Phenol adsorption on high microporous activated carbons prepared from oily sludge: equilibrium, kinetic and thermodynamic studies

N Mojoudi; N Mirghaffari; M Soleimani; H Shariatmadari; C Belver; J Bedia

doi:10.1038/s41598-019-55794-4

Phenol adsorption on high microporous activated carbons prepared from oily sludge: equilibrium, kinetic and thermodynamic studies

Sci Rep. 2019 Dec 18;9(1):19352. doi: 10.1038/s41598-019-55794-4.

Authors

N Mojoudi¹, N Mirghaffari², M Soleimani¹, H Shariatmadari³, C Belver⁴, J Bedia⁴

Affiliations

¹ Department of Natural Resources, Isfahan University of Technology, Isfahan, 84156-83111, Iran.
² Department of Natural Resources, Isfahan University of Technology, Isfahan, 84156-83111, Iran. mnorolah@iut.ac.ir.
³ Department of Soil Science, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111, Iran.
⁴ Departamento de Ingeniería Química, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.

Abstract

The purpose of this study was the preparation, characterization and application of high-performance activated carbons (ACs) derived from oily sludge through chemical activation by KOH. The produced ACs were characterized using iodine number, N₂ adsorption-desorption, Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The activated carbon prepared under optimum conditions showed a predominantly microporous structure with a BET surface area of 2263 m² g^-1, a total pore volume of 1.37 cm³ g^-1 and a micro pore volume of 1.004 cm³ g^-1. The kinetics and equilibrium adsorption data of phenol fitted well to the pseudo second order model (R² = 0.99) and Freundlich isotherm (R² = 0.99), respectively. The maximum adsorption capacity based on the Langmuir model (434 mg g^-1) with a relatively fast adsorption rate (equilibrium time of 30 min) was achieved under an optimum pH value of 6.0. Thermodynamic parameters were negative and showed that adsorption of phenol onto the activated carbon was feasible, spontaneous and exothermic. Desorption of phenol from the adsorbent using 0.1 M NaOH was about 87.8% in the first adsorption/desorption cycle and did not decrease significantly after three cycles. Overall, the synthesized activated carbon from oily sludge could be a promising adsorbent for the removal of phenol from polluted water.