title: Biosorption of Cu(II) by immobilized microalgae using silica: kinetic, equilibrium, and thermodynamic study.
abstract: Immobilized microalgae using silica (IMS) from Micractinium reisseri KGE33 was synthesized through a sol-gel reaction. Green algal waste biomass, the residue of M. reisseri KGE33 after oil extraction, was used as the biomaterial. The adsorption of Cu(II) on IMS was tested in batch experiments with varying algal doses, pH, contact times, initial Cu(II) concentrations, and temperatures. Three types of IMSs (IMS 14, 70, and 100) were synthesized according to different algal doses. The removal efficiency of Cu(II) in the aqueous phase was in the following order: IMS 14 (77.0%) < IMS 70 (83.3%) < IMS 100 (87.1%) at pH 5. The point of zero charge (PZC) value of IMS100 was 4.5, and the optimum pH for Cu(II) adsorption was 5. Equilibrium data were described using a Langmuir isotherm model. The Langmuir model maximum Cu(II) adsorption capacity (q m) increased with the algal dose in the following order: IMS 100 (1.710 mg g(-1)) > IMS 70 (1.548 mg g(-1)) > IMS 14 (1.282 mg g(-1)). The pseudo-second-order equation fitted the kinetics data well, and the value of the second-order rate constant increased with increasing algal dose. Gibbs free energies (ΔG°) were negative within the temperature range studied, which indicates that the adsorption process was spontaneous. The negative value of enthalpy (ΔH°) again indicates the exothermic nature of the adsorption process. In addition, SEM-energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses of the IMS surface reveal that the algal biomass on IMS is the main site for Cu(II) binding. This study shows that immobilized microalgae using silica, a synthesized biosorbent, can be used as a cost-effective sorbent for Cu(II) removal from the aqueous phase.
authors.affiliation: Green City Technology Institute, Korea Institute of Science and Technology, Seoul, 136-791, South Korea.
authors.forename: Hongkyun
authors.initials: H
authors.lastname: Lee
authors.affiliation: Green City Technology Institute, Korea Institute of Science and Technology, Seoul, 136-791, South Korea.
authors.forename: Eunjung
authors.initials: E
authors.lastname: Shim
authors.affiliation: Green City Technology Institute, Korea Institute of Science and Technology, Seoul, 136-791, South Korea.|Department of Environmental Engineering, Yonsei University, Wonju, 220-710, South Korea.
authors.forename: Hyun-Shik
authors.initials: HS
authors.lastname: Yun
authors.affiliation: Green City Technology Institute, Korea Institute of Science and Technology, Seoul, 136-791, South Korea.
authors.forename: Young-Tae
authors.initials: YT
authors.lastname: Park
authors.affiliation: Green City Technology Institute, Korea Institute of Science and Technology, Seoul, 136-791, South Korea.
authors.forename: Dohyeong
authors.initials: D
authors.lastname: Kim
authors.affiliation: Green City Technology Institute, Korea Institute of Science and Technology, Seoul, 136-791, South Korea.
authors.forename: Min-Kyu
authors.initials: MK
authors.lastname: Ji
authors.affiliation: Soil and Groundwater Division, Hyorim Industries Inc., Seoungnam, 463-839, South Korea.
authors.forename: Chi-Kyung
authors.initials: CK
authors.lastname: Kim
authors.affiliation: Department of Environmental Engineering, Kyungpook National University, Daegu, 702-701, South Korea.
authors.forename: Won-Sik
authors.initials: WS
authors.lastname: Shin
authors.affiliation: Green City Technology Institute, Korea Institute of Science and Technology, Seoul, 136-791, South Korea. jchoi@kist.re.kr.
authors.forename: Jaeyoung
authors.initials: J
authors.lastname: Choi
mesh_terms: D000327:Adsorption; D018533:Biomass; D000460:Chlorophyta / Q000378:metabolism; D003300:Copper / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D058086:Microalgae / Q000378:metabolism*; D056951:Photoelectron Spectroscopy; D012822:Silicon Dioxide / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013816:Thermodynamics; D014867:Water; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D014874:Water Pollutants, Chemical; D014867:Water; D012822:Silicon Dioxide; D003300:Copper
keywords: Adsorption; Biosorbent; Copper; Micractinium reisseri KGE33; Microalgae; Silica