Optimum conditions of pH, temperature and preculture for biosorption of europium by microalgae Acutodesmus acuminatus

In this study, we investigated characteristics of europium biosorption by Acutodesmus acuminatus, with particular aim to recover rare earth elements from electronical waste. The adsorption capacity of europium was compared under various time duration, pH, temperature and preculture conditions. The maximum adsorption capacity of 174.2 mg/g-dry was achieved under pH at 4.7 at 40 degrees C. This capacity was higher or comparable to other biosorbents in the past studies. Decrease of adsorption capacity at higher temperature indicated contribution of biological mechanisms rather than physico-chemical adsorption. Presence of intra-cellular europium particles observed by TEM-EDX and effect of preculture conditions suggested that intra-cellular uptake of europium resulted in high capacity of europium biosorption by A. acuminatus.