Preparation and Characterization of Nanoporous Activated Carbon Derived from Prawn Shell and Its Application for Removal of Heavy Metal Ions

The aim of this study was to optimize the adsorption performance of activated carbon (AC), derived from the shell of Penaeus vannamei prawns, on heavy metal ions. Inexpensive, non-toxic, and renewable prawn shells were subjected to carbonization and, subsequently, KOH-activation to produce nanoporous K-Ac. Carbonized prawn shells (CPS) and nanoporous KOH-activated carbon (K-Ac) from prawn shells were prepared and characterized by FTIR, XRD, BET, SEM, and TEM. The results showed that as-produced K-Ac samples were a porous material with microporous and mesoporous structures and had a high specific surface area of 3160 m(2)/g, average pore size of about 10 nm, and large pore volume of 2.38 m(3)/g. Furthermore, batches of K-Ac samples were employed for testing the adsorption behavior of Cd(2+) in solution. The effects of pH value, initial concentration, and adsorption time on Cd(2+) were systematically investigated. Kinetics and isotherm model analysis of the adsorption of Cd(2+) on K-Ac showed that experimental data were not only consistent with the Langmuir adsorption isotherm, but also well-described by the quasi-first-order model. Finally, the adsorption behaviors of as-prepared K-Ac were also tested in a ternary mixture of heavy metal ions Cu(2+), Cr(6+), and Cd(2+), and the total adsorption amount of 560 mg/g was obtained.