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KOH-super activated carbon from biomass waste: Insights into the paracetamol adsorption mechanism and thermal regeneration cycles

Spessato, Lucas, Bedin, Karen C., Cazetta, André L., Souza, Isis P.A.F., Duarte, Vitor A., Crespo, Lucas H.S., Silva, Marcela C., Pontes, Rodrigo M., Almeida, Vitor C.
Journal of hazardous materials 2019 v.371 pp. 499-505
X-ray photoelectron spectroscopy, acetaminophen, activated carbon, adsorption, aqueous solutions, biomass, nitrogen, oxygen, wastes
A super activated carbon (SAC) was produced by KOH-activation of a biomass waste for paracetamol (PCT) adsorption from aqueous solution and for adsorption-thermal regeneration cycles. The SAC and the regenerated SAC after five adsorption-regeneration cycles (RSAC-5th) were fully characterized by several techniques. The N2 physisorption showed that the SBET values of the SAC and RSAC-5th are remarkably different, being 2794 m² g−1 and 889 m² g−1, respectively. The XPS analysis demonstrated that the SAC surface is composed by oxygen containing-groups, whilst the RSAC-5th also presents nitrogen ones, provenient from the PCT molecules. The adsorption studies revealed that the maximum adsorption capacity (Qm) for the SAC (356.22 mg g−1) is higher than that for RSAC-5th (113.69 mg g−1). Also, the results demonstrated that the PCT adsorption is governed by both physisorption and chemisorption and the ab initio calculations showed the chemisorption mainly occurs in carboxylic groups.