Adsorption of Tartrazine onto Activated Carbon Based Cola Nuts Shells: Equilibrium, Kinetics, and Thermodynamics Studies

Dantio Nguela Christian Brice,Che Randy Nangah,Bénédoué Serge Arnold,Ngomo Horace Manga,Kouotou Daouda,Ndongo Ndongo Alain Giresse,Ndi Julius Nsami,Abega Aimé Victoire

doi:10.4236/ojic.2021.111001

Abstract

The uptake of tartrazine from its aqueous solution by powdered activated carbon prepared from cola nut shells chemically activated with potassium hydroxide (ACK) and phosphoric acid (ACP) has been investigated using kinetics models. Batch isotherm data were analysed with the pseudo-first order, pseudo-second order model as well as the intraparticle diffusion model. For structural elucidation, the materials were characterized using FTIR, XRD and SEM. These analyses revealed that the activated carbons (ACK and ACP) were predominantly mesoporous with several oxygen-containing functional groups dispersed on their surface. The reaction was systematically investigated under various experimental conditions such as contact time, adsorbent dose and pH. For the two adsorbents, the quantity adsorbed of 19.256 mg/g and 18.196 mg/g respectively for ACP and ACK at respective contact times of 5 and 10 min were obtained. The adsorption data were tested with the Langmuir, Freundlich models. Langmuir model was found to best describe the adsorption of tartrate ions with maximum monolayer adsorption capacities of 24.57 and 21.59 mg/g for ACP and ACK, respectively. Results analysis indicated clearly that the pseudo-second order kinetic rate model best fitted the experimental data and therefore was the adsorption controlling mechanism for both adsorbents. Thermodynamic studies revealed that the adsorption process was spontaneous and exothermic for ACP with increased randomness at the solid solution interface, then exothermic but non-spontaneous for ACK. The results show that these activated carbons could be an alternative for more costly adsorbents for the purpose of tartrate ions elimination.

Highlights

Though industrial activities have contributed to the development of many countries, they have generated undesirable by-products, which constitute the main part of the discharged effluents
The materials were characterized using FTIR, X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). These analyses revealed that the activated carbons (ACK and ACP) were predominantly mesoporous with several oxygen-containing functional groups dispersed on their surface
The region between 7 and 70 degrees indicates the absence of any crystalline structure with the absence of any well-defined peak, which is an indication of an amorphous structure. This result is in good agreement with the nature of activated carbon prepared by others researchers reported in literature

Summary

Introduction

Though industrial activities have contributed to the development of many countries, they have generated undesirable by-products, which constitute the main part of the discharged effluents These industrial effluents are organic (dyes, pesticides) and inorganic (heavy metals) pollutants. Owing to their appearance, coloured organic compounds are recognizable pollutants. Tartrazine (otherwise known as E102 or FD & C Yellow 5), is a lemon yellow azo dye manufactured from coal-tar derivative and used as a food colouring It is found in certain brands of fruit squash, fruit cordial, coloured fizzy drinks, instant puddings, cake mixes, custard powder, soups, sauces, ice cream, ice lollies, sweets, chewing gum, marzipan, jam, jelly, marmalade, mustard, yoghurt and many convenience foods [3]. It is important to treat wastewaters containing tartrazine before their injection into the environment

Methods

Results

Conclusion