Adsorption–desorption of strontium from waters using aerobic granules

Adsorption of Sr(II) from waters is regarded a unit operation to remediate nuclear contaminations in aquatic systems. Aerobic granules were applied as a biosorbent for removing Sr(II) from waters. At pH 6.2 and 35 °C the adsorption can reach equilibrium within 2 h while the maximum adsorption capacity was estimated as 28.8 mg/g dried biomass. Kinetic model fitting suggested that the pseudo-second-order model best correlated the kinetic data, suggesting that chemical adsorption was the rate-limiting step. Repeated adsorption and then desorption with water, K(I), Na(I) and Ca(II) desorbents suggested that neither water alone or Ca(II) could effectively desorb Sr(II) from the aerobic granule surface. Conversely, Na(I) and K(I) could effectively complex with the functional groups on polysaccharides in the extracellular polymeric substance so could effectively desorb the bound Sr(II) out of the granule surface.

► Adsorption of Sr(II) from water was studied using aerobic granules as adsorbent.
► At pH 6.2 and 35 °C the maximum adsorption capacity was 28.8 mg/g.
► Kinetic model fitting suggested that chemical adsorption was the rate-limiting step.
► Water alone or Ca(II) could not effectively desorb Sr(II) from granule surface.
► Na(I) and K(I) could effectively desorb the bound Sr(II) out of the granule surface.