Degradation of tri(2-chloroethyl)phosphate by a microwave enhanced heterogeneous Fenton process using iron oxide containing waste

Abstract

Iron oxide containing waste was first used in the microwave (MW) enhanced heterogeneous Fenton process for removing tri(2-chloroethyl)phosphate (TCEP) in aqueous solution. The operational parameters that affect the removal efficiency were investigated in detail. Comparing with the traditional Fenton-like reaction and heating assisted Fenton-like reaction, the MW enhanced heterogeneous Fenton process displayed superior treatment efficiency. The iron ore tailing can be reused eight times without significant decrease of catalytic efficiency. The major intermediates were identified and the possible degradation pathways of TCEP were proposed. The acute toxicity gradually decreased during the degradation process and the removal of TOC was 98.8% after 35 min reaction. This study could not only apply the waste tailing as a secondary resource to avoid the tedious preparation of the catalyst, but also proposes a rapid, low-cost and effective alternative method for the removal of polluted water containing TCEP.

Microwave Irradiation and Formamide: A Perfect Match for Ultrafast Carbamoylation via Radical Reactions

“…In contrast to microwave irradiation, where efficient heating of all reaction mixtures by direct coupling of microwave energy with formamide was observed, in the conventional heating, the vessel wall was heated first, and consequently, a longer time was required for the uniform heating of the reaction mixture. Another experiment was carried out to evaluate the possibility of generating hydroxyl radicals without iron since it was reported that the formation of “hot spots” or intensive heating in the microwave can promote the generation of • OH. − In this case, only traces of the desired product 3a were observed. Finally, when the reaction was performed in the presence of TEMPO, the desired product was not observed, revealing that the reaction takes place through a mechanism involving free-radical intermediates (Scheme B).…”

Degradation mechanism of tris(2-chloroethyl) phosphate (TCEP) as an emerging contaminant in advanced oxidation processes: A DFT modelling approach

“…As shown in the left part of have been all detected by experimental techniques (Du et al 2018, Liu et al 2018b, Ye et al 2017, indicating the stable state of these species, with relatively lower Gibbs energy. Since the hydrogen abstraction was energetically more favorable than the •OH attack mechanism, it is surprising to detect both Ma2 and Mb2 as the products.…”

“…H2O2 + O2 Unfortunately only limited theoretical investigations on the mechanism of detailed degradation have been reported compare to the extensive technical and applied studies (Li et al 2017, Luo et al 2018, Zhou et al 2018). Du et al 2018, Liu et al 2018b, Ye et al 2017). These studies indicated two possible pathways for the initial step of TCEP degradation, namely the hydrogen abstraction initiated pathway (HAP) and the •OH attack initiated pathway (RAP), as illustrated in Figure 1.…”

“…Technically, TCEP, as one category of emerging environmental contaminants (Yang et al 2019), is completely recalcitrant to the conventional water and wastewater treatment due to its relatively high-water solubility and non-degradability. However, advanced oxidation processes (AOPs), such as UV/TiO2 (Abdullah and O'Shea 2019, Alvarez-Corena et al 2016, Ye et al 2017, UV/H2O2 (Liu et al 2018b), the Fenton processes (Liu et al 2020 including microwave (MW) enhanced Fenton process (Du et al 2018) have been demonstrated to be viable and effective options to attenuate TCEP in a wide concentration range (Miklos et al 2018, Salimi et al 2017. Scientific consensus is that the hydroxyl radical (OH•) is the common key feature of the above mentioned AOPs for TCEP degradation, due to the fact that OH• is one of the most oxidative radical, second only to the fluorine atom (Miklos et al 2018, Navalon et al 2010.…”

“…The possible routes for OH• generation in various AOPs were summarized in Table 1. For example, when H2O2 in solution of the Fenton reactions was exposed to the MW irradiation, it generated extra OH• due to the molecular stimulation to high vibrational and rotational energy levels, leading to the enhanced TCEP degradation (Du et al 2018).…”