Desorption of Lead Adsorbed from Contaminated Water by Fishbone and Charred Spinach/Grape

Aims: We have studied the adsorption of lead onto many substrates such as biomaterials and inorganic adsorbents and found these substrates to have very high adsorptive capacities for lead. However, limited studies have reported desorption of lead adsorbed by these substrates under mechanical agitation and neutral pH conditions. The study reported here investigated not only the adsorption of lead from contaminated water by biomaterials such as fishbone from stock, salmon, and drum fish, and charred spinach and grapes) but also the bioavailability via desorption of the adsorbed lead when mechanically agitated with deionized water under neutral conditions.
Place and Duration of Study: School of Science, Technology, Engineering, and Mathematics, Dillard University, Between January 2013 and May 2013.
Methodology: Fishbone and charred spinach and grapes were exposed to 1300 PPM lead solution under stirring at room temperature for 48 hrs. The amount of lead adsorbed by each bio-substrate was calculated by difference between control sample and residual lead in the supernatant from each substrate’s reaction vessel. Each exposed substrate was mechanically agitated with deionized water for 48 hr at room temperature. The amount of lead desorbed into the water was analyzed using EPA Method 6010 (Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES)).
Results: The order of percent lead adsorption is Salmon Fishbone (99.9%) >Drum Fish bone (99.7%), > Stock Stock fishbone (86%)> Charred Grape (82% > Charred Spinach (44%) while the order of desorption is Charred grape (6.4%) > Drum fishbone (2%) ~ Charred Spinach (2%) > Salmon Fishbone (0.06%) > Stock Fishbone (0.017%).
Conclusion: The data suggests that very little desorption of adsorbed lead on various substrates occurred and that there is varying lead-adsorption capabilities for various substrates. Furthermore, charring biomaterials diminishes their ability to adsorb lead from contaminated water.