Extraction of nanostructured sodium nitrate from industrial effluent and their thermal properties

The present study describes a process of extraction of high purity sodium nitrate from corrosive chemical industry effluents. Here, we have designed a process to convert highly corrosive effluents of ceramic industries having pH ~13.1 into sodium nitrate nanoparticles. The extraction of sodium nitrate has been carried out via neutralisation of industrial effluent by nitric acid. We have also studied the effect of low boiling point co-solvent during recrystallisation of sodium nitrate. TEM studies of sodium nitrate extracted from the filtrate in the absence of co-solvent show the formation of nanoparticle of ~70 nm. Further, a drastic decrease in particle size to 10 nm have been observed when co-solvents (methanol, ethanol and acetone) were used in combination with filtrate during the recrystallisation process of sodium nitrate. Thermal properties of sodium nitrate extracted from filtrate have been investigated. Our result indicates that the nanoparticles extracted from filtrate having very high heat storage density (453 J/g) without hampering the melting point and boiling point of the materials.