Current Research in Green and Sustainable Chemistry最新文献

In this study, iron oxide biochar nanocomposites made from khat leftover (KL) and coffee husk (CH) are investigated as possibly useful adsorbents for the removal of Cr (VI) from water. Biochar-based iron oxide nanocomposites were synthesized by pretreating 25 g of biomass with a 1:1 M ratio of FeS to FeCl₃ and pyrolyzing at 300 °C for 1 h. Pristine biochar, synthesized through biomass pyrolysis of CH and KL at 300 °C, removed 74.98% and 84.78% of Cr (VI) from aqueous solutions containing 20 mg L⁻¹, respectively. The corresponding nanocomposites showed a maximum removal efficiency for Cr (VI) of 99.83% with the iron oxide-coffee husk biochar nanocomposite (Fe₃O₄–CHBNC) and 99.86% with the iron oxide-khat leftover biochar nanocomposite (Fe₃O₄-KLBNC). A pseudo-second-order model and the Langmuir isotherm are both well-fitted by the adsorption process, suggesting advantageous monolayer adsorption. The Fe₃O₄–CHBNC and Fe₃O₄-KLBNC demonstrated satisfactory removal efficiencies even up to six cycles, indicating their potential effectiveness for large-scale use for treating wastewater contaminated by Cr (VI).

Electroorganic synthesis is a powerful sustainable tool for achieving greener and more efficient chemical processes across various industries. By adhering to the principles of green chemistry, atom economy, and resource efficiency, electroorganic synthesis can play a pivotal role in addressing environmental concerns and promoting a more sustainable future for chemical production. This review focuses on the latest advancements in the emerging application of electrochemistry in C-N bond formation through C-H/N-H cross-coupling. The first part of the review describes the electrochemical amination of arenes using metal catalysis (Cu, Co, Ni) with directing groups on the arene moiety. The next section addresses the same type of electrochemical C-N bond formation on arenes without directing groups, which represents a more general strategy enabling the synthesis of anilines and various heterocyclic-bound arenes in high yields. Further developments on benzylic systems are also discussed. This is followed by developments in the combination of photocatalysis and electrochemistry to activate C-H bonds in arenes, alkanes, and benzylic systems, including the use of flow reactor configurations for these reactions.

Multi-faceted growth and progression of the healthy and economical society, depends upon access to clean and safe water. Rapidly over-growing population, increased in industrialization, urbanisation, and widespread practices in agricultural have all together been contributing to the production of more rapid wastewater discharge, which has not only polluted or contaminated the water but also have played a role in killing the aquatic life. One class of harmful water pollutants that is frequently found in the environment is heavy metals. Almost every transition metal has the ability to dissolve as ions in water. Heavy metals including Pb, Cd, Hg, As, Se and others can contaminate water supplies. Conventional methods for waste-water treatment have peculiar challenges including economic feasibility, energy consumption, environmental hazards, time spent, etc. To overcome these limitations, nanotechnology have been developed, which has its greater extent of application in water treatment area. Nanoparticles have a greater probability of removing heavy metals from wastewater treatment due to their effective surface characteristics and chemical activity. This review focuses on the numerous treatment procedures that have been developed recently and also been applied practically for eradication of heavy metals from waste-water of various industries.

Nanocellulose materials are distinguished by their safety, biodegradability, and adaptability. It was shown that bacterial nanocellulose does not contain lignin and hemicellulose and has an ultrafine network structure. The wide compatibility of such materials with biological molecules and the ability to change their structure makes nanocellulose a promising material for medical applications. Today, in the production of nanocellulose, mainly softwood is used. Despite the obvious advantages of nanocellulose, the limiting factor in production is the high cost of wood raw materials and the environmental damage caused by deforestation. Therefore, there is increasing interest in cheap and annually renewable herbaceous plant biomass, which is a potential raw material with a negative cost for the synthesis of nanocellulose. This review aimed to evaluate the viability of using Miscanthus plant genus as the primary source of nanocellulose. The characteristics of various types of nanocellulose and methods for their preparation from miscanthus are discussed. Miscanthus plants are disease resistant, frost resistant, and grow rapidly. The biomass growth of this plant reaches 35 tons per hectare, and the life span of miscanthus reaches 20 years. Miscanthus is a promising source of nanocellulose crystals because it is rich cellulose. The development of effective methods for obtaining nanocellulose will allow the introduction of a new class of materials for the production of biotechnical composite liquid and solid compositions, as well as raw materials for the food, medical, and pharmaceutical industries.

Clove essential oil (CEO) is recognized for its variety of bioactivities and is widely used in the fields of food and pharmaceuticals. Eugenol is the main component that causes the oil's effectiveness. This study included a bibliometric analysis to demonstrate the novelty of the CEO extraction method. A combination of ultrasound and microwave techniques was utilized to enhance the efficiency of hydrodistillation (HD) extraction of essential oil from clove bud in terms of extraction yield, extraction rate, and eugenol composition, which is a strong antioxidant agent. Meanwhile, the effects of ultrasonic extraction temperature and time, microwave distillation power and time, and the ratio of clove to water were also investigated. The optimum conditions were as follows: ultrasonic extraction was at 40 °C for 45 min, microwave distillation power was 400 W for 45 min, and the clove to water ratio was 1:20 (g/mL). The ultrasound pretreatment prior to microwave-assisted hydrodistillation (U-MHD) method obtained the CEO, which had a significantly higher extraction yield (16.80 ± 0.26 %) and a greater amount of eugenol (78.49 %) than the CEOs obtained by traditional HD and MHD methods. Corresponding to the antioxidant activity of CEO from U-MHD, it possessed the strongest DPPH radical scavenging activity with an IC₅₀ value of 2.79 ± 0.05 μg/mL, and it was comparable to the activity of eugenol. This is the first occurrence of CEO extraction employing the U-MHD procedure. This process could be used to enhance the bioactivity of CEO as well as its extraction efficiency, easy operation, rapid extraction, and eco-friendly technique. In terms of cost-analysis, MHD stands out as the most economically viable extraction method, boasting the lowest cost per 100 g product. The obtained results serve as fundamental data for implementing the scaling up of extraction processes to an industrial level.

Expand emergence of antibiotic resistance in different strains of bacteria has become an essential global problem in the health area. This case leads to several medical difficulties such as increased death rates, high therapy costs and long-infected patients remaining in hospitals. This study is designed to evaluate the efficacy of incorporating antibiotics with nanomaterials to combat MDR bacteria. biogenic FeO NPs were synthesised using Hibiscus sabdariffa calyces extract through an eco-friendly and easy method. FeO NPs were subjected to characterisation using some physical techniques, including UV–Visible, FTIR, XRD, SEM and AFM. Characterisation results indicated that the FeO NPs exhibited a crystalline structure, mainly spherical, absorption peak between 290 and 300 nm, and had an average size of 61 nm. The bactericidal activity of the FeO NPs was estimated against three MDR pathogenic bacteria. The results revealed the efficacy of the FeO NPs in inhibiting the growth of the MDR K. pneumoniae, E. coli, and P. aeruginosa. The MIC of the FeO NPs against these bacteria was determined to be 6.25, 12.5, and 25 μg/ml for K. pneumoniae, E. coli, and P. aeruginosa, respectively. Moreover, when combined with antibiotics, the incorporation of FeO NPs significantly enhanced the effectiveness of multiple antibiotics against MDR bacteria. These findings suggest that FeO NPs have promising applications as antibacterial compounds and as additives to enhance antibiotic efficacy.

In the rapidly expanding field of nanoscience and research, AgNPs and their diverse by-products have been acknowledged as having a green approach. Fruit extract of Limonia acidissima L. is capable of bio-reducing AgNO₃ and stabilizing AgNPs. AgNPs distinctive absorption peak at 417 nm at pH 8 was visible on the UV-Vis spectrophotometer. The fruit extract contained bioactive chemicals, which may be the cause of the AgNPs bio-capping and stabilizing properties, according to Fourier transform infrared (FT-IR) spectroscopy. Using an X-ray diffractometer (XRD) examination, the AgNPs solid crystalline nature and size of 29.05 nm were investigated. Lastly, AFM and HR-TEM studies verified the AgNPs surface morphology, particularly their size and form. The DPPH assay method was used to measure the AgNPs capacity for radical scavenging. As compared to normal ascorbic acid and fruit extract (control), the AgNPs produced from the fruit extract demonstrated good antioxidant effectiveness. To evaluate the antibacterial activity of the AgNPs sample, it was additionally evaluated against E. coli, S. typhi, V. cholera, and S. aureus. With the greatest zone of inhibition and thus the strongest antibacterial activity, S. aureus (12.03 ± 0.043 mm) was the organism that displayed it. On the other hand, the least active strain was V. cholera (9.09 ± 0.013 mm). The data indicates that bio-fabricated silver nanoparticles (AgNPs) exhibited dose-dependent inhibitory efficacy together with a notable zone of inhibition. Additionally, S. aureus was shown to be more effective than V. cholera. Future health and pharmaceutical fields may benefit from the biocompatible method of separating AgNPs from L. acidissima fruit extract.

The first electrogeneration of O-centered radicals from N-alkoxyphthalimides via rapid alternating polarity (RAP) electrolysis, using previous experimental conditions of photoredox catalysis (PRC) is reported. The electrochemical methodology emulates satisfactorily the redox cycle behavior accepted to explain the PRC technique. Notably, the contribution of oxidized Hantzsch ester produced during the anodic reaction is emphasized, which behaves as an efficient proton donor to facilitate N–O cleavage and to extinguish the radical sequence efficiently. The reaction is conducted in a practical way using an undivided cell fitted with glassy carbon electrodes, allowing the same reactions to occur on both electrodes during the overall transformation reaching a 77% yield of the corresponding alcohol. This yield is higher than the electrochemical protocol using direct current electrolysis, confirming that the use of RAP electrolysis favors the proximity where the reactive intermediates are produced, facilitating their reaction to promote the desired reaction pathway.