title: Sedimentation-induced detachment of magnetite nanoparticles from microalgal flocs.
abstract: The objective of this study is to develop a simple, one-step approach to separate adsorbed Fe3O4 nanoparticles from microalgal flocs for further downstream processing. Using the wild-type strain of fresh-water algae Chlamydomonas reinhardtii, effective removal of nanoparticles from microalgal flocs by both centrifugal sedimentation (at 1500 or 2000g) and magnetic sedimentation (at 1500 Oe) is demonstrated. At the physiological pH of the solution (i.e., pH 7.0), where the electrostatic force between the nanoparticles and the microalgal cells is strongly attractive, larger separation force was achieved by simply increasing the density and viscosity of the solution to 1.065g/mL and 1.244cP, respectively. The method described here offers significant opportunity for purifying microalgal biomass after nanoparticle-flocculation-based harvesting and decreasing the cost of microalgal biotechnology. This may also find avenues in other applications that apply flocculation, such as algal biofilm formation in photobioreactors and wastewater treatment.
authors.affiliation: Department of Chemical Engineering, University of Rochester, P.O. Box 270166, Rochester, NY 14627, USA; Graduate School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan.
authors.forename: Shofu
authors.initials: S
authors.lastname: Matsuda
authors.affiliation: Department of Chemical Engineering, University of Rochester, P.O. Box 270166, Rochester, NY 14627, USA.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Durney
authors.affiliation: Materials Science Program, University of Rochester, P.O. Box 270166, Rochester, NY 14627, USA.
authors.forename: Lijie
authors.initials: L
authors.lastname: He
authors.affiliation: Department of Chemical Engineering, University of Rochester, P.O. Box 270166, Rochester, NY 14627, USA; Materials Science Program, University of Rochester, P.O. Box 270166, Rochester, NY 14627, USA. Electronic address: hitomi.mukaibo@rochester.edu.
authors.forename: Hitomi
authors.initials: H
authors.lastname: Mukaibo
mesh_terms: D000327:Adsorption; D018533:Biomass; D002498:Centrifugation / Q000379:methods*; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D058086:Microalgae / Q000737:chemistry* / Q000187:drug effects; D050296:Microbial Viability; D010316:Particle Size; D055672:Static Electricity
chemical_list: D058185:Magnetite Nanoparticles
keywords: Centrifugal sedimentation; Electrostatic adsorption; Fe(3)O(4) nanoparticle removal; Magnetic sedimentation; Microalgae harvesting