Size-tunable effect of CaCO3/nanocellulose hybrid composites on the removal of paracetamol from aqueous solution.

Abstract

Paracetamol is a ubiquitous drug used by animals and humans but is not fully metabolized within their bodies, and thus often finds its way into raw wastewater. This study represents a new class of adsorbent nanocomposite with high adsorption capacity towards paracetamol removal. Herein, both the kinetic study and the removal of paracetamol from aqueous solutions were investigated in terms of diverse CaCO3/nanocellulose composites with different surface charges and different particle sizes. To fine-tune these parameters, the latter was hydrothermally synthesized by manipulating of three nanocelluloses types. Precisely, micro-crystalline cellulose (MCC), nano-crystalline cellulose (CNC), and nano-fibrillated cellulose (NFC) were used as templates for precipitating CaCO3 particles from CaCl2 solution with the aid of Na2CO3. Results revealed the successful in situ deposition of calcite form of CaCO3 with size varied relying on the base of nanocellulose. For MCC, CNC, and NFC, the size of CaCO3 was disclosed in the range of 850-1200nm, 350-600nm, and 150-200nm, respectively, regarding their surface charge. While the process of paracetamol adsorption was described by Freundlich and Langmuir isotherms, it was observed that, for MCC, the best fit of the experimental data was achieved with the Freundlich model, while the Langmuir model was the most appropriate for CNC and NFC. Also, the highest max adsorption capacities of paracetamol varied respectively to both size and surface charge of hybrid composite used. Among them, MCC/CaCO3 composite exhibited the highest max adsorption capacity at 428mgg-1, clarifying that the low surface zeta potential of the latter hybrid nanocomposite is responsible for the accumulation of CaCO3 at a bigger size with a higher affinity to adsorb paracetamol with the highest capacity due to its weak repulsion. Results also demonstrated that the material is highly effective and economical for removal of paracetamol and reusability with marginal diminishing in adsorption capacity up to 10% after five reuse cycles.