Recovery/Reuse of Heterogeneous Supported Spent Catalysts

Green synthesis of manganese ferrite magnetic nanoparticle and its modification with metallic-organic frameworks for the tetracycline adsorption from aqueous solutions: A mathematical study of kinetics, isotherms, and thermodynamics

In the current investigation, MnFe2O4/ZIF-8 nanocomposite was generated as a magnetic nanoadsorber using the extract of Dracocephalum plant and characterized by XRD, FTIR, VSM, BET, FESEM, EDS-mapping, TEM, XPS, TPD-NH3, and TGA analyses. Also, to determine its efficiency in the adsorption process of tetracycline, the effect of pH (3-9), nanocomposite dose (0.025-2 g/L), initial pollutant concentration (5-100 mg/L), contact time (5-200 min), and temperature (5-50 °C) were studied. The results of the morphological properties of the magnetic nanocomposite confirmed the spherical shape of this nanoadsorber with an average size of 54 ± 31 nm. BET analysis showed that modification of MnFe2O4 material with ZIF-8 as a new nanoadsorber leads to excellent modification of SBET (143.8 m2/g) and VTotal (0.44 cm3/g). The highest removal efficiency of tetracycline in optimal conditions (pH = 7, contact time = 120 min, nanocomposite dose = 1.5 g/L, and temperature = 20 °C for a tetracycline concentration of 20 mg/L) was 90.11%. As the temperature increased, the removal efficiency increased from 40.46% to 95.06% during 120 min, which indicates that the adsorption reaction is endothermic. In addition, the data obtained from the isotherms of Langmuir (R2 = 0.958), Freundlich (R2 = 0.534), and Temkin (R2 = 0.747) showed that the tetracycline adsorption is monolayer and on the homogeneous surface of the synthesized magnetic nanoadsorber. The elimination process of tetracycline by nanoadsorber followed the pseudo-second order model (R2 = 0.998). Investigating the effect of interfering ions also confirmed the decrease in the adsorption efficiency. Also, the investigation of the reusability of the synthesized magnetic nanoadsorber in tetracycline adsorption indicates that after eight cycles, the efficiency decreases by %16.51. According to the results, the magnetic nanocomposite synthesized in this work can be a suitable and economical adsorber for the removal of tetracycline from aqueous environments.

3-(Sulfamic acid)-propyltriethoxysilane on biochar nanoparticles as a practical, biocompatible, recyclable and chemoselective nanocatalyst in organic reactions

Recyclable and inexpensive catalysts, waste regeneration, use of available and safe solvents are important principles of green chemistry. Therefore, in this project, biochar nanoparticles (BNPs) were synthesized by the pyrolysis method from chicken manure. Then, 3-(sulfamic acid)-propyltriethoxysilane (SAPES) was immobilized on the surface of BNPs (SAPES@BNPs). The prepared catalyst (SAPES@BNPs) was used as a commercial, practical, biocompatible and reusable catalyst in the selective oxidation of sulfides to sulfoxides. Further, the catalytic application of SAPES@BNPs was explored in the multicomponent synthesis of tetrahydrobenzo[b]pyrans under mild and green conditions. BNPs were characterized using SEM, TGA and XRD techniques. SAPES@BNPs were characterized using SEM, FT-IR spectroscopy, WDX, EDS, TGA, and XRD techniques. Particle size distribution was obtained by histogram graph. SAPES@BNPs can be recovered and reused several times. The purity of the products was studied using NMR spectroscopy.

The covalent immobilization of β-galactosidase from Aspergillus oryzae and alkaline protease from Bacillus licheniformis on amino-functionalized multi-walled carbon nanotubes in milk

This study aimed was to covalently immobilize β-galactosidase from Aspergillus oryzae and protease from Bacillus licheniformis on amino-functionalized multi-walled carbon nanotubes. In this study, a two-level factorial design was employed to investigate the impact of seven continuous variables (activation pH, glutaraldehyde molarity, activation time (0-8 h), buffer solution pH (8-0), buffer solution molarity, MWCNT-NH 2 -glutaraldehyde quantity, and stabilization time (0-180 h)) on the immobilization efficiency and enzymatic activity of protease and β-galactosidase. Furthermore, the effect of time on the percentage of enzymatic activity was examined during specific intervals (24, 48, 72, 96, and 120 h) of the immobilization process. The analysis of variance results for protease enzymatic activity revealed a notable influence of the seven variables on immobilization efficiency and enzymatic activity. Additionally, the findings indicate that activation time, buffer pH, MWCNT-NH 2 -glutaraldehyde quantity, and stabilization time significantly affect the activity of the protease enzyme. The interplay between buffer pH and stabilization time is also significant. Indeed, both activation time and the quantity of MWCNT-NH 2 -glutaraldehyde exert a reducing effect on enzyme activity. Notably, the influence of MWCNT-NH 2 -glutaraldehyde quantity is more significant (p < 0.05). In terms of beta-galactosidase enzymatic activity, the study results highlight that among the seven variables considered, only the glutaraldehyde molarity, activation time, and the interplay of activation time and the quantity of MWCNT-NH 2 -glutaraldehyde can exert a statistically significant positive impact on the enzyme's activity (p < 0.05). The combination of activation time and buffer solution molarity, as well as the interactive effect of buffer pH and MWCNT-NH2-glutaraldehyde, can lead to a significant improvement in the stabilization efficiency of the protease of carbon nanotubes. The analysis of variance results demonstrated that the efficiency of covalently immobilizing β-galactosidase from Aspergillus oryzae on amino-functionalized multi-walled carbon nanotubes is influenced by the molarity of glutaraldehyde, buffer pH, stabilization time, and the interplay of activation time + buffer pH, buffer pH + activation time, activation time + buffer molarity, and glutaraldehyde molarity + MWCNT-NH 2 -glutaraldehyde (p < 0.05). Through the optimization and selection of optimal formulations, the obtained results indicate enzyme activities and stabilization efficiencies of 64.09 % ± 72.63 % and 65.96 % ± 71.77 % for protease and beta-galactosidase, respectively. Moreover, increasing the enzyme stabilization time resulted in a reduction of enzyme activity. Furthermore, an increase in pH, temperature, and the duration of milk storage passing through the enzyme-immobilized carbon nanotubes led to a decrease in enzyme stabilization efficiency, and lactose hydrolysis declined progressively over 8-h. Hence, the covalent immobilization of β-galactosidase from Aspergillus oryzae and protease from Bacillus licheniformis onto amino-functionalized multi-walled carbon nanotubes is anticipated to be achievable for milk applications.

Organosulphur and organoselenium compounds as ligands for catalytic systems in the Sonogashira coupling

Sonogashira coupling is a reaction of aryl/vinyl halides with terminal alkynes. It is used for the synthesis of conjugated enynes. Generally, copper (Cu) is required as a mediator for this reaction. It requires a long reaction time, high catalyst loading, or expensive ligands. Recently, homogeneous, heterogeneous, and nanocatalysts have been developed using organosulphur and organoselenium compounds as building blocks. Preformed complexes of metals with organosulphur and organoselenium ligands are used for homogeneous catalysis. Heterogeneous catalytic systems have also been developed using Cu, Pd, and Ni as metals. The nanocatalytic systems (synthesized using such ligands) include copper selenides and stabilized palladium(0) nanospecies. This article aims to cover the developments in the field of the processes and techniques used so far to generate catalytically relevant organic ligands having sulphur or selenium donor sites, the utility of such ligands in the syntheses of homogeneous, heterogeneous, and nanocatalytic systems, and critical analysis of their application in the catalysis of this coupling reaction. The results of catalysis are analyzed in terms of the effects of the S/Se donor, halogen atom of aryl halide, the effect of the presence/absence of electron-withdrawing or electron-donating groups or substituents on the aromatic ring of haloarenes/substituted phenylacetylenes, as well as the position (ortho or para) of the substitution. Substrate scope is discussed for all the kinds of catalysis. The supremacy of heterogeneous and nanocatalytic systems indicates promising future prospects.

Copper-Based Two-Dimensional Metal-Organic Frameworks for Fenton-like Photocatalytic Degradation of Methylene Blue under UV and Sunlight Irradiation

To efficiently degrade organic pollutants, photocatalysts must be effective under both ultraviolet (UV) radiation and sunlight. We synthesized a series of new metal-organic frameworks by using mild hydrothermal conditions. These frameworks incorporate three distinct bipyridyl ligands: pyrazine (pyr), 4,4'-bipyridine (bpy), and 1,2-bis(4-pyridyl)ethane (bpe). The resulting compounds are denoted as [Cu(pyz)(H2O)2MF6], [Cu(bpy)2(H2O)2]·MF6, and [Cu(bpe)2(H2O)2]·MF6·H2O [M = Zr (1, 3, and 5) and Hf (2, 4, and 6)]. All six compounds exhibited a two-dimensional crystal structure comprising infinitely nonintersecting linear chains. Compound 3 achieved 100% degradation of methylene blue (MB) after 8 min under UV irradiation and 100 min under natural sunlight in the presence of H2O2 as the electron acceptor. For compound 5, 100% MB degradation was achieved after 120 min under sunlight and 10 min under UV light. Moreover, reactive radical tests revealed that the dominant species involved in photocatalytic degradation are hydroxyl (•OH), superoxide radicals (•O2-), and photogenerated holes (h+). The photodegradation process followed pseudo-first-order kinetics, with photodegradation rate constants of 0.362 min-1 (0.039 min-1) for 3 and 0.316 min-1 (0.033 min-1) for 5 under UV (sunlight) irradiation. The developed photocatalysts with excellent activity and good recyclability are promising green catalysts for degrading organic pollutants during environmental decontamination.

Silver oxide doped iron oxide/alginate nanocomposite coated cotton cloth for selective catalytic reduction of potassium ferricyanide

Silver oxide doped iron oxide (Ag2O-Fe2O3) nanocatalyst was prepared and coated on cotton cloth (CC) as well as wrapped in sodium alginate (Alg) hydrogel. Ag2O-Fe2O3 coated CC (Ag2O-Fe2O3/CC) and Ag2O-Fe2O3 wrapped Alg (Ag2O-Fe2O3/Alg) were utilized as catalysts in reduction reaction of 4-nitrophenol (4-NP), congo red (CR), methylene blue (MB) and potassium ferricyanide (K3[Fe(CN)6]). Ag2O-Fe2O3/CC and Ag2O-Fe2O3/Alg were found to be effective and selective catalyst for the reaction of K3[Fe(CN)6]. Further amount of catalyst, K3[Fe(CN)6] quantity, amount of NaBH4, stability of catalyst and recyclability were optimized for the reaction of K3[Fe(CN)6] reduction. Ag2O-Fe2O3/Alg and Ag2O-Fe2O3/CC were appeared to be the stable catalysts by maintaining high activity during recyclability tests showing highest reaction rate constants (kapp) of 0.3472 and 0.5629 min-1, correspondingly. However, Ag2O-Fe2O3/CC can be easily recovered as compared to Ag2O-Fe2O3/Alg by simply removing from the reaction which is the main advantage of Ag2O-Fe2O3/CC. Moreover, Ag2O-Fe2O3/Alg and Ag2O-Fe2O3/CC were also examined in real samples and found useful for K3[Fe(CN)6] reduction involving real samples. The Ag2O-Fe2O3/CC nanocatalyst is a cost and time saving material for economical reduction of K3[Fe(CN)6] and environmental safety.

Significantly enhanced catalytic performance of Pd nanocatalyst on AlOOH featuring abundant solid surface frustrated Lewis pair for improved hydrogen activation

The catalytic performance of a catalyst is significantly influenced by its ability to activate hydrogen. Constructing frustrated Lewis pairs (FLPs) with the capacity for hydrogen dissociation on non-reducible supports remains a formidable challenge. Herein, we employed a straightforward method to synthesize a layered AlOOH featuring abundant OH defects suitable for constructing solid surface frustrated Lewis pair (ssFLP). The results indicated that the AlOOH-80 (synthesized at 80 °C) possessed an appropriate crystalline structure conducive to generating numerous OH defects, which facilitated the formation of ssFLP. This was further evidenced by the minimal water adsorption in the AlOOH-80, inversely correlated with the quantity of defects in the catalyst. As expected, the Pd loaded onto AlOOH (Pd/AlOOH-80) exhibited excellent catalytic activity in hydrogenation reactions, attributed to abundant defects available for constructing ssFLP. Remarkably, the Pd/AlOOH-80 catalyst, with larger-sized Pd nanoparticles, displayed notably superior activity compared to commercial Pd/Al2O3 and Pd/C, both featuring smaller-sized Pd nanoparticles. Evidently, under the influence of ssFLP, the size effect of Pd nanoparticles did not dominate, highlighting the pivotal role of ssFLP in enhancing catalytic performance. This catalyst also exhibited exceptionally high stability, indicating its potential for industrial applications.

Integrated In Situ Fabrication of CuO Nanorod-Decorated Polymer Membranes for the Catalytic Flow-Through Reduction of p-Nitrophenol

We developed a novel method to fabricate copper nanorods in situ in a poly(ether sulfone) (15 wt %) casting solution by a sonochemical reduction of Cu2+ ions with NaBH4. The main twist is the addition of ethanol to remove excess NaBH4 through Cu(0) catalyzed ethanolysis. This enabled the direct use of the resulting copper-containing casting dispersions for membrane preparation by liquid nonsolvent-induced phase separation and led to full utilization of the copper source, generating zero metal waste. We characterized the copper nanorods as presented in the membranes via scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and UV/vis spectroscopy. We could demonstrate that the rapid immobilization from reducing conditions led to the membrane incorporation of copper nanorods in a state of high reactivity, which also promoted the complete oxidation to CuO after fabrication. We further observed a large aspect ratio and crystal straining of the nanorods, likely resulting from growth around the matrix polymer. The entanglement with poly(ether sulfone) further facilitated a selective presentation at the pore surface of the final CuO-decorated membranes. The membranes also exhibit high water permeances of up to 2800 L/m2hbar. Our catalytic membranes achieved exceptionally high activities in the aqueous flow-through reduction of p-nitrophenol (p-NP), with turnover frequencies of up to 115 h-1, even surpassing those of other state-of-the-art catalytic membranes that incorporate Pd or Ag. Additionally, we demonstrated that catalytic hydrolysis of the reducing agent in water can lead to hydrogen gas formation and blocking of active sites during continuous catalytic p-NP hydrogenation. We illustrated that the accompanying conversion loss can be mitigated by facilitated gas transport in the water-filled pores, which is dependent on the orientation of the pore size gradient and the flow direction.

Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of -5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Algal carbohydrate polymers: Catalytic innovations for sustainable development

Algal polysaccharides, harnessed for their catalytic potential, embody a compelling narrative in sustainable chemistry. This review explores the complex domains of algal carbohydrate-based catalysis, revealing its diverse trajectory. Starting with algal polysaccharide synthesis and characterization methods as catalysts, the investigation includes sophisticated techniques like NMR spectroscopy that provide deep insights into the structural variety of these materials. Algal polysaccharides undergo various preparation and modification techniques to enhance their catalytic activity such as immobilization. Homogeneous catalysis, revealing its significance in practical applications like crafting organic compounds and facilitating chemical transformations. Recent studies showcase how algal-derived catalysts prove to be remarkably versatile, showcasing their ability to customise reactions for specific substances. Heterogeneous catalysis, it highlights the significance of immobilization techniques, playing a central role in ensuring stability and the ability to reuse catalysts. The practical applications of heterogeneous algal catalysts in converting biomass and breaking down contaminants, supported by real-life case studies, emphasize their effectiveness. In sustainable chemistry, algal polysaccharides emerge as compelling catalysts, offering a unique intersection of eco-friendliness, structural diversity, and versatile catalytic properties. Tackling challenges such as dealing with complex structural variations, ensuring the stability of the catalyst, and addressing economic considerations calls for out-of-the-box and inventive solutions. Embracing the circular economy mindset not only assures sustainable catalyst design but also promotes efficient recycling practices. The use of algal carbohydrates in catalysis stands out as a source of optimism, paving the way for a future where chemistry aligns seamlessly with nature, guiding us toward a sustainable, eco-friendly, and thriving tomorrow. This review encapsulates-structural insights, catalytic applications, challenges, and future perspectives-invoking a call for collective commitment to catalyze a sustainable scientific revolution.

Aviation fuel based on wastewater-grown microalgae: Challenges and opportunities of hydrothermal liquefaction and hydrotreatment

The current technical issues related to the conversion of algal biomass into aviation biofuel through hydrothermal liquefaction (HTL) and the upgrading of bio-oil through hydrotreatment have been reviewed and consolidated. HTL is a promising route for converting microalgae into sustainable aviation fuel (SAF). However, HTL must be followed by the hydrotreatment of bio-oil to ensure that its composition and properties are compatible with SAF standards. The fact that microalgae offer the possibility of recovering wastewater treatment resources not only makes them more attractive but also serves as an incentive for wastewater treatment, especially in countries where this service has not been universalized. The combination of SAF and wastewater treatment aligns with the Sustainable Development Goals of the United Nations, representing an advantageous opportunity for both aviation and sanitation. In this context, the utilization of HTL by-products in the concept of a biorefinery is essential for the sustainability of aviation biofuel production through this route. Another important aspect is the recovery and reuse of catalysts, which are generally heterogeneous, allowing for recycling. Additionally, discussions have focused on biomass pretreatment methods, the use of solvents and catalysts in HTL and hydrotreatment reactions, and the operational parameters of both processes. All these issues present opportunities to enhance the quantity and quality of bio-oil and aviation biofuel.

Nanomagnetic CoFe2O4@SiO2-EA-H3PO4 as a zwitterionic catalyst for the synthesis of bioactive pyrazolopyranopyrimidines and dihydropyrano[2,3-c]pyrazoles

This study presents the development of a phosphoric acid-based zwitterionic catalyst immobilized on CoFe2O4 nanoparticles [CoFe2O4@SiO2-EA-H3PO4]. The structure of the nanocatalyst CoFe2O4@SiO2-EA-H3PO4 was identified by applying several spectroscopic techniques, i.e. FT-IR, SEM, TEM, XRD, EDX, elemental Mapping, VSM, TGA, and BET techniques. The catalytic efficiency of CoFe2O4@SiO2-EA-H3PO4 was evaluated in the water-based multicomponent synthesis of pyrazolopyranopyrimidine and dihydropyrano[2,3-c]pyrazole derivatives. Subsequently, an exploration of the antibacterial properties of the compounds was conducted. The catalytic system offers several advantages, encompassing high efficiency, brief reaction duration, uncomplicated operation, and facile recycling of the catalyst.

Effect of copper doping on the photocatalytic performance of Ni2O3@PC membrane composites in norfloxacin degradation

In this study, copper (Cu) and nickel oxide (Ni2O3) microtubes (MTs) were synthesized using an electroless template deposition technique within porous polycarbonate (PC) track-etched membranes (TeMs) to obtain Cu@PC and Ni2O3@PC composite membranes, respectively. The pristine PC TeMs featured nanochannels with a pore density of 4 × 107 pores per cm2 and an average pore diameter of 400 ± 13 nm. The synthesis of a mixed composite, combining Cu and Ni2O3 within the PC matrix, was achieved through a two-step deposition process using a Ni2O3@PC template. An analysis of the resultant composite structure (Cu/Ni2O3@PC) confirmed the existence of CuNi (97.3%) and CuO (2.7%) crystalline phases. The synthesized catalysts were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) analysis, and atomic force microscopy (AFM). In photodegradation assessments, the Cu/Ni2O3@PC mixed composite demonstrated higher photocatalytic activity, achieving a substantial 59% degradation of norfloxacin (NOR) under UV light irradiation. This performance surpassed that of both Ni2O3@PC and Cu@PC composites. The optimal pH for maximum NOR removal from the aqueous solution was determined to be pH 5, with a reaction time of 180 min. The degradation of NOR in the presence of these composites adhered to the Langmuir-Hinshelwood mechanism and a pseudo-first order kinetic model. The reusability of the catalysts was also investigated for 10 consecutive runs, without any activation or regeneration treatments. The Cu@PC membrane catalyst demonstrated a marked decline in degradation efficiency after the 2nd test cycle, ultimately catalyzing only 10% of NOR after the 10th cycle. In contrast, the Ni2O3@PC based catalyst demonstrated a more stable NOR degradation efficiency throughout all 10 runs, with 27% NOR removal observed during the final test. Remarkably, the catalytic performance of the Cu/Ni2O3@PC mixed composite remained highly active even after being recycled 4 times. The degradation efficiency exhibited a gradual reduction, with a 17% decrease after the 6th run and a cumulative 35% removal of NOR achieved by the 10th cycle. Overall, the findings indicate that Cu/Ni2O3@PC mixed composite membranes may represent an advancement in the quest to mitigate the adverse effects of antibiotic pollution in aquatic environments and hold significant promise for sustainable water treatment practices.

Applying bottom ash as an alternative Fenton catalyst for effective removal of phenol from aqueous environment

In this study, coal bottom ash from a thermoelectric plant was tested as an alternative Fenton catalyst for phenol degradation in water. The effect of operating parameters such as initial pH, catalyst dosage and H2O2 concentration were evaluated. The characterization results indicated that the material has a mesoporous structure, with active species (Fe) well distributed on its surface. Under the optimal reaction conditions (6 mM H2O2, 1 g L-1 of catalyst and pH = 3), 98.7% phenol degradation efficiency was achieved in 60 min, as well as 71.6% TOC removal after 150 min. Hydroxyl radical was identified as the main oxidizing agent involved on the cleavage of the phenol molecule. After four consecutive reuse cycles, phenol degradation efficiency was around 80%, indicating good reusability and stability of the catalyst. Therefore, the obtained results demonstrated that the bottom ash presents remarkable activity for application in the Fenton reaction towards phenol degradation.

SnAg2O3-Coated Adhesive Tape as a Recyclable Catalyst for Efficient Reduction of Methyl Orange

Silver oxide-doped tin oxide (SnAg2O3) nanoparticles were synthesized and different spectroscopic techniques were used to structurally identify SnAg2O3 nanoparticles. The reduction of 4-nitrophenol (4-NP), congo red (CR), methylene blue (MB), and methyl orange (MO) was studied using SnAg2O3 as a catalyst. Only 1.0 min was required to reduce 95% MO; thus, SnAg2O3 was found to be effective with a rate constant of 3.0412 min-1. Being a powder, SnAg2O3 is difficult to recover and recycle multiple times. For this reason, SnAg2O3 was coated on adhesive tape (AT) to make it recyclable for large-scale usage. SnAg2O3@AT catalyst was assessed toward MO reduction under various conditions. The amount of SnAg2O3@AT, NaBH4, and MO was optimized for best possible reduction conditions. The catalyst had a positive effect since it speed up the reduction of MO by adding more SnAg2O3@AT and NaBH4 as well as lowering the MO concentration. SnAg2O3@AT totally reduced MO (98%) in 3.0 min with a rate constant of 1.3669 min-1. These findings confirmed that SnAg2O3@AT is an effective and useful catalyst for MO reduction that can even be utilized on a large scale for industrial purposes.

Fabricated Gamma-Alumina-Supported Zinc Ferrite Catalyst for Solvent-Free Aerobic Oxidation of Cyclic Ethers to Lactones

The aim of this work was to fabricate a new heterogeneous catalyst as zinc ferrite (ZF) supported on gamma-alumina (γ-Al2O3) for the conversion of cyclic ethers to the corresponding, more valuable lactones, using a solvent-free method and O2 as an oxidant. Hence, the ZF@γ-Al2O3 catalyst was prepared using a deposition-coprecipitation method, then characterized using TEM, SEM, EDS, TGA, FTIR, XRD, ICP, XPS, and BET surface area, and further applied for aerobic oxidation of cyclic ethers. The structural analysis indicated spherical, uniform ZF particles of 24 nm dispersed on the alumina support. Importantly, the incorporation of ZF into the support influenced its texture, i.e., the surface area and pore size were reduced while the pore diameter was increased. The product identification indicated lactone compound as the major product for saturated cyclic ether oxidation. For THF as a model reaction, it was found that the supported catalyst was 3.2 times more potent towards the oxidation of cyclic ethers than the unsupported one. Furthermore, the low reactivity of the six-membered ethers can be tackled by optimizing the oxidant pressure and the reaction time. In the case of unsaturated ethers, deep oxidation and polymerization reactions were competitive oxidations. Furthermore, it was found that the supported catalyst maintained good stability and catalytic activity, even after four cycles.

Construction and demolition waste as a high-efficiency advanced process for organic pollutant degradation in Fenton-like reaction to approach circular economy

The Fenton-like reaction is a promising organic wastewater treatment reaction among advanced oxidation processes (AOP), which has emerged to replace the conventional Fenton reaction. Recycled construction and demolition waste (CDW), which is porous and rich in iron, manganese, and magnesium, can be reused as a Fenton-like catalyst. This study proposes an AOP wastewater treatment strategy using recycled porous CDW mixed with hydrogen peroxide (H2O2) to decompose methylene blue (MB) wastewater. According to the apparent first-order rate (Kapp) of 10 ppm MB adsorption, CDW-3, having the highest specific surface area, also has the highest Kapp of 0.23 min-1 g-1. The optimized conditions recommended by the Taguchi method include a 0.3 g mL-1 CDW-3 concentration, a 0.254 g mL-1 H2O2 concentration, and 10 ppm MB, resulting in an about 2.01 min-1Kapp value. In addition, MB concentration is observed as the most influential factor for Kapp, which decreases with increasing MB concentration and is about 0.62 min-1 at 1000 ppm MB. Repeating the Fenton-like reaction five times at 100 p.m. MB using the same CDW-3, the Kapp is about 0.64 min-1, which is 86% of the initial run. The synergistic effect index (ξ) is defined to quantify the level of interaction between CDW and H2O2, which produces free radicals during the Fenton-like process. The ξ of CDW-3 is about 2.16. Overall, it is demonstrated that CDW is a promising catalyst for Fenton-like reactions, and the synergistic effect index (ξ) can be used as a reference index to evaluate the catalytic generation of free radicals between the catalyst and H2O2.

Pd@GO catalyzed stereo- and regio-selective addition of arenes to alkynes and synthesis of coumarins via C-H functionalization

A stereo- and regio-selective addition of arenes to alkynes via C-H bond functionalization has been developed using palladium nanoparticles supported on graphite oxide (Pd@GO) as the reusable catalyst. The prepared catalyst was characterized by various spectroscopic techniques such as FT-IR, TEM, SEM, EDX, P-XRD, and XPS analysis. The thermal stability of the catalyst was established by TGA. The C-H functionalized products were obtained in good to excellent yields (69-92%) at room temperature. The methodology further extended to the synthesis of biologically and pharmaceutically important coumarin molecules from phenols and alkynes. Good to excellent yields of the coumarins (74-92%) were obtained. After the reaction, the catalyst was separated by centrifugation followed by filtration. The recovered catalyst was washed and reused up to five cycles. The advantages of this method are the simple procedure of the catalyst preparation, high catalytic efficiency, high selectivity, good functional group tolerance, low catalyst loading, and gram-scale synthesis.

Supramolecular Cu(ii) nanoparticles supported on a functionalized chitosan containing urea and thiourea bridges as a recoverable nanocatalyst for efficient synthesis of 1H-tetrazoles

A cost-effective and convenient method for supporting of Cu(ii) nanoparticles on a modified chitosan backbone containing urea and thiourea bridges using thiosemicarbazide (TS), pyromellitic dianhydride (PMDA) and toluene-2,4-diisocyanate (TDI) linkers was designed. The prepared supramolecular (CS-TDI-PMDA-TS-Cu(ii)) nanocomposite was characterized by using Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetry/differential thermogravimetry analysis (TGA/DTA), energy-dispersive X-ray spectroscopy (EDS), EDS elemental mapping and X-ray diffraction (XRD). The obtained supramolecular CS-TDI-PMDA-TS-Cu(ii) nanomaterial was demonstrated to act as a multifunctional nanocatalyst for promoting of multicomponent cascade Knoevenagel condensation/click 1,3-dipolar azide-nitrile cycloaddition reactions very efficiently between aromatic aldehydes, sodium azide and malononitrile under solvent-free conditions and affording the corresponding (E)-2-(1H-tetrazole-5-yl)-3-arylacrylenenitrile derivatives. Low catalyst loading, working under solvent-free conditions and short reaction time as well as easy preparation and recycling, and reuse of the catalyst for five consecutive cycles without considerable decrease in its catalytic efficiency make it a suitable candidate for the catalytic reactions promoted by Cu species.

Recovery of Precious Metals: A Promising Process Using Supercritical Carbon Dioxide and CO2-Soluble Complexing Polymers for Palladium Extraction from Supported Catalysts

Precious metals such as palladium (Pd) have many applications, ranging from automotive catalysts to fine chemistry. Platinum group metals are, thus, in massive demand for industrial applications, even though they are relatively rare and belong to the list of critical materials for many countries. The result is an explosion of their price. The recovery of Pd from spent catalysts and, more generally, the development of a circular economy process around Pd, becomes essential for both economic and environmental reasons. To this aim, we propose a sustainable process based on the use of supercritical CO2 (i.e., a green solvent) operated in mild conditions of pressure and temperature (p = 25 MPa, T = 313 K). Note that the range of CO2 pressures commonly used for extraction is going from 15 to 100 MPa, while temperatures typically vary from 308 to 423 K. A pressure of 25 MPa and a temperature of 313 K can, therefore, be viewed as mild conditions. CO2-soluble copolymers bearing complexing groups, such as pyridine, triphenylphosphine, or acetylacetate, were added to the supercritical fluid to extract the Pd from the catalyst. Two supported catalysts were tested: a pristine aluminosilicate-supported catalyst (Cat D) and a spent alumina supported-catalyst (Cat A). An extraction conversion of up to more than 70% was achieved in the presence of the pyridine-containing copolymer. The recovery of the Pd from the polymer was possible after extraction, and the technological and economical assessment of the process was considered.

Cellulose-Supported Heterogeneous Gold-Catalyzed Cycloisomerization Reactions of Alkynoic Acids and Allenynamides

Herein, we describe efficient nanogold-catalyzed cycloisomerization reactions of alkynoic acids and allenynamides to enol lactones and dihydropyrroles, respectively (the latter via an Alder-ene reaction). The gold nanoparticles were immobilized on thiol-functionalized microcrystalline cellulose and characterized by electron microscopy (HAADF-STEM) and by XPS. The thiol-stabilized gold nanoparticles (Au0) were obtained in the size range 1.5-6 nm at the cellulose surface. The robust and sustainable cellulose-supported gold nanocatalyst can be recycled for multiple cycles without losing activity.

e-Beam and γ-rays Induced Synthesis and Catalytic Properties of Copper Nanoclusters-Deposited Composite Track-Etched Membranes

Effective removal of toxic inorganic and organic pollutants is one of the current leading challenges of wastewater treatment. In this study, the decomposition of methylene blue (MB) under UV light irradiation was investigated in the presence of copper nanoclusters (NCs)-deposited polyethylene terephthalate (PET) track-etched hybrid membranes. PET track-etched membranes (TeMs) with an average pore size of ~400 nm were grafted by functional acrylic acid (AA) monomer under electron beam irradiation after oxidation with H₂O₂/UV system. The radiation dose varied between 46 and 200 kGy. For the deposition of copper NCs, poly(acrylic acid) (PAA)-grafted membranes saturated with Cu(II) ions were irradiated either by electron beam or γ-rays to obtain copper-based NCs for the catalytic degradation of MB. Irradiation to 100 kGy with accelerated electrons resulted in the formation of small and uniform copper hydroxide (Cu(OH)₂) nanoparticles homogeneously distributed over the entire volume of the template. On the other hand, irradiation under γ-rays yielded composites with copper NCs with a high degree of crystallinity. However, the size of the deposited NCs obtained by γ-irradiation was not uniform. Nanoparticles with the highest uniformity were obtained at 150 kGy dose. Detailed analysis by X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the loading of copper nanoparticles with an average size of 100 nm on the inner walls of nanochannels and on the surface of PET TeMs. Under UV light irradiation, composite membranes loaded with NCs exhibited high photocatalytic activity. It was determined that the highest catalytic activity was observed in the presence of Cu(OH)₂@PET-g-PAA membrane obtained at 250 kGy. More than 91.9% of the initial dye was degraded when this hybrid membrane was employed for 180 min, while only 83.9% of MB was degraded under UV light using Cu@PET-g-PAA membrane. Cu(OH)₂@PET-g-PAA membranes obtained under electron beam irradiation demonstrated a higher photocatalytic activity compared to Cu@PET-g-PAA membranes attained by γ-rays.

Green synthesis silver nanoparticles Bougainvillea glabra Choisy/LED light with high catalytic activity in the removal of methylene blue aqueous solution

In this study, we evaluated, in a pioneering way, the influence of wavelengths from the decomposition of white light on the production and physicochemical properties of silver nanoparticles (AgNPs). Bearing in mind a process of green synthesis, an extract of the bracts of Bougainvillea glabra Choisy (BgC) was used, a species native to tropical and subtropical regions and frequently used in ornamentation, possessing in its photochemical composition, biomolecules capable of acting as reducing agents for convert Ag⁺ to Ag⁰. We used light-emitting diodes (LED) to obtain the desired wavelengths (violet, blue, green, yellow, orange, and red) in the test called rainbow, and we evaluated the obtaining of AgNPs compared to white LED light, nature, and absence of light. In the rainbow assay, we obtained a gradual increase in the intensity of the plasmonic band resonance from the red wavelength (0.124 ± 0.067 a.u.) to violet (0.680 ± 0.199 a.u.), indicating a higher reaction yield in obtaining AgNPs. Smaller hydrodynamic sizes (approximately 150 nm) at more energetic wavelengths (violet, blue, and green) about less energetic wavelengths (yellow, orange, and red) (approximately 400 nm) were obtained. Analysis by SEM microscopy, FTIR spectroscopy, and X-ray diffraction indicates the presence of silver nanoparticles in all LED colors used together with white LED light and Laboratory light (natural light). Due to the high environmental demand to remove pollutants from water sources, including textile dyes, we applied AgNPs/BgC to remove methylene blue (MB) dye from an aqueous solution. A minimum removal percentage greater than 65%, with emphasis on formulations synthesized by the colors of violet LED (84.27 ± 2.65%) and orange LED (85.91 ± 1.95%), was obtained.

Synergistic Bonding of Poly(N-isopropylacrylamide)-Based Hybrid Microgels and Gold Nanoparticles Used for Temperature-Responsive Controllable Catalysis of p-Nitrophenol Reduction

Stimuli-responsive hybrid nanoparticles used for controllable catalysis have been attracting increasing attention. This study aims to prepare hybrid microgels with excellent temperature-sensitive colorimetric and catalytic properties through combining the surface plasmon resonance properties of gold nanoparticles (AuNPs) with the temperature-sensitive properties of poly(N-isopropylacrylamide) (PNIPAM)-based microgels. Microgels with hydroxy groups (MG-OH) were prepared by soap-free emulsion polymerization, using N-isopropylacrylamide as the main monomer, hydroxyethyl methylacrylate as the functional monomer, N,N'-methylene bisacrylamide as the crosslinker, and 2,2'-azobis(2-methylpropionamidine) dihydrochloride as an initiator to ensure the microgels are positively charged. Furthermore, chemical modification on the surface of MG-OH was carried out by 3-mercaptopropyltriethoxysilane to obtain thiolated microgels (MG-SH). Two kinds of hybrid nanoparticles, AuNPs@MG-OH and AuNPs@MG-SH, were self-assembled, through electrostatic interaction between positive MG-OH and negative citrate-stabilized AuNPs as well as through synergistic bonding of electrostatic interaction and Au-S bonding between positive MG-SH and negative AuNPs. The morphology, stability, temperature-sensitive colorimetric properties, and catalytic properties of hybrid microgels were systematically investigated. Results showed that although both AuNPs@MG-OH and AuNPs@MG-SH exhibit good temperature-sensitive colorimetric properties and controllable catalytic properties for the reduction reaction of p-nitrophenol, AuNPs@MG-SH with synergistic bonding has better stability and higher catalytic performance than AuNPs@MG-OH. This work has good competitiveness against known PNIPAM-based materials and may provide an effective method for preparing smart catalysts by self-assembly with stimuli-responsive polymers, which has a great potential application for catalyzing a variety of reactions.

Fe3O4/SiO2 decorated trimesic acid-melamine nanocomposite: a reusable supramolecular organocatalyst for efficient multicomponent synthesis of imidazole derivatives

This article describes supramolecular Fe₃O₄/SiO₂ decorated trimesic acid-melamine (Fe₃O₄/SiO₂-TMA-Me) nanocomposite that can be prepared with features that combine properties of different materials to fabricate a structurally unique hybrid material. In particular, we have focused on design, synthesis and evaluation a heterogeneous magnetic organocatalyst containing acidic functional-groups for the synthesis of biologically important imidazole derivatives in good to excellent yields. The introduced Fe₃O₄/SiO₂-TMA-Me nanomaterial was characterized by different techniques such as FTIR, XRD, EDX, FESEM, TEM, TGA and DTA. As a noteworthy point, the magnetic catalytic system can be recycled and reused for more than seven consecutive runs while its high catalytic activity remains under the optimized conditions.

Cu(BF4)2/AC-Catalyzed Synthesis of N-Substituted Anilines, N-Substituted 1,6-Naphthyridin-5(6H)-one, and Isoquinolin-1(2H)-one

Herein, we report practical Cu(BF₄)₂/activated carbon-catalyzed amination of various anilines, isoquinolinone, and naphthyridinone with aryl boronic acids. The ultrasonic and rotary evaporation treatment of the mixture of aq. Cu(BF₄)₂ and activated carbon in methanol afforded a novel Cu(II)-catalyst, which is air-stable and can be effectively applied in the Chan-Lam coupling reaction. The products of N-arylation were isolated in good to excellent yields at low catalytic loading. And Cu(BF₄)₂/AC also showed good reusability.

Recent Developments on Processes for Recovery of Rhodium Metal from Spent Catalysts

Rhodium (Rh) catalyst has played an indispensable role in many important industrial and technological applications due to its unique and valuable properties. Currently, Rh is considered as a strategic or critical metal as the scarce high-quality purity can only be supplemented by refining coarse ores with low content (2–10 ppm) and is far from meeting the fast-growing market demand. Nowadays, exploring new prospects has already become an urgent issue because of the gradual depletion of Rh resources, incidental pressure on environmental protection, and high market prices. Since waste catalyst materials, industrial equipment, and electronic instruments contain Rh with a higher concentration than that of natural minerals, recovering Rh from scrap not only offers an additional source to satisfy market demand but also reduces the risk of ore over-exploitation. Therefore, the recovery of Rh-based catalysts from scrap is of great significance. This review provides an overview of the Rh metal recovery from spent catalysts. The characteristics, advantages and disadvantages of several current recovery processes, including pyrometallurgy, hydrometallurgy, and biosorption technology, are presented and compared. Among them, the hydrometallurgical process is commonly used for Rh recovery from auto catalysts due to its technological simplicity, low cost, and short processing time, but the overall recovery rate is low due to its high remnant Rh within the insoluble residue and the unstable leaching. In contrast, higher Rh recovery and less effluent discharge can be ensured by a pyrometallurgical process which therefore is widely employed in industry to extract precious metals from spent catalysts. However, the related procedure is quite complex, leading to an expensive hardware investment, high energy consumption, long recovery cycles, and inevitable difficulties in controlling contamination in practice. Compared to conventional recovery methods, the biosorption process is considered to be a cost-effective biological route for Rh recovery owing to its intrinsic merits, e.g., low operation costs, small volume, and low amount of chemicals and biological sludge to be treated. Finally, we summarize the challenges and prospect of these three recovery processes in the hope that the community can gain more meaningful and comprehensive insights into Rh recovery.

Outlook on bismuth-based photocatalysts for environmental applications: A specific emphasis on Z-scheme mechanisms

Semiconductor photocatalysis is thought to be a viable solution for addressing the growing problem of environmental pollution. Bismuth (Bi) metal oxides can function as a direct plasmonic photocatalyst or cocatalyst to accelerate the photogenerated charge separation and thus improve their photocatalytic activity. Hence, Bi-based photocatalysts have received a lot of attention due to their extensive environmental applications, including pollutant remediation and energy concepts. Massive efforts have been undertaken in the recent decade to find superior Bi-metal oxides (Bi₂XO_6, X = MO, W, or Cr) and to uncover the corresponding photocatalytic reaction mechanism for the degradation of organic contaminants in water. Herein, the unique crystalline and electronic properties and main synthesis methods, as well as the major Bi-Based direct Z-scheme photocatalysts, are timely discussed and summarized in their usage in water treatment. Besides, the impact of Bi₂XO₆ in energy storage devices and solar energy conversion is reviewed as an energy application. Finally, the future development and challenges of Z-scheme-based Bi₂XO₆ photocatalysts are briefly explored, summarized, and forecasted.

High-frequency ultrasound processes as alternative methods for degrading meropenem antibiotic in water

β-lactam, more specifically carbapenems, are antibiotics used as last resort pharmaceuticals to deal with infections. Despite the medical relevance, they are considered contaminants of emerging concern in water because of their recalcitrance to conventional systems in the municipal wastewater treatment plants. This work aimed to show alternative methods based on the use of high-frequency ultrasound (200-1000 kHz) at a laboratory scale to degrade meropenem (a representative carbapenem antibiotic) in water. The ability of the sonochemical method alone to eliminate meropenem was tested initially. Then, the improvements of degradation by the addition of ferrous iron, or Fe (II) plus UVA light (sono-Fenton, or sono-photo-Fenton methods) were assessed. Finally, the effect of the best ultrasound-based method on the removal of biological activity of meropenem was determined.

• Three high-frequency ultrasound processes were applied to degrade meropenem in water.

• Sono-photo-Fenton degraded 67% of imipenem at 60 min of treatment and decreased significantly H₂O₂ accumulation.

• Antimicrobial activity was removed after only 30 min of sono-photo-Fenton action.

Special Issue on Advanced Materials and Nanotechnology for Sustainable Energy and Environmental Applications

Materials play a very important role in the technological development of a society, greatly impacting people’s daily lives [...]

Application of Nanocatalysts in Advanced Oxidation Processes for Wastewater Purification: Challenges and Future Prospects

The increase in population demands for industrialization and urbanization which led to the introduction of novel hazardous chemicals in our environment. The most significant parts of these harmful substances found in water bodies remain in the background, causing a health risk to humans and animals. It is critical to remove these toxic chemicals from the wastewater to keep a cleaner and greener environment. Hence, wastewater treatment is a challenging area these days to manage liquid wastes effectively. Therefore, scientists are in search of novel technologies to treat and recycle wastewater, and nanotechnology is one of them, thanks to the potential of nanoparticles to effectively clean wastewater while also being ecologically benign. However, there is relatively little information about nanocatalysts’ applicability, efficacy, and challenges for future applications in wastewater purification. This review paper is designed to summarize the recent studies on applying various types of nanocatalysts for wastewater purification. This review paper highlights innovative work utilizing nanocatalysts for wastewater applications and identifies issues and challenges to overcome for the practical implementation of nanocatalysts for wastewater treatment.

Light driven Aspergillus niger-ZnS nanobiohybrids for degradation of methyl orange

Inorganic-microbial hybrid systems have potential to be sustainable, efficient and versatile chemical synthesis platforms by integrating the light-harvesting properties of semiconductors with microbial cells. Here, we demonstrate light-driven photocatalytic semiconducting Aspergillus niger cells-ZnS nanoparticles for enhanced removal of the dye methyl orange. Chemically synthesized ZnS nanoparticles exhibited a zinc blende pattern in X-ray diffraction, had a dimension of 20-90 nm with a band gap (E_bg) of 3.4 eV at 1.83 × 10¹⁸ photons/second. Biologically synthesized ZnS nanoparticles of 40-90 nm showed a hexagonal pattern in the X-ray powder diffraction spectra with an E_bg 3.7 eV at 1.68 × 10¹⁸ photons/second. At a methyl orange (MO) concentration of 100 mg/L, dosage of 0.5 × 10⁵ mol catalyst and pH 4, a 97.5% and 98% removal efficiency of MO was achieved in 90 min and 60 min for, respectively, chemically and biologically synthesized ZnS nanobiohybrids in the presence of UV-A light. The major degradation products of photocatalysis for chemically synthesized ZnS nanobiohybrids were naphtholate (C₁₀H₇O m/z 143) and hydroquinone (C₉H₅m/z 113). For the biologically synthesized ZnS nanobiohybrids, the degradation products were hydroquinone (C₉H₅m/z 113) and 2-phenylphenol (C₁₂H₁₀O m/z 170).

Poisoning and Reuse of Supported Precious Metal Catalysts in the Hydrogenation of N-Heterocycles, Part II: Hydrogenation of 1-Methylpyrrole over Rhodium

Poisoning effect of nitrogen on heterogeneous, supported precious metal catalysts, along with their recycling, was further examined in the liquid-phase hydrogenation of 1-methylpyrrole (MP) to 1-methylpyrrolidine (MPD) over rhodium on carbon or γ-alumina, in methanol, under non-acidic conditions, at 25–50 °C and 10 bar. Reusing a spent, unregenerated 5% Rh/C or 5% Rh/γ-Al2O3 catalyst, it was found that the conversion of this model substrate and the activity of the catalyst were strongly dependent on the amount of catalyst, the type of support, the catalyst pre- or after-treatment, the temperature, and the number of recycling, respectively. An unexpected catalytic behaviour of rhodium was observed when it was used in a prehydrogenated form, because no complete conversion of MP was achieved over even the fresh Rh/C or Rh/γ-Al2O3, contrary to the untreated one. In addition, there was a significant difference in the reusability and activity of these rhodium catalysts, depending on their supports (activated carbon, γ-alumina). These diversions were elucidated by applying dispersion (O2- and H2-titration), temperature-programmed desorption of ammonia (NH3-TPD), and transmission electron microscopy (TEM) measurements.

Efficient biodiesel production from oleic and palmitic acid using a novel molybdenum metal-organic framework as efficient and reusable catalyst

In this study, metal–organic framework based on molybdenum and piperidine-4-carboxylic acid, was synthesized through a simple solvothermal method and employed as an effective catalyst for biodiesel production from oleic acid and palmitic acid via esterification reaction. The prepared catalyst was characterized by XRD, FTIR, TGA, DSC, BET, SEM, TEM, ICP-OES, X-ray mapping and EDX analysis. The resulting Mo–MOF catalyst exhibit a rod-like morphology, specific surface area of 56 m²/g, and thermal stability up to 300 °C. The solid catalyst exhibited high activities for esterification of oleic acid and palmitic acid. Moreover, the catalyst could be simply recovered and efficiently reutilized for several times without significant loss in its activity, also obtained results revealed that metal–organic framework could be used for the appropriate and rapid biodiesel production.

Chirality-driven self-assembly: application toward renewable/exchangeable resin-immobilized catalysts

Resin-immobilized catalysts were prepared through chirality-driven self-assembly. The method allows the resin-immobilized catalyst to be regenerated under mild conditions and in situ catalyst exchange to be carried out quantitatively. The uniqueness of the methodology was demonstrated by the preparation of a catalyst for TEMPO oxidation as well as a two-step sequential TEMPO oxidation/aldol condensation sequence enabled by facile catalyst exchange.

Organosulphur and organoselenium compounds as emerging building blocks for catalytic systems for O-arylation of phenols, a C-O coupling reaction

Diaryl ethers form an important class of organic compounds. The classic copper-mediated Ullmann diaryl ether synthesis has been known for many years and involves the coupling of phenols with aryl halides. However, the use of high reaction temperature, high catalyst loading and expensive ligands has created a need for the development of alternative catalytic systems. In the recent past, organosulphur and organoselenium compounds have been used as building blocks for developing homogeneous, heterogeneous and nanocatalysts for this C-O coupling reaction. Homogeneous catalytic systems include preformed complexes of metals with organosulphur and organoselenium ligands. The performance of such complexes is influenced dramatically by the nature of the chalcogen (S or Se) donor site of the ligand. Nanocatalytic systems (including Pd₁₇Se₁₅, Pd₁₆S₇ and Cu_1.8S) have been designed using a single-source precursor route. Heterogeneous catalytic systems contain either metal (Cu or Pd) or metal chalcogenides (Pd₁₇Se₁₅ or Cu_1.8S) as catalytically active species. This article aims to cover the simple and straightforward methodologies and approaches that are adopted for developing catalytically relevant organosulfur and organoselenium ligands, their homogeneous metal complexes, heterogeneous and nanocatalysts. The effects of chalcogen (S or Se) donor, halogen (Cl/Br/I) of aryl halide, nature (electron withdrawing or electron donating) of substituents present on the aromatic ring of aryl halides or substituted phenols and position (ortho or para) of substitution on the results of catalytic reactions have been critically analyzed and summarized. The effect of composition (Pd₁₇Se₁₅ or Pd₁₆S₇) on the performance of nanocatalytic systems is also highlighted. Substrate scope has also been discussed in all three types of catalysis. The superiority of heterogeneous catalytic systems (e.g., Pd₁₇Se₁₅ immobilised on graphene oxide) indicates the bright future possibilities for the development of efficient catalytic systems using similar or tailored ligands for this reaction.

Catalytic Routes to Produce Polyphenolic Esters (PEs) from Biomass Feedstocks

Polyphenolic esters (PEs) are valuable chemical compounds that display a wide spectrum of activities (e.g., anti-oxidative effects). As a result, their production through catalytic routes is an attractive field of research. The present review aims to discuss recent studies from the literature regarding the catalytic production of PEs from biomass feedstocks, namely, naturally occurred polyphenolic compounds. Several synthetic approaches are reported in the literature, mainly bio-catalysis and to a lesser extent acid catalysis. Immobilized lipases (e.g., Novozym 435) are the preferred enzymes thanks to their high reactivity, selectivity and reusability. Acid catalysis is principally investigated for the esterification of polyphenolic acids with fatty alcohols and/or glycerol, using both homogeneous (p-toluensulfonic acid, sulfonic acid and ionic liquids) and heterogeneous (strongly acidic cation exchange resins) catalysts. Based on the reviewed publications, we propose some suggestions to improve the synthesis of PEs with the aim of increasing the greenness of the overall production process. In fact, much more attention should be paid to the use of new and efficient acid catalysts and their reuse for multiple reaction cycles.

An Approach to Determine Missing Life Cycle Inventory Data for Chemicals (RREM)

Chemicals impact the environment. However, life cycle assessments (LCA) of products containing chemicals are often not possible due to a lack of available datasets. Existing methodologies to address this problem have several shortcomings. Therefore, a new approach to model chemicals is introduced to fill dataset gaps in inventory databases. Further data for 60 chemicals are provided. The approach consists of four steps: (i) general research on the chemical and the synthesis processes, (ii) setting up the reaction equations, (iii) researching the required thermal energy, and (iv) modeling of the dataset (RREM). Depending on the obtained data, calculations are carried out or assumptions are applied. The environmental impact of the chemicals is modeled in the LCA software linking to existing datasets. A case study of the chemical octocrylene illustrates the application of RREM. An overview is given of the environmental profile of 60 chemicals modeled based on RREM. The validity of the assumptions and their influences on the results are examined by a sensitivity analysis. By modeling chemicals with the RREM approach, previously unknown environmental impacts of chemicals and products containing them can be determined.

Functionalized hybrid magnetic catalytic systems on micro- and nanoscale utilized in organic synthesis and degradation of dyes

Herein, a concise review of the latest developments in catalytic processes involving organic reactions is presented, focusing on magnetic catalytic systems (MCSs). In recent years, various micro- and nanoscale magnetic catalysts have been prepared through different methods based on optimized reaction conditions and utilized in complex organic synthesis or degradation reactions of pharmaceutical compounds. These biodegradable, biocompatible and eco-benign MCSs have achieved the principles of green chemistry, and thus their usage is highly advocated. In addition, MCSs can shorten the reaction time, effectively accelerate reactions, and significantly upgrade both pharmaceutical synthesis and degradation mechanisms by preventing unwanted side reactions. Moreover, the other significant benefits of MCSs include their convenient magnetic separation, high stability and reusability, inexpensive raw materials, facile preparation routes, and surface functionalization. In this review, our aim is to present at the recent improvements in the structure of versatile MCSs and their characteristics, i.e., magnetization, recyclability, structural stability, turnover number (TON), and turnover frequency (TOF). Concisely, different hybrid and multifunctional MCSs are discussed. Additionally, the applications of MCSs for the synthesis of different pharmaceutical ingredients and degradation of organic wastewater contaminants such as toxic dyes and drugs are demonstrated.

A heterogeneous peroxymonosulfate catalyst built by Fe-based metal-organic framework for the dye degradation

The regulatory control on dyes is an important issue, as their discharge into the environment can pose significant risks to human health. MIL-101(Fe) prepared by a solvothermal method was used as a catalyst to generate sulfate (SO₄^•-) and hydroxyl (HO^•) radicals from peroxymonosulfate (PMS) for the treatment of orange G (OG). The structural properties of MIL-101(Fe) were assessed by a number of characterization approaches (e.g., Fourier-transform infrared spectroscopy). The factors controlling the removal of OG were explored by a response surface methodology with central composite design (RSM-CCD) plus adaptive neuro-fuzzy inference system (ANFIS). The synthetized MIL-101(Fe) had uniform octahedral nanocrystals with rough surfaces and porous structures. The maximum catalytic removal efficiency of OG with MIL-101(Fe)/PMS process was 74% (the final concentration of Fe²⁺ as 0.19 mg/L and reaction rate of 434.2 μmol/g/h). The catalytic removal of OG could be defined by the non-linear kinetic models based on RSM. The OG removal efficiency declined noticeably with the addition of radical scavengers such as ethanol (EtOH) and tert-butanol (TBA) along with some mineral anions. Accordingly, MIL-101(Fe)/PMS is identified as an effective remediation option for the dyes based on advanced oxidation process (AOPs) based on high treatment efficiency at low dosage of low cost catalyst.

One-pot, facile synthesis and fast separation of a UiO-66 composite by a metalloporphyrin using nanomagnetic materials for oxidation of olefins and allylic alcohols

One-pot facile synthesis of a new composite based on the incorporation of a metalloporphyrin within the UiO-66 metal–organic framework is reported.

Investigation of Fe3O4@boehmite NPs as efficient and magnetically recoverable nanocatalyst in the homoselective synthesis of tetrazoles

Magnetic boehmite nanoparticles (Fe₃O₄@boehmite NPs) were synthesized from a hybrid of boehmite and Fe₃O₄ nanoparticles. At first, boehmite nanoparticles (aluminum oxide hydroxide) were prepared via a simple procedure in water using commercially available materials such as sodium hydroxide and aluminum nitrate. Then, these nanoparticles were magnetized using Fe₃O₄ NPs in a basic solution of FeCl₂·4H₂O and FeCl₃·6H₂O. Fe₃O₄@boehmite NPs have advantages of both boehmite nanoparticles and Fe₃O₄ magnetic materials. Magnetic boehmite nanoparticles have been characterized by various techniques such as TEM, SEM, EDS, WDX, ICP, FT-IR, Raman, XRD and VSM. SEM and TEM images confirmed that particles size are less than 50 nm in diameter with a cubic orthorhombic structure. Then, Fe₃O₄@boehmite NPs were applied as a homoselective, highly efficient, cheap, biocompatibility, heterogeneous and magnetically recoverable nanocatalyst in the synthesis of 5-substituted 1H-tetrazole derivatives. Fe₃O₄@boehmite NPs can be recycled for several runs in the synthesis of tetrazoles. Also, all tetrazoles were isolated in high yields, which reveals high activity of Fe₃O₄@boehmite NPs in the synthesis of tetrazole derivatives. Fe₃O₄@boehmite NPs shows a good homoselectivity in synthesis of 5-substituted 1H-tetrazole derivatives.

Magnetic boehmite nanoparticles were synthesized from a hybrid of boehmite and Fe₃O₄ nanoparticles. Then, it was applied as a homoselective, highly efficient, cheep, heterogeneous and recoverable nanocatalyst in the synthesis of tetrazole derivative.