Removal of Malachite Green using carbonized material derived from disposable facemasks: optimization of removal process through Box-Behnken design

Water resources are being heavily contaminated due to the huge load of toxic pollutants released by industrial activities. Among various physical and chemical methods, adsorption is considered as a promising method for rapidly removing contaminants from wastewater. In the present study, a novel carbon-based adsorbent was prepared through controlled pyrolysis of disposable facemasks. The properties of carbonized compound (CC) were characterized by FTIR, XRD, SEM and EDX. The pollutant removal efficiency of CC was initially investigated with synthetic dyes Malachite Green (MG) and Congo Red (CR). The peaks observed in FTIR spectra corresponding to C=O and C=C and C-N functional groups on adsorbed CC surface confirm the interaction between dye and CC. The XRD spectra of CC showed strong peaks at 2 theta = 26.629, 27.488, 27.810 and 29.404 which correspond to the disordered graphitic plane. The SEM images of CC showed good porosity nature. A quadratic model was developed through response surface methodology by conducting a series of Box-Behnken design experiments. Adequacy of this model variables was ensured by ANOVA tests at P-value P-value (<0.0001) and higher F-value (44.54) of the quadratic model showed it was a significant model for dye removal. Finally, the optimal condition to obtain maximum MG removal (rate >99%) was identified by desirability function as CC 1000 and MG 212 mg/L and adsorption time 180 min. Adsorption kinetic study indicates that a pseudo second-order kinetic model showed the best fit with R-2 = 0.999.