title: Cadmium(II) and zinc(II) adsorption by the aquatic moss Fontinalis antipyretica: effect of temperature, pH and water hardness.
abstract: The biosorption of cadmium(II) and zinc(II) ions onto dried Fontinalis antipyretica, a widely spread aquatic moss, was studied under different values of temperature, initial pH and water hardness. The equilibrium was well described by Langmuir adsorption isotherms. Maximum biosorption capacity of cadmium was independent on temperature and averaged 28.0 mg g(-1) moss, whereas for zinc, capacity increased with temperature, from 11.5 mg g(-1) moss at 5 degrees C to 14.7 mg g(-1) moss at 30 degrees C. Optimum adsorption pH value was determined as 5.0 for both metal ions. Cadmium uptake was unaffected by the presence of calcium ions, but zinc sorption was improved when water hardness increased from 101.1 to 116.3 mg CaCO(3)l(-1). Inversely, as hardness increases, the competition with calcium ions strongly reduces the affinity of the biosorbent for zinc.
authors.affiliation: Department of Chemical Technology, Superior School of Technology, Polytechnic Institute of Bragança, Campus de Santa Apolónia, 5301-857 Bragança, Portugal.
authors.forename: Ramiro J E
authors.initials: RJ
authors.lastname: Martins
authors.forename: Rosana
authors.initials: R
authors.lastname: Pardo
authors.forename: Rui A R
authors.initials: RA
authors.lastname: Boaventura
mesh_terms: D000327:Adsorption; D001673:Biodegradation, Environmental; D044002:Bryophyta / Q000737:chemistry*; D002104:Cadmium / Q000302:isolation & purification* / Q000493:pharmacokinetics; D002122:Calcium Chloride / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D013696:Temperature; D014873:Water Pollutants / Q000302:isolation & purification* / Q000493:pharmacokinetics; D018508:Water Purification / Q000379:methods*; D015032:Zinc / Q000302:isolation & purification* / Q000493:pharmacokinetics
chemical_list: D014873:Water Pollutants; D002104:Cadmium; D015032:Zinc; D002122:Calcium Chloride