Efficient Removal of Perfluorooctane Sulfonic Acid (PFOS) from Aquatic Environment Using Carbon Black/Chitosan Beads Composite

Abstract

Perfluorooctane sulfonic acid (PFOS) is a persistent environmental pollutant, putting human health at risk. Therefore, in this article, a novel composite was prepared by incorporating carbon black into chitosan and used as an adsorbent to efficiently remove PFOS from aqueous environments. The incorporation of carbon black into chitosan showed great modification on the structure of chitosan, which resulted in more porosity and higher surface area, resulting in better adsorption capacity. The best carbon black/chitosan mass ratio under both acidic and neutral conditions was found to be 0.5, and the optimum removal efficiency under the optimum conditions (pH: 2, 0.3 g adsorbent dosage, 5 mg L⁻¹ PFOS concentration, and 5 h contact time) was found to be 92%. The FESEM and BET analysis resulted in greater porosity and more hollow structure as well as enhanced specific surface area of the carbon black/chitosan beads (CBCHB) adsorbent in comparison to chitosan beads (CHB). Freundlich isotherm model fits the equilibrium adsorption isotherm data better than the Langmuir model. The maximum adsorption capacity (q_m) under acidic conditions (pH: 2) was 359.38 mg g⁻¹. Furthermore, the CBCHB adsorbent was capable of being reused after being washed 5 times and exhibiting a slight decline in removal efficiency.