In this work, Guar gum and copper oxide-nickel oxide (GG-CuO-NiO) hydrogel were produced with the help of formaldehyde solution to display an efficient catalytic performance toward the catalytic degradation of selected dyes (Methylene Blue (MB), Methyl Orange (MO), and Eosin Yellow (EY)) in the presence of NaBH₄. The morphological and structural properties of the prepared hydrogel were thoroughly analyzed using SEM, EDX, XRD, and FT-IR techniques. According to the results, the GG-CuO-NiO hydrogel was able to reduce MB by 95% in one minute, 90.0% in four minutes, and 80.0% in 10 min for MO and EY, respectively. The catalytic efficiency of the hydrogel for MB was studied by adjusting its concentrations, varying reducing agent concentrations, and altering the amount of gel used. Using the recyclability method, which involved testing the GG-CuO-NiO hydrogel multiple times for the reduction of MB, the stability, reusability, and loss of catalytic activity of the hydrogel were examined. As a result, the designed GG-CuO-NiO hydrogel was stable for up to four times toward the reduction of MB. Lastly, the efficiency of the GG-CuO-NiO hydrogel was evaluated for MB removal in real samples and displayed exceptional reduction capabilities.

An innovative, sustainable analytical approach was developed by coupling an Epsom salt, E518 (magnesium sulfate)–facilitated salting-out assisted liquid–liquid extraction (SALLE) system with a safe molecular fluorescent probe, Celfia Pink B (CPB), employing a fluorescence turn-off sensing strategy. MgSO₄ acts as a green salting-out agent, enhancing phase separation efficiency and producing cleaner extracts with higher analyte recovery. CPB, a safe, food-grade dye, serves as a selective fluorogenic probe whose emission at 553 nm is quenched upon electrostatic ion-pair complex formation with Cinacalcet HCl under mildly acidic conditions. The method exhibited excellent linearity (0.08–1.3 µg/mL) with high sensitivity (LOD = 0.024 µg/mL; LOQ = 0.075 µg/mL). Validation according to ICH guidelines demonstrated robustness, precision, and accuracy across pharmaceutical formulations and biological matrices. Sustainability assessment using the WAC framework categorized the platform as “white,” highlighting low environmental impact, safe operation, and simplicity. By minimizing organic solvent use and eliminating hazardous reagents, this MgSO₄-assisted SALLE/fluorescence turn-off approach provides a green, highly sensitive, and versatile tool for trace-level determination of Cinacalcet HCl in pharmaceutical and biological matrices.

A zinc oxide–iron oxide embedded graphitic carbon (Zn/Fe@C) photocatalyst was successfully synthesized by pyrolysis of chitosan hydrogel impregnated with zinc and iron salts. Structural characterization confirmed the formation of a predominantly crystalline, multi-phase oxide system, while morphological analysis revealed a rough and heterogeneous surface with aggregated features. Elemental analysis further verified the incorporation of Zn and Fe species within the graphitic carbon matrix. The photocatalytic performance of the prepared material was evaluated through hydrogen peroxide (H₂O₂) production and dye degradation under simulated solar irradiation. Zn/Fe@C exhibited superior H₂O₂ production performance, achieving a maximum concentration of 2.9 mmol L⁻¹. The use of different alcohols as sacrificial agents revealed that 2-propanol significantly enhanced H₂O₂ generation, while increasing catalyst loading improved H₂O₂ production due to the availability of additional active sites. In dye degradation experiments, the photocatalyst demonstrated high efficiency toward the removal of representative organic dyes, including methylene blue, methyl orange, and acridine orange, with the latter showing the highest degradation efficiency of 96.6%. The effect of catalyst loading indicated that lower dosages resulted in optimal performance, which was attributed to improved light penetration and reduced aggregation effects. Control experiments confirmed that photocatalysis was the dominant mechanism over adsorption. Furthermore, increasing the metal precursor concentration enhanced photocatalytic activity, while the material maintained good reusability over multiple cycles. Furthermore, Zn/Fe@C was compared with Cu/Fe@C and Cu/Zne@C where Zn/Fe@C exhibited superior performance among the investigated photocatalysts in H₂O₂ production and dye degradation. Overall, the results highlight the potential of the developed Zn/Fe@C photocatalyst as a promising material for sustainable H₂O₂ production and efficient degradation of organic pollutants.