Adsorption of mercury(II) from aqueous solutions using dried Scrophularia striata stems: adsorption and kinetic studies

This study aimed to assess the performance of dried Scrophularia striata stems (DSSS) in the removal of mercury(II) from aqueous solutions. Detailed experimental investigations were carried out to determine the effects of initial pH, adsorbent dose, initial concentration of mercury(II), and adsorption time on the adsorption capabilities of DSSS. The prepared adsorbent was characterized by Brunauer-Emmett-Teller, scanning electron microscopy, Fourier transform infrared, and energy dispersive X-ray analyses. Moreover, mercury(II) adsorption was theoretically interpreted using kinetics, isotherms, and thermodynamics models. The extent of mercury(II) adsorption was found to depend on the initial pH, adsorbent dose, initial concentration of mercury(II), and adsorption time. It was also found that the pseudo-first-order kinetic model fitted very well for mercury(II) adsorption. The Langmuir isotherm provided the best correlation for the adsorption of mercury(II). The desorption of mercury(II) by a batch process using different DSSS concentrations ranged from 96.2% to 98.7%. The results showed that DSSS could be an appropriate adsorbent for adsorption of mercury(II) from aqueous solutions.