Removal behavior of Pb2+, Cd2+, Zn2+ from wastewater of lead, zinc mining – Cho Don, Bac Kan by halloysite clay

Abstract

Halloysite from Thach Khoan, Phu Tho province showed nanotube structure with a chemical formula Al₂Si₂O₅(OH)₄.2H₂O when fully hydrated and Al₂Si₂O₅(OH)₄ when dehydrated, specific surface areas are 15.7434 and 22.0211 m²/g. Halloysite was used to study on adsorption behaviour of Pb²⁺, Cd²⁺, Zn²⁺ (M²⁺) ions. The effect of factors on the M²⁺ adsorption efficiency was investigated. The adsorption efficiency of Pb²⁺, Cd²⁺, Zn²⁺ obtained 90.75; 73.75 and 67.09 % respectively under the suitable condition: halloysite mass of 0.7 g/50 mL solution, initial concentration of 40 mg/L M²⁺, pH for Pb²⁺, Cd²⁺, Zn²⁺ = 5.31; 6.2; 5.6 espectively, contact time of 80 minutes (for Pb²⁺, Cd²⁺) and 100 minutes (for Zn²⁺) at room temperature (30 ^oC). Adsorption isotherm curves were studied based on Langmuir and Freundlich models. The kinetic of the adsorption process was investigated following the first-order-pseudo and second-order-pseudo models. Removal efficiency of Pb²⁺, Cd²⁺ and Zn²⁺ from the wastewater of lead, zinc mining – Cho Don, Bac Kan was 99,59 %; 92,08 % và 99,46 %, respectively.