Evaluation of nanosilica, extracted from stem sweep, as a new adsorbent for simultaneous removal of crystal violet and methylene blue from aqueous solutions

ABSTRACT In this work, nanosilica was extracted from stem sweep and used as a new adsorbent for the simultaneous removal of the crystal violet (CV) and methylene blue (MB) dyes in a batch mode. The influence of the experimental variables including the solution pH, adsorbent dosage, initial dye concentration, and contact time on the adsorption process was studied. Analysis of the equilibrium data revealed that adsorption of the understudied dyes in single and binary systems can be fitted to the Langmuir and the extended-Langmuir isotherms, respectively. Kinetic investigations carried out on the CV and MB removal suggested that the adsorption processes followed a pseudo-second order kinetics rate. For the first time, a modeling of the simultaneous removal of CV and MB on the prepared adsorbent was presented using the random forest (RF) and multiple linear regression (MLR) methods. The random forest (RF) model, recognized as a reliable and powerful computational technique, was used to predict the removal percentage of the cited dyes in a binary mixture as a function of the experimental parameters. The mean square errors (MSEs) and squared correlation coefficients (R 2 s) for CV were 3.29 and 0.9754, respectively, and those for MB were 2.41 and 0.9781, respectively. These results confirm the ability and accuracy of the proposed RF model (with respect to the multiple linear regression method) for estimating the behavior of the adsorption processes under different experimental conditions. For the first time, a dish-washing liquid was used, as a cheap and available solvent, for the regeneration of the proposed adsorbent.