Moringa oleifera seeds were investigated as a biosorbent for removing metal ions from aqueous effluents. The morphological characteristics as well as the chemical composition of M. oleifera seeds ...were evaluated using Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The FT-IR spectra showed the presence of lipids and protein components. Scanning electron micrographs showed that Moringa seeds have an adequate morphological profile for the retention of metal ions. The results suggest that M. oleifera seeds have potential application in Cd(II), Pb(II), Co(II), Cu(II) and Ag(I) decontamination from aqueous effluents.
This work presents an eco-friendly approach for determining free glycerol in biodiesel samples, using a cellulose monolith stir bar in the sorptive extraction method with analysis by high-performance ...liquid chromatography and a refractive index detector. The cellulose monolith was produced from cellulose acetate by non-solvent-induced phase separation and subsequent alkaline deacetylation. The cellulose monolith presented a hierarchically porous structure, with 68% porosity and almost total deacetylation, with morphological and polarity characteristics that favor an efficient extraction of free glycerol from biodiesel. The sorptive extraction method using a cellulose monolith stir bar was optimized, obtaining a total extraction time of 30 min at 70 °C, using ultrapure water as the desorption solvent, and extraction of free glycerol of 93.6 ± 2.3%. The proposed method showed selectivity in free glycerol extraction, with limits of detection and quantification of 6.60 × 10
−5
% w/w and 2.18 × 10
−4
% w/w, respectively. Compared with the official reference method, the proposed one presented similar precision and accuracy, with few manipulations and any reagent/solvents. Furthermore, it is compatible with the principles of green chemistry and can be considered an eco-friendly method for determining free glycerol in biodiesel.
Cellulose monoliths were used as stir-bar adsorbents in SBSE to extract glycerol from biodiesel samples with HPLC-RID analyses. The proposed method dispenses derivatizing reagents or sophisticated apparatus and uses water as the desorption eluent.
In this work, scaffolds based on poly(hydroxybutyrate) (PHB) and micronized bacterial cellulose (BC) were produced through 3D printing. Filaments for the printing were obtained by varying the ...percentage of micronized BC (0.25, 0.50, 1.00, and 2.00%) inserted in relation to the PHB matrix. Despite the varying concentrations of BC, the biocomposite filaments predominantly contained PHB functional groups, as Fourier transform infrared spectroscopy (FTIR) demonstrated. Thermogravimetric analyses (i.e., TG and DTG) of the filaments showed that the peak temperature (Tpeak) of PHB degradation decreased as the concentration of BC increased, with the lowest being 248 °C, referring to the biocomposite filament PHB/2.0% BC, which has the highest concentration of BC. Although there was a variation in the thermal behavior of the filaments, it was not significant enough to make printing impossible, considering that the PHB melting temperature was 170 °C. Biological assays indicated the non-cytotoxicity of scaffolds and the provision of cell anchorage sites. The results obtained in this research open up new paths for the application of this innovation in tissue engineering.
The chemical modification of hydrophobic polymer matrices is an alternative way to elchange their surface properties. The introduction of sulfonic groups in the polymer changes the surface properties ...such as adhesion, wettability, catalytic ability, and adsorption capacity. This work describes the production and application of chemically modified polyvinyl chloride (PVC) as adsorbent for dyes removal. Chemical modification of PVC was evaluated by infrared spectroscopy and elemental analysis, which indicated the presence of sulfonic groups on PVC. The chemically modified PVC (PVCDS) showed an ion exchange capacity of 1.03 mmol
, and efficiently removed the thionine dye (Lauth's violet) from aqueous solutions, reaching equilibrium in 30 min. The adsorption kinetics was better adjusted for a pseudo second order model. This result indicates that the adsorption of thionine onto PVCDS occurs by chemisorption. Among the models for the state of equilibrium, SIPS and Langmuir exhibited the best fit to the experimental results and PVCDS showed high adsorption capacities (370 mg
). Thus, it is assumed that the system presents homogeneous characteristics to the distribution of active sites. The modification promoted the formation of surface characteristics favorable to the dye adsorption by the polymer.
The suitable combination of active pharmaceutical molecules and polymer matrices is a key factor for the development of systems for controlled release. The proper choice of the bioactive ...species/polymer pair depends strongly on the dispersion capacity and the interaction established between the bioactive species in the polymer matrix. Solid dispersions composed of cellulose acetate (CA) with either naproxen (NPX) or ibuprofen (IBF) are separately evaluated by Thermogravimetry Analysis in decomposition kinetics studies. Ozawa's isoconversional method is used to calculate the Estimated Activation Energy (Eα) values. Eα indicated strong intermolecular interactions between the drugs and the CA matrix that is responsible for the increase in thermal stabilities of the drugs when they are combined with the polymer matrix. Differential scanning calorimetry analyses and solubility parameters showed CA has better compatibility with NPX compared to IBF. Therefore, this work brings exciting information for systems based on CA. Moreover, the approach is promising for the development of new materials, especially those of pharmaceutical relevance.
Conducting films were produced by incorporating 35, 50, and 60 wt.%. of graphite in cellulose acetate. The graphite contents showed to be of pivotal importance to the properties of the materials, ...mainly on the electrochemical performance. Thermal analyses indicated the graphite hinders the crystallization process of cellulose acetate and increases the hydrophobicity of the films. Scanning electron microscopy provided evidence of laminated graphite structures well‐dispersed in the polymeric matrix and exhibited a more porous aspect surface for the 50% G/Composite, which led to a higher surface area obtained by the N2 adsorption/desorption technique. This composite also had a better electrochemical response for ferrocyanide ion. The fabrication method was reproducible, which was associated with the structural uniformity of the resulting material. In addition, the conductive films are ready to use after production, precluding the need for any surface pretreatment. Moreover, the proposed sensor showed analytical potentiality for dopamine and hydroquinone determination, extending the possibilities for new electroanalytical applications.
In this work, methylcellulose (MC) was produced from bacterial cellulose (BC), using dimethyl sulfate in a 3 h (MC3h) or 5 h (MC5h) reaction under heterogeneous conditions, with reagent substitution ...at each hour. MC3h showed a degree of substitution (DS) of 2.26 ± 0.13 and MC5h showed a DS of 2.33 ± 0.05. The two samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), differential thermal analysis (DTA), thermal gravimetric analysis (TGA), 13C nuclear magnetic ressonance (NMR) and 1H NMR techniques. The FTIR spectra of the BC and MC samples present significant differences in the regions from 3750 to 2750 cm−1 and from 1500 to 750 cm−1, which evidence the methylation of the samples. Solid state NMR spectroscopy of the MC samples was used to identify the 13C NMR signals of substitution at sites C-2, C-3 or C-6 in the glucopyranose units. The modification of bacterial cellulose produced a material with a high DS, determined by three different techniques (chemically and using the liquid 1H and solid 13C NMR spectra). These samples also demonstrate high crystallinity and thermal stability. With the MC samples synthesized in this work, transparent and resistant films were prepared and also a highly porous sponge like material.
•Thermal immobilization of cellulose on silica derivative without chemical agents.•Stationary phase with characteristic retention from cellulose and dodecanoyl group.•Cellulose derivative stationary ...phase able to separate optical isomers.•Rapid and efficient HPLC separation of highly polar compounds.
The chemical agent free preparation of a stationary phase using a natural macromolecule was the focus of this paper. Thermal immobilization of cellulose dodecanoate on silica particles was used for the preparation of a stationary phase without the use of chemical reagents. Cellulose modification was performed to produce a hydrophobic macromolecule with solubility in common organic solvents. The new stationary phase was characterized morphologically and physico-chemically, presenting as spherical particles immobilized with a thin cellulose dodecanoate layer. The degree of substitution of cellulose dodecanoate was 1.7, which resulted in a separation mechanism in reversed phase mode, but with lower hydrophobicity and higher steric selectivity, which are properties from cellulose. These characteristics resulted in a stationary phase with intrinsic selectivity that was able to separate mixtures of polar drugs, homologs of an anionic surfactant and omeprazole isomers, which are not well resolved in typical C18 phases. Considering that cellulose is a natural polymer and the preparation method of stationary phase involves only physical processes of silica modification, the final material presents as a stationary phase with specific retention properties coming from both dodecanoate and cellulose.
This work reports the successful use of square‐wave voltammetry (SWV) to directly assess the controlled releasing profile of naproxen from lab‐made cellulose derivative materials (membranes and ...microparticles) in phosphate buffer (pH 7.4) at 36 °C. Particular advantage of SWV refers to the direct real‐time monitoring of released drug from cellulose derivative microparticles, which cannot be easily assessed by UV‐spectrophotometry. Moreover, SWV was able to detect modifications in the naproxen releasing profile due to morphology and processing of membranes and microparticles. The possible miniaturization and versatility of SWV suggest the promising application on the study of several drug delivery systems, including in vivo studies.
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