Abstract:In this study the viability of using guar gum to form films was investigated along with the effectiveness of the cross-linking process employing 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) as the cross-linking agent. In addition, the cross-linked films were evaluated considering the water absorption, thermal stability and mechanical properties. The cross-linking process of guar gum films was confirmed by the low solubility in water and through infrared analysis. The results shown that the properties evaluated were affected by the cross-linking process due to changes in the polysaccharide structure. For example, the swelling behavior and water vapor absorption decreased with an increase in the amount of EDC. The EDC content (10-30%) also affected the polymer structure and hydrogen bond formation, reducing the thermal stability of the system.

This work reports the use of a cross-linked ureasil-PEO hybrid matrix (designated PEO800) as an efficient adsorbent to retain the emerging contaminant bisphenol A (BPA) from an aqueous medium. The in-deep experimental and theoretical results provide information about the interactions between PEO800 and BPA. The in situ UV-vis spectroscopy data and the pseudo-first order, pseudo-second order, Elovich, and Morris-Webber intraparticle diffusion models allowed us to propose a three-step mechanism for the adsorption of BPA onto PEO800. The results indicate that the pseudo-first-order kinetic model effectively describes the adsorption of BPA onto PEO800. Differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy confirmed the interaction of PEO800 with BPA, showing an alteration in the chemical environment of the polymer ether oxygen atoms present in the hybrid matrix. The molecular dynamic simulation provides further evidence that the BPA molecules interact preferentially with PEO. The amount of desorbed BPA depended on the pH and solvent used in the assays. This work provides new opportunities for using the hydrophilic ureasil-PEO matrix which has demonstrated its abilities in being a fast and easy alternative to successfully removing organic contaminants from aqueous mediums and therefore having potential applications in water remediation. Graphical abstract.