Adaptation of Modified Shrinking Core Model for the Description of Salicylic Acid Adsorption on Olive Stones Activated Carbons

Thouraya Bohli

doi:10.11648/j.abb.20170503.12

Abstract

This work aimed to apply a modified shrinking core model (SCM) for describing the kinetic adsorption process of a solute in a microporous activated carbon in an agitated finite batch aqueous system. To apply the SCM, the diffusion-adsorption process in the pore of the adsorbent is transposed to a diagram of diffusion-reaction according to a mobile front. Indeed, solid adsorbent particle is assumed formed by two layers. The first layer is an inner core, not yet reached by the adsorbate, and the second layer is an outer shell, where diffusion and binding to particle sites are occurring. In this study, two mass transfer resistances are considered; the external liquid film resistance and intraparticle resistance. The developed modified SCM, applied to experimental data for the adsorption of salicylic acid onto olive stone activated carbons and a commercial one, give a more realistic prediction and shows a good accuracy in describing batch adsorption in mixed suspension. The kinetic parameters: the effective diffusivity and the mass transfer coefficient were determined. Using the estimated parameters, a parametric study was carried out to observe the effects of the particle size of adsorbent, the initial adsorbate concentration and the stirring velocity on the system kinetics.

Highlights

Water pollution is currently the worldwide subject of important interest, its treatment became one of the more urgent environmental concerns that researchers are facing
From values listed in this table, one can observe that micropore volumes follow the following trend: Norit type (NORIT)>chemical activation with phosphoric acid (COSAC)>MOSAC
Performances of olive stones activated carbons and a commercial one were analyzed as adsorbents for the removal of salicylic acid as phenolic compound from aqueous solution

Summary

Introduction

Water pollution is currently the worldwide subject of important interest, its treatment became one of the more urgent environmental concerns that researchers are facing. Among a variety of organic pollutants, phenolic compounds are considered by many environmental organizations as hazardous contaminants of water causing an unpleasant taste and odor even at low concentration [1, 2], harmful and with a potential toxicity to animals and human health [3]. Among developed wastewaters treatment processes, adsorption is still regarded as the best alternative based on its performances to meet the effluent discharge standards especially when a low cost adsorbent was used, its flexibility in design and operation [6]. Preparation of activated carbon from low cost renewable agricultural byproducts is chosen by some researchers to reduce the cost of the adsorption process [9, 10]. That in industrial scale fixed bed adsorbers are commonly used to treat big volumes of wastewaters with continuous feed flow, Thouraya Bohli et al.: Adaptation of Modified Shrinking Core Model for the Description of Salicylic Acid

Objectives

Methods

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Conclusion