Influence of reaction variables on the surface chemistry of cellulose nanofibers derived from palm oil empty fruit bunches.

Nanocellulose, a versatile nanomaterial with a wide range of applications, is gaining significant attention for its sustainable and eco-friendly properties. In this study, we investigate the influence of reaction variables on the surface chemistry of TEMPO-oxidized cellulose nanofibers (TOCN) from palm oil empty fruit bunch (EFB) fibers, a high cellulose content biomass. Reaction time, primary oxidizing agent, and a pretreatment process affect, to various extents, the surface chemistry of EFB-TOCN. Conductometric titrations (CT), X-ray photoelectron spectroscopy (XPS), and statistical analysis indicate a positive and significant influence of reaction time and primary oxidizing agent on EBF-TOCN degree of oxidation and surface charge density. Partial EFB delignification increased EFB-TOCN oxidation and reaction yield compared to EFB without pretreatment. Interestingly, only reaction time has a significant effect on the EFB-TOCN hydrodynamic radii, with a reaction time of over 120 minutes required to obtain nanocellulose less than 100 nm in size. Utilizing palm oil residual biomass for nanocellulose extraction not only valorizes agricultural waste but also enhances the palm oil industry's economic prospects by reducing waste disposal costs and improving material circularity. This research contributes to the growing body of knowledge on nanocellulose production from renewable sources and highlights the potential of palm oil EFB fibers as a valuable raw material for sustainable nanomaterial development.

Mass Balance and Compositional Analysis of Biomass Outputs from Cacao Fruits.

The global chocolate value chain is based exclusively on cacao beans (CBs). With few exceptions, most CBs traded worldwide are produced under a linear economy model, where only 8 to 10% of the biomass ends up in chocolate-related products. This contribution reports the mass balance and composition dynamics of cacao fruit biomass outputs throughout one full year of the crop cycle. This information is relevant because future biorefinery developments and the efficient use of cacao fruits will depend on reliable, robust, and time-dependent compositional and mass balance data. Cacao husk (CH), beans (CBs), and placenta (CP) constitute, as dry weight, 8.92 ± 0.90 wt %, 8.87 ± 0.52 wt %, and 0.57 ± 0.05 wt % of the cacao fruit, respectively, while moisture makes up most of the biomass weight (71.6 ± 2.29 wt %). CH and CP are solid lignocellulosic outputs. Interestingly, the highest cellulose and lignin contents in CH coincide with cacao's primary harvest season (October to January). CB contains carbohydrates, fats, protein, ash, and phenolic compounds. The total polyphenol content in CBs is time-dependent, reaching maxima values during the harvest seasons. In addition, the fruit contains 4.13 ± 0.80 wt % of CME, a sugar- and nutrient-rich liquid output, with an average of 20 wt % of simple sugars (glucose, fructose, and sucrose), in addition to minerals (mainly K and Ca) and proteins. The total carbohydrate content in CME changes dramatically throughout the year, with a minimum of 10 wt % from August to January and a maximum of 29 wt % in March.

Cellulose biosynthesis using simple sugars available in residual cacao mucilage exudate.

Worldwide only 8% of the biomass from harvested cacao fruits is used, as cacao beans, in chocolate-based products. Cacao mucilage exudate (CME), a nutrient-rich fluid, is usually lost during cacao beans fermentation. CME's composition and availability suggest a potential carbon source for cellulose production. CME and the Hestrin and Schramm medium were used, and compared, as growth media for bacterial cellulose (BC) production with Gluconacetobacter xylinus. CME can be used to produce BC. However, the high sugar content, low pH, and limited nitrogen sources in CME hinder G. xylinus growth affecting cellulose yields. BC production increased from 0.55 ± 0.16 g L-1 up to 13.13 ± 1.09 g L-1 after CME dilution and addition of a nitrogen source. BC production was scaled up from 30 mL to 15 L, using lab-scale experiments conditions, with no significant changes in yields and production rates, suggesting a robust process with industrial possibilities.

Síntesis in situ de nanopartículas de plata sobre fibras de fique / In situ synthesis of silver nanoparticles on fique fibers / Síntese in situ de nanopartículas de prata em fibras de fique

Se realizó la síntesis de un material nanocompuesto mediante la deposiciónin situ de nanopartículas (NPs) de plata sobre fibras de Fique. La influencia de parámetros experimentales, como concentración del precursor, concentración del agente reductor y tiempos de inmersión de las fibras en la solución del precursor y del agente reductor, se evaluó en términos de recubrimiento, tamaño y dispersión del nanomaterial sobre la superficie. Los nanocompositos fueron caracterizados mediante espectroscopia de reflectancia difusa UV-Vis (RD), microscopía electrónica (FESEM) y difracción de rayos X (DRX). El control de los parámetros experimentales mencionados permitió obtener un material que exhibe recubrimiento uniforme y completo de NPs sobre la superficie y tamaños promedio de NPs de 40 nm.

A nanocomposite material was synthesized by silver nanoparticles (NPs) in situ deposition on Fique fibers. The influence of experimental conditions such as precursor concentration, reducing agent concentration and immersion times of fibers in precursor and reducing agent solutions was evaluated in terms of nanomaterial coating, size and dispersion on the fibers surface. The nanocomposites were characterized by UV-Vis diffuse reflectance spectroscopy (DR), electron microscopy (FESEM) and X-ray diffraction (XRD). By carefully controlling experimental conditions we were able to produce a material with uniforme and complete coating of NPs on the surface of the fiber, and average sizes of 40 nm.

Nanocompósito foi sintetizado através de deposição in situ de nanopartículas (NPs) de prata sobre as fibras de Fique. A influência dos parâmetrosexperimentais, tais como a concentração do sal metálico, a concentração do agente de redução e os tempos de imersão das fibras na solução do sal metálico e o agente de redução, foram avaliadas em termos do revestimento, tamanho e a dispersãona superfície do nanomaterial. Os nanocompósitosforam caracterizados por espectroscopia de refletância difusa no UV-Vis (RD), microscopia eletrônica (FESEM) e difração de raios X (XRD). O controle dos parâmetrosexperimentais mecionados originaram um material que exibe um revestimento uniforme e completo das NPs sobre a superfície das fibras e tamanhos médios de 40 nm.

Polymeric inverse micelles as selective peptide extraction agents for MALDI-MS analysis.

Analyses of peptides in complex mixtures are significant challenges in proteomics applications. Here, we report an amphiphilic polymer-based nanoassembly that is capable of selectively extracting peptides, on the basis of their isoelectric points, into an immiscible organic phase from an aqueous solution. The isoelectric point (pI) cutoff in these extractions depends on the pH of the aqueous solution, and thus, sequential fractionation of peptide mixtures based on pI can be accomplished by varying the pH of the aqueous solution. Additionally, we observe an unexpected enhancement in the MALDI-MS signal for extracted peptides ionized in the presence of the polymer, which allows us to obtain reproducible ion signals for some peptides at concentrations as low as 10 pM.

Are gas-phase reactions of five-coordinate divalent metal ion complexes affected by coordination geometry?

Five-coordinate metal complex ions of the type [ML](2+) [where M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II) and L= 1,9-bis(2-pyridyl)-2,5,8-triazanonane (DIEN-(pyr)(2)) and 1,9-bis(2-imidazolyl)-2,5,8-triazanonane (DIEN-(imi)(2)] have been reacted with acetonitrile in the gas phase using a modified quadrupole ion trap mass spectrometer. The kinetics and thermodynamics of these reactions show that the reactivity of these complexes is affected by metal electronic structure and falls into three groups: Mn(II) and Ni(II) complexes are the most reactive, Fe(II) and Co(II) complexes exhibit intermediate reactivity, and Cu(II) and Zn(II) complexes are the least reactive. To help explain the experimental trends in reactivity, theoretical calculations have been used. Due to the relatively large size of the metal complexes involved, we have utilized a two-layered ONIOM method to perform geometry optimizations and single point energy calculations for the [ML](2+) and [ML + CH(3)CN](2+) systems. The calculations show that the reactant five-coordinate complexes ([ML](2+)) exhibit structures that are slightly distorted trigonal bipyramidal geometries, while the six-coordinate complexes ([ML + CH(3)CN](2+)) have geometries that are close to octahedral. The Delta G values obtained from the ONIOM calculations roughly agree with the experimental data, but the calculations fail to completely explain the trends for the different metal complexes. The failure to consider all possible isomers as well as adequately represent pi-d interactions for the metal complexes is the likely cause of this discrepancy. Using the angular overlap model (AOM) to obtain molecular orbital stabilization energies (MOSE) also fails to reproduce the experimental trends when only sigma interactions are considered but succeeds in explaining the trends when pi interactions are taken into account. These results indicate that the pi-donor character of the CH(3)CN plays a subtle, yet important, role in controlling the reactivity of these five-coordinate complexes. Also, the AOM calculations are consistent with the experimental data when the [ML](2+) complexes have high-spin trigonal bipyramidal configurations. Generally, these results suggest that ion-molecule reactions can be very sensitive to metal complex coordination geometry and thus may have some promise for providing gas-phase coordination structure.

Gas-phase ion-molecule reactions of transition metal complexes: the effect of different coordination spheres on complex reactivity.

Using a modified quadrupole ion trap mass spectrometer, a series of metal complex ions have been reacted with acetonitrile in the gas phase. Careful control of the coordination number and the type of coordinating functionality in diethylenetriamine-substituted ligands enable the effects of the coordination sphere on metal complex reactivity to be examined. The association reaction kinetics of acetonitrile with these pentacoordinate complexes are followed in order to obtain information about the starting complexes and the reaction dynamics. The kinetics and thermodynamics of acetonitrile addition to the metal complex ions are strongly affected by the chemical environment around the metal center such that significant differences in reactivity are observed for Co(II) and Cu(II) complexes with various coordination spheres. When thiophene, furan, or benzene moieties are present in the coordination sphere of the complex, addition of two acetonitrile molecules is readily observed. In contrast, ligands with better sigma donors react mainly to add one acetonitrile molecule. Among the ligands with good sigma donors, a clear trend in reactivity is observed in which complexes with nitrogen-containing ligands are the least reactive, sulfur-containing complexes are more reactive, and oxygen-containing complexes are the most reactive. In general, equilibrium and reaction rate constants seem to be consistent with the hard and soft acid and base (HSAB) principle. Interestingly, the presence of certain groups (e.g., pyridine and imidazole) in the coordination sphere clearly can change the acid character of the metal as seen by their effect on the binding properties of other functional groups in the same ligand. Finally, we conclude that because complexes with different coordination spheres react to noticeably different extents, ion-molecule (I-M) reactions may be potentially useful for obtaining coordination structure information for transition metal complexes.