No abstract

Congo red (CR), an anionic dye, is very harmful to the environment and should be removed via an easy and inexpensive technique. The adsorption of CR from an aqueous solution onto a mixture of illite-kaolinite clay minerals and surfactant-modified illite-kaolinite was investigated at different temperatures. The characterization of the raw clay mixture and the organified sample was confirmed with X-ray diffraction, FTIR spectroscopy, nitrogen gas adsorption at 77 K and transmission electronic microscopy techniques. Factors influencing the adsorption such as pH, adsorbent dosage and temperature were tested. The thermodynamic parameters G˚, H˚and S˚have been calculated, and it was found that the adsorption is exothermic in nature. The isotherm data were fitted by the linear form of the Langmuir and Freundlich models and showed a good fit with the Langmuir approach. The maximum adsorption capacity of surfactant-modified clay (83 mg/g) was found to be around 14 times higher than that of unmodified clay. Kinetic studies of CR on illite-kaolinite and organified illite-kaolinite were evaluated by pseudo-first-order and pseudo-second-order models.

Stable metal oxides insoluble in acidic medium have been prepared and characterized. The influence of the type of metal oxide (MOx) on the activity of Pt towards ethylene glycol oxidation in acidic medium has been examined. All modified Pt/MOx/glassy carbon (GC) electrodes exhibited a better activity compared to Pt/GC. While Pt/SnO2/GC electrode exhibited the highest activity, Pt/CeO2/GC revealed the best tolerance against poisoning process.