ABSTRACT
Electric arc furnace dust (EAFD) and waste pickle liquor (WPL); two major side products of the steel industry with negative environmental impact were used for the synthesis of nickel zinc ferrite (NZF); the important magnetic ceramic material of versatile industrial applications. The structural and magnetic properties of the prepared material were examined which showed good magnetic properties (high saturation magnetization and low coercivity) compared with those synthesized from pure reagents. In the applied process, nano sized nickel zinc ferrite (NZF) with a composition of Nix(Zn + impurities)1-xFe2O4 (where x = 0, 0.25, 0.5, 0.75 and impurities of manganese, magnesium, and calcium were prepared using zinc-containing electric arc furnace dust (EAFD) and waste pickle liquor (WPL). The chemical compositions of the prepared samples were determined using X-ray fluorescence (XRF) analysis. The optimum acetic acid concentration for EAFD treatment was found 2% v/v that decreased Ca content of EAFD by 70.6% without loss of Fe and Zn. The structural and morphological characterization was done by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Field Emission Scanning Electron Microscope (FESEM) to confirm the formation of Ni-Zn ferrite nanoparticles and estimate the particle sizes. The maximum saturation magnetization (Ms) of 73.89 emu/g was achieved at 0.5 Ni content and the minimum coercivity of 2.55 Oe was obtained at 0.25 Ni content.
ABSTRACT
The kinetics of Cu ion exchange on Na-montmorillonite clay has been investigated at 20, 30, and 40 degrees C in water, methanol, and ethanol. The reaction is endothermic in nature. Solvent effects on the reaction rate have been discussed. The thermodynamic activation parameters were calculated and discussed in terms of solvation effects. A multiple reaction rate order equation was used to describe the adsorption process. Lower rates and higher activation energies (Ea) were observed in aqueous solution than in either of the alcohols. The Ea values ranged from 20.88 kJmol(-1) in water to 9.20 kJmol(-1) in ethanol, while at 20 degrees C the rate constant (k) varied from 0.111 ppm(-1)s(-1) in water to 0.205 ppm(-1)s(-1) in ethanol. The main factor influencing the rate of the adsorption process is the mobility of the adsorbed Cu cations, which is apparently larger in alcohols than in water, due to the difference in the molar activation energy of the solvent. The determined isokinetic temperature indicates that the reaction is enthalpy-controlled, where the interaction between solvent and clay surface plays an important role. A reaction mechanism that describes the solvent effect on the rate of Cu ion exchange is proposed.
