TY - JOUR
T1 - Surface complexation mechanism and modeling in Cr(III) biosorption by a microalgal isolate, Chlorella miniata
AU - Han, Xu
AU - Wong, Yuk Shan
AU - Tam, Nora Fung Yee
N1 - Funding Information:
The research work was supported by the Areas of Excellence Scheme established under the University Grants Committee of the HKSAR (Project No. AoE/P-04/2004). The funding support of the Research Centre for Coastal Pollution and Conservation, City University of Hong Kong, was also acknowledged.
PY - 2006/11/15
Y1 - 2006/11/15
N2 - The mechanism involved in the removal of Cr(III) by a green microalgal isolate, Chlorella miniata, was examined based on a series of batch experiments and microscopic analyses, and a mathematical model was proposed. Results showed that Cr(III) biosorption increased with the increase of pH from 2.0 to 4.5, and no significant changes in biosorption outside this pH range. Langmuir isotherm indicated that the maximum Cr(III) sorption capacity of Chlorella miniata was 14.17, 28.72, and 41.12 mg g-1 biomass at pH 3.0, 4.0, and 4.5, respectively. Results from desorption studies, SEM (scanning electron microscopy), TEM (transmission electron microscopy), and EDX (energy-dispersive X-ray spectroscope) analyses confirmed that surface complexation was the main process involved in Cr(III) biosorption. Potentiometric titration revealed that carboxyl (p Ka 1 = 4.10), phosphonate (p Ka 2 = 6.36) and amine (p Ka 3 = 8.47) functional groups on the surface of Chlorella miniata were the possible sites for Cr uptake, and their average amounts were 0.53, 0.39, and 0.36 mmol g-1 biomass, respectively. A surface complexation model further indicated that carboxyl group played the main role in Cr(III) complexation, with a binding constant of K11 = 1.87 × 10-4 and K12 = 6.11 × 10-4 for Cr3+ and Cr(OH)2+, respectively. This model also suggested that the hydroxy species was more easily to complex with the cell surface of Chlorella miniata.
AB - The mechanism involved in the removal of Cr(III) by a green microalgal isolate, Chlorella miniata, was examined based on a series of batch experiments and microscopic analyses, and a mathematical model was proposed. Results showed that Cr(III) biosorption increased with the increase of pH from 2.0 to 4.5, and no significant changes in biosorption outside this pH range. Langmuir isotherm indicated that the maximum Cr(III) sorption capacity of Chlorella miniata was 14.17, 28.72, and 41.12 mg g-1 biomass at pH 3.0, 4.0, and 4.5, respectively. Results from desorption studies, SEM (scanning electron microscopy), TEM (transmission electron microscopy), and EDX (energy-dispersive X-ray spectroscope) analyses confirmed that surface complexation was the main process involved in Cr(III) biosorption. Potentiometric titration revealed that carboxyl (p Ka 1 = 4.10), phosphonate (p Ka 2 = 6.36) and amine (p Ka 3 = 8.47) functional groups on the surface of Chlorella miniata were the possible sites for Cr uptake, and their average amounts were 0.53, 0.39, and 0.36 mmol g-1 biomass, respectively. A surface complexation model further indicated that carboxyl group played the main role in Cr(III) complexation, with a binding constant of K11 = 1.87 × 10-4 and K12 = 6.11 × 10-4 for Cr3+ and Cr(OH)2+, respectively. This model also suggested that the hydroxy species was more easily to complex with the cell surface of Chlorella miniata.
KW - Desorption
KW - EDX
KW - Potentiometric titration
KW - SEM
KW - TEM
UR - http://www.scopus.com/inward/record.url?scp=33749595356&partnerID=8YFLogxK
U2 - 10.1016/j.jcis.2006.08.028
DO - 10.1016/j.jcis.2006.08.028
M3 - Article
C2 - 16962604
AN - SCOPUS:33749595356
SN - 0021-9797
VL - 303
SP - 365
EP - 371
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
IS - 2
ER -