Kinetics and Thermodynamics of the Adsorption of Lead (II) on a Activated Carbon from Coconut Shells

The effect of temperature on the adsorption of lead by an activated carbon from coconut shells is investigated. The pseudo second order equation is applied to the kinetic data obtained at different temperatures in order to determine the adsorption rate constants at these temperatures. Then, the Arrhenius equation is applied to the rate constants to determine the activation energy of the sorption reaction and the pre-exponential factor. By applying the Eyring equation to the rate constants, the standard thermodynamic activation parameters of the sorption reaction can also be calculated. In addition, the isotherms of lead adsorption on the activated carbon from coconut shells, at different temperatures, are determined and fitted by the Langmuir equation. The Van’t Hoff equation is applied to the Langmuir equilibrium constants in order to determine the standard enthalpy of the sorption reaction. The other standard thermodynamic parameters (Gibbs standard enthalpy and standard entropy) are deduced. The isosteric standard sorption enthalpy is also determined by using both the classical approach and an adapted Clausius Clapeyron equation. The results are identical. The value obtained is higher, but more correct than that of Langmuir. On the basis of these thermokinetic parameters, the activated carbon from Coconut shells can be considered as a very efficient carbon for the sorption of lead and its sorption efficiency (rate and quantity) increase with the temperature

A process for developing standards to promote quality in general practice

Background: Since 1991, the Royal Australian College of General Practitioners (RACGP) Standards for general practices (the Standards) have provided a framework for quality care, risk management and best practice in the operation of Australian general practices. The Standards are also linked to incentives for general practice remuneration. These Standards were revised in 2017. Objective: The objective of this study is to describe the process undertaken to develop the fifth edition Standards published in 2017 to inform future standards development both nationally and internationally. Method: A modified Delphi process was deployed to develop the fifth edition Standards. Development was directed by the RACGP and led by an expert panel of GPs and representatives of stakeholder groups who were assisted and facilitated by a team from RACGP. Each draft was released for stakeholder feedback and tested twice before the final version was submitted for approval by the RACGP Board. Results: Four rounds of consultation and two rounds of piloting were carried out over 32 months. The Standards were redrafted after each round. One hundred and fifty-two individuals and 225 stakeholder groups participated in the development of the Standards. Twenty-three new indicators were recommended and grouped into three sections in a new modular structure that was different from the previous edition. Conclusion: The Standards represent the consensus view of national stakeholders on the indicators of quality and safety in Australian general practice and primary care

Effect of the drying technique on the sorption properties in cementitious materials

info:eu-repo/semantics/publishe

Influence of the Surface Properties of the Bois Carre Seeds Activated Carbon for the Removal of Lead From Aqueous Ssolutions

An activated carbon from Bois carré (Citharexylum Fruticosum L.) seeds was prepared by chemical activation with phosphoric acid. The activated carbon obtained has a surface area of 594 m2/g and a high content of acid groups of 3.44 mmol.g-1. This carbon was studied for the removal of lead from water. Sorption studies were performed at 30 °C at different pH and adsorbent doses, in batch mode. Maximum adsorption occurred at pH 7 for an adsorbent dose of 1g/L. Kinetic studies, at the initial concentration of 150 mg/L of lead, pH 5 and an adsorbent dose of 1 g/L, yielded an equilibrium time of 30 h for this activated carbon. The kinetic data were modelled with the pseudo first order, the pseudo second order and the Bangham models. The pseudo second order model fitted the data well. The sorption rate constant (2.10-3 mol-1.Kg.s-1) and the maximum amount of lead adsorbed are quite good (0.18 mol.kg-1) compared to the data found in literature. Sorption equilibrium studies were conducted in a concentration range of lead from 0 to 150 mg/L, at pH 5, adsorbent dose 1 g/L. In an aqueous lead solution with an initial concentration of 30 mg/L, activated Bois carré seed carbon removed (at equilibrium) 48 % of the heavy metal. The equilibrium data were modelled with the Langmuir and Freundlich equations, of which the latter gave the best fit. The Freundlich constants n (3.76 L.mol-1) and Kf (1.06 mol.kg-1) are in good agreement with literature. The Bois carré seed activated carbon is a very efficient carbon in terms of the metal amount adsorbed per unit of surface area (0. 06 m2 /g). This good result is due to the presence of many active acid sites on the surface of this activated carbon