Green Chemistry最新文献

In order to develop intermittent renewable energy sources, the development of energy storage systems (ESSs) has become a research hotspot, but high capital and operating costs remain their main drawbacks. Vanadium redox flow batteries (VRFBs) have emerged as promising large-scale electrochemical EESs due to their environmental friendliness, persistent durability, and commercial value advantages. Significant efforts have been devoted to VRFB electrode modification to improve their economic applicability and electrochemical performance while retaining environmental friendliness. In this review, the progress of VRFBs’ electrode treatment is summarized from the practical perspective. Considering the commercial prospects, this review provides an overview of these treatments for VRFB electrodes in terms of environmental friendliness, economic applicability, and electrochemical performance, which can be referred to as the “3Es”. The advantages and disadvantages of each processing method are analyzed with “3Es” as the standard, which provides a reference for the large-scale commercialization process of VRFBs. In the end, practical recommendations are put forward on the relationship between the development plan and the objectives of VRFB.

The necessary use of large amounts of a homogeneous electrolyte represents a major issue and challenge for the whole sustainability of electrosynthetic procedures. Herein, we report the use of a solid ammonium salt (e.g. Amberlyst-400-Cl, Amb-400-Cl) as a reusable electrolyte with excellent performance in the representative electrosynthesis of 2-arylbenzoxazoles. Amb-400-Cl works efficiently without adding any additional supporting electrolytes or mediators, and it can be reused without the need for a regeneration procedure. Exploiting this finding, a sustainable electro-promoted protocol has been developed under batch and flow conditions, which proves that the reported chemical and technological innovation leads to significant improvements compared to the literature processes. Extensive green metrics analysis has also been reported to fully quantify the advances in terms of sustainability.

Extraction of compounds with different physicochemical properties from a complex matrix usually involves several individual steps and requires large volumes of organic solvents. In this pioneering study, we propose a comprehensive two-step supercritical fluid extraction using carbon dioxide, ethanol, and water. This novel approach allows the extraction of non-polar and polar analytes within one run in two consecutive steps. Indeed, the first step with a dominant amount of CO₂ with only 2% cosolvent allowed the selective extraction of non-polar volatile terpenes only in 20 min. The conditions were then automatically switched. Increasing the cosolvent volume in the extraction solvent up to 44% (v/v) resulted in the extraction of more polar compounds, including flavonoids and phenolic acids, in 60 min. Importantly, switching the supercritical fluid extraction (SFE) conditions does not require any manual intervention but results in two separate fractions containing target compounds with distinctly different physicochemical properties. The novel method was verified in terms of repeatability, accuracy, precision, and greenness. Two-step SFE was applied to seven plant species differing in volatile terpenes and phenolic profiles. The results proved that this concept is suitable for the analysis of complex plant samples. In addition, it enables a reduction in the toxic solvents consumption, extraction time, and manual intervention required for traditional extraction approaches when isolating different groups of metabolites.

The key to extractive distillation separation lies in screening a suitable entrainer. Based on chemical process system engineering (PSE) concepts, a novel heuristic process prediction model is proposed with a minimized process economic cost index (PECI) for the efficient screening of an optimal green entrainer with the advantages of cost-effectiveness, environmental friendliness, and sustainability, followed by outlining the principles of characterizations and mathematical modeling in chemical ED processes. The relationships of α_HC/SOL and NTR with Q_R, TAC, PECI, and LTEDI indicated that the heuristic process prediction model was scientifically valid as well as efficient. Moreover, the proposed model progresses from binomial intersecting influencing factors to trinomial juxtaposing influencing factors; summarizes and discloses the system's theoretical rules and influencing elements of the changes in parameters and their relative volatility, avoiding the new azeotropes in the solvent recovery column; reduces the workloads of process simulation and optimization of distillation processes from (M × N) times to (1 + N) times; can be extended efficiently and accurately to provide the targeted prediction and systematic theoretical principles for separating different feed azeotropes, predicting and screening organic solvents, ionic liquids, deep eutectic solvents, and mixed solvents with the optimal TAC and environmental friendliness (AP and GWP) and sustainability (FETP, HTP, and TETP) as LCA impacts; has broad predictability and applicability combined with different process optimization algorithms; and provides infinite composite patterns and opportunities for integrating and developing innovative optimization module algorithms for future green chemical separation processes.

Developing highly active and low-cost electrocatalysts for efficient water electrolysis is of great significance for energy and environment sustainability. In this work, a highly efficient, durable and stable bi-functional electrocatalyst nickel carbide/nickel heterojunction on Ni foam (NF) (Ni₃C/Ni@NF) with an interconnected nano-sized nodule architecture was facilely synthesized via an in situ nickel metal–organic framework (Ni-MOF) pyrolysis process at relatively low temperature. The optimized Ni₃C/Ni@NF electrode exhibits outstanding catalytic performance with extremely low overpotentials of only 16 and 268 mV at current densities of 10 mA cm⁻² for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Furthermore, it exhibits overpotential as low as 1.55 V (η₁₀) for overall water splitting. The experimental studies and density functional theory (DFT) calculations clarified that the optimized synergistic effect of the Ni₃C/Ni heterojunction triggers the enlarged active surface area and rapid charge transfer, thus enhancing the intrinsic catalytic activity. This work paves a convenient pathway for the rational construction of robust Ni-based heterojunction electrocatalysts with high activity for hydrogen/oxygen production and energy conversion in practical applications.

The adoption of green chemistry principles has ushered in significant advancements in environmental safety and cost efficiency across various synthetic processes. One notable area of improvement lies in reducing the hazardous waste generated by using organic solvents in organic reactions. In contrast, the utilization of water as a solvent has emerged as a sustainable and environmentally friendly alternative. Micellar catalysis, driven by tailor-made surfactants, has played a pivotal role in enhancing water's efficacy as a solvent in organic synthesis. These designer surfactants boast unique structures that enhance the solubility of organic compounds in water and act as initiators or stabilizers for nanoparticle catalysts, facilitating efficient catalysis. Micelles function as nanoreactors, creating localized high concentrations of reactants that lead to unprecedented reaction rates and exceptional selectivity. This review underscores the plethora of sustainable protocols that have yielded outstanding results by leveraging aqueous micellar chemistry in pharmaceutical synthesis. Moreover, the review explores the integration of nanocatalysis using readily available first-row transition metals, with a particular emphasis on the role of surfactants in stabilizing the catalyst. The versatility of the proline-based surfactant PS-750-M as a ligand or capping agent, enabling ligand-free metal nanocatalysis, is also addressed. Lastly, the review addresses current challenges and future avenues in green chemistry, stressing the importance of ongoing research and innovation.

Enzymatic synthesis of enantiopure chiral halogenated aryl alcohols by ketoreductases (KREDs) is emerging but still challenging, due to the low solubility and slow mass transfer in aqueous media. As an eco-friendly tool for this issue, amphiphilic micelles are attractive. Herein, KRED-catalyzed reduction of halogenated aryl ketones in a TPGS-750-M formed aqueous micellar solution was conducted, achieving the corresponding chiral alcohols with moderate to excellent yields of up to 99% and remarkable enantioselectivities of >99% ee under the optimal conditions. Notably, the performance strengthening mechanisms of micelles in this process are illustrated, in which the solubilization position of the substrate plays an essential role and the substrates solubilized in the palisade layer of the micelles exhibit the highest increases in conversion and enantioselectivity. These findings provide guidance for rational design of enzyme catalysis in aqueous micellar media.

One of the major problems affecting the energetic characteristics and cycle life of electrochemical capacitors (ECs) utilizing aqueous electrolytes is the narrow operating voltage range, which is limited by the thermodynamic stability of water (1.23 V). An improvement in the EC energy can be realized by a capacitance and/or voltage increase. For that purpose, cost-effective and environmentally friendly iodides have been added to aqueous electrolytes to improve the redox activity. Moreover, buffer agents (acetate, citrate, and phosphate) that are well known for adjusting the pH of an electrolyte have been applied, which enabled ECs to reach a stable operating voltage of 1.5 V. After adding iodide to the buffer system, the conductivity increased notably, whereas the pH values remained nearly the same. Galvanostatic charge/discharge test (0.5 A g⁻¹) for ECs operating in buffer electrolytes containing 0.2 mol L⁻¹ NaI showed that this additive noticeably increased the specific capacitance values from 91 to 149 F g⁻¹ for acetate buffer, from 7 to 101 F g⁻¹ for citrate buffer, and from 22 to 132 F g⁻¹ for phosphate buffer. The long-time performance of the ECs was investigated through accelerated potentiostatic floating. The electrochemical performance was studied using various activated carbons. During the floating aging test, the YP50F-based EC working in acetate buffer with 0.2 mol L⁻¹ NaI displayed the best long-term performance (310 h) compared to YP80F and BP2000 carbons, which exhibited 212 h and 126 h, respectively. The highly microporous YP50F carbon in the acetate buffer/iodide electrolyte revealed the best wettability. Interestingly, the citrate buffer/iodide EC system with YP50F demonstrated an extremely long floating performance (1006 h). Thus, this study presents a new strategy for improving the energetic metrics and cycling performance of carbon-based ECs operating in buffer electrolytes with an iodide redox pair.

Herein, we present electrochemical depolymerisation as a promising new technique for chemical recycling of polylactic acid. Using platinum electrodes and a current density of 50 mA cm⁻², a maximum yield of 87% lactic acid was obtained. Moreover, first mechanistic insights, the effect of the reaction conditions, and application to real waste streams are discussed in the following.