Samer Aouad

Light-up luminescent covalent organic framework (COF) sensors hold promise for rapid and selective detection of molecular pollutants, yet their performance is often limited by insufficient guest-induced rigidity and incomplete mechanistic understanding. Here, we introduce a pyrene-functionalized flexible covalent organic framework (PY-TTA COF) that undergoes a guest-induced molecular-locking process upon exposure to perfluorooctanoic acid (PFOA), producing a pronounced fluorescence turn-on response in aqueous media. The pendent pyrene chromophores, which project into the pore interior, create an adaptable microenvironment in which PFOA binding, involving hydrogen-bonding interactions, possible proton-transfer processes at imine/pyridine nitrogen sites, and C–F···π interactions, restricts local molecular motions and enhances radiative emission. Solid-state NMR spectroscopy, supported by semiempirical calculations, provides molecular-level insight into the hydrogen-bonding and fluorine–aromatic proximities associated with this locking effect, while PXRD and TEM reveal guest-induced structural modulation while confirming preservation of framework crystallinity. This guest-locked luminescence enhancement enables fluorescence-based and recyclable detection of PFOA with a limit of detection of 2.7 μg L–1. The demonstrated mechanism establishes a design strategy for developing stimuli-responsive COFs with tunable photophysical properties and environmentally relevant sensing capabilities.

In this work, the use of a banana peel-derived basic heterogeneous catalyst is investigated for producing biodiesel from sunflower oil. The catalyst is produced by treating dried banana peels at 700 °C under normal atmosphere for 4 h. The reaction parameters were optimized by varying the methanol-to-oil molar ratio (MOMR) and the catalyst-to-oil ratio (CTOR). The highest conversion of sunflower oil to biodiesel (99.4%) was attained after a reaction time of 90 min using an MOMR of 9:1, a catalyst loading of 4 wt%, and a stirring rate of 300 rpm. The catalyst demonstrated good stability, with a yield of 99.4% (±0.28%) obtained over three consecutive runs. No active phase loss was observed during the consecutive reactions, as confirmed by the leaching test. The physical and chemical properties of the formed biodiesel were in good accordance with the American Society for Testing and Materials (ASTM) standards. The kinetic study allowed for the determination of the activation energy (Ea = 58.1 kJ/mol) and pre-exponential factor (A = 7.4 × 10⁷ min⁻¹) of the catalyzed reaction. Additionally, the valorization of waste cooking oil (WCO) (a second-generation feedstock oil) using the waste banana peel-derived catalyst under optimum reaction conditions achieved a yield of 99.1% (±0.14%).

A major hurdle in the commercialization of biodiesel production is the cost of the process especially the cost of the raw feedstock material. Waste cooking oil is a very prominent and economical energy source for producing biodiesel as its use can greatly reduce waste whilst also generating a renewable and sustainable biofuel. In this work, an energy balance and an economic analysis of biodiesel production using both edible sunflower oil and waste cooking oil (WCO) were conducted. Two types of catalyst were studied: a homogeneous catalyst (KOH) and a heterogeneous catalyst (CaO derived from Noble Pectin seashells). The use of WCO for biodiesel production using CaO derived from Noble Pectin seashells was found to be an energy gain process, with a net energy gain of 8.64 MJ per liter of produced biodiesel and an energy use efficiency greater than 1. The total energy input and output were calculated as 36.18 and 44.82 MJ/L respectively. Moreover, the economic analysis of the process showed a benefit‐to‐cost ratio of 2.60. Hence, the use of WCO as a second‐generation feedstock serves as a novel and cost‐effective approach for the production of biofuels. Although studies, such as this one, prove the potential of WCO for biodiesel production on an economic and energy basis, several research gaps still remain before practical application can be adopted. Therefore, more research efforts are still required to study the use and application of WCO for biodiesel production on an industrial scale.

Layered double hydroxides (LDHs) are promising because of some of their several interesting characteristics. LDHs can be synthesized using different preparation methods. The application of ultrasounds (US) in the preparation method leads to reduced synthesis times and better dispersion of particles characterized by small size and narrower particle size distribution. Consequently, the specific surface area is higher in US-prepared samples compared to materials prepared by classical methods. These modified characteristics are responsible for improving the performances of LDHs used as catalyst precursors, adsorbents of dyes and heavy metals, fire suppressants, and other applications.

The production of biodiesel from refined sunflower vegetable oil over basic CaO/ZSM‐5 catalysts was investigated. Several catalysts with various loadings of CaO on ZSM‐5 were prepared, calcined at 800 °C, and characterized by N₂ adsorption‐desorption, X‐ray diffraction, Fourier transform infrared spectroscopy, and CO₂‐temperature‐programmed desorption techniques. Calcined catalysts were tested in the transesterification reaction and reaction conditions were optimized by varying the catalyst‐to‐oil ratio and reaction time. The most active catalyst was the CaO/ZSM‐5 catalyst with a 35 wt % loading which gave the highest fatty acid methyl ester yield. The high catalytic activity was attributed to the active basic sites generated following CaO addition. Furthermore, the catalyst demonstrated stability against the leaching process.