Issaraporn Rakngam

Sustainable conversion of agricultural residues into functional nanomaterials offers new opportunities for biomass valorization and advanced biomedical applications. Herein, we report a single‐feedstock strategy for converting rice husk into cellulose nanocrystals (CNCs) and lysine‐doped carbon dots (L‐CDs), followed by their integration into a hybrid nanocarrier system. CNCs were obtained through alkali bleaching and sulfuric acid hydrolysis, while L‐CDs were synthesized via hydrothermal carbonization with in situ lysine doping. The resulting CNC/L‐CD hybrid exhibited excitation‐dependent photoluminescence, enhanced thermal stability, altered surface charge, and an increased optical bandgap (4.91 eV). Spectroscopic and surface analyses confirmed successful hybrid formation through electrostatic and hydrogen bonding interactions. To evaluate drug delivery performance, the CNC/L‐CD hybrid was incorporated into sodium alginate (SA) beads for tetracycline loading and release studies. SA‐CNC beads showed the highest tetracycline loading capacity (7.56 mg g ⁻¹ ), whereas SA‐CNC/L‐CD beads exhibited enhanced pH‐responsive release behavior under physiologically relevant conditions. The released tetracycline retained antibacterial activity against Escherichia coli , Staphylococcus aureus , and Salmonella typhimurium . Control experiments confirmed that unloaded carrier materials exhibited no intrinsic antibacterial activity. These findings demonstrate the potential of rice husk‐derived CNC/L‐CD hybrids as sustainable nanocarriers for pH‐responsive tetracycline delivery and highlight a practical route for transforming agricultural waste into value‐added biomedical materials.

Nitrogen-rich post-synthetic surface engineering is systematically investigated as an effective strategy to enhance CO2 a capture in zirconium-based metal organic frameworks UiO-67 through controlled modification of surface chemistry. Urea and melamine were employed as nitrogen-rich modifiers under mild conditions using ethanol as a green solvent, making the approach attractive for post-treatment process. Powder X-ray diffraction confirms that the crystalline framework of UiO-67 is fully preserved after modification. In contrast, synchrotron-based X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS), supported by FT-IR analysis, provide direct insight into changes in local electronic structure and surface chemistry. These advanced characterization techniques unambiguously reveal that nitrogen-rich modifiers do not incorporate into the framework but instead act as indirect structure-directing and surface-activating agents, promoting the formation of hydroxylated extra-framework species and Zr–OH sites. The modified UiO-67 materials exhibit enhanced CO2 capacity and affinity at temperatures relevant to post-combustion conditions. Adsorption isotherms are best described by the Toth model, reflecting increased surface heterogeneity, while kinetic studies follow a pseudo-second-order model, indicating a surface-controlled adsorption process. Isosteric heat analysis confirms moderate and reversible CO2 binding, consistent with cooperative adsorption involving Zr4+ centers, hydroxylated extra-framework sites, and aromatic linkers. Among the modified materials, melamine-treated UiO-67 exhibits the strongest enhancement due to a higher density of hydroxyl-mediated adsorption sites. This study demonstrates that nitrogen-rich surface engineering under mild, green conditions is a viable route toward efficient and regenerable MOF adsorbents for post-combustion carbon capture.

With the growing necessity of achieving carbon neutrality in the industrial sector, the catalytic hydrogenation of carbon dioxide into methanol has been widely considered one of the key strategies for the utilization of captured CO₂.