Optimization of adsorptive removal of α-toluic acid by CaO 2 nanoparticles using response surface methodology

The present work addresses the optimization of process parameters for adsorptive removal of α-toluic
acid by calcium peroxide (CaO 2 ) nanoparticles using response surface methodology (RSM). CaO 2 nanoparticles
were synthesized by chemical precipitation method and confirmed by Transmission electron microscopy
(TEM) and high-resolution TEM (HRTEM) analysis which shows the CaO 2 nanoparticles size
range of 5–15 nm. A series of batch adsorption experiments were performed using CaO 2 nanoparticles
to remove α-toluic acid from the aqueous solution. Further, an experimental based central composite
design (CCD) was developed to study the interactive effect of CaO 2 adsorbent dosage, initial concentration
of α-toluic acid, and contact time on α-toluic acid removal efficiency (response) and optimization of
the process. Analysis of variance (ANOVA) was performed to determine the significance of the individual
and the interactive effects of variables on the response. The model predicted response showed a good
agreement with the experimental response, and the coefficient of determination, ( R 2 ) was 0.92. Among
the variables, the interactive effect of adsorbent dosage and the initial α-toluic acid concentration was
found to have more influence on the response than the contact time. Numerical optimization of process
by RSM showed the optimal adsorbent dosage, initial concentration of α-toluic acid, and contact time
as 0.03 g, 7.06 g/L, and 34 min respectively. The predicted removal efficiency was 99.50%. The experiments
performed under these conditions showed α-toluic acid removal efficiency up to 98.05%, which confirmed
the adequacy of the model prediction.