A typical sorption procedure is as
follows: after the longan shell particles of 300 mg were added
to 25 mL of lead-ion aqueous solution, the suspension was
stirred for 2 h in a water bath at 30 °C. The particles were filtered
from the aqueous solution, and then the concentration of Pb(II)
ions in the filtrate was measured by a direct complex titration
based on EDTA.