Determination of the rate control step of purin and pyrimidine bases adsorption on cobalt(II)–CDAE-sporopollenin

Isolation of sporopollenin-like biopolymer from Aspergillus niger and its characterisation

The study sought to isolate asporopollenin-like biopolymer from

Kinetics of Diffusion-Controlled Adsorption of Adenine and Adenosine in a Carboxymethyl Diaminoethane Pvc-Mediated Column System

The adsorption kinetics of adenine and adenosine on a ligand-exchange matrix, carboxymethyl diaminoethane poly(vinyl chloride) in cobalt form (cobalt-CMEDA-PVC), have been studied in a fixed-bed column system. The initial ligand concentrations ranged between 1.25×10−5 and 2.0×10−4 mol L−1. The kinetic studies were carried out spectrophotometrically, in order to determine the ratecontrolling step of the adsorption. The kinetic data of the single-component systems were acquired from the breakthrough curves of the ligands on the basis of the equivalent points method. In this study, the homogeneous diffusion model was adapted to a fixed-bed column system to describe the differentiation in the ligand concentration of the effluent, beginning from breakthrough point as a function of time. The results obtained for the adsorption kinetics indicated that the diffusion step plays a significant role in the adsorption kinetics of the ligands, due to the fact that the adsorption performance was strongly affected by the initial concentration of ligands.

The adsorption behavior of crystal violet in functionalized sporopollenin-mediated column arrangements

The adsorption behavior of Crystal Violet (CV) on a sporopollenin-based solid phase, carboxylated diaminoethane sporopollenin (CDAE-S), was investigated under column conditions, and the obtained breakthrough profiles were used in evaluations and quantifications. The adsorption capacity of the CDAE-S was observed to be considerably higher than that of diaminoethane sporopollenin (DAE-S), revealing the importance of electrostatic interactions and carboxyl groups in the adsorption of CV on the CDAE-S. The binding of CV on the DAE-S was found to be a typical nonspecific adsorption, whilst cation-exchange was proposed as the main mechanism for monolayer adsorption of CV on the CDAE-S. Hence in the present study, the cation-exchange is suggested as an effective process for removal and recovery of CV from aqueous effluents, and in view of the pH point of zero charge matter, multifunctionality of the CDAE-S is discussed in detail, and various application possibilities based on "aminocarboxylic acid" functionality are also drawn.

Removal of aniline from aqueous solution by PVC-CDAE ligand-exchanger

The adsorption of aniline from aqueous solutions onto cobalt(II)-poly(vinyl chloride)-carboxylated diaminoethane (PVC-CDAE) resin has been studied using a mini-column apparatus at 25+/-0.1 degrees C. First of all, experimental data obtained from the breakthrough curves were tested by using the Scatchard plot analysis, to have a preliminary prediction about the types of interaction of the resin with aniline. Our aim was to determine the model which best describes the experimental data. The aspect of the Scatchard plot indicated that the aniline adsorption did not follow the Langmuir model and the presence of two types of binding sites for aniline on the resin. However, the dynamics of aniline uptake were represented by the Freundlich model reasonably well. The kinetics of aniline adsorption from aqueous solution on the cobalt(II)-PVC-CDAE have also been tested using continuous column runs and rate-controlling step of the process was determined. In this study, homogeneous diffusion model was adapted to a column system to describe the change in the aniline concentration at the column exit beginning from breakthrough point as a function of time. Kinetic studies revealed that the rate-controlling step of the aniline adsorption was predominately film diffusion controlled rather particle diffusion.

Oxidation of benzaldehyde in films by Oxo-Cr(V) salen derivatives at solid/liquid interface

The oxidation of benzaldehyde as a film on a solid surface by various substituted oxochromium(V) salen in solution has been studied by monitoring the change in contact angle of the oxidant at the film/liquid interface utilizing a Teflon cell of known hydrodynamics and controlled convection/diffusion. The kinetics of the redox reaction in bulk has been monitored by measuring the change in absorbance of the oxidant solution. The interfacial study permits analysis of adsorption of the oxidant followed by the oxidation of the substrate under pseudo-first-order conditions. A comparison of the independent surface-averaged kinetic data with those obtained in the solution phase oxidation reaction is made and a model is presented for the mechanism of the interfacial reaction. The kinetic investigation shows that the rate of oxidation is accelerated in the presence of an electron-withdrawing group and is faster at the solid/liquid interface compared to the bulk. The probable mechanism of the redox reaction is discussed.