2. Experimental
2.1. Materials
Raw eggshell was collected from local breakfast shop and hotels. Eggshell was immediately washed thoroughly with water and air dried. Hen eggshell was immersed in 5% H2SO4 for 1 h and then hen eggshell was manually stripped from eggshell membrane after cleaning of the raw material. The stripped eggshell and eggshell membrane was washed with water and dried at room temperature. The eggshell and eggshell membrane were further ground to prepare powder particles.
2.2. Reagents
Aluminium nitrate and all other chemicals used in this study were analytical grade obtained from E-Merck India Ltd., Mumbai, India. Total ionic strength adjustor buffer (TISAB III) solution was purchased E-Merck India Ltd., Mumbai, India. A stock solution of fluoride was prepared by dissolving NaF in RO (reverse osmosis)-deionized water and working solution was obtained by appropriate dilutions of the stock solution.
2.3. Synthesis protocol of EC
EC was synthesized using Eggshell (ES), Eggshell membrane (ESM) and aluminium sulphate. The synthesis procedure mainly involves mixing, shaking drying and calcination steps. Step by step synthesis procedure is shown in Scheme 1.