Adsorption kinetics, thermodynamic studies, and high performance of CdO cauliflower-like nanostructure on the removal of Congo red from aqueous solution

Azadeh Tadjarodi,Hamed Kerdari,Mina Imani

doi:10.1186/2193-8865-3-51

Abstract

In this work, CdO cauliflower-like nanostructure synthesized by mechanochemical method was employed to evaluate the adsorption ability of Congo red (CR) from the aqueous solution for the first time. UV-visible absorption spectroscopy was used to record the adsorption behavior. This special structure composed of nanorods and tubes with the high contact sites and surface area of 104 m2 g−1 can be operated as a capable adsorbent to absorb the dye molecules via adsorption process. The adsorption capacity of this material (0.01 g) was studied in high concentrations of CR (50 to 300 mg L−1) and represented an excellent efficiency to eliminate this toxic dye. Maximum adsorption capacity (qmax) calculated using Langmuir isotherm model, at room temperature and neutral pH, was found to be 588.24 mg g−1. Electrostatic interactions were conceived as the main adsorption mechanism, and the calculated dimensionless separation factor (R L ), 0.023, indicated a favorable adsorption process. The kinetic and thermodynamic parameters for this proceeding were evaluated and confirmed the high performance of the synthesized adsorbent.

Highlights

Dyes and pigments are the most common environmental pollutants widely used in various industries
Congo red (CR) dye was selected as the model contamination to investigate the capability of the synthesized CdO nanostructure for decolorizing this dye from an aqueous solution
The structural description of the prepared adsorbent The structural and morphological characterization of the prepared adsorbent, CdO cauliflower-like nanostructure, was carried out using the techniques clearly described in our previous work [21]

Summary

Introduction

Dyes and pigments are the most common environmental pollutants widely used in various industries. There are some techniques such as coagulation, flocculation, advanced oxidation processes, membrane filtration, and adsorption in order to eliminate the contaminants from wastewaters [3,4]. For this purpose, one of the most effective and economical methods is adsorption procedure which has attracted much attentions in recent years [5]. Congo red is a toxic and carcinogenic dye, which despite it being forbidden is still used in some developing countries in the textile industry and via their wastewaters is entered to the environment without treatment. CR dye was selected as the model contamination to investigate the capability of the synthesized CdO nanostructure for decolorizing this dye from an aqueous solution

Methods

Results

Conclusion