Adsorption of Direct Blue 78 Using Chitosan and Cyclodextrins as Adsorbents.

The dyeing industry is one of the most polluting in the world. The adsorption of dyes by polymeric matrixes can be used to minimize the discharge of dyes into the environment. In the present study, chitosan-NaOH and ß-cyclodextrin-epichlorohydrin polymers were used to remove the dye Direct Blue 78 from a wastewater model. To understand the adsorption behavior of Direct Blue 78 onto the polymers, adsorption rate and maximum adsorption capacity were calculated using kinetic tests and isotherm curves respectively. The kinetic data and mechanism of the adsorption process were analyzed by three models and the equilibrium data by three adsorption isotherms; also the different thermodynamic parameters were calculated. Results showed that the adsorption process follows pseudo-second-order kinetics in both polymers and the Langmuir isotherm best-fitted data for chitosan-NaOH polymer and the Freundlich isotherm for the ß-CDs-EPI polymer. The adsorption process is exothermic in both cases and spontaneous for the ß-CDs-EPI polymer to a certain temperature and not spontaneous for the chitosan-NaOH polymer and ß-CDs-EPI polymer at higher temperatures. The complementary action of an advanced oxidation process eliminated >99% of the dye from water. The coupled process seems to be suitable for reducing the environmental impact of the dyeing industry.

Adsorption Properties of ß- and Hydroxypropyl-ß-Cyclodextrins Cross-Linked with Epichlorohydrin in Aqueous Solution. A Sustainable Recycling Strategy in Textile Dyeing Process.

ß-cyclodextrin (ß-CD) and hydroxypropyl-ß-cyclodextrin (HP-ß-CD) were used to prepare insoluble polymers using epichlorohydrin as a cross-linking agent and the azo dye Direct Red 83:1 was used as target adsorbate. The preliminary study related to adsorbent dosage, pH, agitation or dye concentration allowed us to select the best conditions to carry out the rest of experiments. The kinetics was evaluated by Elovich, pseudo first order, pseudo second order, and intra-particle diffusion models. The results indicated that the pseudo second order model presented the best fit to the experimental data, indicating that chemisorption is controlling the process. The results were also evaluated by Freundlich, Langmuir and Temkin isotherms. According to the determination coefficient (R²), Freunlich gave the best results, which indicates that the adsorption process is happening on heterogeneous surfaces. One interesting parameter obtained from Langmuir isotherm is qmax (maximum adsorption capacity). This value was six times higher when a ß-CDs-EPI polymer was employed. The cross-linked polymers were fully characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA). Also, morphology and particle size distribution were both assessed. Under optimized conditions, the ß-CDs-EPI polymer seems to be a useful device for removing Direct Red 83:1 (close 90%), from aqueous solutions and industrial effluents. Complementarily, non-adsorbed dye was photolyzed by a pulsed light driven advanced oxidation process. The proposed methodology is environmental and economically advantageous, considering the point of view of a sustainable recycling economy in the textile dyeing process.

Dietary habits of patients with schizophrenia: a self-reported questionnaire survey.

The present study was carried out to determine the dietary habits of patients with schizophrenia and the influence of these habits on the degree of obesity. The study was developed in a sample of 159 patients, who were given a self-reported questionnaire, to ascertain the influence of socio-familiar aspects, pharmacological treatment, and dietary habits. Anthropometric measurements (body mass index (BMI) and waist circumference (WC)) were also taken. Patients with schizophrenia presented unhealthy dietary habits, as indicated by the finding that 51% of the patients took no longer than 15 min to eat, 40.8% did not eat fruit daily, and 63.1% did not eat fish. Women were three times more likely to be obese than men (odds ratio (OR) = 2.91, P = 0.021). Patients classified as having unhealthy dietary habits have a 2.33-fold higher risk of obesity than patients with good dietary habits (OR = 2.33, P = 0.034). In summary, this paper highlights the fact that patients with schizophrenia have a detrimental dietary pattern that is associated with an increase in BMI and WC, with the consequent development of obesity and related metabolic alterations, regardless of the pharmacological treatment being followed. Future research directions will include exploring the need for nutritional education programmes to improve the dietary habits of such patients.