Study on potential environmental adsorption of egg shells to removal of lead and cadmium from Oryza sativa rice

Removal of heavy metal ions from contaminated systems by agricultural and fruit and vegetable processing waste materials is an innovative and auspicious technology .The current study was designed for utilization of bio-adsorption white hard eggshell, as less expensive and much frequently available food waste materials, due to prospective metal bio-sorption capacity to toxic heavy metal ions, including cadmium (Cd) and lead (Pb) from Oryza sativa in Iran.

The effect of soaking rinsed rice samples by NaCl 2% and modified white eggshell adsorbent by different concentration as adsorbent, pH, contact time and association of cooking methods on cadmium and lead contents were studied. Heavy metal contents in raw, rinsed, soaked by adsorbent and cooked and drained rice samples were determined by flame atomic absorption spectrophotometer in 925 samples in 4 different state of raw, soaking, cooked and drained.

Cooking rice by soaking rinsed rice samples by NaCl 2% and white eggshell for 1 hour had the greatest effect with regards to removal of Pb and Cd levels in cooked rice. It significantly reduced the cadmium content by 90.35% and lead content by 91.21% from the cooked rice, when soaked by white eggshell for one hour contact time.

The results of the current study suggest that eggshell waste adsorbent can be used beneficially in treating rice containing heavy metal ions.