Rapid removal of lead (II) ions from aqueous solutions by saffron flower waste as a green biosorbent

Abstract

In this work for the first time Saffron flower waste as a low cost and green adsorbent for removal of lead toxic ions from aqueous solution by shaking and ultrasonic waves is reported. Properties of this natural absorbent are characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray diffraction (EDX). The specific surface area of the saffron flower waste is measured via Brunauer–Emmett–Teller. The effect of some important parameters such as solution pH, the initial concentration, mixing method and time on the removal of lead ions is studied. The adsorption results show that the adsorption process could reach equilibrium rapidly at 9 min. The maximum adsorption capacity is 36.97 mg g−1 and 45.62 mg g−1 for ultrasonic and shaking process, respectively. Three errors functions including Chi-square statistic (χ2), root mean square error (RMSE) and average relative error (ARE) are used for isotherm optimization prediction that has the best fitting with Langmuir model. Furthermore, the adsorption kinetic data could be well described by pseudo-second order model. According to excellent adsorption time and performance the proposed biosorbent can be a good candidate for green removal of Pb ions from wastewater.