Optimization of TiO2-P25 photocatalyst dose and H2O2 concentration for advanced photo-oxidation using smartphone-based colorimetry

Abstract

Color images taken by a smartphone camera were used to estimate the rate of advanced photooxidation reaction of Direct Red 23 (DR23) azo dye as a model organic pollutant. The RGB color coordinates were tested to quantify the dye. Images of the reaction mixture were taken at specified intervals to obtain kinetic lines and reaction rate constants. Both the reaction rate constant and the final degree of degradation were plotted as functions of the photocatalyst dose and the concentration of H2O2. The smartphone measurements are fully consistent with the reference spectrophotometry data. The maximum degradation efficiency of the DR23 dye was recorded at C0(H2O2) = 2.5 mM and photocatalyst dose equal to 1.0 mg/L. Higher H2O2 concentrations reduce the degradation rate as a result of the side reaction of H2O2 with OH radicals. A two-factor experimental design was used to study the effects of photocatalyst dose and H2O2 concentration with 5 and 7 levels, respectively. The ANOVA results indicated that the concentration of H2O2 had the greater influence. The smartphone provides quick and easy measurement of the photodegradation rate directly in the solutions without sampling. The proposed approach can be applied under field conditions in wastewater treatment plants.

Performance of commercial titanium dioxide samples in terms of dye photodegradation assessed using smartphone-based measurements

“…The micro-photoreactor has been described in detail in our previous articles [11,16]. The UV LED (3 W) was a source of UV light.…”

“…It is known that the photocatalytic activity of TiO2 depends on a set of factors such as phase structure, crystallite size, specific surface area, and pore structure [11,12]. Many different types of commercial catalysts are commonly used in photocatalytic reactions, including TiO2 Degussa P25 (Evonik) and Millennium PCs catalysts (Millennium Chemicals).…”

Photocatalytic degradation of Congo red dye using Fe-doped TiO2 nanocatalysts

“…A titanium aquacomplex [Ті(ОН2)6] 3+ •3Cl − precursor was obtained according to [27] and [36]. Ferric chloride hexahydrate was added to the precursor solution to obtain Fe-doped TiO2 (2, 5, 10, 15 and 20% wt.).…”

Hydrogenated Amorphous Titania with Engineered Surface Oxygen Vacancy for Efficient Formaldehyde and Dye Removals under Visible-Light Irradiation

“…This unique configuration not only provides additional O V -induced states to absorb long-wavelength light, thereby enabling colorful TiO 2−x , but also encourages photoinduced charge separation to achieve superior visible-light photoactivity [ 13 , 14 , 15 ]. To obtain photocatalysts with superior efficiency, the polymorph modifications of crystalline titanium dioxide also attracted much attention [ 16 , 17 ]. Alternatively, compared with crystalline TiO 2 , amorphous TiO 2 , which also exhibits an intrinsic narrow bandgap, thermodynamic metastability, and a large surface area, should be a great promising templet for surface hydrogenation [ 18 , 19 , 20 ].…”