STUDY ON THE PHYSIC-CHEMICAL PROPERTIES OF BIOSORPTION OF SILVER BY LAMINARIA JAPONICA

Biosportion of heavy metals is an effective technology for the treatment of industrial wastewater. In this paper, dried biomass of Laminaria japonica was used as biosorbent for Ag+. The physic-chemical properties of biosorption of silver by Laminaria japonica were studied. The results showed that Laminaria japonica had relatively strong ability of adsorbing Ag+, and its theoretical maximum uptake capacity was 273mg/g dry biomass. Ag+ biosorption by Laminaria japonica was a rapid and temperature (20~40℃) independent process. In the range of pH value from 2 to 6, biosorptive process was unrelated to pH, and even in strong acid solution (pH1) Laminaria japonica still showed a high efficiency for Ag+ uptake. During the process of biosorption, pH value of solution rose from 5.5 to 6.4, which suggested that ion exchange might be one of the biosorptive mechanisms. Ag+ adsorption followed Langmuir model. The biosorptive capacity (q) of Ag+ decreased with increase of biomass concentration (Cb) (0.5~4.0g/L), and rose with increase of initial Ag+ concentration (Ci) (10~800mg/L). TEM observation indicated that the Ag+ ions could be reduced to Ag0 particles by Laminaria japonica. Moreover, Laminaria japonica could be used to recover Ag+ from strong acid wastewater, and the biosorptive efficiency (E) reached 98.3%. As the Ag+ concentration (Ci) was 121.9mg/L. The result indicated that Laminaria japonica was suitable for the development of effective biosorbent for the removal and recovery of silver from wastewater.