title: Evaluation of the potential of microalgae Microcystis novacekii in the removal of Pb2+ from an aqueous medium.
abstract: In this study, the absorption capacity of active and inactive biomass of the microalgae Microcystis novacekii to remove Pb(2+) from aqueous solutions was investigated. This is the first reported study of biosorption by a cyanobacterium species, which is abundant and easily found in eutrophic lakes and ponds in tropical areas of the world. We also evaluated the effects of different concentrations of Pb(2+) on growth rates of M. novacekii. Inactive biomass was characterized by elemental composition, surface area, potentiometric titration, infrared spectroscopy and thermogravimetric analysis (TGA). The biosorption data of Pb(2+) by inactive biomass were analyzed using the Langmuir and Freundlich isotherms. Pb(2+) concentrations higher than 0.5 mg L(-1) inhibited species growth. Potentiometric titrations showed a significantly higher negative surface charge (1.48+/-0.22 mmol g(-1)) with two acidic groups (pKa(1)=3.74+/-0.12 and, pKa(2)=7.25+/-0.30). Analysis of inactive M. novacekii cells by infrared spectroscopy suggests that the cell wall carboxyl and amide groups participate in Pb(2+) biosorption. The maximum Pb(2+) adsorbed was found to be 70 mg g(-1), and the biosorption of Pb(2+) on inactive M. novacekii correlated well (R(2)=0.931) with the Langmuir equation compared to the Freundlich isotherm equation (R(2)=0.823) in the concentration range studied.
authors.affiliation: Departamento de Farmácia Social, Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil. ritaflavia@gmail.com
authors.forename: Rita F L
authors.initials: RF
authors.lastname: Ribeiro
authors.forename: Sérgia M S
authors.initials: SM
authors.lastname: Magalhães
authors.forename: Francisco A R
authors.initials: FA
authors.lastname: Barbosa
authors.forename: Clésia C
authors.initials: CC
authors.lastname: Nascentes
authors.forename: Iara C
authors.initials: IC
authors.lastname: Campos
authors.forename: Débora C
authors.initials: DC
authors.lastname: Moraes
mesh_terms: D000327:Adsorption; D000465:Algorithms; D018533:Biomass; D002021:Buffers; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism; D052918:Environmental Restoration and Remediation; D007202:Indicators and Reagents; D007854:Lead / Q000737:chemistry* / Q000378:metabolism* / Q000633:toxicity; D046931:Microcystis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D011199:Potentiometry; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D002021:Buffers; D007202:Indicators and Reagents; D014874:Water Pollutants, Chemical; D007854:Lead