Reusing spent fluid catalytic cracking catalyst as an adsorbent in wastewater treatment applications

Abstract

Spent fluid catalytic cracking (FCC) catalyst is a waste from oil industry generated in very high amounts globally, being a major environmental burden as it is mostly landfilled. The direct use of this waste in wastewater treatment applications is rare, and the present study aims to fill the existing research gap. This is the first systematic investigation regarding the use of spent FCC catalyst as adsorbent material, for extracting methylene blue (MB) (pollutant model molecule) from wastewater.The effects of contact time (5 min–48 h), adsorbent dosage (0.5–3 g/L), adsorbate concentration (5–400 mg/L), and the reaction kinetics, were investigated. MB concentrations above 200 mg/L achieved a maximum uptake of 90.8 mg/g after 48 h. For MB concentrations below 10 mg/L, very fast dye removal was observed, reaching 100% after 1 h. The adsorption of MB followed a pseudo-second-order model (chemisorption), and the Langmuir model better described the experimental data (monolayer adsorption). The novel strategy here reported is aligned with key Sustainable Development Goals – 6, 9, 12 and 13 – and with the concept of the Circular Economy, and these results might add value to industrial waste whose availability is still expected to grow substantially soon.