Josy Anteveli Osajima

Phosphated Cellulose as an Efficient Biomaterial for Aqueous Drug Ranitidine Removal

Crystalline cellulose chemically modified through a reaction with sodium trimetaphosphate (STMP) in an acidic or basic condition yielded Cel-P4 and Cel-P10. These phosphated solids were characterized by elemental analysis, X-ray diffraction (XRD), infrared (IR) spectroscopy, scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) at the solid state for phosphorus nucleus and dispersive X-ray energy. The elemental results demonstrated that the phosphorylation reaction was more efficient in the basic medium, as supported by the amount of phosphorous content. The synthesized biomaterials decreased in crystallinity in comparison to the precursor cellulose, with an increase in roughness and present two distinct phosphorus environments in the formed structure. The phosphated cellulose in an alkaline condition was applied to sorb the drug ranitidine. This process was applied in varying pH, time, temperature and concentration. The best sorption kinetic model to fit the experimental data was the pseudo-second-order with a coefficient correlation of 0.8976, and the Langmuir isotherm model was the most adjusted to the variation in concentration. The efficient drug sorption has a low dependence on temperature, with maximum values of 85.0, 82.0 mg and 85.7 mg·g−1 for Cel-P10 at 298, 308 and 318 K, respectively. The best sorption occurred at pH = 6 with a saturation time of 210 min.

Development of new phosphated cellulose for application as an efficient biomaterial for the incorporation/release of amitriptyline

In the last years has increased the study about the using of natural biopolymers and theirs derivatives in the removal (adsorption/incorporation) of contaminats of medium aqueous, and theirs utilization in the desorption (release) de drugs. However, there not in the literature studies about the utilization of the cellulose and cellulose phosphate in the adsorption (incorporation)/desorption (release) of the drug amitriptyline (AMI). Therefore, in this study was accomplished the synthesized of the phosphated cellulose (PC) through the reaction of pure cellulose (C) with sodium trimetaphosphate (P) under-reflux, for 4h and at 393K. The efficiency of the reaction was observed by XRD, TG/DTG, (31)P NMR and EDS. The adsorption study for the AMI in aqueous medium was carried out by varying the time, pH, concentration, temperature and ionic strength. The results showed that the PC showed a greater adsorption capacity of AMI than pure cellulose, presenting an increase of about 102.72% in the adsorption capacity of the drug by cellulose after the phosphating reaction. In desorption of drug from the surface of biomaterials was performed by varying the pH and time, where it was observed that PC showed a maximum release of 40.98% ± 0.31% at pH 7.

Sorption of the anionic reactive red RB dye in cellulose: Assessment of kinetic, thermodynamic, and equilibrium data

Abstract The cellulose matrix was characterized by FTIR, 13C NMR, XRD, TG, SEM and applied in the removal of the reactive red RB dye in an aqueous medium, with a capacity of adsorption at a pH of 2.0, and an adsorption equilibrium time which was reached at around 200 mins. The kinetic study for the system followed the Elovich model. The adsorption isotherms for the system at temperatures of 35°C, 45°C, and 55°C were adjusted to the Langmuir, Freundlich, Sips, and Redlich-Peterson non-linear models, with a capacity of adsorption for adsorbent of 5.97 mg g-1, 5.64 mg g-1, and 4.62 mg g-1, respectively. The adsorption occurred by electrostatic interactions and it was favorable and spontaneous, with the influence of temperature.

Evaluation of physico-chemical properties and antimicrobial synergic effect of ceftazidime-modified chitosan

The high prevalence of infections caused by antibiotic-resistant bacteria has stimulated the development of new therapeutic strategies. Polymeric materials have aroused the interest of many researchers because of their large field of applications. This work aimed to evaluate the synergistic antimicrobial effect of chitosan in association with ceftazidime as well as possible chemical interactions from this combination by FTIR, XRD and TG/DTG curves. Through these analyses, it was possible to conclude that the proposed method was efficient to incorporate the drug with no changes in the fundamental structure of chitosan. In addition, the developed carrier was responsible for increasing the thermal and hydrolytic stability of the drug. The antibacterial activity of chitosan and ceftazidime-modified chitosan was evaluated against Staphylococcus aureus 25,923 and Escherichia coli 25,922 strains, revealing a possible time-dependent drug release.

Potential of amino-functionalized cellulose as an alternative sorbent intended to remove anionic dyes from aqueous solutions

Adsorption has been explored to minimize the pollution caused by dyes. This work relates the preparation of diethylenetriamine-modified cellulose (DetaCel) by reacting phthalic anhydride-modified cellulose (PhCel) with diethylenetriamine (Deta). Materials were characterized by Elemental Analysis and results showed a degree of incorporation of 5.55 ± 0.02 mmol of nitrogen per gram of modified material. The main bands observed for DetaCel by Fourier-Transform Infrared Spectroscospy (FTIR) were attributed to CN deformation (1330 cm-1) and NH stretching of amide (3400 cm-1), while Solid State Nuclear Magnetic Resonance of 13C (13C{1H}CP-MAS NMR) showed a signal at 164.6 ppm characteristic of amide group. Crystallinity index (CrI) obtained by X-Ray Diffraction (XRD) was 74.99 (Cel), 58.64 (PhCel) and 46.12% (DetaCel). Adsorbent matrices were employed to remove methyl orange (MO) and eosin (EY) dyes in aqueous medium. Data obtained experimentally from kinetic study had a better fit to the pseudo-first order, thus the adsorption process occurs in monolayer, with MO adsorption capacity by Cel and DetaCel of 2.19 and 65.45 mg g-1, respectively. For EY adsorption by Cel and DetaCel was 1.30 and 56.69 mg g-1, respectively. These results suggest that DetaCel can be used as an alternative potential for removal dyes in aqueous solution.

Antibacterial Activity of a Chitosan Derivative Obtained in the Absence of a Solvent

A novel chitosan derivative was prepared through direct reaction of pure chitosan with acetylacetone in the absence of a solvent, and it was characterized by elemental analysis, Fourier transform infrared spectrometry (FTIR), and 13C Nuclear Magnetic Ressonance (NMR) spectroscopy. Moreover, the antibacterial properties of the new biomaterial were tested by the direct contact method against multi-drug resistant strains of Staphylococcus aureus and Escherichia coli. The results from the characterization were consistent with the modification of the chemical structure made. The new derivative showed a better antibacterial activity than raw chitosan against E. coli strains, indicating that incorporation of imine link (Schiff base) enhanced its antibacterial activity against Gram-negative bacterium. On the contrary, this chemical change did not decrease its antibacterial activity against Gram-positive bacterium.

Effective Removal of the Remazol Yellow GR Dye Using Cellulose Functionalized by Basic Groups

Adsorption has been researched attempting to minimize the pollution caused by dyes, which represents a serious environmental problem as contamination of surface and ground water. Therefore, cellulose and its modified forms with amine and thiols groups constitute a class of versatile adsorbents for the removal of anionic dyes in aqueous solution. In this context, this work reports the preparation of cellulose modified by ethylene sulfide and ethylenediamine (Cel-ESEN), through the reaction of the cellulose modified by ethylene sulfide (CEL-ES) and ethylenediamine (EN). Materials were characterized by elemental analysis, which showed in the Cel-ESEN matrix 10.12 ± 0.10%, 5.52 ± 0.06% of sulfur and nitrogen, respectively. Nuclear magnetic resonance in the solid state of 13C (13C NMR) showed, for the Cel-ESEN matrix, a peak related to CH2 groups from the molecules incorporated in the cellulose biopolymer. Crystalline Index obtained by X-ray diffraction (XRD) was in the order pure Cellulose > Cel-Cl > Cel-ES > Cel-ESEN. The adsorbent matrix (Cel-ESEN) was used in the removal of the remazol yellow GR (RY) dye in aqueous medium. Data obtained experimentally from kinetic study had the best adjustment to the proposed pseudo-second-order model. The adsorption process occurs in monolayer, is endothermic and thermodynamically favorable. Adsorption capacity of the modified material became 118 times higher than the starting material. These results suggest that the obtained biopolymer can be used as an alternative material to remove RY in aqueous solution.

Modifying cellulose with metaphosphoric acid and its efficiency in removing brilliant green dye

In this study, cellulose was chemically modified through the addition of the phosphorylating agent, metaphosphoric acid in order to obtain a new material (MPCel) with higher adsorptive properties than the starting material. Both materials were characterized by infrared spectroscopy, X-ray diffraction, solid-state phosphorus-31 nuclear magnetic resonance spectroscopy and thermogravimetric analysis. Maximal adsorption capacity, at 45°C for pure cellulose, was 90.5mgg-1, at pH=10 and contact time of 40min, with experimental isotherms better adjusted to the Langmuir model. MPCel at the same temperature conditions showed contact time of 10min, pH=10, and maximal adsorption capacity of 150.0mgg-1, being better adjusted to the Temkin model. The kinetic study of both materials followed the pseudo-second-order model. Modification successfully occurred and both adsorbents were shown able to be capable of removing the brilliant green dye, but MPCel was more efficient for purpose, when compared to the pure cellulose.

Alkaline earth stannates applied in photocatalysis: prospection and review of literature

The ABO3 mixed oxide class known for its perovskite-like structure has aroused great scientific and technological interest in recent decades, due to its optical, magnetic and conductive properties. The objective of this work was to search the articles and patent databases for papers that relate the activity of the alkaline earth metal stannates BaSnO3, CaSnO3 and SrSnO3 as photocatalysts for environmental application. The databases researched were the Web of Science, Scopus and Scielo for articles and USPTO, EPO and INPI for patent banks. From the exclusion criteria, 21 review articles presented different experimental parameters and conditions. Due to the excellent photocatalytic performance, the stannates presented as promising candidates in the heterogeneous photocatalysis. A description of the main papers published in literature is provided for an overview of the literature data about these materials.

Photocatalysis of Coomassie Brilliant Blue Using Clay Mineral

The presence of organic pollutants, which cannot be eliminated by conventional processes of primary and secondary treatment, can be problematic. Photocatalytic processes offer an efficient breakdown of organic pollutants into non-toxic compounds such as CO2 and H2O. This paper proposes the use of the titanium dioxide embedded in palygorskite as a photoactive material in the degradation of cationic dye, Coomassie Brilliant Blue. The system was irradiated using UV light for a maximum time of 120 minutes. The concentration of the dye used was 1.0x10-4 mol L-1 in 0.5 g L-1 of the photoactive material. The kinetics of the system was monitored by UV-Vis spectrophotometry. In 120 minutes of radiation, the process of photocatalysis reduced the initial concentration of the Coomassie Brilliant Blue dye in half.