Evaluation of micro- and nano-carbon-based adsorbents for the removal of phenol from aqueous solutions

Abstract

This work reports on the adsorption efficiency of two classes of adsorbents: nano-adsorbents including carbon nanotubes (CNTs) and carbon nanofibers (CNFs); and micro-adsorbents including activated carbon (AC) and fly ash (FA). The materials were characterized by thermogravimetric analysis, transmission electron microscopy, Brunauer–Emmett–Teller (BET) specific surface area, zeta potential, field emission scanning electron microscopy, and UV spectroscopy. The adsorption experimental conditions such as pH of the solution, agitation speed, contact time, initial concentration of phenol, and adsorbent dosage were optimized for their influence on the phenol. The removal efficiency of the studied adsorbents has the following order: AC > CNTs > FA > CNFs. The capacity obtained from Langmuir isotherm was found to be 1.348, 1.098, 1.007, and 0.842 mg/g of AC, CNTs, FA, and CNFs, respectively, at 2 hours of contact time, pH 7, an adsorbent dosage of 50 mg, and a speed of 150 rpm. The higher adsorption of phenol on AC can be attributed to its high surface area and its dispersion in water. The optimum values of these variables for maximum removal of phenol were also determined. The experimental data were fitted well to Langmuir than Freundlich isotherm models.

Keywords:

• phenol
• carbon nanotubes
• carbon nanofibers
• activated carbon
• fly ash

Acknowledgments

The authors acknowledge the financial support provided by King Abdulaziz City for Science and Technology (KACST) through the Science and Technology Unit at King Fahd University of Petroleum and Minerals (KFUPM) through project no. AR-30-92.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors are thankful for the financial support provided by King Abdulaziz City for Science and Technology (KACST) through the Science and Technology Unit at King Fahd University of Petroleum and Minerals (KFUPM) [project number AR-30-92].