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EN
In order to achieve hydrogel and drug release profiles, a comprehensive knowledge of the types, properties and syntheses of hydrogel polymer networks are needed. For this reason, a natural biopolymer hydrogel based on chitosan was described. Chitosan has many advantages, which meet the requirements necessary for the preparation of medical materials; for example, wound dressings. This article focused on the biomedical use of a chitosan hydrogel: chitosan–poly(vinyl alcohol) (PVA). The method of preparation of hydrogels containing a drug as an active wound dressing was described. To obtain a hydrogel dressing to be applied in patients with burns or difficult curative wounds, gentamicin (an aminoglycoside antibiotic) was used as a medicament. The effect of the PVA concentration in hydrogels on the release rate of the antibiotic was examined. For this, the crosslinking agent of the hydrogel, glutaraldehyde, was used. The release process of gentamicin was described by using an equation of first order kinetics.
EN
This study was aimed at determining the possibility of applying non-cross-linked chitosan (CHs) as well as chitosan cross-linked with glutaraldehyde (CHs-GLA) and epichlorohydrin (CHSECH) for the removal of nitrates (V) from aqueous solutions. The scope of the study included determinations of: optimal pH value of nitrates sorption (from pH range of 2-11), equilibrium time of sorption process, and maximum N-NO3 sorption capacity of the analysed chitosan sorbents. Kinetics of nitrates sorption was described with pseudo-first and pseudo-second order equations, and with the intraparticle diffusion model. Sorption capacity analysis was conducted with the heterogeneous Langmuir model, the double Langmuir model and the Freundlich model. The optimal pH value of N-NO3 sorption onto CHs-GLA and CHs-ECH was pH 3, whereas onto CHs this was pH 4. The equilibrium time of sorption reaction was the same for all chitosan sorbents and reached 120 min. The maximum sorption capacity of CHs, CHs-GLA and CHs- ECH accounted for 12.71 mg N-NO3/g, 34.99 mg N-NO3/g and 38.47 mg N-NO3/g.
EN
The study was undertaken to analyze the effect of chitosan cross-linking with glutaraldehyde on the adsorption capacity of chitosan beads during adsorption of Reactive Black (RB5) and Basic Green (BG4) dyes. Analyses were conducted at three pH values: pH 3.0; 5.0 and 9.0. Results obtained were evaluated with the use of four models of adsorption isotherms  Freundlich, Langmuir, Double Langmuir and Redlic-Petreson. The cross-linking of beads with glutaraldehyde turned out to be beneficial for the anionic dye RB5. Compared to the non-cross-linked beads, a comparable adsorption capacity (over 500 mg/g d.m.) was obtained at pH 3.0 and pH 5.0. In the case of the cationic dye, chitosan cross-linking reduced the quantity of adsorbed dye, irrespective of the pH value of the adsorption process.
EN
The study was established to analyze the effectiveness of Reactive Black (RB5) and Basic Green (BG4) dyes adsorption onto chitosan beads and onto chitosan beads cross-linked with glutaraldehyde depending on the initial dye concentration in the solution (1, 5, 100 and 200 mg/dm3). It demonstrated that both the initial concentration of dye in the solution as well as the type of adsorbent affected the effectiveness of the adsorption process. An increase in the initial dye concentration in the solution was increasing adsorption effectiveness, irrespective of the type of dye and adsorbent. The cross-linking of chitosan beads with glutaraldehyde turned out to be beneficial only in the case of the RB5 dye.
EN
This study investigated the effectiveness of phosphate adsorption onto non-cross-linked chitosan beads [CHs], and onto chitosan beads cross-linked with glutaraldehyde [ALD-CHs] and epichlorohydrin [ECH-CHs]. The weight ratio of glutaraldehyde to chitosan was 1:2 (w/w), whereas that of epichlorohydrin to chitosan was 2:1 (w/w). The optimal pH value of the phosphate adsorption process was determined at pH 3 for cross-linked chitosan and at pH 4 for noncross- linked chitosan. The time needed to reach the equilibrium concentration reached 60 min for both adsorbents. Experimental data were described with the heterogeneous Langmuir model (double Langmuir equation). The most effective adsorbent of phosphates was shown to be chitosan cross-linked with epichlorohydrin [ECH-CHs] - for which the adsorption capacity reached 139.4 mg/g d.m.CHs. In the case of the remaining adsorbents (chitosan [CHs] and chitosan crosslinked with glutaraldehyde [ALD-CHs]) the adsorption capacity was lower and accounted for 44.38 mg/g d.m.CHs and 108.24 mg/g d.m.CHs, respectively.
EN
Modified chitosan hydrogel membranes were prepared using glutaraldehyde (GA) and sodium citrate (NaCIT) as crosslinking agents. Molecular and supermolecular structure analyses of unmodified and modified chitosan membranes have been conducted by FTIR and X-ray spectroscopy. FTIR results showed covalent and ionic crosslinks formation between chitosan (Ch) and GA or simultaneously Ch, GA and NaCIT. The state of water in noncrosslinked and crosslinked chitosan membranes were analysed by differential scanning spectroscopy (DSC). Three types of water in hydrogel membranes were found: non-freezing bound water, freezing bound water and freezing free water, while there were variations in the amount of non-freezing bound water in these polymers. The effect of ionic crosslinking on water state, mainly on the nonfreezing water content, was discussed.
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