title: The influence of acid treatments over vermiculite based material as adsorbent for cationic textile dyestuffs.
abstract: The influence of different acid treatments over vermiculite was evaluated. Equilibrium, kinetic and column studies have been conducted. The results showed that vermiculite first treated with nitric acid and then with citric acid has higher adsorption capacity, presenting maximum adsorption capacities in column experiments: for Astrazon Red (AR), 100.8 ± 0.8 mg g(-1) and 54 ± 1 mg g(-1) for modified and raw material, respectively; for Methylene Blue (MB) 150 ± 4 mg g(-1) and 55 ± 2 mg g(-1) for modified and raw material, respectively. Materials characterization by X-ray diffraction, UV-vis-diffuse reflectance spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, X-ray fluorescence, N2 adsorption and CEC determination, has been performed. The results suggest the existence of exchange of interlayer cations, leaching of metals from vermiculite's sheets and formation of an amorphous phase in the material. Adsorption follows pseudo 2(nd) order model kinetics for both dyestuffs and equilibrium occurs accordingly to Langmuir's model for AR and Freundlich's model for MB. In column systems Yan's model is the best fit. The enhanced properties of acid treated vermiculite offer new perspectives for the use of this adsorbent in wastewater treatment.
authors.affiliation: REQUIMTE, LAQV, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida 431, 4200-072 Porto, Portugal. Electronic address: stawor@gmail.com.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Stawiński
authors.affiliation: REQUIMTE, LAQV, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida 431, 4200-072 Porto, Portugal. Electronic address: omf@isep.ipp.pt.
authors.forename: Olga
authors.initials: O
authors.lastname: Freitas
authors.affiliation: Faculty of Chemistry, Jagiellonian University, ul. Ingardena 3, 30-060 Kraków, Poland. Electronic address: chmielar@chemia.uj.edu.pl.
authors.forename: Lucjan
authors.initials: L
authors.lastname: Chmielarz
authors.affiliation: Faculty of Chemistry, Jagiellonian University, ul. Ingardena 3, 30-060 Kraków, Poland. Electronic address: wegrzyn@chemia.uj.edu.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Węgrzyn
authors.affiliation: Mössbauer Spectroscopy Laboratory, Pedagogical University, ul. Podchorążych 2, 30-084, Kraków, Poland. Electronic address: kamilakom@op.pl.
authors.forename: Kamila
authors.initials: K
authors.lastname: Komędera
authors.affiliation: Mössbauer Spectroscopy Laboratory, Pedagogical University, ul. Podchorążych 2, 30-084, Kraków, Poland. Electronic address: sfblacho@cyf-kr.edu.pl.
authors.forename: Artur
authors.initials: A
authors.lastname: Błachowski
authors.affiliation: REQUIMTE, LAQV, Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, Rua Dr. António Bernardino de Almeida 431, 4200-072 Porto, Portugal. Electronic address: saf@isep.ipp.pt.
authors.forename: Sónia
authors.initials: S
authors.lastname: Figueiredo
mesh_terms: D000143:Acids / Q000737:chemistry; D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D001391:Azo Compounds / Q000032:analysis*; D002412:Cations; D004396:Coloring Agents / Q000032:analysis*; D007700:Kinetics; D008751:Methylene Blue / Q000032:analysis*; D013784:Textiles; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D000143:Acids; D000538:Aluminum Silicates; D001391:Azo Compounds; D002412:Cations; D004396:Coloring Agents; C003760:vermiculite; C050846:basic red 46; D008751:Methylene Blue
keywords: Acid treatment; Adsorption; Citric acid; Column; Nitric acid; Vermiculite