2.4. Photocatalytic degradation
The photocatalytic degradation experiments were carried out in
a cylindrical photochemical reactor. Simulated solar light irradiation
was provided by a 300 W halogen lamp (General Electric) with
light intensity of 120 mW/cm2
. The reactor was cooled by circulating
water and maintained at room temperature. In each experiment,
50 mg of catalysts was added to a 50 mL reaction solution
containing initial metoprolol concentration of 10.0 lg/mL. Prior
to irradiation, the suspension was magnetically stirred in darkness
for 30 min to achieve adsorption equilibrium. An aliquot of 1 mL of
the suspensions was sampled at given time intervals and centrifuged
at 3000 rpm for 5 min. The supernatant was filtered through
0.45 lm membrane and transferred to a 2 mL HPLC vial for metoprolol
analysis. The conversion of compounds was calculated by
the following equation: conversion (%) = 1 – Ct/C0, where C0 and
Ct were the initial adsorption equilibrium concentration and reaction
concentration at time t (min), respectively.