title: Kinetics and thermodynamics of textile dye adsorption from aqueous solutions using babassu coconut mesocarp.
abstract: Extracted babassu coconut (Orbignya speciosa) mesocarp (BCM) was applied as a biosorbent for aqueous Blue Remazol R160 (BR 160), Rubi S2G (R S2G), Red Remazol 5R (RR 5), Violet Remazol 5R (VR 5) and Indanthrene Olive Green (IOG) dye solutions. The natural sorbent was processed batchwise while varying several system parameters such as stirring time, pH and temperature. The interactions were assayed with respect to both pseudo-first-order and second-order reaction kinetics, with the latter the more suitable kinetic model. The maximum adsorption was obtained at pH 1.0 for all dyes due to available anionic groups attached to the structures, which can be justified by pH(pzc) 6.7 for the biosorbent BCM. The ability of babassu coconut mesocarp to adsorb dyes gave the order R S2G>VR 5>BR 160>IOG>RR 5, which data were best fit to Freundlich model, but did not well-adjusted for all dyes. The dye/biopolymer interactions at the solid/liquid interface are all spontaneous as given by free Gibbs energy, with exothermic enthalpic values of -26.1, -15.8, -17.8, -15.8 and -23.7 kJ mol(-1) for BR 160, R S2G, RR 5, IOG and VR 5, respectively. In spite of the negative entropic values contribution, the set of thermodynamic data is favorable for all dyes removal. However, the results pointed to the effectiveness of the mesocarp of babassu coconut as a biosorbent for removing textile dyes from aqueous solutions.
authors.affiliation: Departamento de Química/CCET, Universidade Federal do Maranhão, Av. dos, Portugueses S/N, Campus do Bacanga, 65080-540 São Luís, Maranhão, Brazil.
authors.forename: Adriana P
authors.initials: AP
authors.lastname: Vieira
authors.forename: Sirlane A A
authors.initials: SA
authors.lastname: Santana
authors.forename: Cícero W B
authors.initials: CW
authors.lastname: Bezerra
authors.forename: Hildo A S
authors.initials: HA
authors.lastname: Silva
authors.forename: José A P
authors.initials: JA
authors.lastname: Chaves
authors.forename: Júlio C P
authors.initials: JC
authors.lastname: de Melo
authors.forename: Edson C
authors.initials: EC
authors.lastname: da Silva Filho
authors.forename: Claudio
authors.initials: C
authors.lastname: Airoldi
mesh_terms: D000327:Adsorption; D000880:Anthraquinones; D003059:Cocos / Q000737:chemistry*; D004396:Coloring Agents / Q000302:isolation & purification*; D007220:Industrial Waste / Q000517:prevention & control*; D007700:Kinetics; D009281:Naphthalenes; D009282:Naphthalenesulfonates; D012996:Solutions; D013431:Sulfates; D013784:Textiles; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification; D018508:Water Purification / Q000379:methods*
chemical_list: D000880:Anthraquinones; D004396:Coloring Agents; D007220:Industrial Waste; D009281:Naphthalenes; D009282:Naphthalenesulfonates; C506998:Remazol Red F3B; D012996:Solutions; D013431:Sulfates; D014874:Water Pollutants, Chemical; C111247:C.I. Reactive Violet 5; C024758:Remazol Brilliant Blue R