Decolorization of Cationic Dye from Aqueous Solution by Multiwalled Carbon Nanotubes

Abstract

Methylene blue is a synthetic and cationic dye that finds utility in different fields including pharmaceutical, paper, textile, printing, carpet, and photography industry. Adsorption is a very effective technique to decolorize contaminated wastewater. This study aimed to determine the efficacy of Multiwalled Carbon Nanotubes (MWCNTs) as an adsorbent for decolorization of MB dye from aqueous solutions. The study has examined various characteristics affecting adsorption, including concentration of dye, pH value, dosage of MWCNTs, and contact time. Show results that growing the adsorbent dosage from (25 to 120) mg increased the dye efficiency rate from 62% to 98%, respectively. The study also evaluated pH, which is among the most critical factors influencing removal efficiency. The best pH for the removal efficiency was 6 at an initial concentration of MB dye 20 mgL-1, a contact time 60 min, and an MWCNT dosage 100 mg. To describe the adsorption equilibrium using Langmuir, Freundlich, and Temkin isotherms. The Langmuir isotherm with an R2 value of 0.9968 and a maximum capacity for adsorption of 19.6 mgg-1 provided a suitable fit for the data of experimental. In comparison between the suitability of kinetic models pseudo-first-order, pseudo-second order, and Weber–Morris, the kinetics model's correlation value was shown to be greater around the pseudo-second order kinetic model with an R2 value of 0.9982.

Keywords

• methylene blue
• adsorption
• multiwalled carbon nanotubes
• adsorption equilibrium
• and the kinetics model