title: Removal of hazardous pharmaceutical dyes by adsorption onto papaya seeds.
abstract: Papaya (Carica papaya L.) seeds were used as adsorbent to remove toxic pharmaceutical dyes (tartrazine and amaranth) from aqueous solutions, in order to extend application range. The effects of pH, initial dye concentration, contact time and temperature were investigated. The kinetic data were evaluated by the pseudo first-order, pseudo second-order and Elovich models. The equilibrium was evaluated by the Langmuir, Freundlich and Temkin isotherm models. It was found that adsorption favored a pH of 2.5, temperature of 298 K and equilibrium was attained at 180-200 min. The adsorption kinetics followed the pseudo second-order model, and the equilibrium was well represented by the Langmuir model. The maximum adsorption capacities were 51.0 and 37.4 mg g(-1) for tartrazine and amaranth, respectively. These results revealed that papaya seeds can be used as an alternative adsorbent to remove pharmaceutical dyes from aqueous solutions.
authors.affiliation: Chemical Engineering Department, Federal University of Santa Maria, 97105-900, Santa Maria, Brazil E-mail: guilherme_dotto@yahoo.com.br.
authors.forename: Caroline Trevisan
authors.initials: CT
authors.lastname: Weber
authors.affiliation: Chemical Engineering Department, Federal University of Santa Maria, 97105-900, Santa Maria, Brazil E-mail: guilherme_dotto@yahoo.com.br.
authors.forename: Gabriela Carvalho
authors.initials: GC
authors.lastname: Collazzo
authors.affiliation: Chemical Engineering Department, Federal University of Santa Maria, 97105-900, Santa Maria, Brazil E-mail: guilherme_dotto@yahoo.com.br.
authors.forename: Marcio Antonio
authors.initials: MA
authors.lastname: Mazutti
authors.affiliation: Chemical Engineering Department, Federal University of Santa Maria, 97105-900, Santa Maria, Brazil E-mail: guilherme_dotto@yahoo.com.br.
authors.forename: Edson Luiz
authors.initials: EL
authors.lastname: Foletto
authors.affiliation: Chemical Engineering Department, Federal University of Santa Maria, 97105-900, Santa Maria, Brazil E-mail: guilherme_dotto@yahoo.com.br.
authors.forename: Guilherme Luiz
authors.initials: GL
authors.lastname: Dotto
mesh_terms: D000327:Adsorption; D000548:Amaranth Dye / Q000302:isolation & purification; D029441:Carica / Q000378:metabolism*; D004396:Coloring Agents / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012639:Seeds / Q000378:metabolism*; D013645:Tartrazine / Q000302:isolation & purification; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D004396:Coloring Agents; D014874:Water Pollutants, Chemical; D000548:Amaranth Dye; D013645:Tartrazine