In the present research, humic acid (HA) embedded chitosan (CHT)-poly (vinyl alcohol) (PVA) pH-sensitive hydrogels have been synthesized using glutaraldehyde as a crosslinker. The hydrogels were characterized by Fourier-transform infrared (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) analysis. The effect of HA content, pH, and temperature on the equilibrium solvent uptake has been investigated. With higher HA contents, the equilibrium swelling capacity increases while lower concentrations of acid cause a decrease in the degree of the swelling. The hydrogels have been found to undergo a number of swelling/deswelling cycles when pH of the swelling medium changes from 1.5 to 11.0. Fick’s law, first-order, and second-order kinetic models were applied to the swelling ratio of hydrogels to explain the mass transfer mechanism and specify swelling kinetic parameters. The swelling parameters such as equilibrium swelling capacity, swelling rate constant, swelling exponent, initial swelling rate, diffusion coefficient, etc., have been evaluated.

In the present study, activated carbon/alginate (AC/ALG) beads were successfully synthesized with different AC:ALG ratios of 1.0–3.0 (w/v) and used for the adsorption of the nonsteroidal anti-inflammatory drug naproxen from wastewater. The beads were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis, and adsorbent dosage, initial pH, initial naproxen concentration, and contact time in removal efficiency were investigated. Maximum naproxen removal percentage was achieved using 350 mg of AC/ALG beads with a ratio of 3.0% (w/v) within six hours and naproxen removal performance was determined to be 98.0%. Freundlich, Temkin, and Dubinin–Radushkevich (D-R) isotherm models were fitted to the equilibrium data better than the Langmuir model. According to kinetics results, the equilibrium time for the AC/ALG beads was reached in four hours and the kinetic model was determined by the pseudo-second-order equation. The thermodynamic parameters were calculated and enthalpy of naproxen adsorption was found to be positive for all AC/ALG beads. After the adsorption process the beads can easily be regenerated by ethanol and reused within seven cycles.

The objective of this work was to determine the total phenolic compounds and antioxidants in raw and cooked Sakiz and Bayrampasa variety artichokes in parts such as inner bracts, stems, receptacles, and outer bracts. The artichokes were cooked by boiling, microwaving, and baking methods, and total phenolic compounds and antioxidants of cooked artichokes were evaluated. While TPC (total phenolic content), DPPH (2,2-diphenyl-1-picryl-hydrazine), and CUPRAC values for the leaves of raw Bayrampasa artichoke were found to be 686 mg gallic acid equivalent (GAE)/100 g, 478 mg TE/100 g, and 4,875 mg TE/100 g, respectively, TPC, DPPH, and CUPRAC values for stems of Sakiz artichoke were determined to be 1,579 mg GAE/100 g, 1,259 mg TE/100 g, and 3,575 mg TE/100 g. A significant increase in the content of TPC, DPPH, and CUPRAC values was observed for all cooking applications of both artichokes. DPPH and CUPRAC values increased by 11 and 43 times and 17 and 6.7 times after baking of Sakiz and microwave cooking of Bayrampasa, respectively. Chlorogenic acid, cynarine, and cynaroside content of both artichokes had an increment after all cooking applications. Chlorogenic acid content was improved 29 and 58 times after baking of Sakiz and microwave cooking of Bayrampasa, respectively.

Replacing traditional extraction technology with ultrasonic or microwave-assisted extraction has attracted considerable attention. In order to maximize the yield of extracted polyphenolic compounds and antioxidants from Sakiz artichoke by-products, a central composite design (CCD) was applied to optimize the microwave-assisted extraction (MAE) in the current study. The study found that the optimal conditions for MAE of Sakiz artichoke by-products were: extraction time 6 min; ethanol/water ratio 50:50 (v/v); (ethanol-water)/solid ratio 15:1 mL/g; microwave power 320 W; and temperature 80°C; resulting in the total phenolic compounds (TPC), DPPH, and CUPRAC antioxidant activity values of 607 mg GAE/100 g, 878 mg TE/100 g, and 2922 mg TE/100 g, respectively. The extraction of TPC, DPPH, and CUPRAC antioxidants from artichoke by-products was investigated by the first-order, second-order, Peleg’s, and Page’s kinetic models. These results confirmed that MAE has a great potential for the extraction of polyphenolic compounds and antioxidants from Sakiz artichoke by-products.