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2 2019

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Equilibrium, kinetic and thermodynamic studies on methylene blue adsorption by Trichosanthes kirilowii Maxim shell activated carbon

Wang Yuqi, Li Yanhui, Zheng Heng

Polish Journal of Chemical Technology

2019

Vol. 21, nr 4

89--97

New kind of adsorbent was produced from Trichosanthes kirilowii Maxim shell. The KOH activation technology for preparation of Trichosanthes kirilowii Maxim shell activated carbon (TKMCK) was optimized. Using methylene blue as the sample adsorbate, the adsorption behavior was systematically investigated in terms of the activation agent and temperature, the adsorption temperature and time, the initial adsorbate pH and concentration, as well as the dosage of adsorbent. Surface physical morphology of the TKMCK prepared was observed by scanning electron microscopy (SEM), while the functional groups were determined with Fourier transform infrared (FTIR) spectra. Kinetic studies indicated that the adsorption process was more consistent with the pseudo-second-order kinetic. Both Langmuir and Freundlich isotherms were employed to fit the adsorption data at equilibrium, with the former giving a maximum adsorption capacity of 793.65 mg/g at 323 K. BET surface area of as-prepared TKMCK was 657.78 m2/g.

Novel (Ag,Y) doped TiO2 plasmonic photocatalyst with enhanced photocatalytic activity under visible light

Kallel Wannes, Chaabene Sirine, Bouattour Soraa

Physicochemical Problems of Mineral Processing

2019

Vol. 55, iss. 3

745--759

Nano-sized Y- Ag doped and co-doped TiO2 particles were synthesized using the sol–gel method and Ti(OBu)4 as TiO2 precursor. Their structural and optical properties were examined by scanning electron microscopy (SEM), XRD, thermogravimetric-differential thermal analysis (TG-DTA), FT-IR and UV-vis absorption spectroscopies. The photocatalytic activity of these materials was investigated for the photodegradation of methylene blue (MB) as a model reaction under visible light irradiation. Ground state diffuse reflectance absorption studies reveal that both Y and Ag dopant cause deviations of the band gap to higher energies attesting that co-doping the TiO2 with Y and Ag could enhance the photocatalytic activity by delaying the electron–hole recombination by means of higher energy band gaps. Co-doping TiO2 at a level of 4% (Y, Ag) samples leads to a significant decrease in the crystallite size of photocatalyst and containing both anatase and Ag/AgCl components. However, the high photocatalytic performance is attributed to an efficient electron-hole pairs separation at the photocatalyst interfaces in addition to localized surface plasmon resonance of Ag particles. The development of these visible light- activated nanocatalysts has the potential of providing environmentally benign routes for water treatment.