Removal of heavy metal ions (Pb2+ and Ni2+) from aqueous solution using nonwovens produced from lignocellulosic milkweed fibers

Batch-adsorption technique was employed to evaluate the adsorption capacity of the nonwovens produced from lignocellulosic milkweed fibers for the removal of heavy metal ions, i.e. Pb2+ and Ni2+, from aqueous solutions. The impact of controllable factors such as solution pH, initial concentration, contact time and operating temperature on the adsorption quantity of Pb2+ and Ni2+ was investigated using Atomic Absorption Spectrophotometer. The kinetic and isotherm of the adsorption process were also modeled. The milkweed fibers demonstrated superior performance for the removal of Pb2+ ions from wastewater over Ni2+ ions. The results demonstrated that the equilibrium concentration of heavy metal ions in solution varies with solution pH and the least equilibrium concentration is observed at pH = 6, regardless of ion type. The results also revealed that the removal percentage of Ni2+ ions reached the value of 65.58% at contact time of 60 min while Pb2+ ions removal percentage was as high as 96.16% at contact time of 90 min. It was concluded that an increase in operating temperature from 26 to 45 degrees C causes to slight decrease of the removal percentage for both Pb2+ and Ni2+ ions by similar to 5.7% and similar to 9.5%, respectively. The adsorption behavior of milkweed fibers toward Pb2+ and Ni2+ ions followed Freundlich and Langmuir isotherm models, respectively. Moreover, pseudo-second order model was the best to describe the adsorption kinetics of both metal ions.