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Biodiesel is generally obtained by transesterification and esterification of appropriate feedstocks facilitated by a catalyst. It has emerged to be one of the most potential alternatives for the conventional fuels gaining worldwide attention. Heterogeneous catalysts are usually preferred than homogeneous for biodiesel synthesis due to facile separation and insignificant soap formation. However, the separation still possesses difficulty leading to mass transfer hindrance. Therefore, these catalysts can be further modified using magnetic separation techniques to develop magnetically separable catalysts. The magnetic nanoparticles (MNPs) are notable appealing catalysts due to huge surface area, high activity, amicable functional groups and structures, adaptable properties, conformity in pore size, and facile separation have made them desirable catalyst carriers for biodiesel synthesis. The MNPs are modified via functionalization to construct magnetically recoverable heterogeneous nanocatalysts. Magnetic catalysts can be utilized as a befitting option for biodiesel synthesis as these are environmentally benign, highly reusable and economically viable. The current review article discusses different magnetic solid catalysts such as magnetic base, acid, biocatalysts and bifunctional of acid base catalysts for efficient biodiesel synthesis. The prime focus of this paper rest on the catalytic performances of various magnetically recoverable catalysts, mechanisms and recyclability for biodiesel production processes. The synthesis methods of magnetic heterogeneous base and acid nanocatalysts, magnetic properties, functionalization and their reciprocity on the catalytic activity are reviewed in this article.

The study involves a collection of data from the published article titled “Active sites engineered biomass-carbon as a catalyst for biodiesel production: Process optimization using RSM and life cycle assessment “Energy Conversion Management” journal. Here, the activated biochar was functionalized using 4-diazoniobenzenesulfonate to obtain sulfonic acid functionalized activated biochar. The catalyst was comprehensively characterized using XRD, FTIR, TGA, NH3-TPD, SEM-EDS, TEM, BET, and XPS analysis. Further, the obtained catalyst was applied for the transesterification of Jatropha curcas oil (JCO) to produce biodiesel. An experimental matrix was conducted using the RSM-CCD approach and the resulting data were analyzed using multiple regressions to fit a quadratic equation, where the maximum biodiesel yield achieved was 97.1 ± 0.4%, under specific reaction conditions: a reaction time of 50.3 min, a molar ratio of 22.9:1, a reaction temperature of 96.2 °C, and a catalyst loading of 7.7 wt.%. The obtained product biodiesel was analyzed using NMR and GC-MS analyzed and is reported in the above-mentioned article.

It is no longer unfamiliar to the world that usage of fossil-derived fuel is accompanied by several downsides, including environmental fatality associated with toxic gas emissions from diesel engines and the recurring surging price of diesel fuel. The concern regarding the exploitation of natural resources and subsequent environmental threats has caught the attention of all nations. Therefore, scientists have stepped forward to come up with the most suitable alternative to conventional diesel fuel. They utilized abundance of oil feedstocks and performed transesterification reactions with short-chain alcohols to produce less toxic, eco-friendly diesel fuel termed biodiesel which was considered to be a viable substitute. In order to carry out the transesterification reaction feasibly, certain homogeneous and heterogeneous catalysts were employed. Heterogeneous catalysts got more recognition among researchers; however, many of these catalysts did not attain large-scale production. Among many heterogeneous catalysts, calcium oxide (CaO) appeared to be one of the most suitable heterogeneous solid base catalysts for biodiesel synthesis. CaO can be derived chemically as well as from natural sources such as chicken eggshells, snail shells, biont shells and many more. CaO exhibits high catalytic activity to perform transesterification reactions. Additionally, CaO is a cheap and eco-friendly catalyst that can also be used as support material for various catalyst systems. Constructing effective CaO-based catalysts for industrial biodiesel production unlock the scope for process advancements in this area. This paper aims to review the catalytic performances of recently reported CaO as heterogeneous solid-base catalytic systems for the production of biodiesel. Moreover, the catalyst preparation conditions, various reaction parameters, properties of biodiesel obtained, advantages and disadvantages, life cycle assessment, and circular economy are discussed.

While formamidinium lead iodide (FAPbI3) halide perovskite (HP) exhibits improved thermal stability and a wide band gap, its practical applicability is chained due to its room temperature phase transition from pure black (α-phase) to a non-perovskite yellow (δ-phase) when exposed to humidity. This phase transition is due to the fragile ionic bonding between the cationic and anionic parts of HPs during their formation. Herein, we report the synthesis of water-stable, red-light-emitting α-phase FAPbI3 nanocrystals (NCs) using five different amines to overcome these intrinsic phase instabilities. The structural, morphological, and electronic characterization were obtained using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), and X-ray photoelectron spectroscopy (XPS), respectively. The photoluminescence (PL) emission and single-particle imaging bear the signature of dual emission in several amines, indicating a self-trapped excited state. Our simple strategy to stabilize the α-phase using various amine interfacial interactions could provide a better understanding and pave the way for a novel approach for the stabilization of perovskites for prolonged durations and their multifunctional applications.

In the present work, the preparation of AA-6082/ZrSiO4/TiC hybrid composite is studied along with an analysis of the effects of electrochemical machining parameters such as feed rate of electrode (FE), voltage (VO), electrolyte concentration (EL), and electrolyte discharge (ED) rate on the output responses of the material removal rate (MRR) and surface roughness (SR) for Al hybrid composites. The experiments are carried out based on the Taguchi L16 orthogonal array and the important process parameters are found for MRR and SR. Each parameter contains four different levels that are FE (0.10, 0.15, 0.20, and 0.25 mm/min), VO (10, 15, 20, and 25 V), EL (15, 20, 25, and 30 g/lit), and ED (1.5, 2, 2.5, and 3 lit/min).The optimization software, namely, Minitab-17 version helps to find the contribution of each parameter on MRR and SR. The ANOVA result reveals that the feed rate of electrode is the highest contributing parameter, trailed by the electrolyte discharge rate and other process parameters for MRR and SR. A linear model of regression and interaction plots is also included to show the relationship between the parameters. From the observational results, the highest MRR (0.00953 mg/min) is attained by the parameter combination level of the feed rate of electrode of 0.20 mm/min, voltage of 25 V, electrolyte concentration of 20 g/lit, and electrolyte discharge rate of 1.5 g/, whereas the lowest MRR is found at FE of 0.10 mm/min, VO of 10 V EL-15 g/lit and ED of 2.5 g/litre. For SR, the maximum and minimum are recognized at FE2-VO4-EL3-ED2 (0.15 mm/min, 25 V, 25 g/lit, and 2 lit/min) and FE1-VO1-EL1-ED1 (0.10 mm/min, 10 V, 15 g/lit, and 1.5 lit/min), respectively. Finally, the increment of MRR and SR values is mostly dependent on the feed rate of the electrode.

Photothermal (PT)-enhanced Fenton-based chemodynamic therapy (CDT) has attracted a significant amount of research attention over the last five years as a highly effective, safe, and tumor-specific nanomedicine-based therapy. CDT is a new emerging nanocatalyst-based therapeutic strategy for the in situ treatment of tumors via the Fenton reaction or Fenton-like reaction, which has got fast progress in recent years because of its high specificity and activation by endogenous substances. A variety of multifunctional nanomaterials such as metal-, metal oxide-, and metal-sulfide-based nanocatalysts have been designed and constructed to trigger the in situ Fenton or Fenton-like reaction within the tumor microenvironment (TME) to generate highly cytotoxic hydroxyl radicals (·OH), which is highly efficient for the killing of tumor cells. However, research is still required to enhance the curative outcomes and minimize its side effects. Specifically, the therapeutic efficiency of certain CDTs is still hindered by the TME, including low levels of endogenous hydrogen peroxide (H2O2), overexpression of reduced glutathione (GSH), and low catalytic efficacy of Fenton or Fenton-like reactions (pH 5.6–6.8), which makes it difficult to completely cure cancer using monotherapy. For this reason, photothermal therapy (PTT) has been utilized in combination with CDT to enhance therapeutic efficacy. More interestingly, tumor heating during PTT not only causes damage to the tumor cells but can also accelerate the generation of ·OH via the Fenton and Fenton-like reactions, thus enhancing the CDT efficacy, providing more effective cancer treatment when compared with monotherapy. Currently, synergistic PT-enhanced CDT using multifunctional nanomaterials with both PT and chemodynamic properties has made enormous progress in cancer theranostics. However, there has been no comprehensive review on this subject published to date. In this review, we first summarize the recent progress in PT-enhanced Fenton-based CDT for cancer treatment. We then discuss the potential and challenges in the future development of PT-enhanced Fenton-based nanocatalytic tumor therapy for clinical application.