Catalyst Recovery Research Articles

In-Situ Synthesis of PN-Doped Carbon Nanofibers for Single-Atom Catalytic Hydrosilylation.

Single-atom catalysts have become a popular choice in various catalysis applications, as they take advantages of both homogeneous catalysis (e.g., high efficiency) and heterogeneous catalysis (e.g., easy catalyst recovery). The atom support plays an indispensable role in anchoring atomic species and interplaying with them for ultimate catalytic performance. Therefore, development of new support materials for superior catalysis is of great importance. Here the synthesis of carbon nanofibers based on the reaction between phosphorus pentoxide (P2 O5 ) and N-methyl-2-pyrrolidone (NMP) is reported. The underlying reaction process is systematically investigated by Fourier-transform infrared(FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The carbon nanofibers have interesting PN units in their chemical structure, which act as anchoring sites for the single-atom catalyst. The Pt atoms anchoring carbon nanofibers exhibit high activity for hydrosilylation with a turnover frequency (TOF) of 9.2×106 h-1 and a selectivity of >99%. This research affords not only a new in situ chemical strategy to synthesize multiatom doped carbon nanofibers but also presents a potential superior support in catalysis, which opens a hopeful window in materials chemistry and catalysis applications.

Enhancing charge transfer efficiency of cerium-iron oxides via Co regulated oxygen vacancies to boost peroxymonosulfate activation for tetracycline degradation

Enhancing the charge transfer efficiency and accelerating the redox cycle are effective approaches for improving the ability of catalysts to activate peroxymonosulfate (PMS). Herein, cobalt regulated cerium-iron oxides (CFO-Co) were constructed successfully. Cobalt doping significantly reduces the particle size of cerium-iron oxides (CFO) and increases the concentration of oxygen vacancies, which further enhances the charge transfer efficiency and accelerates the redox cycle to generate more reactive oxygen species (ROS). Therefore, CFO-Co exhibits boosted PMS activation which could degrade 71.2% of tetracycline (TC) within 3 min and the rate constant can be up to 0.39 min−1, which is 5.6 times higher than that of pure CFO. In the meantime, CFO-Co still showed excellent catalytic performance under wide range of pH values, temperature, various polluted water bodies, coexisting ions, and long-term cycling conditions. Moreover, CFO-Co displayed easy catalysts recovery for its magnetic behavior. DFT calculation shows that the introduction of cobalt can significantly reduce the adsorption energy of PMS on the catalyst and lengthen peroxy bond (IO-O), which promotes the activation of PMS to produce ROS. The mechanism studies demonstrated that 1O2, ∙OH, O2–∙ and SO4−∙ generated during the reaction were the main active species. The possible degradation pathways and the toxicity were also analyzed. This work offers a new view on the design of PMS-activated catalysts.

Towards Green Reductions in Bio‐Derived Solvents

AbstractThe hydrogenation processes, and all the reactions that formally add two hydrogen atoms to an unsaturated bond, are among the most used transformations in the manufacture of bulk and fine chemicals. Although their potential as powerful tool for the sustainable synthesis of organic compounds, hydrogenations, and more generally the reductions, have been typically carried out in volatile organic solvents deriving from petroleum; indeed, all studies and fascinating advances related to the catalysts’ activity or the reducing agents’ reactivity have been limited to such volatile and often toxic reaction media. In this review, recent advances in the reducing methodologies with an improved degree of sustainability have been described. In particular, a series of examples have been reported to highlight the chance to reduce an organic compound by using a benign solvent deriving from renewable sources, without waiving to the process efficiency and selectivity. Some important key points of green chemistry, such as the easiness of catalyst recovery or the simplicity of product isolation, have been considered in the choice of the described studies.

Synthesis of functionalized janus hybrid nanosheets for one-step construction of pickering emulsion and selective photodegradation of water-soluble dyes

Recently, Pickering emulsions stabilized by photocatalytic nanomaterials have become a hotspot in the field of catalysis due to their high interfacial activity. However, since most photocatalytic nanomaterials are extremely hydrophilic, using them as stabilizers is unconvenient for Pickering emulsions construction. Herein, a novel magnetic Janus nanosheets (JMPSN/α-FeOOH) with Janus SiO2 nanosheets as the carrier and iron oxyhydroxide (α-FeOOH) as the catalyst species, respectively, was successfully fabricated through a simple synthetic strategy, which could act as an environmental-friendly Pickering emulsion emulsifier and catalyst simultaneously. We demonstrated that JMPSN/α-FeOOH exhibited good emulsifying properties of various oil phases. Morever, JMPSN/α-FeOOH in the formed Pickering emulsion-based photocatalytic system displayed significantly enhanced photocatalytic efficiency in degradation of dyes as compared to traditional non-emulsified systems while maintaining the stability of Pickering emulsion under constant irradiation. JMPSN/α-FeOOH could also quickly respond to external magnetic fields so as to achieve rapid recovery of catalyst, and catalyst still showed high catalytic activity after many catalytic cycles. Finally, a convenient and promising synthesis strategy for preparing Janus catalyst with low toxicity was proposed, which provided a guidance on how to effectively use the emulsion system stabilized by Janus catalyst to improve the degradation efficiency of various pollutants.

Photocatalytic Degradation of Organic and Inorganic Pollutants to Harmless End Products: Assessment of Practical Application Potential for Water and Air Cleaning

It is well-documented that large-scale pollution generated by human activity has a dramatic impact on ecosystems. In this context, removing harmful chemicals via photocatalysis has tremendous potential as a depollution method, utilizing freely available solar light and catalytic materials with low or negligible ecotoxicity. The main drawbacks, which aren’t often addressed in the available literature, are the formation of harmful intermediate products, low reaction rates, limited catalyst stability, and difficult catalyst recovery. In most cases, published works assess the efficiency of tested photocatalysts from pollutant degradation studies, whereas identifying and quantifying by-products is not often conducted. This review summarizes the recent advances reported for the photocatalytic removal of some organic (e.g., alcohols, carboxylic acids, volatile organic compounds, phenol) and inorganic (e.g., NO3−) contaminants. The efficiency of various UV- and visible-light active photocatalysts and the reaction degradation pathways were explained, emphasizing the main factors contributing to their mineralization. The reaction mechanisms, the identification and quantification of degradation intermediates, and the implication of reactive active species (ROS) were discussed and analyzed for each category of model target pollutant. Additionally, the actual challenges and future photocatalytic approaches to improve environmental remediation were presented.

Facile fabrication of mesoporous carbon-anchored cobalt ferrite nanoparticles as a heterogeneous activator of peroxymonosulfate for efficient degradation of Congo red.

Herein, mesoporous carbon-anchored cobalt ferrite nanocomposites (nano-CoFe2O4@MC) were fabricated using a hydrothermal method for application as heterogeneous catalysts to activate peroxymonosulfate (PMS), in order to solve the problems of low activation performance and secondary pollution caused by the inter-particle agglomeration, metal ion leaching, and difficult recovery of nano metal catalysts. Analysis techniques such as SEM, TEM, XRD, BET, FTIR, VSM, TGA, and Raman spectroscopy indicated that the prepared nanocomposites have excellent surface properties, structural stability, and magnetic properties. The performance of nano-CoFe2O4@MC for Congo red (CR) degradation was evaluated by comparison with other treatment systems and study of the influence of experimental parameters, including the anchoring ratios, catalyst dosage, PMS concentration, initial pH, CR concentration, coexisting anions, and humic acid. Both radical and nonradical pathways were observed in the activation process of PMS by nano-CoFe2O4@MC. The analysis results of the element composition and ionic state of the catalyst show that the redox cycle of two ion pairs, Co3+/Co2+ and Fe2+/Fe3+, could enhance the multipath electron transfer on the catalyst surface to promote the generation of reactive oxygen species. Identification of the intermediate products revealed CR was transformed into 12 intermediates through two branch pathways in the nano-CoFe2O4@MC/PMS system. After five cycles of use, the catalytic efficiency of the catalyst did not decrease significantly. Nanocomposites with high catalytic performance, stability, recyclability, and a low ion leaching rate have broad application prospects in the treatment of antibiotic wastewater.

Metal-free nitrogen-doped porous carbon nanofiber catalyst for solar-Fenton-like system: Efficient, reusable and active catalyst over a wide range of pH

Water pollution is a growing environmental crisis caused by industrialization. In-situ production of reactive oxygen species (ROS) is one of the most promising strategies to challenge this problem. However, developing a robust and efficient catalyst that can operate in harsh conditions without generating secondary pollution and tackle the recycling difficulties of powder catalysts remains a challenge. In this study, a graphitized N-doped carbon nanofiber (CNF) catalyst was synthesized in a direct synthesis approach, which is more efficient in time and cost and suitable for industrial applications, by means of electrospinning and carbonization process. Zinc acetate and iron nitrate functioned as a template for porous structure generation and carbon graphitizing catalysts. The as-synthesized catalyst was used in the wide pH range. This was mainly due to: i) the high surface area (∼ 652 m2 g−1) and the micro-mesoporous structure, which have reduced the inner diffusion resistance and facilitated mass transport radically during the reaction. ii) The enhanced electron transfer kinetics through the long 1D CNF revealed by the cyclic voltammetry analysis. iii) The abundance of oxygen-containing function groups, graphitic-C pyridinic-N and graphitic-N active sites that facilitated the activation of H2O2 and the generation of the ROS responsible for the degradation of the organic pollutants. The catalysts’ 1D structure and lightweight enabled the catalyst recovery and reuse.

Toward a General Protocol for Catalytic Oxidative Transformations Using Electrochemically Generated Hypervalent Iodine Species.

A simple catalytic electrosynthetic protocol for oxidative transformations mediated by hypervalent iodine reagents has been developed. In this protocol, electricity drives the iodine(I)/iodine(III) catalytic cycle enabling catalysis with in situ generated hypervalent iodine species, thereby eliminating chemical oxidants and the inevitable chemical waste associated with their mode of action. In addition, no added electrolytic salts are needed in this process. The developed method has been validated using two different hypervalent iodine-mediated transformations: (i) the oxidative cyclization of N-allylic and N-homoallylic amides to the corresponding dihydrooxazole and dihydro-1,3-oxazine derivatives, respectively, and (ii) the α-tosyloxylation of ketones. Both reactions proceeded smoothly under the developed catalytic electrosynthetic conditions without reoptimization, featuring a wide substrate scope and excellent functional group tolerance. In addition, scale-up to gram-scale and catalyst recovery were easily achieved maintaining the high efficiency of the process.

Synthesis of hybrid POSS based heterogeneous catalysts for N-alkylation of amines with alcohols

Herein, novel hybrid catalysts Cu@APPOSS-2 PC and Ni@APPOSS-2 PC have been synthesized by grafting the 2-pyridinecarboxaldehyde (2-PC) ligand on octa-aminopropyl polyhedral oligomeric silsesquioxanes (APPOSS) followed by immobilizing copper and nickel. The as-synthesized sustainable catalysts were characterized by FT-IR, SEM, and pXRD. Catalytic studies showed that both catalysts were excellent for CN coupling reactions to synthesize N-alkylated amines. Moreover, the facile synthesis, easy catalyst recovery, and good sustainability were the advantages from the catalytic point of view.

Al3+ doped CuFe2O4 efficiently activates peroxymonosulfate for long-term and stable degradation of tetracycline: Synergistic and regulatory role of Al3+

The water pollution caused by the proliferation of tetracycline hydrochloride (TC) has seriously harmed human beings and the environment. Therefore, it is necessary to design a catalyst that can effectively remove TC and immobilize it for practical applications. Spinel catalysts can effectively resolve the problem of TC contamination in water. In this research, in order to solve the problems of poor dispersion, inferior performance and weak stability of copper ferrate (CuFe2O4). Al3+-doped CuFe2O4 was prepared by the one-step sol–gel-combustion method and used as a peroxymonosulfate (PMS) activator to promote the degradation of tetracycline (TC). A series of degradation experiments and characterization indicated that Al3+-doped CuFe2O4 could remove more than 95 % of TC within 20 min, its first-order kinetic degradation constant was 2.5 times higher than that of CuFe2O4. The mechanism by which Al3+ could improve the degradation of CuFe2O4 may be as follows: the presence of Al3+ increased the electron transfer rate of the metal; effectively increased the specific surface area of the catalyst, provided more active sites; the Al-O-Fe and Al-O-Cu bonds generated by Al3+ immobilized the highly reactive metal ions, reducing ion leaching and improving the stability of the catalyst. Electron paramagnetic resonance and quenching experiments identified the synergistic effect of both radicals and non-radicals in the reaction. Electrochemistry and X-ray photoelectron spectroscopy (XPS) further verified the possible catalytic mechanism. Furthermore, by further immobilization, the 1 g of catalyst could continuously degrade 9 L of TC in water without stirring, showing excellent practical applications. This work provides a reference for improving the catalytic performance of ferrite spinel materials and solving the difficult problem of catalyst recovery in the real environment.

Designing of a magnetically recoverable (Ce+3, +4/Fe+2. Fe+3) oxide@ 2D g-C3N4 surface for enhanced photo-Fenton catalytic degradation of Bismarck-Brown R and Congo red dyes: kinetics, optical properties,and mechanistic pathway studies

ABSTRACT Co-precipitation-assisted hydrothermal synthesis was employed to synthesize Fe3O4/CeO2 nanohybrids over 2D g-C3N4 (CF@GCN) for photo-Fenton catalytic degradation of Bismarck brown R (BBR) and Congo Red (CR) dyes. Initially, Fe loading was deployed in CF@GCN with different sets of molar ratios of Fe against the 1 mole of Ce (Ce: Fe=1:0.2-1). Among different sets, the one with 0.8 moles of Fe against the 1 mole of Ce (C1F0.8@GCN) performed excellently for BBR and CR dye degradation via aiding in the photo-Fenton process. Morphological, structural, compositional, and electronic states of the final nanocomposite were evaluated using powder X-ray diffraction, transmission electron microscopy/high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. BET analysis of the final nanocomposite showed an excellent surface area of 56.76 m2g−1, allowing for effective degradation. UV–vis spectrophotometry, UV-DRS, and PL (photoluminescence) techniques were performed to monitor the optical properties of the final nanocomposite. Taulc’s plots estimated the band gaps of catalysts, and the final nanocomposite’s band gap was 2.2 eV, which was key for capturing photons from the light source and functioning the degradation process. Further, operating parameters such as catalyst dose, dye concertation, pH, H2O2 dose, and contact time studies were done with the final nanocomposite. C1F0.8@GCN degraded BBR up to 94.5 % within 30 minutes with a first-order rate constant of 0.09747 min−1 and CR dye up to 97.7 % within 45 minutes with a first-order rate constant of 0.07391 min−1. All results supported a nanocomposite of Fe3O4 nanoparticles and CeO2 nanorods grown over 2D g-C3N4 sheets. As predicted, composing Fe3O4 sped up catalyst recovery. Also, the final nanocomposite’s dye degradation rate was consistent till the 6th run. So, the study proposes a cost-effective plan for dealing with organic water contaminants like hazardous dyes.

Copper (II) Complex Immobilized on Magnetic Nanoparticles Functionalized with Imine/Thio Ligand (Fe3O4@SiO2-Imine/Thio-Cu(II)): A Novel, Efficient and Reusable Nanomagnetic Catalysts for the Synthesis of 2,4,6-Triaryl Pyridines

Herein we introduce a novel and reusable nanomagnetic copper catalyst (Fe3O4@SiO2-Imine/Thio-Cu(II)) constructed by immobilizing copper (II) complex on the surface of magnetic nanoparticles functionalized with Imine/Thio group. The structure of the as-constructed Fe3O4@SiO2-Imine/Thio-Cu(II) nanomaterial was well analyzed by a number of spectroscopic techniques including: FT-IR, SEM, TEM, EDX, XRD, VSM, AAS and ICP-OES. Experimental studies have well revealed that Fe3O4@SiO2-Imine/Thio-Cu(II) nanomaterial is an ecofriendly and efficient nanocatalyst for synthesis of 2,4,6-triaryl pyridines (82%–98%) via a C-N bond cleavage of benzylamines under aerobic oxidations in PEG at 120 °C. The grafting of the copper catalyst to the surface of magnetic nanoparticles has increased the catalytic activity of the material and also simplified catalyst recovery from the reaction mixture by an external magnet. The Fe3O4@SiO2-Imine/Thio-Cu(II) nanocatalyst was readily recovered by simple magnetic decantation and can be reused seven cycles without considerable loss in catalytic activity.

Economic analysis for the hydrogenation of sunflower oil using Pt monolith catalysts

In the present work, the economic feasibility of the hydrogenation of vegetable oil using a platinum structured catalyst in a monolithic stirrer reactor (MSR) is examined. An 80 t day−1 hydrogenation plant with a reactor with a capacity of 10 t and a final product with 70 iodine index was selected. The study considered process equipment made of carbon steel and A304 stainless steel. Through simulation, the optimal conditions for the hydrogenation performed adiabatically were determined in order to reduce the processing costs: initial reaction temperature = 453 K, hydrogen pressure = 7 atm, stirrer speed = 200 rpm, and catalyst loading = 0.04 kgPt,sup m−3. The economic indicators showed that the proposed catalytic process is profitable, with a higher net present value using carbon steel instead of stainless steel A304. The sensitivity analysis revealed that vegetable oil cost is the most influential variable on the economy of the project, followed by hydrogen consumption and taxes. The changes in labor costs and catalyst recovery were negligible. The selection of A304 stainless steel carries a considerable economic risk, whereas when using carbon steel, the risk is lower, showing promising profit.

A nano-organo catalyst mediated approach towards the green synthesis of 3-methyl-4-(phenyl)methylene-isoxazole-5(4H)-one derivatives and biological evaluation of the derivatives as a potent anti-fungal and anti-tubercular agent

An efficient and green protocol for the one-pot synthesis of 3-methyl-4-(phenyl)methylene-isoxazole-5(4H)-one derivatives catalyzed by a novel acid functionalized Fe3O4 nanoparticles (NPs) is reported herein. The catalyst was synthesized and characterized by various analytical techniques. Ultrasound energy has been efficiently exploited for the preparation of the catalyst as well as the synthesis of a series of the aforesaid compounds. The salient features of this protocol include mild reaction condition, easy catalyst recovery, shorter reaction time and use of environmental-friendly solvents. In addition, preliminary in-vitro antifungal and antimycobacterial screening of the synthesized compounds were conducted against three pathogenic fungi viz., Aspergillus fumigatus, Aspergillus flavus, Fusarium oxysporum and M. tuberculosis H37Rv respectively. Interestingly, 3-chloromethyl-4-(phenyl) methylene-isoxazole-5(4H)-one series exhibited over 50% growth inhibition against the mycelial growth of the fungi Fusarium oxysporum at 100 μg/mL. Whereas 4-(1H-indol-3-ylmethylene)-3-methyl-4H-isoxazol-5-one and 3-chloromethyl-4-(2,4,6-trimethyl-benzylidene)-4H-isoxazol-5-one displayed antimycobacterial activity against Mycobacterium tuberculosis H37Rv strain equipotent to the standard drug, ethambutol (MIC 1.56 μg/mL).

A trible-functional anatase composite with ultrafast visible light-catalytic performance for water decontamination

Developing highly performance TiO2-based photocatalyst for pollutant removal from environmental media is of increasing interest from both research and practical perspectives. However, there are currently few developed materials effective for fully addressing all limitations in the catalytic performance and real application. Herein, we report the fabrication of triple-functional {001}-N-TiO2/VSCF/Fe3O4 through a one-step hydrothermal-template synthesis coupled with composite methods as an effective material towards resolving most of the dilemmas. The resultant composite incorporated efficient pollutant capture and photocatalytic degradation, material recovery into one individual, which consists of a hollow-spherical {001}-N-TiO2 photocatalytic site, a vine-shaped carbon fiber adsorptive loader and a Fe3O4 magnetic-responsive part. When exposed to the pollutant under light irradiation, the {001}-N-TiO2/VSCF composite showed remarkable photocatalytic performance. The magnetic-responsive property of {001}-N-TiO2/VSCF/Fe3O4 facilitated catalyst recovery, the composite exhibited good catalytic stability during recycling uses. Our triple composite {001}-N-TiO2/VSCF/Fe3O4 may be applied as a comprehensive functional, efficient and recyclable material for eliminating the current problems in environmental remediation and purification.

2‐Arylbenzyl Methyl Ethers as Precursors for the Tandem Synthesis of Benzo[c]coumarins Over Heterogeneous Visible‐Light Photoredox Catalysis with Graphitic Carbon Nitride (g‐C3N4)

AbstractUtilizing readily accessible 2‐arylbenzyl methyl ethers as precursors, an unprecedented three reactions in one‐pot protocol for the synthesis of benzo[c]coumarins over heterogeneous visible‐light photoredox catalysis with graphitic carbon nitride (g‐C3N4) has been developed. Also, a possible reaction mechanism has been explored. Upon irradiation, g‐C3N4 converts molecular oxygen into superoxide radical anion, which facilitates the benzylic oxidation of 2‐arylbenzyl methyl ethers into methyl [1,1′‐biaryl]‐2‐carboxylate. The required benzo[c]coumarins are then produced through the hydrolysis and dehydrogenative lactonization of methyl [1,1′‐biaryl]‐2‐carboxylate. The main attributes of this transformation include mildness, convenience in catalyst recovery and reuse, compatibility with lithium persulfate produced from the spent lithium‐ion batteries, works in aqueous medium, and is a multiple C−H functionalization processes happen via three reactions (oxidation, hydrolysis and dehydrogenative lactonization) in one‐pot at ambient conditions.

DBU-MIm coupled ionic liquids as reusable catalysts for the Biginelli reaction

In present work, the application of a novel set of 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) and methylimidazole (MIm) coupled ionic liquids (ILs) in the Biginelli reaction has been investigated. In the modified Biginelli reaction, cinnamaldehyde, urea, and 1,3-diketone condensed in the presence of 10 mol% of the DBU-MIm coupled IL catalyst at 90 °C to afford dihydropyrimidinones in high to excellent yields in 45 min. Additionally, the effect of temperature, catalytic amount, and solvent has also been unfolded. The reaction has been found to the follow iminium ion mechanism and the synergic role played by the [DBUH]+ and [MIm]− moieties has been established by DFT calculations. The easy post-procedure recovery and reusability of the DBU-MIm IL catalysts make the present protocol of Biginelli synthesis simple, benign and reproducible.

Reusable nano-catalyzed green protocols for the synthesis of quinoxalines: an overview.

Heterocyclic compounds are very widely distributed in nature and are essential for life activities. They play a vital role in the metabolism of all living cells, for example, vitamins and co-enzyme precursors thiamine, riboflavin etc. Quinoxalines are a class of N-heterocycles that are present in a variety of natural and synthetic compounds. The distinct pharmacological activities of quinoxalines have attracted medicinal chemists considerably over the past few decades. Quinoxaline-based compounds possess extensive potential applications as medicinal drugs, presently; more than fifteen drugs are available for the treatment of different diseases. Diverse synthetic protocols have been developed via a one-pot approach using efficient catalysts, reagents, and nano-composites/nanocatalysts etc. But the use of homogeneous and transition metal-based catalysts suffers some demerits such as low atom economy, recovery of catalysts, harsh reaction conditions, extended reaction period, expensive catalysts, the formation of by-products, and unsatisfactory yield of products as well as toxic solvents. These drawbacks have shifted the attention of chemists/researchers to develop green and efficient protocols for synthesizing quinoxaline derivatives. In this context, many efficient methods have been developed for the synthesis of quinoxalines using nanocatalysts or nanostructures. In this review, we have summarized the recent progress (till 2023) in the nano-catalyzed synthesis of quinoxalines using condensation of o-phenylenediamine with diketone/other reagents with plausible mechanistic details. With this review, we hope that some more efficient ways of synthesizing quinoxalines can be developed by synthetic chemists.

Development of heterogeneous catalyst from assorted periwinkle snail shells for sustainable biodiesel synthesis

Owing to the environmental friendliness of biodiesel compared to fossil fuels, its application in internal combustion engines has gained wide recognition. The biodiesel industry requires effective heterogeneous catalysts developed from agricultural biomass/residues due to their overall cost-effectiveness, recoverability, and reusability. Scientific reports on developing active heterogeneous catalysts from periwinkle snail shells for application in transesterification reactions are limited, as there is no evidence of stability test results for the catalyst’s structural and elemental composition analysis. Also, there is a deficit of information on the catalytic effect on biodiesel yields. This research developed a heterogeneous catalyst derived from periwinkle snail shells (PSS) for biodiesel production. Pulverized PSS were sieved through several apertures to separate the samples into different particle sizes, viz. 250 mm, 500mm, and 1000 mm. The samples were calcined in an electric furnace at 500 oC for 3 and 5 hrs. The calcined catalyst samples were characterized using XRD, SEM, and EDS. Purified WCO was transesterified using the CPSS with the highest metallic oxides percentage under different experimental levels. All the CPSS samples exhibited a change in colour and weight loss after the calcination period. XRD observations revealed that calcium oxide (CaO) is the principal constituent of the calcined PSS (CPSS). The results showed that the highest (93%) traces of CaO was found in PSS 500 mm size calcined at 500 oC for 5 hrs. EDS results showed that the same sample had the highest calcium (Ca) composition with a weight percent of 57.38%. The highest biodiesel yield of 94.6% was obtained at optimum conditions of 70 oC reaction temperature, 9:1 molar ratio, 60 minutes reaction period, and catalyst content of 3 wt%. It was observed that biodiesel yields decreased when the catalyst concentration increased beyond 3wt%. Compared to the same amount of homogeneous catalyst, KOH, an average biodiesel yield of 90% was recorded from the same transesterification reaction conditions. The development of heterogeneous catalysts from PSS was established as a cost-effective means of catalyzing transesterification reactions and obtaining high biodiesel yields from WCO with the prospects of possible catalyst recovery and reuse.

Sulfonated phenylamine ionic liquids as efficient phase-separation catalysts for the synthesis of trimethylolpropane triacrylate

PS3-PA with multi-SO3H exhibits excellent catalytic performance for the esterification of TMP with acrylic acidviahydrogen bond formation. The phase-separation behavior of PS3-PA plays an important role in catalyst recovery and stable reuse.