Adsorptive removal of Cr(VI) from water using silver nanoparticle modified-diatomite nanocomposite.

Keeping the sustainability concept in view, the present study aimed to valorize diatomite for adsorptive removal of Cr(VI) ions from waters and wastewaters. A modified diatomite nanocomposite was prepared via its impregnation with silver nanoparticles, using a one-pot technique, and the silver nanoparticles-diatomite nanocomposite potency was comprehensively investigated for Cr(VI) adsorption. The raw diatomite and silver nanoparticles-diatomite nanocomposite were characterized via XRD, SEM, and BET techniques. A statistical technique, based on response surface method, was exploited for finding the optimized conditions for adsorption. Accordingly, a maximal chromium sorption of 94.0% was observed at pH 4.61, sorption duration 60.37 min, and adsorbent dosage 2 g, for an initial level of 45 mg/L for the composite adsorbent. The equilibrium scrutinization shows that Langmuir isotherm model has a better fitness with the adsorption data. In addition, the adsorption kinetic analyses demonstrated the best fit to the pseudo-second order equation and multiple distinct phases of intraparticle diffusion for both adsorbents. Overall, silver nanoparticles-diatomite nanocomposite showed excellent properties for adsorption of Cr(VI) ions and could be exploited as an adsorbent in full-scale treatment plants.