Nanoparticle Materials Research Articles

Dicarboxylate cellulose nanofibrils-supported silver nanoparticles as a novel, green, efficient and recyclable catalyst for 4-nitrophenol and dyes reduction

This study reports dicarboxylate cellulose nanofibrils (DCNF) as a novel reducing and supporting agent for producing silver nanoparticles (AgNPs) with high efficiency (63.82 % reduction) and loading (6.88 %) using UV light. Unlike previous research, AgNPs formation with DCNF doesn't involve cellulose oxidation. Instead, it appears to involve a loss of carboxyl groups from DCNF. In comparative studies, pristine CNF (PCNF) and TEMPO-oxidized CNF (TOCNF) were also examined for AgNPs production. The resulting AgNPs from DCNF exhibited a significantly smaller average size (3.9 ± 0.7 nm) compared to those from PCNF (26.9 ± 10.9 nm) and TOCNF (13.5 ± 4.5 nm). Catalytic activity evaluation by the 4-nitrophenol (4-NP) reduction reaction revealed a high rate constant of 8.47× 10−3 s−1 by AgNPs/DCNF, which surpassed AgNPs/TOCNF (1.79 × 10−3 s−1) and AgNPs/PCNF (0.63 × 10−3 s−1) by 4.7 and 13.4 times, respectively. Besides 4-NP, AgNPs/DCNF aerogels were also applied for methyl orange and Rhodamine B dyes reduction. The aerogels showed excellent reusability, maintaining over 95 % conversion even after five cycles and also effective in treating real samples and mixed dye solutions. This study opens the door for future research exploring DCNF as a support material for various metal, metal oxide, and carbon nanoparticles.

High Sensing Performance of n-Butanol Gas Sensor Based on Mesoporous Cu-Doped α-Fe₂O₃ Nanoparticle Materials

High Sensing Performance of n-Butanol Gas Sensor Based on Mesoporous Cu-Doped α-Fe₂O₃ Nanoparticle Materials

Formation and agglomeration of nanoparticles and carbon debris in MnO2@C/GO

Carbon-loaded manganese dioxide (MnO2) nanoparticle materials have potential applications in energy storage and conversion, environmental and sensing applications. Carbon-coated MnO2 nanoparticles can avoid particle agglomeration. However, the process of forming MnO2 nanoparticles and carbon shells is unclear when carbon material is used as a carrier. In this work, the generation and convergence processes of nanoparticles and carbon debris were probed at bulk and monolayer levels using graphene oxide as carrier. And it is deduced that MnO2 nanoparticles first nucleate and aggregate at GO plane. As the size of the nanoparticles increases, the surrounding nanoparticles further aggregate. GO is etched during the formation of nanoparticles, resulting in the formation of carbon debris. Amorphous carbon shells are mainly formed by the aggregation of carbon debris. The MnO2@C/GO obtained was tested for H2O2 detection and showed superior H2O2 reduction properties.

Versatility of the Templated Surface Assembly of Nanoparticles from Water-in-Oil Microemulsions in Equivalent Hybrid Nanostructured Films.

Water-in-oil microemulsions, as stable colloidal dispersions from quasi-ternary mixtures, have been used in diverse applications, including nanoreactors for confined chemical processes. Their use as soft templates not only includes nanomaterial synthesis but also the interfacial assembly of nanoparticles in hybrid nanostructures. Especially the hierarchical arrangement of different types of nanoparticles over a surface in filament networks constitutes an interesting bottom-up strategy for facile and tunable film coating. Herein, we demonstrate the versatility of this surface assembly from microemulsion dispersions. Transmission and Scanning Electron Microscopy, in addition to UV-Vis Transmittance Spectroscopy, proved the assembly tunability after solvent evaporation under different conditions: the nanostructured films can be formed over different surfaces, using different compositions of liquid phases, as well as with the incorporation of different nanoparticle materials while keeping equivalent surface functionalization. This offers the possibility of adapting different components and conditions for coating tuning on a larger scale with simple procedures.

Laser Treatment Effect on Fatigue Characterizations for Steel Alloy Beam Coated with Nanoparticles

Previous work investigated the effect of nano coating for steel beams on the fatigue characterization and calculated that the coating for beams leads to modifying the fatiguelife and stress. Therefore, this work modifies the fatigue characterizations for beams by using laser treatment. The main aim of this work is to modify the fatigue properties of steel materials by using a coating surface, with nanoparticle materials, in addition to the laser treatment technique, at the same time. The experimental work was divided into three parts; first, the fabricated fatigue steel samples were coated by zinc oxide (ZnO) nanoparticle; second, treatment of the fatigue sample by laser technique using (low-high) and (high–low) loading; and finally, testing the fatigue samples to calculate the fatigue life and stress, with and without laser treatment. A scanning electron microscope (SEM) was used to study the surface morphology of the samples. In addition, the numerical technique, using the finite element, was employed to evaluate the fatigue characterizations for steel samples and the results were compared. The comparison of the numerical and experimental results shows that the maximum discrepancy did not exceed about 10.86%. Finally, the treatment of nanomaterials coated steel samples shows that the fatigue characterizations were more than 35%.

Advancing gamma radiation shielding with Bitumen-WO₃ composite materials

This research focuses on a manner in which bitumen-WO₃ (petroleum-derived bitumen mixed with tungsten trioxide nanoparticles) materials can be a good shielding candidate against gamma radiation. The objective we set in mixing WO₃ nanoparticles with bitumen was to take advantage of both the bitumen's natural qualities and the WO₃'s excellent shielding capabilities. The prepared composites were tested against various gamma-ray energies emitted from multiple gamma-ray sources to examine their shielding capabilities. The X-ray diffraction (XRD) analysis of the composites' structural properties verified the effective integration of the WO₃ with the bitumen structure. Scanning electron microscopy (SEM) showed that microstructural changes, such as an increase in material density and an improvement in particle dispersion, are caused by a rise in WO3 concentration, which is an essential step toward efficient shielding. Then, the Mean Free Path (MFP), Half-value Layer (HVL), and Linear Attenuation Coefficients (μl) were computed, showing that the composite's capacity to reduce gamma radiation is much enhanced by raising the WO₃ content, especially at lower gamma-ray energies. For instance, at 20 keV, the LAC of 50 wt% WO₃-bitumen composite increased to 9.18 cm⁻1 compared to pure bitumen's 0.40 cm⁻1, while the HVL decreased from 1.73 cm to 0.08 cm, and the MFP dropped from 2.3 cm to 0.1 cm” The results demonstrate the potential of bitumen-WO₃ composites as a sustainable and efficient material for radiation shielding, particularly highlighting their applicability in various sectors, including the development of building wall paints against gamma radiation.

Effect of nano particulate preservation materials on the combustion temperatures of the wood

It is acknowledged that boron, ammonium, and nitrogenous compounds, which are used today as fire retardants, cause an increase in the hygroscopicity of wood materials. In this study, Scots pine (Pinus sylvestris L.), Anatolian chestnut (Castanea sativa Mill.), and Eastern spruce (Picea orientalis Link) woods were impregnated with 1.5% nano-sized hexagonal boron nitride (NB) according to ASTM D1413-76 (1976) standards. Flame-induced combustion (FIC), self-combustion (SC), and glowing combustion (GC) temperatures were determined. The highest retention amount was measured in spruce and the lowest was in chestnut among the wood samples taken for testing and measurement. When compared with the control samples, NB application caused an increase in SC and FIC temperatures (at higher rates). According to the glowing combustion temperature control samples, an increase was observed in chestnut and spruce and a decrease was observed in Scots pine among the samples applied with NB.

Solar‐Assisted CO2 Methanation via Photocatalytic Sabatier Reaction by Calcined Titanium‐based Organic Framework Supported RuOx Nanoparticles

AbstractCO2 reduction by sunlight under mild reaction conditions is a research area of increasing interest expected to favor decarbonization and produce fuels and chemicals in the circular economy. We hereby report on the development of a series of titanium oxide‐based solids produced by calcination of MIL‐125(Ti)‐NH2 decorated with RuOx nanoparticles (1 wt %) material at temperatures from 350 to 650 °C and used as photocatalysts for CO2 methanation under simulated sunlight irradiation (45 mW/cm2) at <200 °C and 1.5 atm total pressure. The material synthesized at 350 °C produced the highest photoactivity of the series (4.73 mmol g−1 CH4 at 22 h and an apparent quantum yield at 400, 500 and 750 nm of 0.76, 0.65 and 0.54 %, respectively), comparing favorably with the activities of other MOF‐based materials reported so far. Insights into the material's photocatalytic performance and a study of the possible reaction pathways during CO2 methanation were obtained by electrochemical impedance, electron spin resonance, photoluminescence and in situ FT‐IR spectroscopies together with transient photocurrent and hydrogen temperature programed desorption measurements. The study showed the possibility of using MOF‐based materials as precursors to develop metal oxide photocatalysts with enhanced activities for solar‐driven gaseous CO2 photomethanation.

Magnetite Fe3O4 nanoparticles impregnated on Chlorella vulgaris microalgae: Its role in obtaining hydrogen from the sodium borohydride-hydrolysis

Recently, the single-celled green freshwater microalgae species “Chlorella vulgaris” has attracted the attention of researchers due to its different usage areas. In particular, research focuses on the technology of obtaining bio‑hydrogen with various techniques. This research involves, for the first time, the use of the microalga Chlorella vulgaris as a bio-supporting material for magnetite Fe3O4 nanoparticles (Fe3O4NPs@Chlorella vulgaris) and the production of hydrogen through catalytic hydrolysis of NaBH4 (sodium borohydride, SB) in the presence of the resulting magnetite nanoparticles. Here, detailed kinetic studies were carried out during the SB-hydrolysis by taking magnetite Fe3O4NPs@Chlorella vulgaris and SB in varying amounts and at varying temperatures, and the activation energy and lifetime of magnetite Fe3O4NPs@Chlorella vulgaris was found to be 23.49 kJ mol−1 and 93,280 mol H2 (mol Fe3O4)−1, respectively. No change in the chemical and physical structure of the biocatalyst was observed during the hydrolysis of SB, so only detailed characterization of microalgae and magnetite Fe3O4NPs@Chlorella vulgaris was performed, and the particle size of the catalyst was calculated as 10.19 ± 2.17 nm. The results showed that these Fe3O4NPs@Chlorella vulgaris, which can be easily separated magnetically and have high catalytic activity, are a “clean” and quite surprising catalyst in terms of hydrogen production.

Use of Dialysis Membranes for the Purification of Fe/Ni and Fe/Cu Nanoparticles Synthesized from Green Tea Extract

AbstractTo ensure the quality and effectiveness of nanoparticle material for specific applications, it is essential to eliminate contaminants or unreacted substances produced during the green synthesis process using leaf extract. In this study, dialysis membranes with a molecular weight cut‐off (MWCO) of approximately 12,000–14,000 Dalton (Da) were employed to remove metal ions, chlorides, and polyphenols from the zerovalent bimetallic nanoparticles (BNPs) suspension, instead of using centrifugation or filtration, which causes solvent loss to the environment. Our research results showed that the efficiency of removing impurities and residual components achieved by the dialysis membrane was relatively high. Furthermore, alterations in specific characteristics of BNPs following dialysis were also observed and discussed.

Research on the Mechanism of Nanoparticle materials in Oil Displacement and its Application

Abstract The application of nanoparticles in the field for enhanced oil recovery (EOR) is a new technology, which has attracted widespread concern. However, there is a lack of systematic research on the types and mechanisms. In order to clarify the types and characteristics of the material, oil displacement mechanism and its effect on oil and water flow, this paper systematically sorted out the classification of nanoparticle materials used in the field of petroleum development, and analysed its percolation and oil displacement mechanism. Numerical simulation and field data analysis were carried out to study the applications of two types of nanomaterials in improving reservoir water injection and oil displacement efficiency quantitatively. The results show that the main mechanism of nanoparticle flooding is to change reservoir wettability, reduce oil-water interfacial tension, modify the mobility ratio between water and oil phases, and reduce asphaltene precipitation. Lipophilic and hydrophobic nanoparticle may reduce injection pressure, and increases significantly injection in low permeability reservoirs, and the average water injectability of 6 wells is increased by 177.76%. The displacement efficiency of hydrophilic and oleophobic nanoparticles can be increased by 14.78%. This paper reveals the oil displacement mechanism of nanoparticle materials and establishes a new method to quantitatively predict the oil displacement effect of nanoparticle materials, which provides a basis and reference for the application of oilfield.

Numerical modeling and optimization of fillet height of reinforced SAC305 solder joint in an ultra-fine capacitor assembly

PurposeThis study aims to investigate the design configuration for an optimum solder height of reinforced SAC305 solder joint in an ultra-fine capacitor assembly.Design/methodology/approachA multiphase finite volume model is developed for reflow soldering simulations to determine the fillet height of reinforced SAC305 solder joint in an ultra-fine capacitor assembly. Different solders, namely SAC305-x, SAC305-xNiO and SAC305-xTi, with varying percentage weight compositions of nanoparticles (x = 0 Wt.%, 0.01 Wt.%, 0.05 Wt.%, 0.10 Wt.%, 0.15 Wt.%) are investigated. A reflow soldering experiment is also conducted, and the cross-sections of the reflowed packages are examined using a High-Resolution Transmission Electron Microscope (HRTEM). The optimum design configurations (nanoparticle composition and material) for the solder fillet height are investigated using the Taguchi orthogonal array method.FindingsGood correlations were recorded between the HRTEM micrographs and the numerical predictions of the nanoparticles' distribution in the molten solder. The numerical prediction of the fillet height also agrees with the experiment, with a maximum disparity of 5.43%. It was found that Ti nanoparticles, having the smallest density compared to NiO and, exhibit the highest buoyancy effect in the molten solder. The Taguchi analysis revealed that the nanoparticles' material factor is more significant than the Wt.% factor for an optimum fillet height. An optimum design configuration for fillet height was established as SAC 305–0.15 Wt.% Ti, corresponding to a 41.13% improvement of the plain SAC 305 solder.Practical implicationsThe fillet height of solder joints greatly influences the solder joint reliability of miniaturized electronic packages. Solder joint reliability of ultra-fine capacitors can be improved using this study's findings on the optimum design configuration for the capacitor's solder fillet. The study’s findings can be practically implemented in industries such as electronics manufacturing, where enhanced solder joint reliability is critical.Originality/valueInvestigation of the optimum design configuration for reinforced SAC305 solder fillet is almost nonexistent in the literature. This study explored the optimization of fillet height of reinforced SAC305 solder joints in miniaturized capacitor assembly.

Biotoxicity of silver nanoparticles complicated by the co-existence of micro-/nano-plastics

Silver nanoparticles (AgNP) and polystyrene (PS) plastics have been broadly utilized in various field, e.g., food storage, packaging materials, and medical therapies. However, investigation on the potential biotoxicity induced by the co-exposure to AgNP and PS plastics remains understudied. Thus, we performed this study to examine the toxicological profile of the co-exposure to AgNP and PS in mice. Biochemical and microbial characterizations were performed in mice receiving 90-day oral gavage feeding to examine the hepatotoxicity, neurotoxicity, inflammatory responses, gut microbial alterations. It has been found that the presence of plastic particles aggravates the toxicity of silver nanoparticle materials. Regardless of the plastic type and size, energy and choline metabolisms will be altered by the co-exposures. Moreover, microplastics may induce cell damage by modulating fatty acid peroxidation in unison with stimulating inflammatory responses. Due to the smaller size of nanoplastics, they may pass through blood-brain barrier to induce neuronal damage and increase vascular risks. Changes in the microbial functional abundances are sensitive to the microplastics doses. These results support the necessity of reducing the co-exposure between AgNP and multiscale plastics, and advocate further developments of biodegradable package materials to improve food safety.

Influence of Nanofluid Types on the Enhancements of Solar Collector Performance

Nowadays, solar energy is attracting a great deal of research interest. Optimizing solar collectors by incorporating nanoparticles into the base fluid is one area of current research focus. This study investigates how the types of nanoparticles affect the performance of solar collector. We investigated the effects of various nanoparticles types on performance of solar collector. Nanofluid 1 (alumina nanoparticles; Al2O3) and nanofluid 2 (silicon dioxide nanoparticles; SiO2) were combined with water. Nanofluids are made with a constant nanoparticle concentration of 0.5 vol. %. Data collection was conducted under Iraqi environments during the three-month study period (January, February, and March) from 9 a.m. to 3 p.m. In particular, the data for every two-hour period is displayed. The results demonstrated the collector’s efficiency significantly influenced by nanoparticles’ type. At 1 p.m. in February, nanofluid 1 was 4.8% in front of nanofluid 2. The significance of nanoparticle materials in enhancing solar collector efficiency is highlighted by this outcome. When water-based fluid in the solar collector was compared to nanofluids 2 and 1, the latter demonstrated a typically better efficiency. Nanoparticle owns higher thermal conductivity which is one of the reasons behind the increments of the nanofluid's overall conductivity.

Bio-derived mesoporous carbon confinement synthesis of ultra-small α-Fe2O3 nanoparticles as electrocatalysts for overall water splitting

The use of high-surface-area materials in loading α-Fe2O3 nanoparticles presents an intriguing approach to improve the electrocatalytic efficiency of overall water splitting. Nevertheless, the effective management of α-Fe2O3 nanoparticle size to prevent their agglomeration continues to pose a significant challenge. This study used bio-based porous carbon with a specific surface area of 2876 m2/g and a mesoporous ratio of 95 % as a carrier to effectively disperse and inhibit the growth of α-Fe2O3 nanoparticles. The Fe2O3/NSC-30 was synthesized using urea as a precipitant through an ethylene glycol-assisted hydrothermal method accompanied by high-temperature calcination, with the α-Fe2O3 nanoparticle size being approximately 5.5 nm. The synergistic effect between the ultra-small nanoparticles and the mesoporous structure facilitates the effective diffusion of electrolyte and exposes more catalytic active sites. The Fe2O3/NSC-30 exhibited remarkable catalytic performance in the OER and HER, as evidenced by the respective low overpotentials of 270 mV and 250 mV at 20 mA cm−2. Furthermore, when Fe2O3/NSC-30 was utilized in the overall water-splitting reaction, a low cell voltage of 1.70 V was sufficient to achieve a current density of 20 mA cm−2. In this study, a new method was proposed for loading ultra-small nanoparticles onto bio-derived mesoporous carbon for promoting overall water splitting with remarkable efficiency.

Modulating the DNA/Lipid Interface through Multivalent Hydrophobicity.

Lipids and nucleic acids are two of the most abundant components of our cells, and both molecules are widely used as engineering materials for nanoparticles. Here, we present a systematic study of how hydrophobic modifications can be employed to modulate the DNA/lipid interface. Using a series of DNA anchors with increasing hydrophobicity, we quantified the capacity to immobilize double-stranded (ds) DNA to lipid membranes in the liquid phase. Contrary to electrostatic effects, hydrophobic anchors are shown to be phase-independent if sufficiently hydrophobic. For weak anchors, the overall hydrophobicity can be enhanced following the concept of multivalency. Finally, we demonstrate that structural flexibility and anchor orientation overrule the effect of multivalency, emphasizing the need for careful scaffold design if strong interfaces are desired. Together, our findings guide the design of tailored DNA/membrane interfaces, laying the groundwork for advancements in biomaterials, drug delivery vehicles, and synthetic membrane mimics for biomedical research and nanomedicine.

Structural Modification Effect of Se-doped Porous Carbon for Hydrogen Evolution Coupled Selective Electrooxidation of Ethylene Glycol to Value-added Glycolic Acid.

The ethylene glycol oxidation reaction (EGOR) has attracted attention because ethylene glycol (EG), which exhibits large-scale production and a low market price, can be reformed into valuable glycolic acid (GCA) with the cogeneration of high-purity hydrogen gas during the reaction. In this study, a noble catalyst material of Pt nanoparticles supported on Se-doped porous carbon (Pt/SePC) is prepared and investigated for the selective electrochemical oxidation of EG to GCA. Pt/SePC achieved a maximum EG conversion of 94.6% and GCA selectivity of 84.4% and maintained this high performance with negligible degradation during durability tests. Furthermore, the EGOR required lower overpotential rather than the oxygen evolution reaction, thus the EGOR coupled with the hydrogen evolution reaction can reduce the cell overpotential to 0.60 V, which is much lower than that of water electrolysis (1.58 V). The effect of Se doping is investigated through experimental analyses and density functional theory (DFT) calculations, and they shows that Se modified the binding energy of Pt nanoparticles and the adsorption energy of reactants by lattice deformation and charge density modification. This study provides scientific insights and strategies for electrocatalyst design for the selective oxidation of polyols to value-added chemicals via the cogeneration of hydrogen gas.

Thiocarbohydrazide-cross-linked pectin: A promising support material for palladium nanoparticles in the water-mediated Suzuki-Miyaura cross-coupling reaction and the catalytic reduction of 4-nitrophenol

Suzuki-Miyaura reaction is a classic palladium-catalyzed reaction for forming Csp2-Csp2 bonds. However, the leaching of Pd species and using organic solvents are two important problems that adversely affect their performance, reusability, and greenness. Considering the abundant resources, cheapness, and availability of pectin (Pec), a Pec-based catalyst for the Suzuki reaction in pure water as a non-toxic reaction medium was developed for the first time. In this regard, Pec was chosen as a benign support and cross-linked by thiocarbohydrazide (TCH) to prepare Pec-TCH. The Pec-TCH acted as an efficient reducing and stabilizing agent for in-situ fabrication of Pd(0) nanoparticles. The heterogeneous and air-stable Pec-TCH-Pd(0) nanoparticles were thoroughly characterized. The results exhibited a significant catalytic activity (up to 99%) and reusability (at least 7 times) for in-water Suzuki-Miyaura cross-coupling reaction. The use of TBAB as a phase-transfer catalyst improved the yield of Suzuki reaction since it prevented the problems related to the immiscibility of water and aryl halides as well as the gelation of catalyst. The catalyst was also utilized for water-mediated 4-nitrophenol reduction to 4-aminophenol with NaBH4 which showed excellent activity (k = 9.2 × 10−3 s−1). A very good compatibility with iodobenzene, bromobenzene, and chlorobenzene was observed for the Suzuki reaction. Because of various binding sites such as amino, hydroxyl, carbonyl and thiocarbonyl groups, negligible leach of Pd nanoparticles was observed, as shown by ICP-MS after runing 7th of reusability studies. Moreover, the leaching, mercury poisoning, and large-scale tests showed its potential for industrial applications.

Significance of nanoparticle aggregation for thermal transport over magnetized sensor surface

Abstract This article explores the dynamics of nanofluids consisting of copper (TiO2) nanoparticles suspended in water, as they interact with sensor surfaces between two parallel squeezing plates with porous characteristics. This research specifically targets applications involving enhanced heat transfer and magnetohydrodynamic (MHD) control in nanofluid systems. The primary aim is to analyze the effects of nanoparticle aggregation and non-aggregation on sensor surfaces, considering MHD formations and heat transfer in the energy and momentum equations. The research adopts a steady-state fluid condition and utilizes similarity transformations to convert partial differential equations into more manageable ordinary differential equations. The methodology involves shooting methods for solving these nonlinear ordinary differential equations and employs graphical analyses to study the impacts of various parameters such as permeability, magnetic influence, squeeze flow, and radiation on the temperature and velocity profiles of the nanofluid. The results reveal significant dependencies of temperature and velocity profiles on the studied parameters, illustrating varied behaviors in scenarios of both aggregation and non-aggregation of nanoparticles. The findings emphasize how each parameter distinctively influences the heat and flow characteristics of the nanofluid, offering insights into optimizing conditions for better performance and control in practical applications. Future research could focus on extending the model to include transient fluid states and exploring the effects of other nanoparticle materials and shapes. There is also potential to investigate the interactions under different environmental conditions and to incorporate more complex boundary conditions to simulate real-world applications more accurately. Further experimental validation of the theoretical predictions would be beneficial to enhance the reliability and applicability of the findings.

Synthesis of Jasminaldehyde (α-pentylcinnamaldehyde) using Cs-AlMCM-41 Nanoparticle as Heterogeneous Solid Base Catalyst

In this study, the ultra-small mesoporous Cs-AlMCM-41 nanoparticle materials were obtained with high specific BET surface areas in the range of 426 m2g-1 with 1.97 nm pore size. The pore volume was found to be 0.86 cm3. The material possesses a basic site due to caesium ions (Cs+) counterbalancing the negative rise by Al in the mesoporous framework. The basicity of the sample was found to be 115.48 mol g-1. The basicity was proven via the condensation reaction of heptanal and benzaldehyde using microwave irradiation with a microwave power of 800 W. The sample (Cs-MCM-41) gave a higher conversion of heptanal (73.8%) with (70.1%) selectivity to jasminaldehyde. The CsMCM-41 can be a promising base catalyst in aldol condensation reaction for the synthesis of jasminaldehyde under autogenous pressure. Hence, the solid catalyst is easily recycled up to five (5) times with minimal loss of activity due to washing.