resumo
kappa-Carrageenan coated magnetic iron oxide nanoparticles (NPs) were synthesized and tested as adsorbents for the magnetically assisted removal of methylene blue (MB) from aqueous solutions, a cationic dye commonly present in wastes from the textile industry. The resulting composite NPs were superparamagnetic and contained ca. 12 wt% carrageenan. The MB uptake ability was found to vary with the pH solution and was larger in alkaline conditions. Both pseudo-first-order and pseudo-second-order equations predicted well the kinetics with the maximum adsorption achieved very fast, within 5 min. The MB adsorption has shown an unusual Z-type isotherm which suggests the generation of new adsorbing sites with increasing MB initial concentration. Under the experimental conditions used (23 degrees C, pH 9) the materials presented here displayed MB adsorption capacity (185.3 mg/g) higher than other magnetic sorbents previously reported. Thus x-carrageenan coated magnetic NPs are very promising eco-friendly materials for removing MB from wastewater using magnetic separation. (c) 2013 Elsevier B.V. All rights reserved.
palavras-chave
WASTE-WATER TREATMENT; METHYLENE-BLUE; AQUEOUS-SOLUTIONS; MAGNETITE NANOPARTICLES; CHITOSAN NANOPARTICLES; EFFICIENT REMOVAL; CATIONIC DYES; ACID; ADSORBENTS; ISOTHERM
categoria
Engineering
autores
Salgueiro, AM; Daniel-da-Silva, AL; Girao, AV; Pinheiro, PC; Trindade, T
nossos autores
Ana Luísa Daniel da Silva
Investigador Principal
Ana Margarida Martins Salgueiro Carta
Estudante de doutoramento
Ana Violeta Girão
Investigador Júnior
Paula Pinheiro
Bolseiro de investigação
Tito Trindade
Professor CatedráticoGrupos
G1 - Materiais Porosos e Nanossistemas
G3 - Materiais Eletroquímicos, Interfaces e Revestimentos
Projectos
agradecimentos
The authors acknowledge FCT - Fundacao para a Ciencia e Tecnologia (ERA-Eula/0003/2009, PTDC/CTM-NAN/120668/2010, Pest-C/CTM/LA0011/2011, post-doctoral grant SFRH/BPD/66407/2009 (A.V. Girao)), FSE and POPH for funding. We thank the RNME (National Electronic Microscopy Network) for TEM facility and to Dr. G. Goya (INA, Zaragoza, Spain) for magnetic measurements. The authors are very grateful to MSc. M.C. Azevedo for technical support.