Comparative study of in-situ and ex-situ activated carbon/ maltodextrin functionalized dendritic fibrous nano-silica for emerging pharmaceutical contaminants removal: 3D multivariate optimization and mechanistic insights

The persistent presence of emerging pharmaceutical contaminants in aquatic environments necessitates the development of high performance, reusable adsorbents. This study focuses on the synthesis and evaluation of dendritic fibrous nano-silica (DFNS)-based hybrid materials for the removal of acetaminophen (ACE) and amoxicillin (AMOX) from water. Two functionalized composites were prepared via distinct routes: in-situ and ex-situ incorporation of activated carbon (AC) and maltodextrin (MD) onto DFNS, denoted as AC/MD@DFNS-IN and AC/MD@DFNS-EX, respectively. Bare DFNS and bare AC were used in preliminary experiments to benchmark individual adsorption capacities. Comprehensive characterization using FESEM-EDX, AFM, BET, XRD, FTIR and XPS confirmed morphological and chemical differences among the adsorbents. Comparative adsorption studies revealed that the ex-situ functionalization approach led to superior removal efficiencies. The optimized AC/MD@DFNS-EX composite achieved up to 97% ACE and 86% AMOX removal under conditions determined using Face-Centred Central Composite Design (FCCCD). Additionally, the adsorbent exhibited excellent reusability over five adsorption-desorption cycles, demonstrating its potential for sustainable pharmaceutical pollutant remediation. This work highlights the significance of functionalization strategy in the design of DFNS-based biohybrid adsorbents for water treatment applications.