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Mesoporous TiO2-BiOBr Microspheres with Tailorable Adsorption Capacities for Photodegradation of Organic Water Pollutants: Probing Adsorption-Photocatalysis Synergy by Combining Experiments and Kinetic Modeling
摘要： Understanding adsorption-photocatalysis synergy helps advance solar-driven photodegradation of organic wastewater pollutants. To evaluate the synergy, mesoporous TiO2(amorphous)-BiOBr microspheres were facilely synthesized as model photocatalysts and characterized by XRD, SEM, TEM/HRTEM, XPS, nitrogen adsorption-desorption, UV-vis DRS, photoluminescence, and FTIR. The characterizations and photodegradation tests suggested that the composites had both adsorption sites and photocatalysis sites on BiOBr phase, while homogeneously distributed TiO2 in BiOBr microplates tailored the size of BiOBr crystallites. Accordingly, surface areas of the composites spanned from 22 to 155 m2/g and adsorption capacities for methyl orange (MO) ranged from 16 to 54 mg/g, controlled by the TiO2 content. In addition to experiments, kinetic modeling that combined adsorption with photocatalysis was developed and aided elucidating the synergy and quantitatively evaluating the composites with extracted rate constants from experimental data. The rate constant of the composite (Ti/Bi = 0.6) was calculated to be 3 times that of the pure BiOBr. Though adsorption promoted MO photodegradation, the capacity of the composite for MO adsorption and photodegradation decreased dramatically during the cycling tests. Nevertheless, this problem did not happen during photodegradation of rhodamine B and phenol on the composite and photodegradation of MO on pure BiOBr. This was explained by possible accumulation of degradation intermediates on the composite surface. This study provides a useful approach to investigate the adsorption-photocatalysis synergy from the perspectives of experiments and kinetic modeling and implies the necessity of scrutinizing the adverse effects of high levels of adsorption on recyclability of the photocatalysts.
关键词： Organic pollutants photodegradation,Kinetic modeling,TiO2-BiOBr microspheres,Tailorable adsorption capacities,Adsorption-photocatalysis synergy
更新于2025-11-14 17:03:37
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Synergy of adsorption and photocatalysis on removal of high-concentration dye by Ag/AgCl/Bi6O4(OH)4(NO3)6·H2O nanocomposite using Bi12O17Cl2 as bismuth source
摘要： Novel basic bismuth nitrite nanocomposite-Ag/AgCl/Bi6O4(OH)4(NO3)6·H2O has been applied to remove high-concentration methyl orange (MO). The nanocomposite was prepared by a two-step method with Bi12O17Cl2 as bismuth source. XRD, TEM, HRTEM and IR analyses were performed to clarify the composition and microstructure. TEM and HRTEM images reveal that the nanocomposite is consisted of plate-stacking Bi6O4(OH)4(NO3)6·H2O ultrathin nanosheets, where monodispersed AgCl (3-7 nm) and Ag (10-120 nm) nanoparticles are uniformly distributed. Influences of contact time, MO concentration and solution pH on adsorption capacity have been studied. Adsorption capacity is 349 mg g-1 at natural state, 740 mg g-1 at pH=3, and 141 mg g-1 at pH=9. Visible-light photocatalytic performance was evaluated by degradating high-concentration MO of 500 mg L-1 at natural state, 1500 mg L-1 at acidic condition, and 300 mg L-1 at the alkaline condition. Combining with distinct composition and structure of the nanocomposite, removal mechanism is proposed based on the synergy of adsorption and photocatalysis.
关键词： Adsorption,Photocatalysis,Synergy,High-concentration methyl orange,Ag/AgCl/Bi6O4(OH)4(NO3)6·H2O
更新于2025-09-23 15:19:57