Study of copper binding by humic acids from an acidic pond using fluorescence spectroscopy

CABRERA, JM; DIAZ, MM; GARCÍA EINSCHLAG, FS.

Ioannina

Encuentro; The 17th Meeting of the International Humic Substances Society; 2014

IHSS

Apparent binding constants (KS) and site concentration (LC) were studied for humic acid (HA) ? copper complexes using fluorescence spectroscopy. Humics were extracted from the sediments of Lake Caviahue (pH=2,8). Since downstream, water is used for human consumption, understanding heavy metal sedimentary chemistry is of key importance. Previous studies showed high affinity of HA for Cu+2. For studying this system, experiments were conducted at pH=3, within the sedimentary metal concentration range (μM to mM). Matrix analysis showed three fluorescent components, although component C2 was found to be of minor importance. Non-linear regression was used to calculate the above mentioned parameters associated to each component. Excitation and emission maxima were (λexc/λem) C1=465/505 nm and C3=360/445 nm. KS values (~2,0 ± 0,8 104 M-1 ) did not differ significantly between components, whereas LC values ranged from 4,8 ± 0,5 10-5 M for C1 to 7,7 ± 0,8 10-5 M for C3