Retention of Organic Matter Contained in Industrial Phosphoric Acid Solution by Raw Tunisian Clays: Kinetic Equilibrium Study

Wiem Hamza,Chaker Chtara,Mourad Benzina

doi:10.1155/2013/218786

Abstract

Purification of industrial phosphoric acid (H3PO4) is considered a major problem and several methods have been evaluated. In this study, two different types of clay, raw bentonite clay (RBC) and raw grey clay (RGC), were used for removal of SOM contained in H3PO4at low pH. The used samples were characterized by X-ray diffraction, chemical analysis, and specific surface area and MET was also realized. The ability of clay samples to remove S.O.M from aqueous solutions of industrial phosphoric acid has been studied at different operating conditions: temperature, agitation speed, contacting time, and so on. The results indicated that adsorption is an exothermic process for lead S.O.M removal. The equilibrium adsorption data were analysed using the Langmuir and Freundlich isotherms. The results showed that the equilibrium adsorption capacities for the two adsorbents followed best the Langmuir model. Thermodynamic parameters showed that the adsorption process was spontaneous and exothermic.

Highlights

The phosphoric acid is manufactured using different processes; the most commonly used area is thermal and wetprocess [1, 2]
With the aging of H3PO4, the colloidal organics coagulate with the precipitating gypsum, while the soluble organics remain in solution [9]
To evaluate the nature of adsorption of organic matter (OM) contained in industrial phosphoric acid onto raw studied clays, the removal process was analysed in terms of thermodynamic behaviour

Summary

Introduction

The phosphoric acid is manufactured using different processes; the most commonly used area is thermal and wetprocess [1, 2]. Depending on the industrial phosphoric acid origin and quality, organic matter content is generally between 300 and 700 ppm [5]; these organic impurities affect the acid grade. Many of these impurities, the solid impurities, are removed from the acid, whatever their uses are, by techniques such as clarification. The solid impurities, are removed from the acid, whatever their uses are, by techniques such as clarification The presence of these impurities affects the quantity and the quality of the product [6]. Most of the adopted processes to achieve this task are mainly based on either liquid-liquid extraction or adsorption on suitably chosen solid supports [11]

Objectives

Methods

Results

Conclusion