Adsorption of manganese and zinc in synthetic wastewater by tea waste (TW) as a low cost adsorbent

In this study, tea waste (TW) is investigated as a low cost adsorbent for the treatment of Mn(II) and Zn(II) in synthetic wastewater. Experimental design, the variables are the adsorbent dosage (0.5g, 1.0g, 1.5g, 2.0g, 2.5g and 3.0g) and contact time (20, 40, 60, 80, 100 and 120 minutes). The percentage of heavy metal ions removal in the solution are measured using DR2800 Spectrophotometer. Adsorption Isotherm and Adsorption Kinetic modelling are applied to further prove the correlation of the experimental data obtained for the removal of Mn(II) and Zn(II). The equilibrium data satisfactorily fitted into Langmuir Isotherm model for both Mn(II) and Zn(II) with R² value of 0.9906 and 0.9854, respectively. Based on the result, TW is capable to adsorb more than 90% of both Mn(II) and Zn(II) at optimum dosage of 2g/100ml. The kinetic studies show that the absorption mechanisms satisfied the Pseudo-Second-Order model and have the best equilibrium data with R² value of 0.9998 and 1.0000 for Mn(II) and Zn(II), respectively. The maximum adsorption achieved at 60 minutes for Mn(II) and 80 minutes for Zn(II). Thus, the Langmuir Isotherm and Pseudo-Second-Order Kinetic models proved that TW is capable of being an efficient and effective adsorbent for Mn(II) and Zn(II) removal in synthetic wastewater. (paper)