title: Sorption of basic and acid dyes from aqueous solutions onto oxihumolite.
abstract: Naturally occurring kind of weathered and oxidised young brown coal called oxihumolite was used for an adsorptive removal of basic (Methylene Blue, Malachite Green) as well as acid (Egacid Orange, Midlon Black) dyes from waters. It was shown that both kinds of dyes can be sorbed onto oxihumolite. The maximum sorption capacities determined from the parameters of Langmuir isotherms ranged from 0.070 mmol g-1 (for Midlon Black) to 0.278 mmol g-1 (for Malachite Green) and did not differ significantly for basic and acid dyes. The dye sorption (except of Midlon Black) increased in the presence of inorganic salt. Non-ionic surfactants, and surfactants bearing the same charge as the dye exhibited only a minor effect on the dye sorption, whereas oppositely charged surfactants enhanced the dye sorption to a certain extent. The pH value of the aqueous phase exhibited rather pronounced effect on the sorption of acid dyes causing a suppression of the sorption with increasing pH. The sorption of basic dyes, on the other hand, remained almost unchanged in the examined pH range. Oxihumolite is recommended for the treatment of acid wastewaters because of its limited stability in alkaline aqueous solutions.
authors.affiliation: Faculty of the Environment, University of Jan Evangelista Purkynĕ, Králova Výsina 7, 400 96 Ustí nad Labem, Czech Republic. janos@fzp.ujep.cz
authors.forename: Pavel
authors.initials: P
authors.lastname: Janos
authors.forename: Pavel
authors.initials: P
authors.lastname: Sedivý
authors.forename: Milena
authors.initials: M
authors.lastname: Rýznarová
authors.forename: Sylvie
authors.initials: S
authors.lastname: Grötschelová
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000737:chemistry / Q000302:isolation & purification; D001557:Benzenesulfonates; D003031:Coal; D004396:Coloring Agents / Q000737:chemistry / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D008751:Methylene Blue / Q000737:chemistry / Q000302:isolation & purification; D012394:Rosaniline Dyes / Q000737:chemistry / Q000302:isolation & purification; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D001391:Azo Compounds; D001557:Benzenesulfonates; D003031:Coal; D004396:Coloring Agents; D012394:Rosaniline Dyes; D012996:Solutions; C005095:malachite green; D012965:Sodium Chloride; C014722:2-naphthol orange; D008751:Methylene Blue