic and sulfur bio-oxidation, with model fit variances greater than 0.98. Based on the experimental and fitting results, the bio-oxidation cycle was determined to be 60 days, and the bio-oxidation mechanisms are summarized. This study has significant practical implications for the rational utilization of gold resources and provides theoretical and practical guidance for similar gold ores.

The development of sustainable techniques to produce high-performance zeolite is essential to achieve green production in industry. Herein, we report an eco-friendly route to synthesizing hierarchical Beta zeolite from kaolinite and recycled mother liquor. The results reveal that the unutilized species (such as silicon species and Na⁺) in mother liquor stayed in a stable concentration during eleven recycled experiments. Moreover, the synthesized Beta zeolites still have comparable physicochemical properties and catalytic performance in the esterification of levulinic acid with ethanol over the initial zeolite although eleven recycled experiments. Life cycle assessment exhibits that the synthesis of Beta zeolite with recycled mother liquor can reduce global warming potential by 23% and resource depletion-water use by 36% compared to that without recycled mother liquor. This quantitatively demonstrates that the approach proposed in this work is really a sustainable one, extremely increasing the utilization efficiency of raw materials and decreasing the environmental burden.

Organic dye pollutants present in wastewater pose a significant global challenge. Among pollutants, the synthetic dye Rhodamine B (RB) stands out due to its non-biodegradable nature and associated neurotoxic, carcinogenic, and respiratory irritant properties. Extensive research has been conducted on the efficacy of adsorption and photodegradation techniques for the removal of RB from wastewater. While adsorption and advanced oxidation processes (AOPs) have gained considerable attention for their effectiveness in recent years, the underlying behaviors and mechanisms of these technologies remain incompletely understood. Therefore, a comprehensive summary of recent research progress in this domain is imperative to clarify the basics and present the up-to-date achievements.

This review provides an in-depth exploration of the fundamentals, advancements, and future trajectories of RB wastewater treatment technologies, mainly encompassing adsorption and photodegradation. This work starts with a general introduction of outlining the sources, toxicity, and diverse applicable removal strategies. Subsequently, it thoroughly examines crucial techniques within non-photochemical, photochemical, and adsorption technologies, such as UV light assisted AOP, catalyst assisted AOP, ozonation, Fenton system, electrochemical AOP, and adsorption technology. The primary objective is to furnish a broad overview of these techniques, elucidating their effectiveness, limitations, and applicability. Following this, the review encapsulates state-of-the-art computational simulations pertaining to RB adsorption and interactions with clays and other adsorbents. Lastly, it delves into column adsorption of RB dye, and elucidates various influencing factors, including bed height, feed concentration, pollutant (RB) feeding or flow rate, and column regeneration. This panoramic review aims to provide valuable insights into suitable techniques, research gaps, and the applicability of non-photochemical, photochemical, and adsorption technologies in the treatment of wastewater containing RB dye.

Utilizing ionic liquid (IL)-water mixtures as selective extraction solvents for raw materials from natural sources represents an efficacious approach; however, elucidating the underlying mechanisms inherent in various types of IL-aqueous solutions continues to pose a significant challenge. In this study, molecular dynamics simulations and density functional theory calculations are employed to illuminate the influence of the functional anion within ILs and the water content on the solvation mechanism and phase separation phenomena observed during the extraction of camptothecin (CPT) using aqueous IL solutions. The simulation results show that the anions in ILs preferentially dissolve CPT through hydrogen bonding at low water concentrations. As the water concentration increases, the hydrophobic IL binds more tightly to CPT, enabling the water to self-aggregate. The anions in hydrophilic IL form hydrogen bonds with water instead, further enhancing the dissolution of CPT. This work reveals the mechanism of phase separation and solvation of different types of IL aqueous solutions, which is helpful in developing new drug extraction and purification technologies.

Research on solvent effects is an important and long-standing topic, but there still is some room, especially for the special solvent effect of fluoroalcohols. In this work, we investigated the stability of phenoxyl radical in monohydric alcohol solvents through in-situ electron paramagnetic resonance detections. The decay behavior of phenoxyl radical showed a reasonable relationship with the mesoscopic structure of alcohols, characterized by small- and wide-angle X-ray scattering. Moreover, the distinct solvent effects of fluoroalcohols were emphasized, and the significant influence of van der Waals distance in the solvents was suggested. Overall, the stability of phenoxyl radical in alcohols was quantified and correlated with the solvent structures. We believe that the established method for stability study on radicals will encourage solvent effect studies on various organic reactions, and the proposed solvent effects in fluoroalcohols may inspire the development of green solvents in both industrial conversions and organic synthesis.