BIOSORPTION OF Zn2+ AND Cd2+ IN A TWO-METAL SYSTEM BY NANNOCHLOROPSIS SALINA

use of marine microalgae Nannochloropsis salina to absorb both types of metals is still very little. A marine microalga, N. salina, was used\ud as biosorbent for the metal ions in water. Concentration of each ion (Zn2+ and Cd2+) was 10 mg L???1 and the concentration ratio of Zn2+ to\ud Cd2+ in the two-metal system (a combination of Zn2+ and Cd2+ in the culture medium) was 1:1. Experimental conditions were as follows:\ud salinity = 25 ???, temperature = 20 ??C, and pH = 7. Addition of each ion individually or the combination of ions was conducted when the\ud optimum growth of microalgae was achieved (i.e. at the 8th day after cultivation). The N. salina growth after the exposure of metal ions was\ud observed daily and the metal ion concentration adsorbed was determined by using atomic absorption spectrophotometer. Results showed\ud that N. salina can be used as biosorbent for Zn2+ and Cd2+ both in single metal ion and two-metal system. Biosorption of Zn2+ by N. salina\ud was higher than that of Cd2+ in the single metal ion. The amount of Zn2+ adsorbed in the two-metal system was higher than the one in the\ud single metal ion. However, the opposite trend was observed in the case of Cd2+ io