Linear and nonlinear investigations for the adsorption of paracetamol and metformin from water on acid-treated clay

Mohamed R Elamin,L Khezami,Faisal K Algethami,Babiker Y Abdulkhair

doi:10.1038/s41598-021-93040-y

Abstract

Natural clays are considered a safe, low-cost, and sound sorbent for some pharmaceutical and body care products from water. Metformin (MF) and paracetamol (PA) are of the most consumable drugs worldwide. A portion of natural clay was treated with distilled water, and another part was treated with hydrochloric acid. The water-treated clay (WTC) and the acid-treated clay (ATC) were characterized by scanning electron microscopy-energy dispersive spectroscopy, X-ray diffraction, Fourier transforms infrared spectroscopy, and nitrogen adsorption isotherm. Batch experiments were employed to investigate the influence of contact time and solution parameters on the adsorption of PA and MF on WTC and ATC. 30 min attained the equilibrium for all sorbent-sorbate systems. Both sorbents fitted the pseudo-second-order kinetic model with a preference to the nonlinear fitting, and the mechanism of adsorption partially fitted the liquid-film diffusion model. The PA and MF adsorption on WTC and ATC fitted the Freundlich model in preference to nonlinear fitting. The adsorption of pollutants on both sorbents was spontaneous, exothermic, and physisorption in nature. Even at low concentrations, both WTC and ATC showed efficiency above 80% in removing PA and MF from tab water, groundwater, and Red seawater. These findings nominated natural clay as an alternative to the costly nanomaterials as sorbents for removing pharmaceutical contaminants from water.

Highlights

Natural clays are considered a safe, low-cost, and sound sorbent for some pharmaceutical and body care products from water
Characterization of water-treated clay (WTC) and acid-treated clay (ATC).The surface topography of WTC and ATC was scanned with SEM
For the ATC sample, the low magnification reflected no difference for the acid treatment (Fig. 1d), the medium magnification showed an efficient removal of debris-cover revealing a diatomaceous structure (Fig. 1e)

Summary

Introduction

Natural clays are considered a safe, low-cost, and sound sorbent for some pharmaceutical and body care products from water. To improve the adsorption capacity, water treated clay (WTC) and an acid-treated clay ATC were employed for the removal of MF and PA from real water samples. BET surface area of the sorbents was determined; for instance, Fig. 2e, f showed the evolution of N 2 adsorption–desorption isotherms for WTC and ATC, respectively.

Results

Conclusion