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    Green recovery of phenolic-rich extracts from pineapple crowns using deep eutectic solvents: FTIR characterization and chemometric optimization
    (MDPI Publishing, 2026) Ertaş, Ayşe Nur; Akkın, Zeynep Azra; Bozkurt, Rabia Nur; Toprakçı, İrem; Cadar, Oana; Şahin, Selin
    This study presents an integrated green analytical strategy combining deep eutectic solvent (DES) screening, Fourier transform infrared spectroscopy (FTIR), principal component analysis (PCA), and Box–Behnken response surface optimization for the valorization of pineapple crowns, an underexplored agro-industrial by-product. An ultrasound-assisted extraction (UAE) method was developed using DESs to obtain phenolic-rich extracts from pineapple (Ananas comosus) crowns. Five DES formulations were characterized by FTIR to evaluate their characteristic vibrational features, while extraction performance was assessed using total phenolic content (TPC) and antioxidant activity determined by the DPPH assay. Among the tested solvents, glycerol/urea (1:1, molar ratio) exhibited the highest extraction performance based on TPC and antioxidant activity measurements. PCA was used as a complementary tool to visualize the relationships among the DES formulations. Following preliminary temperature screening, 50 ◦C was selected for the optimization experiments. The extraction conditions were optimized using a Box–Behnken design coupled with response surface methodology (BBD–RSM), while desirability function analysis was applied to identify the optimum extraction conditions. The predicted optimum conditions were a sample mass of 1.09 g, an extraction time of 24.75 min, and a water content of 38.21%, yielding predicted responses of 34.66 mg GAE/g air-dried sample (ADS) for TPC and 12.30 mg Trolox equivalent antioxidant capacity (TEAC)/g-ADS for antioxidant activity. Experimental confirmation at the optimum showed deviations below 2% between predicted and observed responses, supporting the adequacy of the models. The quadratic models showed high goodness of fit (R2 = 0.9871 for TPC, and R2 = 0.9906 for antioxidant activity). Overall, the integration of DES-based UAE, FTIR characterization, PCA, and chemometric optimization provides a sustainable analytical approach for producing phenolic-rich extracts from pineapple crown biomass.
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    Green synthesis of titanium dioxide nanoparticles using a deep eutectic solvent-based extract of Prunus spinosa L. for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid
    (Elsevier, 2026) Bozkurt, Rabia Nur; Şahin, Selin; Cadar, Oana
    In this study, polyphenol-rich extract obtained from Prunus spinosa L. fruit using choline chloride/lactic acid (1/ 1) deep eutectic solvent was used as reducing, stabilizing and capping agent in the green synthesis of TiO2 nanoparticles (TiO2-NPs). The extraction system using a homogenizer was optimized using the Response Surface Methodology (RSM). The conditions providing the highest efficiency for total phenolic content (40.885 mg-GAE/ g-FF) and antioxidant activity (86.22%) were determined as 46.179% (v/v) water ratio to DES, 1.478 g sample amount and 65.513 s extraction time. UV–Vis DRS, PL, SEM-EDX, HR-TEM-EDX, FTIR, XRD, DLS, and Zeta Potential analyses revealed that the TiO2-NPs had a band gap of 2.8 eV, a spherical morphology, nanosize, and high crystalline purity. Comparative DLS and zeta potential analyses of aqueous extract and DES-based systems showed that the DES-based environment yields smaller and more stable TiO2-NPs. Furthermore, TiO2-NPs showed notable antioxidant activity, with an IC50 value of 52.4 μg/mL. The TiO2-NPs were utilized as photo catalysts to degrade 2,4-dichlorophenoxyacetic acid (2,4-D). Photocatalytic tests showed the highest efficiency, achieving 66.9% degradation of an 80 mg/L 2.4-D solution with 50 mg of TiO2-NPs at pH 5.5 within 120 min. The photocatalyst remained stable after three cycles. A nanomaterial has been sustainably created using an extremely environmentally friendly method for photocatalytic pollutant destruction.