Efficient removal of aqueous lead by leached sea nodules residue

Abstract

The sea nodule leaching residue/wastes (generated after recovery of copper, nickel and cobalt) are hazardous to the environment due to fine nature and heavy metal contents. Here we demonstrate highly efficient adsorptive remediation of aqueous lead using the residue generated in reduction roast – ammonia leaching of sea nodules. Characterization of leached sea nodule residue (SNR) revealed fine granulometry (d50 = 11.4 µm) and high surface area of 66.7 m2 g-1. Batch adsorption experiments are performed varying temperature, pH of solution, contact time, initial lead concentration, adsorbent dose etc to determine lead removal capacity of SNR. Excellent adsorption capacity of lead onto SNR to the tune of 2500 mg g-1 is achieved, which is quite high in comparison to other adsorbents. Kinetics and thermodynamic aspects of adsorption are studied. The pseudo second-order model is found applicable to the lead removal kinetics. SEM and XRD investigations showed lead adsorbed on the surface of SNR in the form of hexagonal crystalline hydrocerussite.