مشخصات پژوهش

The nanoparticles of Cu-Fe-NO3 layered double hydroxide (LDH) were prepared with Cu/Fe molar ratio of 2:1 by a thermal process and co-precipitation method at pH 9 and were characterized by X-ray powder diffraction (XRPD), thermal gravimetric analysis (TGA), atomic adsorption spectroscopy (AAS) and fourier infrared spectroscopy (FT-IR). The size andmorphology of nanoparticles were examined by transmission electron microscopy (TEM). Cu-Fe-NO3-LDH was studied as a potential adsorbent of the acid herbicide MCPA [(4-chloro-2-methylphenoxy) acetic acid] as function of pH, contact time and temperature. The results showed high and rapid adsorption of MCPAon the LDH. The characterization of the adsorption products by XRD indicates that the intercalation of MCPA between the LDH layers has not occurred and surface adsorption has happened. The adsorption kinetic was tested for pseudo-first-order, pseudosecond- order, elovich and intra-particle diffusion kinetic models and rate constants were calculated. Freundlich and Langmuir isotherm models were applied to experimental equilibrium data obtained from the measurements of pesticide adsorption. Langmuir isotherm slightly better fitted to the experimental data than that of Freundlich. In the adsorption experiments, the Gibbs free energy G0 values, the enthalpy H0, and entropy S0 were determined.