İlhan Uzun

Adsorption of basic dyestuffs from aqueous solution by modified chitosan

ABSTRACT The capability of chitosan to adsorb the basic dyestuffs is very low. For this purpose, chitosan was modified to increase its adsorption capability with some cyclic acid anhydrides in dimethyl sulfoxide. Then, chitosan and its derivatives, chitosan modified with maleic anhydride (CMA), chitosan modified with phthalic anhydride (CPA), and chitosan modified with trimellitic anhydride (CTA), were compared according to their capabilities to remove brilliant green (BG) and methylene blue (MB) from aqueous solution. It was determined that CTA adsorbed much more BG and MB. The 70.57% of BG (C o: 50 ppm) and 71.86% of MB (C o: 50 ppm) in the samples of 50 mL by 0.1 g CTA were adsorbed at room temperature and at a shaking rate of 140 rpm within 24 h. As a result of this, the adsorption of BG and MB by CTA was kinetically investigated as dependent on temperature and pH. Besides, the adsorption isotherms of each dyestuff by CTA were determined at different temperatures. Then, some kinetical and thermodynami...

Synthesis and Physicochemical Characterization of Chitin Derivatives

Firstly, chitin derivatives were synthesized. For this purpose, chitin was modified via ring-opening reaction with cyclic anhydrides in lithium chloride/N,N-dimethylacetamide. Then, chitin derivatives synthesized were characterized by FTIR, 1H NMR, 13C NMR, and U-Vis spectroscopies and scanning electron microscopy. Thermogravimetric analysis was performed to investigate the thermal stability of chitin derivatives. Thermogravimetric analysis results showed that chitin modified with trimellitic anhydride is thermally more stable than chitin modified with phthalic anhydride. In addition, the electrical conductivity of chitin modified with phthalic anhydride and trimellitic anhydride was also measured. Electrical conductivity measurement results showed that the electrical conductivity of chitin modified with trimellitic anhydride (1.2×10−4 S cm−1) is higher than that of chitin modified with phthalic anhydride (9.2×10−5 S cm−1).

Synthesis, characterization, and Schottky diode applications of low-cost new chitin derivatives

In this study, low-cost two new chitin derivatives were first synthesized. Products formed in the consequence of the reaction of chitin with 4-nitrobenzoyl chloride and 3,5-dinitrobenzoyl chloride were named C4NC and C35DC, respectively. Then, C4NC and C35DC were characterized by FTIR and 13C CP-MAS solid-state NMR spectroscopies and X-ray powder diffraction technique. Surface topography and composition of C4NC and C35DC with a scanning electron microscope were investigated. Mass loss in C4NC and C35DC with thermogravimetric analysis method was determined as a function of increasing temperature. Endothermic and exothermic transitions in C4NC and C35DC were investigated with differential thermal analysis and differential scanning calorimetry techniques. Later on, charge carrier density, hole mobility, and electrical conductivity values of C4NC and C35DC were determined. Besides, Schottky diodes of C4NC and C35DC were constructed, and several parameters related to these diodes were determined. Finally, the sensitivity of these diodes to light was studied.