Removal of methylene blue on micro- and nano-sized egg shells from aqueous solutions

Abstract

The aim of the study was to investigate the effects of initial solution concentration of dye, pH and temperature on the removal of methylene blue on micro- and nano-sized egg shells from aqueous solutions. The particle sizes, surface areas and surface images of the egg shell particles were analyzed using Malvern Zetasizer NanoS, Bruner-Emmet-Teller (BET) method, and scanning electron microscopy (SEM). Then, the zeta potential of micro- and nano-sized egg shell suspensions were measured as a function of solid/liquid ratio and pH. Finally, adsorption experiments were performed under acidic and basic conditions and at different temperatures. In the adsorption experiments, a spectrophotometer was used to quantify the amount of methylene blue and a pH meter to adjust the acidic and basic conditions of the dye solution. BET surface area of the nano-sized egg shell was higher by approximately 16 times than that of micro-sized egg shell. FTIR spectrum showed that methylene blue was adsorbed on the surface of the egg shell, SEM analysis also that the nano-sized egg shell particles were in flat folin and electrokinetic measurements that isoelectric points of micro- and nano-sized egg shells were 4.2 and 4.0, respectively. From the adsorption experiments, it was found that i. the egg shell could be used to remove dyes causing environmental pollution, and, ii. the adsorption capacity of egg shell for methylene blue increased by increasing surface area, pH and temperature, and the decreasing particle size.