title: Surface modification of chitin using ultrasound-assisted and supercritical CO2 technologies for cobalt adsorption.
abstract: Ultrasound-assisted (UA) and supercritical CO2 technologies (SCO2) were used to modify the chitin surface and, improve its adsorption characteristics regarding to cobalt. Chitin, before and after the treatments, was characterized by N2 adsorption isotherms (BET), infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Unmodified and surface modified chitins were used as adsorbents to remove cobalt from aqueous solutions. The adsorption study was performed by equilibrium isotherms and kinetic curves. The chitin particle characteristics, such as, surface area, pore volume and porosity were improved by the UA and SCO2 treatments. The crystallinity index decreased after the UA and SCO2 treatments, and also, intense surface modifications were observed. Langmuir and Freundlich models were adequate to represent the adsorption equilibrium. The maximum adsorption capacities were 50.03, 83.94 and 63.08 mg g(-1) for unmodified chitin, UA surface modified chitin and SCO2 surface modified chitin. The adsorption kinetic curves were well represented by the pseudo-second order model. UA and SCO2 technologies are alternatives to modify the chitin surface and improve its adsorption characteristics.
authors.affiliation: Environmental Processes Laboratory (LAPAM), Chemical Engineering Department, Federal University of Santa Maria - UFSM, 1000 Roraima Avenue, 97105-900, Santa Maria, RS, Brazil. Electronic address: guilherme_dotto@yahoo.com.br.
authors.forename: Guilherme L
authors.initials: GL
authors.lastname: Dotto
authors.affiliation: Environmental Processes Laboratory (LAPAM), Chemical Engineering Department, Federal University of Santa Maria - UFSM, 1000 Roraima Avenue, 97105-900, Santa Maria, RS, Brazil. Electronic address: jeaninecunha@gmail.com.
authors.forename: Jeanine M
authors.initials: JM
authors.lastname: Cunha
authors.affiliation: Environmental Processes Laboratory (LAPAM), Chemical Engineering Department, Federal University of Santa Maria - UFSM, 1000 Roraima Avenue, 97105-900, Santa Maria, RS, Brazil. Electronic address: camila.itepjr@gmail.com.
authors.forename: Camila O
authors.initials: CO
authors.lastname: Calgaro
authors.affiliation: Environmental Processes Laboratory (LAPAM), Chemical Engineering Department, Federal University of Santa Maria - UFSM, 1000 Roraima Avenue, 97105-900, Santa Maria, RS, Brazil. Electronic address: edutanabe@yahoo.com.br.
authors.forename: Eduardo H
authors.initials: EH
authors.lastname: Tanabe
authors.affiliation: Environmental Processes Laboratory (LAPAM), Chemical Engineering Department, Federal University of Santa Maria - UFSM, 1000 Roraima Avenue, 97105-900, Santa Maria, RS, Brazil. Electronic address: dbertuol@gmail.com.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Bertuol
mesh_terms: D000327:Adsorption; D000818:Animals; D002245:Carbon Dioxide / Q000737:chemistry*; D002686:Chitin / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure; D003035:Cobalt / Q000737:chemistry*; D007700:Kinetics; D033561:Penaeidae; D000069453:Ultrasonic Waves
chemical_list: D002686:Chitin; D002245:Carbon Dioxide; D003035:Cobalt
keywords: Adsorption; Chitin; Cobalt; Supercritical CO(2); Ultrasound-assisted