Chitosan-praseodymium complex for adsorption of fluoride ions from water

Engineering of chitosan by praseodymium has been investigated to improve the adsorption properties as well as physical characteristics of chitosan. Modification of chitosan changes the original properties of chitosan so that it can be more suitable for adsorption of fluoride ions. In this study, chitosan-praseodymium （Chi-Pr） was synthesized by impregnation method. The Chi-Pr complex was characterized by scanning electron microscopic-energy dispersive X-ray spectroscopy （SEM-EDX）, Fourier transform infrared （FTIR） and employed as an adsorbent for removal of fluorides ions from water in the batch system. The variables such as contact time, concentration of Pr, adsorbent dose, initial concentration of fluoride ions, and competitor anions were studied. The adsorption efficiency of fluoride ions （n） with increasing Pr loading into chitosan （5 wt.%, 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%） were 35.5%, 56.1%, 72.0%, 68.5% and 62.5%, respectively. The Chi-Pr （15 wt.%） complex had the highest fluoride removal efficiency （72.0%）. The experimental data fitted well to the Langmuir isotherm with maximum adsorption capacity （qmax） of 15.87 mg/g and an equilibrium constant （kL） of 0.15 mg. Kinetic study revealed that the adsorption of fluoride ions from water followed pseudo-second-order model with a maximum adsorption capacity （q2） of 8.20 mg/g and a rate constant （k2） of 0.01 g/mg.min. Adsorption efficiency of fluoride ions in the simulated drinking water was diminished with the changes in pH levels. The presence of Pr3＋ in chitosan increased chitosan＇s performance as an adsorbent for adsorption of fluoride ions.

Junction properties and conduction mechanism of new terbium complexes with triethylene glycol ligand for potential application in organic electronic device

Terbium-picrate triethylene glycol（EO3-Tb-Pic） complex was prepared in thin film and single layer device structure of ITO/EO3-Tb-Pic/Al, using spin coating technique. The UV-Vis absorption spectroscopy analysis was performed to evaluate the electronic molecular transition of the complex. The optical band gap, Eg estimated from the Tauc model revealed that EO3-Tb-Pic thin film exhibited a direct transition with Eg of 2.70 eV. The electronic parameters of the ITO/EO3-Tb-Pic/Al device such as the ideality factor n, barrier height Φb, saturation current Io, and series resistance Rs, were extracted from the conventional lnI-V, Cheung＇s functions and Norde＇s method. It was found that the evaluated parameters calculated from Norde＇s and Cheung＇s methods were consistent with those calculated from the conventional I-V method. In the double logarithmic I-V plot, three distinct regions based on the slope were identified, and the conduction mechanisms were discussed and explained. The mobility, μ value was estimated from SCLC region as 2.58×10^–7 cm2/（V·s）. This newly obtained lanthanide complex may be potentially utilized in electronic devices.