Deactivation of a RuO2–IrO2–TiO2/Ti oxide anode was investigated during an accelerated life test in 0.5moldm−3 NaCl by use of cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy/energy-dispersive X-ray analysis. The variations in double-layer capacitance, film resistance, and charge-transfer resistance during electrolysis were recorded at different potentials. A comprehensive deactivation mechanism of titanium anodes has been proposed by the growth of an insulating TiO2 layer at the coating–substrate interface due to the titanium substrate oxidation. The impedance interpretation of the deactivation mechanism in chloride solutions changes with an increase in potential due to an increase in oxygen evolution on the anode surface at higher potentials.

Existence of heavy metals like zinc within water source is considered as one of the most important environmental problems. Accumulating within alive tissues, zinc raises various diseases and disorders. Chitosan is a hydrophilic polymer which is raised from acetyl groups of chitin from alkaline solution: it is employed widely as a well-known adsorbent for removing heavy metal ions. Present study aimed at optimizing the production of chitosan nano size particles by method of calvo and compared the adsorption of Zn (II) ions by chitosan macro and nano size particles. Adsorption experiments were conducted in a batch system and the effects of temperature, pH, contact time and initial concentration of metal ions on productivity of adsorption of zinc ions have been considered. Performing analysis DLS revealed that mean size of nano chitosan particles is 19.84 nm. Optimal adsorption by chitosan and nano chitosan has been done in pH 7 and about of 5. Efficiencies of both adsorbent were increased by increasing contact time. Both adsorbent had maximum efficiency at the temperature of 25°C. At the concentration of 10 mg/ L of zinc metal ions, maximum effective removal of chitosan macro and nano size particles were 90.80 and 99.10 %, respectively. Maximum capacity of adsorption by chitosan macro and nano size particle was 196.07 and 370.37 mg/g, respectively. Adsorption kinetics followed a pseudo second order model. Nanochitosan compared to chitosan particles had higher removal efficiency for Zinc metal ions due to nano size of particles, larger adsorption surfaces and more functional groups.

No abstract

No abstract

No abstract