Tracking the adsorptive effect of nano silicate–ginkgo residue composite for Sr(II) and Cd(II) removal from aqueous solutions

Abstract

Ginkgo biloba (Ginkgo)/calcium silicate nanocomposite (NG-CSA) was prepared as a novel sorbent. Nanomaterial was characterized using different techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, differential thermal analysis and thermal gravimetric analysis (DTA and TG). Adsorption of Sr(II) and Cd(II) ions was performed taking into account significant parameters such as initial pH of the solution, shaking time and initial concentration of metal ions as well as temperature. The acquired results were disclosed that the adsorption of both ions is notably improved using NG-CSA composite. The monolayer capacity of NG-CSA for Sr(II) and Cd(II) from binary system is 122.45 and 64.68 mg/g for Sr(II) and Cd(II), respectively. The kinetic studies exposed that the adsorption process followed nonlinear pseudo-first-order model. The isotherm studies show that the extended Langmuir model is more applicable than Freundlich model for binary system adsorption process. The value of diffusion coefficient for the Sr(II) and Cd(II) is in range 10−10 m2/s which indicates the chemisorption nature of the process. The maximum value of desorption for the Sr(II) and Cd(II) is 98.41% and 97.66 utilized 0.3 M of nitric acid. This indicated that NG-CSA composite can be regenerated and reused for further adsorption of Sr(II) and Cd(II) from wastewater.