Quantifying evolving toxicity in the TAML/peroxide mineralization of propranolol

Abstract

Summary Oxidative water purification of micropollutants (MPs) can proceed via toxic intermediates calling for procedures for connecting degrading chemical mixtures to evolving toxicity. Herein, we introduce a method for projecting evolving toxicity onto composite changing pollutant and intermediate concentrations illustrated through the TAML/H 2 O 2 mineralization of the common drug and MP, propranolol. The approach consists of identifying the key intermediates along the decomposition pathway (UPLC/GCMS/NMR/UV-Vis), determining for each by simulation and experiment the rate constants for both catalytic and noncatalytic oxidations and converting the resulting predicted concentration versus time profiles to evolving composite toxicity exemplified using zebrafish lethality data. For propranolol, toxicity grows substantially from the outset, even after propranolol is undetectable, echoing that intermediate chemical and toxicity behaviors are key elements of the environmental safety of MP degradation processes. As TAML/H 2 O 2 mimics mechanistically the main steps of peroxidase catalytic cycles, the findings may be relevant to propranolol degradation in environmental waters.

MoS2 and MoS2 Nanocomposites for Adsorption and Photodegradation of Water Pollutants: A Review

“…This means fully converting the contaminants to a gaseous form, water, salts, and minerals [ 145 ]. However, several photodegradation reactions may lead to toxic intermediate compounds, which can harm the environment [ 146 ]. The total organic carbon (TOC) quantification method can be employed to evaluate the mineralization of a contaminant achieved by photocatalysis.…”

The Mechanism of Formation of Active Fe-TAMLs Using HClO Enlightens Design for Maximizing Catalytic Activity at Environmentally Optimal, Circumneutral pH

“…The simplest stoichiometric mechanism of Fe-TAML-catalyzed oxidations by H 2 O 2 in aqueous media is straightforward. , The iron(III) resting state of any Fe-TAML catalyst is activated by an oxidant such as H 2 O 2 (step 1), and the active catalyst formed then attacks an electron donor, S (step 2). If S is a dye, the primary products are usually oxidized fast (step 3), which is typically not the case for more difficult-to-oxidize targets. , [ L Fe III ] 0.25em ( resting state ) + normalH 2 normalO 2 → active 0.25em catalyst 0.25em ( k I ) active 0.25em catalyst + normalS → [ L Fe III ] + primary 0.25em product 0.25em ( k II ) active 0.25em catalyst + primary 0.25em product → [ L Fe III ] + product / normals 0.25em ( fast ) …”

“…If S is a dye, the primary products are usually oxidized fast (step 3), which is typically not the case for more difficult-to-oxidize targets. 12 , 13 …”

“…The simplest stoichiometric mechanism of Fe-TAML-catalyzed oxidations by H 2 O 2 in aqueous media is straightforward. , The iron­(III) resting state of any Fe-TAML catalyst is activated by an oxidant such as H 2 O 2 (step 1), and the active catalyst formed then attacks an electron donor, S (step 2). If S is a dye, the primary products are usually oxidized fast (step 3), which is typically not the case for more difficult-to-oxidize targets. , …”

An Iron Macrocyclic Complex Containing Four “Hybrid” Pyridinium Amidate/Amidate N‐Donors as a Catalyst for Oxidations with Hydrogen Peroxide

“…[11] The application of iron-TAMLs [12] (which are small molecule mimics of natural cytochrome P450 enzymes) as catalysts for the oxidative destruction of micropollutants in water by hydrogen peroxide, presents a promising alternative because studies have shown that iron-TAML/hydrogen peroxide oxidation systems can degrade a range of organic micropollutants. [13][14][15][16][17][18][19][20][21] The catalytic performance of iron catalysts with the TAML structural motif (e. g., TAML B, Scheme 1) has been improved through an iterative design protocol over many years with the latest design incorporating two amidate and two sulfonamidate donors within the macrocyclic ring (TAML C, Scheme 1). [22][23][24][25][26][27] During this improvement process, electron-withdrawing groups on the ligand framework were found to both increase the oxidising power of the activated iron-TAMLs and also cause the pH at which the maximum oxidation rate occurs to move closer to neutral.…”