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Removal of heavy metal ions from drinking water by alginate-immobilised Chlorella sorokiniana
Petrovič, A. & Simonič, M.
Abstract
This paper investigates the potential of alginate-immobilised
Chlorella sorokiniana for removing Cu2+,
Ni2+ and Cd2+ ions from drinking water solutions. The
effects of initial metal concentrations, contact times and
temperatures on the biosorptions and removal efficiencies
of the tested metals were investigated at initial pH values
of 5, and pH effects were studied within the range of 3–7.
When studying the effects of initial metal concentrations,
the highest experimental removal yields achieved for Cu2+,
Ni2+ and Cd2+ ions were 97.10, 50.94 and 64.61 %,
respectively. The maximum biosorption capacities
obtained by the Langmuir isotherm model for the
biosorptions of Cu2+, Ni2+ and Cd2+ ions by alginate-immobilised
C. sorokiniana were found to be 179.90, 86.49
and 164.50 mg/g biosorbent, respectively. The experimental
data followed pseudo-second-order kinetics. At an
initial metal concentration of 25 mg/L, immobilised algae
could be used in at least 5 successive biosorption–desorption
cycles. SEM and EDS analyses revealed that the
metals bonded to the biosorbent. Bi- and multi-metal systems
of Cu2+, Ni2+ and Cd2+ were investigated at initial
metal concentrations of 30, 50 and 100 mg/L. The removal
of Cd2+ as well as Ni2+ in such systems was negatively
affected by the presence of Cu2+. The removal efficiency
for Cu2+ in multi-metal systems decreased by 5–7 %,
whilst in the cases of Cd2+ and Ni2+ the efficiencies
decreased by up to 30 %. Nevertheless, the results obtained
show that alginate-immobilised C. sorokiniana can
efficiently remove the metals tested from polluted drinking
water sources.
Keywords
Algae; Alginate immobilised; Chlorella sorokiniana; Biosorption; Heavy metals; Drinking water
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