Investigation of the Ni(II) Adsorption, in Respect to Kinetics and Thermodynamics, by Carbonized Walnut Shell from Aqueous Solution

The objective in this study was to investigate the adsorption, in terms of reaction speed and thermodynamics, of the Ni(II) from aqueus solution. Carbonized walnut shell was used as an adsorbent. The effect of contact time (0-90min) and temperatures (26-45degC) on the adsorption properties have been studied. The adsorption process follows the pseudo-second-order kinetic model very well. The thermodynamic parameters, such as Gibb#39s free energy change (DeltaGdeg), standard enthalpy change (DeltaHdeg) and standard entropy change (DeltaSdeg) were also evaluated. The thermodynamic parameters (DeltaGdeg lt 0, DeltaS = -17.37 J/mol/K, DeltaHdeg = -5.72 kJ/mol) indicated that it was a spontaneously exothermic reaction

Modeling of mass transfer of uranium on different nanoadsorbents for the remediation of contaminated aquatic system

Abstract: Iron oxides, as a group, have important applications as pigments, catalysts, gas sensors, magnetic recording media, etc. Among these iron oxides, akaganeite (ß-FeOOH) and goethite (?-FeOOH) have attracted much investigation because of its unique sorption, ion exchange, and catalytic properties. The present study on uranium transport through akaganeite and goethite has been performed using batch experiments. The transport mechanism of uranium which comprises a diffusion process from aqueous phase on akaganeite and goethite was described by two kinetic models consisting of derived equations: the homogenous particle diffusion model (HPDM) and the shell progressive model (SPM). It was confirmed that the process was controlled by diffusion rate of uranium that penetrated the reacted layer at uranium concentrations in range of 75–150 mg/L. The effective particle diffusion coefficient Deff values were calculated from both the HPDM and SPM equations. The theory–experiment comparison has revealed that predicted values are in excellent agreement with the experimental values. © 2014 Balaban Desalination Publications. All rights reserved

Improving strength properties of recycled and virgin pulp mixtures with dry strength agents

In the paper industry, the increasing use of recycled fibers as a substitute for virgin fibers has resulted in decreased strength properties. In this study, old corrugated container fibers were added in different ratios to virgin kraft fibers, and the effects on paper properties were investigated. Furthermore, 0.75% cationic starch and 0.75% Luredur® with respect to oven-dry fibers were added separately to old corrugated container fiber-containing/fiber-free suspensions, and the effects on handsheet strength properties were determined. Starch is the oldest and most common additive for improving the strength of paper. Luredur®, a cationic polymer-based vinyl amine and N-vinylformamide, is used for the same purpose in papermaking. Results indicated that, except for the tear index, old corrugated container fiber addition decreased handsheet strength properties in the agent-free samples. The cationic starch addition was more efficient than the Luredur® with regard to tensile index, stretch, tensile energy absorption, and burst index. However, the effect of Luredur® on the tear index was more pronounced compared to that of the cationic starch. Consequently, comparable handsheets strength was achieved in the 100% virgin and dry strength additive-free fibers with the addition of 0.75% cationic starch to a suspension containing 20% old corrugated containers and 80% virgin fiber. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

thermodynamic data

Adsorption experiments were performed under batch process, using Th(IV) initial concentration, pH of solution, contact time and temperature as variables. Th(IV) uptake by calcined (C-D) and flux calcined diatomite (FC-D) was pH dependent (pH range, 3.0-6.0) and maximum sorption was observed at pH 4.0. Sorption capacities for Th(IV) were found to be 0.52 (121.22 mg Th/g) and 0.50 mmol/g (116.69 mg Th/g) for calcined diatomite (C-D) and flux calcined diatomite (FC-D), respectively. Adsorption process is well described by Freundlich and Dubinin-Radushkevich (D-R) isotherms in comparison with Langmuir, Temkin and Flory-Huggins isotherms. Thermodynamic data (Delta H degrees, Delta S degrees, Delta G degrees) were calculated from the temperature-dependent sorption isotherms. Results suggested that the adsorption of Th(IV) on calcined and flux calcined diatomite was a spontaneous and endothermic process. A comparison of kinetic models applied to the adsorption of Th(IV) onto C-D and FC-D was evaluated for the pseudo-first-order, pseudo-second-order, intraparticle diffusion and film diffusion kinetic models. The experimental data fitted very well the pseudosecond-order kinetic model and also followed by intra-particle diffusion model, whereas intraparticle diffusion and film diffusion are both the rate limiting steps for Th(IV) onto calcined and flux calcined diatomite. (C) 2012 Elsevier B.V. All rights reserved

The effect of old corrugated container (OCC) pulp addition on the properties of paper made with virgin softwood kraft pulps

In this study, old corrugated container (OCC) pulp was added in different ratios (5%, 10%, 15%, 20%, and 25% w/w) to unbleached virgin pulps of both European black pine and Scots pine, and its effects on paper properties were investigated. As a control, OCC pulp-free handsheets were separately produced from European black pine and Scots pine pulps. The results indicated that the addition of OCC pulp decreased the strength properties, except for the tear index, of the handsheets. In addition, compared to the control handsheets, the paper containing the OCC pulp displayed higher air permeability. The results showed that up to 10% of the virgin softwood kraft pulp could be replaced with OCC pulp without bringing about considerable loss of strength. Also, this ratio of OCC addition could be suitable for production of wrapping papers