Synthesis, Characterization and Kinetic Studies of Chelate Polymer Derived from 3-Nonyl Benzene and its Use for the Removal of Some Heavy Metals from Aqueous Solutions

A new chelate polymer (2-5-hydroxy-3-methyl-2- (3-nonyl benzene) imino) methyl) benzyl) 4-6-dimethyphenol] (K4) was prepared by using the condensation reaction method and identified by several techniques, including FT-IR, NMR, and atomic absorption spectroscopy, as well as TG-DTA thermal analysis. The kinetic equilibrium for the sorption of lead and cadmium ions on the chelate polymer surface was also investigated. The results showed that the sorption of both ions followed the pseudo-first-order and pseudo-second-order kinetic equilibrium. The rate constant values of pseudo-first-order reaction were equal to 0.062 and 0.057 min-1 , while the values of pseudo-second-order were 0.0103 and 0.053 L.mg-1 min-1) for the sorption of Pb (II) and Cd (II) on chelate polymer, respectively. Thermodynamic parameters were also investigated and the sorption values for Pb+2 were achieved at 25 oC, ΔG = 0.436 KJ/mole, ΔH = 10.55 KJ/mole, and ΔS= 0.08 KJ/mole, , whereas those for Cd+2 were 25 oC , ΔG = -2.345 KJ/mole, ΔH = 4.378 KJ/mole, and ΔS= 0.09 KJ/mole. The results showed that the sorption process was spontaneous and endothermic in nature for the sorption of each of Pb+2 and Cd+2 on polymer surface.

An Efficient Electrocatalyst for Oxygen Evolution Reaction in Alkaline Solutions Derived from a Copper Chelate Polymer via In Situ Electrochemical Transformation

Efficient oxygen evolution reaction (OER) electrocatalysts are highly desired in the field of water electrolysis and rechargeable metal-air batteries. In this study, a chelate polymer, composed of copper (II) and dithiooxamide, was used to derive an efficient catalytic system for OER. Upon potential sweep in 1 M KOH, copper (II) centers of the chelate polymer were transformed to CuO and Cu(OH)2. The carbon-dispersed CuO nanostructures formed a nanocomposite which exhibits an enhanced catalytic activity for OER in alkaline media. The nanocomposite catalyst has an overpotential of 280 mV (at 1 mA/cm2) and a Tafel slope of 81 mV/dec in 1M KOH solution. It has a seven-fold higher current than an IrO2/C electrode, per metal loading. A catalytic cycle is proposed, in which CuO undergoes electrooxidation to Cu2O3 that further decomposes to CuO with the release of oxygen. This work reveals a new method to produce an active nanocomposite catalyst for OER in alkaline media using a non-noble metal chelate polymer and a porous carbon. This method can be applied to the synthesis of transition metal oxide nanoparticles used in the preparation of composite electrodes for water electrolyzers and can be used to derive cathode materials for aqueous-type metal-air batteries.