Surfactant supported chitosan for efficient removal of Cr(VI) and anionic food stuff dyes from aquatic solutions.

In order to develop a novel and cost-effective adsorbent with outstanding adsorption capacity and excellent recyclability for anionic pollutants, the chitosan-modified cetyltrimethylammonium bromide sorbent (CS@CTAB) was fabricated. Fourier-transform infrared spectroscopy, N2 adsorption-desorption isotherm, elemental analysis, Thermogravimetric analysis, X-ray diffraction, and Scanning electron microscopy have been applied to evaluate both raw and surfactant modified chitosan (CS@CTAB). Azorubine, Sunset Yellow, and hexavalent chromium were used to study the adsorption behavior of CS@CTAB under various parameters such as adsorbent dose, initial dye and metal ion concentration, contact time, and temperature. Adsorption equilibrium, kinetics models and thermodynamic parameters were investigated. The adsorption isotherm fitted well with the Langmuir isotherm model, with a maximum adsorption capacity of 492.6 mg/g, 492.6 mg/g, and 490.196 mg/g for Azorubine, Sunset Yellow, and Hexavalent Chromium, respectively. The kinetic studies showed that the pseudo-second-order model provided a better correlation between experimental data. Furthermore, the calculated thermodynamic parameters confirmed that the adsorption of Cr(VI), E110, and E122 by CS@CTAB material is a spontaneous and exothermic process. The fabricated CS@CTAB adsorbent was employed for the efficient elimination of Azorubine, Sunset Yellow, and hexavalent chromium from real water samples, synthetic mixtures, and colored soft drinks, with a percentage of recovery of ~ 96%. The plausible adsorption mechanisms of Azorubine, Sunset Yellow, and hexavalent chromium on the surface of CS@CTAB are elucidated. The adsorption anticipated to be due to electrostatic interaction and hydrogen bond formation for hexavalent chromium; while the adsorption of Azorubine and Sunset Yellow, was assumed to be due to electrostatic interaction, hydrogen bonding, and n-π interaction. Finally, the study demonstrates the efficiency of CS@CTAB for the removal of anionic species from several samples, including natural water and colored beverages.

Preparation and physicochemical studies on polymeric nanocomposites containing copper oxide nanoparticles.

The current work aims to modify carboxymethyl cellulose (CMC) and polyvinylpyrrolidone (PVP) with copper oxide nanoparticles (CuO NPs) to obtain new nanocomposites of CMC, PVP, and CuO NPs (CMC/PVP/CuO NPs) with distinguished properties. The interaction between the components of the nanocomposites was suggested and supported by using Gaussian 09W 07 Software and the average particle size was manually determined from TEM images using ImageJ software developed at the National Institutes of Health (NIH). The preparation methods were optimized, and the obtained nanocomposites were characterized with suitable techniques to explore their characteristics and to help expect or predict the suitable fields of applications.

Synthesis of chitosan nanocomposites for controlled release applications.

Chitosan (CS) was modified using hydroxyapatite (HA) and multiwalled carbon nanotubes (MWCNT) followed by crosslinking with glutaraldehyde (GA). The obtained products were characterized and investigated with thermal analysis. The modified CS suffered a slight weight loss % up to 240 °C then extensive weight loss (EWL)% up to 420 °C and a slight weight loss again until the end of measurement at 700 °C. The treatment showed more thermal stability of modified CS over the blank CS. The 20% HA modified CS showed the highest thermal stability among CS/HA composites while adding CNT to the matrix in CS/HA/CNT composites enhances their thermal stability. Ability of the modified CS to uptake metal ions was investigated by using Cu(NO3)2 where CS/HA/CNT/GA showed higher metal ion uptake than CS/HA/GA. Modified CS was preliminary checked for controlled release of 5-fluorouracil (FU), as an antitumor model drug, in aqueous media where the maximum release of FU was obtained after 48 h. This is concluding the ease of release of FU from the investigated matrices which can be arranged in the order of P111F > P121F > P211F > P311F > P221F > P321F.

Chitosan based atorvastatin nanocrystals: effect of cationic charge on particle size, formulation stability, and in-vivo efficacy.

Cationic charged chitosan as stabilizer was evaluated in preparation of nanocrystals using probe sonication method. The influence of cationic charge densities of chitosan (low CS(L), medium CS(M), high CS(H) molecular weights) and Labrasol(®) in solubility enhancement and modifying the release was investigated, using atorvastatin (ATR) as poorly soluble model drug. Compared to CS(M) and CS(H); low cationic charge of CS(L) acted as both electrostatic and steric stabilizer by significant size reduction to 394 nm with charge of 21.5 meV. Solubility of ATR-CS(L) increased to 60-fold relative to pure ATR and ATR-L. Nanocrystals were characterized for physiochemical properties. Scanning electron microscopy revealed scaffold-like structures with high surface area. X-ray powder diffractometry and differential scanning calorimetry revealed crystalline to slight amorphous state changes after cationic charge size reduction. Fourier transform-infrared spectra indicated no potent drug-excipient interactions. The enhanced dissolution profile of ATR-CS(L) indicates that sustained release was achieved compared with ATR-L and Lipitor(®). Anti-hyperlipidemic performance was pH dependent where ATR-CS(L) exhibited 2.5-fold higher efficacy at pH 5 compared to pH 6 and Lipitor(®). Stability studies indicated marked changes in size and charge for ATR-L compared to ATR-CS(L) exemplifying importance of the stabilizer. Therefore, nanocrystals developed with CS(L) as a stabilizer is a promising choice to enhance dissolution, stability, and in-vivo efficacy of major Biopharmaceutical Classification System II/IV drugs.

Modification of chitosan derivatives of environmental and biological interest: a green chemistry approach.

Chitosan is a non-toxic polyaminosaccharide that is available in a variety of useful forms, and its chemical and biological properties make it a very attractive biomaterial that could be used in a wide variety of medicinal applications. This work focuses on the preparation of different chitosan derivatives by treatment with ethyl cellulose, cellulose triacetate and different carbohydrates in both neutral and slightly acidic media. It also addresses modification with glycidyltrimethyl ammonium chloride, phthalic anhydride and succinic acid derivatives. The obtained derivatives were crosslinked with glutaraldehyde. Thermo-gravimetric (TGA) and FT-IR spectroscopic analyses and electron scanning microscopy (SEM) were used to characterize the obtained products and demonstrate the success of the chitosan-modification process. The obtained products were tested for their ability to uptake transition metal ions from aqueous solutions, and their ion-uptake efficiency was determined with the aid of the ICP-AES technique. The bioactivity of some selected products was tested to study the effect of their concentrations on selected microorganisms. Burkholderia cepaci, Aspergillus niger, and Candida albicans were selected as representative examples of bacteria, yeasts and fungi, respectively.