Modified Oyster Waste Shells as a Value-Added Sorbent for Lead Removal from Water.

Used oyster shells are considered a waste product of the seafood industry. Herein, we hypothesize that oyster shells can be used as a raw ingredient to synthesize effective sorbents. This study investigated the lead sorption ability of modified oyster shells [phosphoric-acid treated oyster shell (POS) and oyster shells with phosphoric acid (OS + P)] from water. XRD confirmed the presence of calcium phosphate. Lead removal efficiency as a function of sorbent type was as follows: OS + P > POS > OS. Sorption was quantified effectively using Freundlich isotherms with correlation coefficients ranging from 0.98 to 0.99. The Freundlich parameter values of K and n indicate that POS and OS + P exhibit stronger lead sorption than OS. These results indicate that modified oyster shells with OS + P and POS could be effective sorbents for lead removal from water. Kinetic models were well described by a pseudo-second-order rate constant for all the sorbents.