Sorption of Cu, Zn, Pb and Cd from a Contaminated Aqueous Solution Using Starfish (Asterina pectinifera) Derived Biochar

Abstract

Objectives : Heavy metal contamination and accumulation have a harmful effect on the health of humans and animals and are serious problems worldwide. Currently, various technologies have been used for the treatment of contaminated wastewater, of which adsorption is the most commonly known and economically feasible technology. Many researchers are making attempts to find an effective and easily available adsorbent in terms of cost. In this study, starfish (<i>Asterina pectinifera</i>, SF) derived biochar was prepared and its characteristics were evaluated through various device analyses. After the biochar evaluation, the adsorption capacity was evaluated by conducting batch experiments.Methods : Biochar (Pyrolyzed Starfish at 500℃, PSF500) was produced by pyrolysis at 500℃ for 2 h in anaerobic conditions. Moreover, the characteristics of the surface were evaluated through SEM, TGA, XRD, elemental analysis and FT-IR analysis. In addition, batch experiments using heavy metal contaminated wastewater were conducted.Result and Discussion : In PSF500, CaCO3, Ca(OH)2 and CaCO3 were identified as the main phases by XRD analyses and various functional groups and pores that affect adsorption were observed on the surface of the sample. The batch experiment confirmed that the maximum adsorption was 153.8, 270.3, 434.8, and 147.1 mg/g for Cu, Zn, Pb and Cd, respectively. Also, it was confirmed that all heavy metals fit the similar Pseudo-second-order kinetic model and Langmuir model, which are the most suitable models for analyses of inorganic pollutants. After the sorption experiment, XRD and SEM analyses were conducted using the residue of PSF500, and in each sample CuO, Zn5(CO3)2(OH)6, Pb3(OH)2(CO3)2, Cd(OH)2 and CdCO3 were confirmed to be deposited on the surface of the sample.Conclusions : It was confirmed that PSF500 follows the complex mechanism of adsorption and precipitation with respect to heavy metals. Based on the experimental results, PSF500 could be used as an eco-friendly sorbent with CaCO3 as its main ingredient.