2.3. Physical and chemical characteristics
The pH, electrical conductivity (EC) and bulk density of the AC samples was determined by following standard methods [45]. For pH determination, 1% (w/w) suspension of activated carbon in de-ionized water was prepared and the suspension was heated to 90°C with stirring for 20 minutes. The suspension was then allowed to cool to room temperature and the pH was measured using pH meter (Ecoscan, Eutech, Singapore). For EC determination, 1% (wt/wt) solution of activated carbon in water was stirred at room temperature for 20 min and the electrical conductivity was measured using an Ecoscan conductivity meter (Eutech, Singapore) and values were presented in micro Siemens (μS).