Hexavalent chromium (Cr(VI)) is a highly toxic metal that has been accused to be carcinogen with prolonged inhalation by humans and is toxic to aquatic life even at low concentrations. The objective of this work was to use water‐soluble functionalized chitosan in the removal of chromate ions in aqueous solution. Functionalized chitosan was obtained by grafting molecules with quaternary ammonium groups in a heterogeneous process under alkaline conditions. Chitosan modified was characterized by FTIR, 1H‐NMR spectroscopy, and TGA. The retention tests were carried out using the liquid‐phase polymer‐based retention technique (LPR) by means of the washing method, studying the effects of the variation of pH, interfering ions, and variations of hydrodynamic flow. The results showed 94.0% retention with regard to the modification of chitosan. For the removal studies, a trend in the retention percentages was presented as the pH increased, obtaining a maximum retention of 92.0% at pH 9.0. In studies of interfering ions, a decrease was found as the concentrations of interferent increased, obtaining the highest retention >70.0%. In conclusion, the functionalization of chitosan with quaternary ammonium groups in conjunction with the LPR technique is a great alternative in the removal of chromate ions and is friendly to the environment.
Semantic memory (SM) is a type of long-term memory associated with the storage of general information about the world. Here we assessed the characteristics of the SM battery, developed by Catricalà et al. (2013), in a sample of Colombian children. This battery was originally conceived to evaluate adults, and features six subtests that assess SM in different modalities, using a common set of 48 stimuli in both living and nonliving categories. The design of the current study is of a cross-sectional and exploratory type. The sample was composed of 111 children, 57 boys (51%) and 54 girls (49%), who were 6 (n = 68) and 7 (n = 43) years old and had no intellectual disability. Robust linear regression models and correlation networks were used. We found an effect of age on general intelligence after correcting for gender, and no differences on the six subtest scores after corrections for gender and age were performed. Furthermore, age was found to be positively associated with the naming of colored photographs (β = .75, p = .039), naming in response to an oral description (β = 1.81, p = .039), picture sorting at four levels (β = 7.22, p = .029), and sentence verification (β = 26.66, p = .01). In addition, there were differences between the results obtained in adults in the original study and in the children of our study. This exploratory study supports the feasibility of the Spanish translation of the Catricalà et al. (2013) battery to assess SM in children with a nonclinical condition. Future studies are needed to evaluate the psychometric properties of this SM battery, and to corroborate and expand our findings in a larger sample of control children, and in children with some degree of intellectual disability or suffering of some neurodegenerative or psychiatric conditions.
Polysulfone (PSf) is a high-performance polymer often used in water treatment applications. Polyethylene glycol (PEG) and Nanozeolite (NZ) were used as additives to improve the membrane’s porosity, chemistry, and overall performance in ion adsorption. PSf, PSf with PEG, and PSf with PEG and varying concentrations of Nanozeolite were prepared via non-solvent induced phase separation (NIPS) and tested using: Scanning Electron Microscopy (SEM) for the surface morphology, Fourier Transform Infrared Spectroscopy (FTIR) for the chemical composition, Contact Angle Goniometer for the wettability, Zeta Potential for the stability, and conductivity test through salt-water bath for ion adsorption application.
Self-healing composites are smart materials that can be fabricated through the dispersion of tubular nanofillers loaded with appropriate healing agents in a polymeric matrix. In this study, polysulfone (PSf) containing epoxy-loaded halloysite nanotubes (e-HNTs) were successfully fabricated via non-induced phase separation (NIPS) method at varying concentrations. Fourier Transform Spectroscopy (FTIR) analysis showed that epoxy (healing agent) and amine (hardener) were successfully loaded into the lumen of the HNT through the observed functional groups of the epoxy system along the HNT spectrum. The tensile strength of the loaded membranes compared to their unloaded counterpart slightly decreased due to the possible embrittlement of the unreacted epoxy. However, the membranes with epoxy-loaded HNTs garnered lower wettability on average due to the hydrophobic character of the epoxy system, which is a preferable trait for smart coatings. The self-healing capability of the membranes with 5% filler (loaded and unloaded) was investigated by scratch test and Scanning Electron Microscopy (SEM). The result revealed a high tendency of healing for the epoxy-infused nanocomposite film.
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