Acid Dye Removal from Aqueous Solution by Using Neodymium(III) Oxide Nanoadsorbents.

Shahin Ahmadi,Chinenye Adaobi Igwegbe,Leili Mohammadi,Abbas Rahdar,George Z Kyzas,Ramin Dehghani,Somayeh Rahdar

doi:10.3390/nano10030556

Abstract

In the current work, neodymium oxide (Nd2O3) nanoparticles were synthesized and characterized by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The major aim/investigation of this research was to fit/model and optimize the removal of Acid Blue 92 (AB92) dye from synthetic effluents (aqueous solutions) using the adsorption process based on neodymium oxide (Nd2O3) nanoparticles. To optimize the adsorption conditions, central composite design (CCD) based on response surface methodology (RSM) was applied. The effects of pH (3–9), adsorbent dosage (0.1–1 g/L), initial concentration of AB92 (100–300 mg/L), and contact time (10–100 min) on the adsorption process were investigated. Apart from equilibrium and kinetic experiments, thermodynamic evaluation of the adsorption process was also undertaken. The adsorption process was found to have the best fitting to Langmuir isotherm model and pseudo-second-order kinetic equation. Also, the process was found to be spontaneous and favorable with increased temperature. The optimal conditions found were: pH = 3.15, AB92 concentration equal to 138.5 mg/L, dosage of nanoadsorbent equal to 0.83 g/L, and 50 min as contact time, which resulted in 90.70% AB92 removal. High values for the coefficient of determination, R2 (0.9596) and adjusted R2 (0.9220) indicated that the removal of AB92 dye using adsorption can be explained and modeled by RSM. The Fisher’s F-value (25.4683) denotes that the developed model was significant for AB92 adsorption at a 95% confidence level.

Highlights

It is generally accepted that dyestuffs are very hazardous species of industrial effluents and need to be treated [1,2,3]
The major target of the present study is to model the reduction of Acid Blue 92 (AB92) dye from aqueous solutions by adsorption onto Nd2O3 nanoparticles synthesized and optimized in experimental conditions
The Nd2O3 sample consists of irregular shapes with pores of varying sizes, which will make available the active sites for the adsorption process and the take in of the AB92 dye particles

Summary

Introduction

It is generally accepted that dyestuffs are very hazardous species of industrial effluents and need to be treated [1,2,3]. Due to the presence of azo bonds (–N=N–), sulfonic groups and aromatic rings in dye compounds, azo dyes are hardly decomposed in the natural environment and have toxic, mutagenic, and carcinogenic effects [4]. They are unwanted compounds in the environment because they reduce the penetration of light and impair the process of photosynthesis [5,6]. These compounds can cause negative effects on the appearance and quality of water [6]. Different studies have reported that there are several methods for removing dyes from textile wastewaters, including the application of photodecomposition [6], electrolysis [7,8], adsorption [9,10,11,12,13,14,15,16,17,18], oxidation [19], biodegradation [20], combined sonochemical and adsorption [21], coagulation-flocculation [22,23], etc

Methods

Results

Conclusion