Cd²+-Adsorption Properties in Wastewater of Composite Modified Maifan Stone

A new kind of Cd²⁺-adsorption material was prepared using maifan stone by composite modification with chemical and heat treatment methods. The modified maifan stones were characterized by SEM and EDS. Effects of the modified maifan stone content, contact time and the initial pH of the solution on the adsorption of Cd²⁺ were studied. The research results show as follows: 1) The composite modified maifan stone was prepared with heat treatment for 1 h at 340°C after the chemical dipping for 24 h with 2 mol/L CaCl₂ solutions; 2) The composite modified maifan stone had even more obvious poor porosity holes and more contact area for ion exchange and adsorption of Cd²⁺; 3)In the condition of the initial Cd²⁺ concentration=50 mg/L, the maifan stone content=50 g/L, the contact time=40 min and pH=8, the adsorption of Cd²⁺ was up to 87.6 %.