Sorption and Desorption of Strontium using Silica extracted from Acid Treated Rice Husk. I: Effect of ph and Interfering Ions

Strontium, one of the radio-nuclides most frequently released from low-level radioactive waste to the environment, is a known carcinogen. Migration of Sr +2 from waste disposal and nuclear test sites has contaminated adjacent aquifers showing up as hardness in water. Therefore, understanding Sr+2 retention and removal through sorption processes is critically important. The effect of contact time, ph, adsorbent weight and interfering ions on the sorption of strontium from solution using silica extracted from acid treated rice husk followed by thermal activation was investigated by using batch experiments. The sorption and desorption of Sr+2 were determined at room temperature (20±1 degree C) and ph 6.6. It was found that 5 hours is sufficient for prepared samples to attain equilibrium. The presence of interfering ions, whether organic or inorganic, is influenced by and affected on the sorption of Sr+2 in the aqueous solution. Desorption of Sr+2 using different mineral and organic acid illustrated that HNO3 is the best de sorbing agent for recovery of Sr+2 from loaded silica and the sorption of Sr+2 on silica can be described by a reversible sorption process. Finally, the prepared silica can be used as good alternative sorbents for sorption and pre-concentration of Sr+2 from aqueous solution.