Removal of mutagen X "MX" from drinking water using reduced graphene oxide coated sand particles

Mutagen X is a hazardous by-product of disinfection by chlorine, which is responsible for most of the mutagenicity in chlorinated drinking water. It has the cancer potency value of 100-fold higher than bromodichloromethane and 6000-fold higher than chloroform, In this study, Mutagen X was removed from aqueous media by a thermally reduced graphene oxide bonded on the surface of amino-functionalized sand particles.

A Box-Behnken design was applied to optimize the adsorption process. Characterization of the adsorbent and graphene oxide was accomplished using scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman analysis. The effects of three independent parameters, including initial concentration (20-200 μg L^-1), temperature (5-30 °C), and adsorbent dose (2-80 g L^-1) were examined using batch experiments.

Characterization results confirmed that the graphene oxide was successfully coated on the surface of sand particles. Regression analysis of experimental results showed a great fit with a quadratic polynomial model with the R² = 0.999. Optimum conditions (initial concentration: 20 μg L^-1, temperature: 30 °C, and adsorbent dose: 80 g L^-1) with the desirability of 1.0 resulted in the minimum residual concentration of Mutagen X (2 μg L^-1). Equilibrium study results depicted that the experimental data were fitted well to the Freundlich and UT isotherm models.