Adsorption and Photocatalytic Decomposition of theβ-Blocker Metoprolol in Aqueous Titanium Dioxide Suspensions: Kinetics, Intermediates, and Degradation Pathways

Abstract

This study reports the photocatalytic degradation of theβ-blocker metoprolol (MET) using TiO2suspended as catalyst. A series of photoexperiments were carried out by a UV lamp, emitting in the 250–400 nm range, providing information about the absorption of radiation in the photoreactor wall. The influence of the radiation wavelength on the MET photooxidation rate was investigated using a filter cutting out wavelengths shorter than 280 nm. Effects of photolysis and adsorption at different initial pH were studied to evaluate noncatalytic degradation for this pharmaceutical. MET adsorption onto titania was fitted to two-parameter Langmuir isotherm. From adsorption results it appears that the photocatalytic degradation can occur mainly on the surface of TiO2. MET removed by photocatalysis was 100% conditions within 300 min, while only 26% was achieved by photolysis at the same time. TiO2photocatalysis degradation of MET in the first stage of the reaction followed approximately a pseudo-first-order model. The major reaction intermediates were identified by LC/MS analysis such as 3-(propan-2-ylamino)propane-1,2-diol or 3-aminoprop-1-en-2-ol. Based on the identified intermediates, a photocatalytic degradation pathway was proposed, including the cleavage of side chain and the hydroxylation addition to the parent compounds.

Occurrence and fate of pharmaceuticals in WWTPs in India and comparison with a similar study in the United States

“…However, the likelihood for sorption on biomass, i.e., electrostatic interaction of the pharmaceuticals with cell surfaces of microorganisms, should not be excluded. Photodegradation of bblockers may be an additional removal mechanism that is more effective during summer season (Romero et al, 2013). That may explain highest removal of b-blockers during the summer season observed in this study.…”

Synthesis and characterization of B-doped TiO2 and their performance for the degradation of metoprolol

“…The used solar simulator was a Solarbox (Co.fo.me.gra, 220 V, 50 Hz) with a Xenon lamp (Phillips XOP 1 kW) on the top and a filter (cut-off <280 nm) located just below the lamp [28,29]. A stirred reservoir tank (1.0 L) was filled with MET aqueous solution (50 mg L −1 ) with 0.4 g L −1 of catalyst.…”

“…Romero et al [28] found that this behavior can be explained because MET absorption spectrum overlaps only slightly the spectrum of the incoming radiation. The authors calculated the coefficient of molar absorptivity molar and obtained a value of 281 L mol −1 cm −1 .…”

“…The advanced oxidation processes (AOPs) have been highlighted, with satisfactory results in the removal of several organic compounds including pharmaceuticals [10,[18][19][20][21][22][23]. Studies have reported the removal of MET by different AOPs, including ozonation [12], UV/H 2 O 2 [24], photo-Fenton [25][26][27], photocatalysis [12,14,[28][29][30][31].…”

Hybrid nanoadsorbents for the magnetically assisted removal of metoprolol from water

“…Several processes have been proposed for the elimination and degradation of MTP from water, including advanced oxidation processes [7,8], photocatalytic treatment [9]- [11] and adsorption [12]- [14]. Compared to other methods, adsorption is an attractive process in view of its simplicity of implementation and low cost.…”