Researches on the Removal of Pb(II) by Hydrothermally Modified Oyster Shells

A novel wastewater purification material was prepared by a hydrothermal method. It was mainly made from oyster shells with the merits of long service time, large surface area, high lead removal efficiency and excellent recyclable properties. The technological conditions were decided respectively based on the lead removal efficiencies. At pH = 5 and 30 degrees C, for the wastewater with the initial concentration of Pb(2+) to be 5 mg/L, adsorption time 24 h, and 1 mg to 40 mL of mass ratio between adsorbent and Pb(2+), the maximum adsorption capacity can reach 0.19 mg/g. The lead removal material prepared by hydrothermal method has excellent recycle performance. The equilibrium adsorption capacity can get to 9.71 mg/g and the average Pb(2+) removal rate is as high as 66.39%. After reusing for 60 times, the SEM observation shows that the hydrates of reticular formation is formed after hydrothermal modification, which provides a good attachment position for Pb(2+), indicating the physical adsorption is dominant.