Evaluating the Efficiency of Microwaved Sludge in the Removal of 2, 4-Dinitrophenol from Aqueous Solutions: Equilibrium and Kinetics Studies

Hadi  Niknejad; Ali  Esrafili; Majid  Kermani; Mahdi  Farzadkia; Somayeh  Hoseinvandtabar; Samira  Mojerlou; Khadijeh  Sajjadpour; Hassan  Rasoulzadeh

doi:10.18502/jehsd.v7i2.9788

Hadi Niknejad Department of Environmental Health Engineering, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Ali Esrafili Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.
Majid Kermani Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.
Mahdi Farzadkia Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.
Somayeh Hoseinvandtabar Department of Environmental Health Engineering, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Samira Mojerlou Behshahr Health Center, Mazandaran University of Medical Sciences, Mazandaran, Iran.
Khadijeh Sajjadpour Department of Psychology, Faculty of Educational Sciences and Psychology, Payame Noor University, Amol, Iran.
Hassan Rasoulzadeh Department of Environmental Health Engineering, School of Public Health, Bam University of Medical Sciences, Bam, Iran.

DOI: https://doi.org/10.18502/jehsd.v7i2.9788

Keywords: 2,4-Dinitrophenol, Adsorption, Sludge, Aqueous Solution, Kinetic.

Abstract

Introduction: Nitrophenol compounds are toxic compounds found in industrial wastewaters. 2,4-dinitrophenol is the most dangerous compound among phenolic compounds. The aim of this study was to evaluate the removal of 2,4-DNP from wastewater by microwaved dried sludge adsorbent.

Materials and Methods: The results of 2,4-DNP removal were discontinuously obtained by the high performance liquid chromatography (HPLC) at a wavelength of 360 nm with various effective factors, such as contact time, pH, initial concentration of 2,4-DNP, and microwaved sludge dose. Finally, the results were analyzed using the kinetics and isotherm models. The equilibrium time was obtained 120 min. The maximum removal rate was obtained at pH 7.

Results: The findings indicated that the removal efficiency increased by increasing the adsorbent dose and decreasing the 2,4-DNP concentration. It was revealed that the removal of 2,4-DNP by microwaved sludge was 86%. The correlation coefficient value of linear and non-linear regression showed that kinetic studies follow the pseudo-second order model and isotherm studies follow the Freundlich isotherm model. The adsorption method relied entirely on pH and affected the adsorbent area attributes, ionization rate, and Delete percentage. When the pH was high, there was competition for the adsorption sites between hydroxide ions (OH) and 2,4-DNP molecules. At first, the adsorption process was high speed and gradually reached a stable level, because after a while, the adsorption sites become saturated.

Conclusion: As the absorbent dose increases, the efficiency of the adsorption process increases, because larger amounts of adsorbent cause higher adsorption places.