Removal of methylene blue from aqueous media using activated carbon web

Abstract

Activated carbon web is prepared by controlled pyrolysis of acrylic fibrous waste under the layer of charcoal using physical activation in high-temperature furnace. The carbonization was carried out at 1200 °C under different heating rate (i.e. 150 to 450 °C h⁻¹) with different holding time (i.e. 0 to 60 min) to decide optimum pyrolysis parameters. The heating rate of 300 °C h⁻¹ with no holding time revealed higher specific surface area of 280 m² g⁻¹. The prepared activated carbon web was later employed as adsorbent for removal of methylene blue from aqueous media. The effect of initial dye concentration, adsorbent dosage, stirring speed, and pH of solution was studied. The obtained results were later compared with adsorption isotherms (i.e. Langmuir and Freundlich). The Freundlich model was found to fit closely with results due to heterogeneous adsorption of dye molecules. Finally, virgin activated carbon and dye adsorbed activated carbon were tested for desorption behavior using differential scanning calorimetry and thermo gravimetric analysis. The significant reduction in desorption enthalpy from 172.46 to 52.43 J g⁻¹ is attributed to less adsorption energies of dye molecules on the surface of activated carbon due to nonhomogeneous distribution of active sites.

Keywords:

• Acrylic fiber waste
• textile recycling
• pyrolysis
• activated carbon
• specific surface area