New composite adsorbent using agricultural waste from rice husk and banana peels to remove Cu(II) and Zn(II) in synthetic wastewater

Abstract

Heavy metal contaminants present in wastewater from many industries such as metal manufacturing, chemicals, fertilizer, and transportation. Nowadays heavy metal removal has become the main priority for environmental concern due to their toxicity. The presence of high dissolved Zn(II) and Cu(II) concentrations in industrial wastewater contributes decoloration of water and can cause a health problem. Even though the adsorption study related to agricultural waste has been well established using the single adsorbent but are not many study-related using composite adsorbent especially using rice husk and banana peels. Hence, this study investigates agricultural waste from rice husk and banana peel as a new composite adsorbent with three different sets for the treatment of Zn(II) and Cu(II) in synthetic wastewater. Set 1 consists of 80% rice husk and 20% banana peels, Set 2 consists of 50% rice husk and 50% banana peels, and Set 3 consists of 20% rice husk and 80% banana peels. The effects of contact time and adsorbent dosage are analyzed in batch experiments. The percentage of Zn(II) and Cu(II) ions removal in the solution is measured using DR6000 UV-Vis Spectrophotometer. Adsorption Isotherm and Adsorption Kinetic modeling are applied to further prove the correlation of the experimental data obtained for the removal of Zn(II) and Cu(II) ions. Based on the results, the new composite adsorbent from Set 3 is capable to absorb more than 98% of both Zn(II) and Cu(II) at an optimum dosage of 1.5 g/100ml and 2g/100ml respectively. The equilibrium data satisfactorily fitted into the Freundlich Isotherm model for both Zn(II) and Cu(II) with R² values of 0.9723 and 0.9904, respectively. The optimum contact time for Zn(II) and Cu(II) is 90 minutes and 60 minutes respectively. The kinetic studies show that the adsorption mechanisms satisfied the Pseudo-Second-Order model and have the best equilibrium data with R² value of 0.999 and 1.0000 for Zn(II) and Cu(II), respectively. Thus, the Freundlich Isotherm and Pseudo-Second-Order Kinetic models proved that new composite agricultural waste from rice husk and banana peels are potential of being an efficient and effective adsorbent for Zn(II) and Cu(II) removal in synthetic wastewater.