Research On The Adsorption Of Heavy Metal Ions From Wastewater Using Tea Wastes

Recently, the heavy metal pollution in water was an serious environmental issue, which had threated to human health and ecological environment and related reports were emerging endless. Each government had unveilled various control standard, which to restraint the influence of the heavy metals pollution in wastewater. Unfortunately, the level of techniques, which could effectively degrade the heavy metals liquid, were limited. Therefore, various technologys to eliminate the heavy metals pollution became an hotspot topic.The adsorption ability of tea wastes on three heavy metal ions, lead, cadmium and zinc were investigated in this research. The results showed that the surface of the tea wastes had widely porose area. The specific surface area reached 0.86 m2/g. The pore diameter was in micropore level, the average pore size was 3.62 nm. In the existence of high concentration of calcium ions, the tea wastes exihibited good adsorption ability, and the concentration of calcium ions was fifty times higher than the target ions, the removal rate of three heavy metal ions increased significantly. The adsorption of heavy metal was pH value. Whan the pH value ranged from 2 to 3, the adsorption ability of tea wastes was decreased; when the pH value enhanced from 3 to 6, the adsorption ability increased significantly. The adsorption ability of tea wastes also reinforced with the temperature, and the adsorption isotherm of blumbum and cadmium were consistent well with the Langmuir isothermal model and the theoretical maximum adsorption capacities were 31.16 mg/g and 16.04 mg/g, respectively. The adsorption isotherm of zinc was consistent with Freundlich isothermal model. The adsorption kenitics of all three heavy metal ions were consistent with pseudo first reaction kinetic model, with a fitting coefficient of 0.96. The adsoption could reach equilibrium in a limited time of 150-180 min. The removal efficiency decreased with the rise of the initial metal ions concentration, indicating that tea wastes are more appropriate for the slightly polluted water. The removal efficiency increased when the size of tea wastes particle reduced. The FITR results indicated that the -CN, C=O, -SO3, secondary amine group, aliphatic C-H group and bonded-OH groups played an important role in removing the heavy metal ions. The results reflected that the tea wastes presented a good alternative of removing heavy metal ions in waste aqueous.