Remarkable dye adsorption capabilities in CaO-Doped-Zirconia systems

Abstract

The realm of dye adsorption involving zirconia systems remains an untapped frontier, awaiting the unveiling of its complete prowess. The present work investigates the adsorption potentials of CaO-doped ZrO2 nanoparticles with varying doping of CaO (0, 7, 10, and 16 mol.%). With the highest adsorption capacity (of 760 mg/g) reported ever for any zirconia system, the 16 mol.% CaO-doped ZrO2 (16CaSZ) ultrafine nanoparticles portrayed fastest kinetics of dye (Congo red) removal. Along with effect of different pHs (in the presence of different anions such as Cl-, NO3–, SO42- and the mixture of them), a simulated wastewater (comprising urea, different salts, dye, sand, grass, engine oil etc.) was made to examine the efficacy of our nano-adsorbent. The 16CaSZ nanoparticles depicted excellent adsorption (∼99 %) in simulated industrial effluent and duplicated the same performance for pHs ranging from 2 to 10. Multitude of factors (e.g., phase-pure cubicity, highest oxygen vacancy content, pronounced surface area etc.) were credited for this chemisorption-based (R-SO3- interactions, as revealed by the structural and spectroscopic investigations on the post-adsorption products) remarkable adsorption process.