Mercury(II) adsorption by a novel adsorbent mercapto-modified bentonite using ICP-OES and use of response surface methodology for optimization

The presence of mercury(II) ions in aqueous media is a major concern due to toxicity and the threat to public health and ecological systems. Thus, the development of novel adsorbents that are highly efficient and selective is of critical importance for the removal of mercury(II) ions from aqueous media. The adsorption of mercury(II) from aqueous media by a new adsorbent, 3-mercaptopropyl trimethoxysilane-modified bentonite (B-SH), and the optimization of adsorption parameters was investigated in this study. B-SH was used as a novel sorbent for mercury(II) adsorption, and the analysis of adsorption conditions was performed by response surface methodology (RSM). The characterization of B-SH was executed using Brunauer, Emmett and Teller (BET), Fourier Transform Infrared (FTIR) Spectroscopy, Energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analyses. The most important parameters for Hg(II) adsorption were initial pH, initial mercury(II) concentration (Co), temperature (T (°C)), and adsorbent dosage (g). The RSM results showed that the optimal adsorption conditions yielding the best response were 6.17, 36.95 mg/L, 37.28 °C, and 0.19 g, for pH, Co, T (°C), and adsorbent dosage, respectively. At optimum adsorption conditions obtained by program, the maximum adsorption capacities and the adsorption yield were 19.30 mg/g and 99.23%, respectively. Among the adsorption isotherm models (the Langmuir, Freundlich and Dubinin-Radushkevich), the adsorption data showed a better fit to the Langmuir isotherm model. The thermodynamic studies revealed that the adsorption process was spontaneous, feasible and endothermic. According to these results, B-SH has high mercury(II) adsorptive removal potential from aqueous media. In addition, a new adsorbent has been added to the literature for the uptake of toxic metals like mercury.