Experimental and Modeling Studies of Sorption of Tetracycline onto Zeolite in the Presence of Copper(II)

The sorption performance of tetracycline on zeolite under different conditions was investigated in presence and absence of Cu(Ⅱ).The presence of Cu(Ⅱ) greatly increased the adsorption of tetracycline on zeolite. Adsorption kinetics and adsorption equilibrium isotherms were studied by conducting series of batch experiments. The kinetic analysis indicated that the pseudo-second-order kinetic model was well described the sorption equilibrium process of tetracycline onto zeolite in the presence and absence of Cu(Ⅱ), and intra-particle diffusion was not the only rate-limiting in the sorption process. The qmax value calculated from Langmuir model were 17.37 and 68.26 mg/g in the absence and the presence of Cu(Ⅱ). The value of E calculated from Dubinin-Radushkevich (D-R) model confirmed that the adsorption in the absence and presence of Cu(Ⅱ) were mainly controlled by physical combined with chemical adsorption mechanism. The tetracycline sorption amount decreased in the absence of Cu(Ⅱ) and increased in the presence of Cu(Ⅱ) as the pH increasing. The adsorption removal rate of wastewater containing 0.1 mmol/L tetracycline was 95.5% in the presence of Cu(Ⅱ) and 34.5% in the absence of Cu(Ⅱ) when the dosage of zeolite was 0.05g.