Enhanced Removal of Diclofenac by CaO-Nanoparticles-ModifiedCocoa-Pod-Husk-Activated-Carbon: Adsorption Behavior, Modeling with Uncertainty Quantification, Regeneration and Scale-Up Potential
Year: 2026
Type: article
Abstract: This study reports the synthesis of a green nano-adsorbent for the effective removal of diclofenac, awidely detected pharmaceutical contaminant in aquatic environments. Cocoa pod husk was valorizedinto activated carbon and modified with green-synthesized calcium oxide nanoparticles (CaO–NPs) toenhance surface reactivity and adsorption performance. Process optimization was carried out using aDefinitive Screening Design, considering initial diclofenac concentration, adsorbent dosage, contacttime, and temperature as governing factors. Under optimal conditions (100 mg L⁻¹, 0.5 g, 75 min, and323 K), a maximum removal efficiency of 99.08% was achieved. Adsorbent characterization confirmedthe successful modification of the adsorbent using CaO–NPs. Equilibrium and kinetic analyses revealedthat the Dubinin-Radushkevich isotherm and pseudo-second-order kinetics best described the adsorptionprocess, indicating that the process is chemisorption dominated. The spontaneity and endothermic natureof the adsorption process were confirmed through thermodynamic analysis. The reliability of the modelwas further assessed using uncertainty quantification and global sensitivity analysis through MonteCarlo simulation. Monte Carlo simulation confirmed the strong influence of adsorbent dosage and initialconcentration on removal efficiency variability. The reusability study proved that the adsorbent can bereused several times, as it retained over 80% of its adsorption capacity after five regeneration cycles, andthe cost of the adsorbent for diclofenac removal was 0.83 $/g. Overall, CaO–NPs–CPHAC presents arobust, sustainable, and statistically reliable adsorbent for the treatment of pharmaceutical-contaminatedwastewater.
Author: Salam, Kazeem
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7163133179
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