400 nm long pass filter

To evaluate the photocatalytic activity of the as-prepared nanoparticles, a home-built irradiation apparatus was used. The setup incorporates a 200 W Xenon Arc Lamp (L.O.T.-Oriel GmbH & Co. KG, Darmstadt, Germany), a 400 nm long pass filter (Thorlabs Inc., Newton, NJ, USA) to isolate the visible spectrum radiation, and a sample cuvette holder. Aqueous solutions of Rhodamine B (40 mg/L) and of textile dyes, C. I. Reactive Red 195 (“Red”), C. I. Reactive Blue 250 (“Blue”) and C. I. Reactive Yellow 145 (“Yellow”) (80 mg/L) were assayed for 2.5 h. In the first 30 min, the nanoparticles were added to the solution, in constant stirring, under dark. After this initial time, the sample solution was exposed to light under magnetic stirring, and aliquots were taken at 0, 5, 10, 15, 30, 60, 90 and 120 min. The photocatalyst content of each aliquot was removed by centrifugation and the absorption spectra were recorded in a Shimadzu UV-3600 Plus UV-Vis-NIR (Shimadzu Corporation, Kyoto, Japan) spectrophotometer.

A home-built irradiation apparatus was used to evaluate the photocatalytic activity of the prepared samples in the degradation of aqueous solutions of the dyes Rhodamine B (40 mg/L), C.I. Reactive Yellow 145 (80 mg/L), and C.I. Reactive Blue 250 (80 mg/L). The setup incorporates a 200 W Xenon Arc Lamp (L.O.T.-Oriel GmbH & Co. KG, Darmstadt, Germany), a 400 nm long-pass filter (Thorlabs Inc., Newton, NJ, USA) to isolate the visible spectrum radiation, and a sample cuvette holder. Nanoparticles were dispersed, at a concentration of 2 mg/mL, in an aqueous solution of dye and allowed to equilibrate by magnetic stirring in the dark for 30 min. Absorption spectra of aliquots taken at given irradiation times and centrifuged to remove photocatalyst were measured in a Shimadzu UV-3600 Plus UV-Vis-NIR spectrophotometer (Shimadzu Corporation, Kyoto, Japan).
The kinetic constants of dye photodegradation can be estimated by applying a pseudo-first-order kinetic model (Equation (1)),
$\ln \left(C/C_0\right)=-kt$
where k is the photodegradation rate constant (min⁻¹), C₀ is the initial concentration of the dye, and C is the concentration of the dye at different irradiation times, t.