Document Type : Research Paper
Authors
1 Department of Soil Science, Faculty of Agriculture, Malayer University, Malayer, Iran
2 Department of Civil Engineering, Faculty of Civil and Architecture, Malayer University, Malayer, Iran
Abstract
Keywords
Main Subjects
The discharge of colored wastewater from various industries, especially aromatic dye compounds with complex structures and high water solubility, creates serious environmental problems as they are toxic, carcinogenic, and non-biodegradable. Azo dyes, including Remazol Black B (RB-B) and Levafix Blue (LBB), are considered common pollutants in effluents due to their stability and widespread use in the textile industry. Adsorption, due to its efficiency, economic viability, and environmental compatibility, has attracted attention as an effective method for removing these pollutants. Nickel oxide (NiO) nanoparticles, owing to their unique magnetic, electronic, and optical properties, are suitable adsorbents for treating colored wastewater. However, specific and comprehensive studies on the removal of Remazol Black B and Levafix Blue dyes using nickel oxide nanoparticles have been less frequently reported in domestic scientific sources. The aim of this research was to investigate the efficiency of nickel oxide nanoparticles for the removal of these two dyes from aqueous solutions by examining the effect of parameters including adsorbent dosage, pH, temperature, and contact time.
In this study, Remazol Black B and Levafix Blue dyes (Sangchun Company, South Korea) and nickel oxide nanoparticles were used as adsorbents. The pH of the solutions was adjusted with HCl and NaOH, and dye concentrations were measured using an Analytik Jena 205 UV-Vis spectrophotometer. Adsorption experiments were conducted using the One-Factor-At-a-Time (OFAT) method to investigate the effect of various parameters including adsorbent dosage (1-5 g/L), pH (3-8), temperature (20-40 °C), and contact time (60-180 minutes). The structural characteristics of NiO were determined by FTIR, SEM, XRD, and EDX analyses. Adsorption capacity and removal efficiency were calculated. Adsorption kinetics and isotherms (Langmuir, Freundlich, Temkin) were also investigated.
NiO Nanoadsorbent Characterization: SEM images showed that NiO nanoparticles have a dense morphology with sizes around 45.67 nm, creating a porous and active surface for adsorption. EDX analysis confirmed the presence of nickel and oxygen elements, indicating the high purity of the nanoadsorbent. FTIR spectroscopy identified O-H and C-O functional groups and Ni-O bonds. XRD analysis determined the average crystallite size to be 94.4 nm. The specific surface area of the adsorbent, as determined by BET, was reported as 127.18 m²/g.
Effect of Adsorbent Dosage: Increasing the adsorbent dosage from 1 to 5 g/L increased the removal efficiency for Levafix Blue dye by up to 47.17% and for Remazol Black B dye from 65.72% to 93.85%. An optimal adsorbent dosage of 5 g/L was selected for both dyes.
Effect of pH: Maximum removal efficiency for Remazol Black B dye was observed at pH 7 (approximately 96%) and for Levafix Blue dye at pH 8 (approximately 94.1%). These results indicate that alkaline conditions are more favorable for the removal of these dyes.
Effect of Temperature and Thermodynamics: Increasing the temperature from 20 to 35 °C increased the adsorption efficiency for both dyes. A temperature of 35 °C was identified as the optimal temperature, at which the removal efficiency for Remazol Black B was 96.75% and for Levafix Blue was 98.22%. Thermodynamic results showed that the adsorption process for both dyes was spontaneous (ΔG<0) and endothermic (ΔH>0), and accompanied by an increase in disorder (ΔS>0).
Effect of Contact Time: The time to reach adsorption equilibrium for both dyes was determined to be approximately 180 minutes. At this time, the adsorption efficiency for Remazol Black B increased to approximately 99% and for Levafix Blue to approximately 91%.
Adsorption Isotherms and Kinetics: Levafix Blue dye followed the Temkin adsorption isotherm model, while Remazol Black B did not show a sufficient fit with the models investigated. Kinetic results showed that the adsorption of both dyes followed the pseudo-second-order model. The maximum adsorption capacity obtained was 13.83 mg/g for Levafix Blue and 17.49 mg/g for Remazol Black B. The removal efficiency for Levafix Blue was reported as 94.6% and for Remazol Black B as 97.25%.
Nickel oxide nanoadsorbent was introduced as an effective adsorbent for the removal of Remazol Black B and Levafix Blue dyes from contaminated wastewater. The optimal conditions for Remazol Black B removal included pH 7, adsorbent dosage of 5 g/L, temperature of 35 °C, and contact time of 180 minutes, with a maximum efficiency of 87.45% and an adsorption capacity of 17.49 mg/g. For Levafix Blue, the optimal conditions were determined to be pH 8, adsorbent dosage of 5 g/L, temperature of 35 °C, and contact time of 180 minutes, with a maximum efficiency of 69.16% and an adsorption capacity of 13.83 mg/g. The adsorption process for both dyes was spontaneous and endothermic, and followed pseudo-second-order kinetics. This research paves the way for the development of effective and cost-efficient methods for treating textile industry dye wastewater.
Conceptualization and idea development: First author; Experimental work and data collection: Second author; Final editing and data review: Third author; Data analysis: Fourth author. All authors have read and approved the final version of the manuscript.
The data are available upon request from the corresponding author via email (Smahdaviha@yahoo.com).
This research was conducted in the Soil Chemistry Research Laboratory, Department of Soil Science and Engineering, Faculty of Agriculture, Malayer University.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The author declares no conflict of interest.
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