Toluene adsorption on porous Cu-BDC@OAC composite at various operating conditions: optimization by response surface methodology

In Situ Design of a Nanostructured Interface between NiMo and CuO Derived from Metal-Organic Framework for Enhanced Hydrogen Evolution in Alkaline Solutions

Hydrogen shows great promise as a carbon-neutral energy carrier that can significantly mitigate global energy challenges, offering a sustainable solution. Exploring catalysts that are highly efficient, cost-effective, and stable for the hydrogen evolution reaction (HER) holds crucial importance. For this, metal-organic framework (MOF) materials have demonstrated extensive applicability as either a heterogeneous catalyst or catalyst precursor. Herein, a nanostructured interface between NiMo/CuO@C derived from Cu-MOF was designed and developed on nickel foam (NF) as a competent HER electrocatalyst in alkaline media. The catalyst exhibited a low overpotential of 85 mV at 10 mA cm-2 that rivals that of Pt/C (83 mV @ 10 mA cm-2). Moreover, the catalyst's durability was measured through chronopotentiometry at a constant current density of -30, -100, and -200 mA cm-2 for 50 h each in 1.0 M KOH. Such enhanced electrocatalytic performance could be ascribed to the presence of highly conductive C and Cu species, the facilitated electron transfer between the components because of the nanostructured interface, and abundant active sites as a result of multiple oxidation states. The existence of an ionized oxygen vacancy (Ov) signal was confirmed in all heat-treated samples through electron paramagnetic resonance (EPR) analysis. This revelation sheds light on the entrapment of electrons in various environments, primarily associated with the underlying defect structures, particularly vacancies. These trapped electrons play a crucial role in augmenting electron conductivity, thereby contributing to an elevated HER performance.

Development of a Green Single Drop Microextraction Based on Deep Eutectic Solvent and HPLC-UV for Trace Residue Analysis of Three Frequent-Used Pesticides

Background

A green sample preparation method named deep eutectic solvent-based single drop microextraction (DES-SDME) was developed and optimized for determining trace metribuzin, dichlorvos, and fenthion.

Methods

Two hundred seventy experimental runs were performed, and the optimal values of the five influential factors in the DES-SDME method were determined. The design of the study was based on one factor at a time and the peak area of high-performance liquid chromatography was used as a benchmark for comparing analysis results.

Results

After optimizing the effective factors, the linearity range, detection limit and quantification limit of the method were determined by drawing calibration curves for the studied analytes.

Conclusion

The results indicated the success of the developed method in obtaining acceptable figures of merit as a green preparation method with accuracy and precision.

Phenolic Compounds Removal from Olive Mill Wastewater Using the Composite of Activated Carbon and Copper-Based Metal-Organic Framework

As the industry of olive oil continues to grow, the management of olive mill wastewater (OMW) by-products has become an area of great interest. While many strategies for processing OMW have been established, more studies are still required to find an effective adsorbent for total phenolic content uptake. Here, we present a composite of a Cu 1,4-benzene dicarboxylate metal-organic framework (Cu (BDC) MOF) and granular activated carbon (GAC) as an adsorbent for total phenolic content removal from OMW. Experimental results demonstrated that the maximum adsorption capacity was 20 mg/g of total phenolic content (TPC) after 4 h. using 2% wt/wt of GAC/Cu (BDC) MOF composite to OMW at optimum conditions (pH of 4.0 and 25 °C). The adsorption of phenolic content onto the GAC/Cu (BDC) MOF composite was described by the Freundlich adsorption and pseudo-second-order reaction. The adsorption reaction was found to be spontaneous and endothermic at 298 K where ΔS° and ΔH° were found to be 0.105 KJ/mol and 25.7 kJ/mol, respectively. While ΔGº value was -5.74 (kJ/mol). The results of this study provide a potential solution for the local and worldwide olive oil industry.

Toward High-Performance CO2 -to-C2 Electroreduction via Linker Tuning on MOF-Derived Catalysts

Copper (Cu)-based metal-organic frameworks (MOFs) and MOF-derived catalysts are well studied for electroreduction of carbon dioxide (CO₂ ); however, the effects of organic linkers for the selectivity of CO₂ reduction are still unrevealed. Here, a series of Cu-based MOF-derived catalysts is investigated with different organic linkers appended, named X-Cu-BDC (BDC = 1,4-benzenedicarboxylic acid, X = NH₂ , OH, H, F, and 2F). It is found that the linkers affect the faradaic efficiency (FE) for C₂ products with an order of NH₂  < OH < bare Cu-BDC < F < 2F, thus tuning the FE_C2 :FE_C1 ratios from 0.6 to 3.8. As a result, the highest C₂ FE of ≈63% at a current density of 150 mA cm^-2 on 2F-Cu-BDC derived catalyst is achieved. Using operando Raman measurements, it is revealed that the MOF derives to Cu₂ O during eCO₂ RR but organic linkers are stable. The fluorine group in organic linker can promote the H₂ O dissociation to *H species, further facilitating the hydrogenation of *CO to *CHO that helps CC coupling.