Kinetics and Equilibrium Studies on Adsorption of Acid Red 18 (Azo‐Dye) Using Multiwall Carbon Nanotubes (MWCNTs) from Aqueous Solution

Mohammad Shirmardi,Simin Nasseri,Amir Hossein Mahvi,Ramin Nabizadeh,Alireza Mesdaghinia

doi:10.1155/2012/541909

Abstract

Azo dyes are one of the synthetic dyes that are used in many textile industries. Adsorption is one of the most effective techniques for removal of dye‐contaminated wastewater. In this work, efficiency of multiwalled carbon nanotubes (MWCNTs) as an adsorbent for removal of Acid Red 18 (azo‐dye) from aqueous solution was determined. The parameters affecting the adsorption process such as contact time, pH, adsorbent dosage, and initial dye concentration were studied. Experimental results have shown by increasing the adsorbent dosage, the rate of dye removal was increased, but the amount of adsorbed dyes per mass unit of MWCNTs was declined. pH as one of the most important influencing factors on the adsorption process was evaluated. The best pH for adsorption process was acidic pH of about 3. To describe the equilibrium of adsorption, the Langmuir, Freundlich and Temkin isotherms were used. The Langmuir isotherm (R2=0.985) was the best fitted for experimental data with maximum adsorption capacity of 166.67 mg/g. A higher correlation value of the kinetic′s model was observed close to pseudo second order (R2=0.999) compared to other kinetic models.

Highlights

There are more than 1,00,000 types of dyes commercially available, with over 7×105 tonnes of dyestuff produced annually, which can be classified according to their structure as anionic and cationic[1]
Effect of Contact Time To evaluate the effect of contact time on adsorption process, minimal dose of adsorbent was selected and was added to different dye concentrations (25, 50, 75, 100). pH of solutions was adjusted to 5 that was much close pH to the actual pH of solutions
Isotherm is the relationship between the equilibrium amount of dye (AR18) adsorbed on multiwalled carbon nanotubes (MWCNTs) surface and residual concentration of dye in solution

Summary

Introduction

There are more than 1,00,000 types of dyes commercially available, with over 7×105 tonnes of dyestuff produced annually, which can be classified according to their structure as anionic and cationic[1]. The adsorption behavior of multiwalled carbon nanotubes (MWCNTs), its removal capacity and other adsorption condition of an azo dye such as AR18 from aquatic solution have been investigated. The influence of contact time, pH, adsorbent dosage and initial dye concentration was studied.

Results

Conclusion