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Catalytic degradation of tartrazine in the presence of Oxone® activated by a catalyst constituted of cobalt supported on a nanocomposite of smectite with chitosan-derived carbon was investigated. The catalyst was synthesized using cobalt impregnation followed by carbonization at 773 K in an inert atmosphere. The synthesized catalyst was previously fully characterized using appropriate characterization methods, including XRPD, XPS, FTIR, HRTEM, and low-temperature N2-physisorption analysis. The catalytic experiments were performed by varying different experimental parameters (dye concentration, Oxone® concentration, temperature, and initial pH of the reaction solution). The kinetic and thermodynamic parameters were estimated from the experimental results. The kinetics data showed the best fit with the pseudo-first-order kinetics model. The activation energy of the investigated degradation process was calculated according to the Arrhenius equation. The catalyst showed excellent performance at low temperatures even at 298 K, and in the wide range of pH values.

The employment of compounds obtained from natural sources to produce adsorbents and their application in the elimination of antibiotics from industrial effluents have gained significant attention because of their low production cost and sustainability. Herein, chitosan (biopolymer) and smectite (abundant clay mineral) were used for the low-cost and eco-friendly synthesis of a new type of adsorbent. A low-energy-consumption hydrothermal process was applied to the synthesis of the chitosan-derived carbon–smectite nanocomposite with cobalt (H_Co/C-S). The produced nanocomposite was characterized using elemental analysis, ICP-OES, XRPD, low-temperature N2 adsorption–desorption isotherms, FTIR analysis, and point of zero charge. H_Co/C-S (SBET = 0.73 m2 g−1, d001 = 1.40 nm, pHPZC = 5.3) was evaluated as a ciprofloxacin adsorbent in aqueous solution. Experimental data were fitted with different kinetic models and interpreted by selected adsorption isotherms. The pseudo-second-order model was found to be the most appropriate, while ciprofloxacin adsorption onto H_Co/C-S was best described by the Redlich–Peterson isotherm (R2 = 0.985). The maximum adsorption capacity of H_Co/C-S, according to the Langmuir isotherm (R2 = 0.977), was 72.3 mg g−1. Desorption and thermodynamic studies were performed. The obtained results indicated that the new hierarchically designed H_Co/C-S has promising potential to be further tested for application in real wastewater treatment. [ABSTRACT FROM AUTHOR]