In the present work, we analyzed the linear and nonlinear model suitabilities for adsorption data from aqueous As(III) removal by manganese ferrite nanoparticles (NPs). Hence, As(III) adsorption onto ferrite NPs was formerly analyzed by the intraparticle diffusion model (IPD). Then, adsorption kinetics was described by the pseudo-first-order (PFO), pseudosecond-order (PSO), and Elovich models, while equilibrium adsorption was fitted to the Freundlich and Langmuir isotherms. Linear and nonlinear kinetic and isotherm models were solved and compared. The nonlinear data fitting was applied through the lsqcurvefit user-defined function (Matlab ver. 7.10.0). The initial adsorption rate was influenced by intraparticle diffusion and surface or film diffusion from the arsenic bulk solution to ferrite NPs, according to the IPD model. Adsorption kinetics of As(III) on manganese ferrite NPs was better described by the PSO model, followed by the Elovich model and then the PFO model. Equilibrium adsorption data were only worthily described by the Freundlich isotherm model. While the PSO, Elovich and Freundlich linear models showed even better fit than the nonlinear models, determinant bias was depicted for the PFO and Langmuir linear models. Thus, to use nonlinear adsorption models is highly advisable, having the Matlab lsqcurvefit function been proven very useful to face such task.

Three possible reaction pathways have been studied for the Cl 2 (PMe 3 ) 2 RudCH 2 and Cl 2 (PCy 3 ) 2 RudCH 2 (Cy ) cyclohexyl) mediated metathesis reaction of propylene by quantummechanical DFT calculations. It was found that in all cases the metathesis reaction proceeds via dissociative substitution of a phosphine ligand with propylene, giving a monophosphine complex. This tendency increases with ligand volume, and in the case of smaller PMe 3 groups it is the entropy contribution to the reaction energetics that causes the monophosphine complex to participate in the metathesis reaction, according to the modeling data.

A family of modularly designed phosphine−phosphites (P−OP), possessing a C−C−O backbone, has been synthesized and evaluated in the iridium-catalyzed asymmetric hydrogenation of N-aryl imines. The enantioselectivity of this reaction is highly dependent on the nature of the ligand, and catalysts bridged by an oxyethylene fragment have produced significantly higher enantiomeric excesses (Δee > 20%) than their o-oxyphenylene counterparts. Structural studies by X-ray crystallography and NMR spectroscopy of complexes with the formulation [Ir(COD)(P−OP)]BF4 and Ir(Cl)(CO)(P−OP), complemented by DFT calculations of model compounds of the chlorocarbonyls, have shown important differences between complexes bridged by an aliphatic or an aromatic bridge, regarding the iridacycle conformation and the location of phosphine substituents. Catalyst optimization has afforded enantioselectivities from 72 to 85% ee in the hydrogenation of several N-aryl imines.