Functionalized Biopolymer for Enhanced Pt(IV) Recovery from Aqueous Solutions

In this study, chitosan (Chi) functionalized with the amino acid serine (Ser) was synthesized for the adsorption-based recovery of Pt(IV) from aqueous solutions. To identify the active functional groups of the amino acid and the support material, the synthesized AcademicEditor: Chi-JungChang Received: 31March2025 Revised: 15April2025 Accepted: 20April2025 Published: 22 April2025 Citation: Babău,T.;Ciopec,M.; Mosoarca,G.; Vancea,C.; Negrea,A.; Neme¸ s, N.S.; Pascu, B.; Negrea, P.; Ian㸠si, C.; Buzatu, A.R. Functionalized BiopolymerforEnhancedPt(IV) RecoveryfromAqueous Solutions. Polymers 2025, 17, 1132. https://doi.org/10.3390/ polym17091132 Copyright: ©2025bytheauthors. Licensee MDPI,Basel,Switzerland. This article is an open access article distributed under the termsand conditions of the Creative Commons Attribution (CC BY)license (https://creativecommons.org/ licenses/by/4.0/). adsorbent was characterized using SEM, FT-IR, and EDX analyses, and its point of zero charge (pHPZC) was determined. Static and dynamic adsorption studies were conducted to optimize process parameters. Under static conditions, equilibrium studies established the maximum Pt(IV) concentration that could be adsorbed onto Chi–Ser, as well as its maximumadsorption capacity. At pH > 4, with an S-L ratio of 0.1 g:25 mL Pt(IV) solution, a contact time of 90 min, and a temperature of 298 K, the maximum adsorption capacity reached 7.23 mg/g. The adsorption process was best described by the Sips isotherm. The Taguchi methodwasemployedtooptimizestaticadsorptionconditions. TheClarkequation most accurately modeled the adsorption process under dynamic conditions. Additionally, multiple adsorption–desorption cycles evaluated the adsorbent’s reusability.