EAAOP 7

During the EAAOP7 held in Italy between June 10th and 13th, Dr. Olivier Monfort and Dr Shalu have presented their results via interesting talk and poster communication, both focused on the use of nanomaterials in wastewaters treatment, along with the fundamental insights into reaction mechanism. You can read below the abstracts of their presentation:

VERSATILITY OF MXENES IN EFFICIENT AOPS: NANOMATERIALS’ PRECURSORS AND COCATALYSTS (S. Atri)

The products of our daily lives, such as personal care products, pharmaceutically active compounds and drugs like antibiotics, analgesics, anti-inflammatories, and antiepileptics, etc., have been considered as contaminants of emerging concern (CECs). Among them, sulfamethoxazole (SMX) and caffeine (CAF) are some of the most detected CEC in surface waters resulting from inefficient treatments in wastewater treatment plants (WWTP). This issue leads to their accumulation in the natural environment, which poses a serious public health issue. In this scenario, the generation of advanced oxidation processes (AOPs) triggered by 2D materials appears one of the most promising solutions. Thin multilayered transition metal carbides and nitrides, known as MXenes, have emerged as co-catalysts because of their unique structure and electronic properties, as well as ability to tailor the functionalities present on their surface. On the other hand, their functional groups associated with MXenes can bestow the formation of MXene-derived metal oxides (MOx) and MOx/MXene heterojunction materials by a mild, partial, and full oxidation process. The beauty of utilizing MXene as the precursor to attain MOx is that it provides a unique morphology and physicochemical properties that cannot be accessed by other synthetic routes.  

In this work, we have emphasized on the use of MXenes as both co-catalysts and material precursors to design innovative catalysts for peroxymonosulfate (PMS) activation in wastewaters treatment. In this context, TiNbOx nano-heterostructures derived from the oxidation of binary MXene i.e., (Ti0.75Nb0.25)2CTx (with Tx = OH, F and Cl) has been prepared. Also, another MXene i.e., Ti3C2Tx, has been used to decorate with CoFe2O4. The designed nanomaterials have shown remarkable performance in the degradation of CECs in the presence of PMS. The mechanism of PMS activation has been elucidated for the first time using such systems and the degradation mechanism has been also investigated by EPR, XPS and scavenging techniques. Treatments in tertiary effluents of municipal WWTP have highlighted the potential integration of such treatments into conventional WWTP.

ACTIVATION MECHANISM OF SULFATE RADICAL-AOP USING TRANSITION METAL FERRITES IN WASTEWATERS TREATMENT (O. Monfort)

Many transition metal ferrites (MFe2O4) have been already reported as efficient catalysts for the degradation of organic pollutants via sulfate radical-AOP i.e., activation of persulfates (PS) like peroxydisulfate (PDS, S2O82-) and peroxymonosulfate (PMS, HSO5-). Beside their photocatalytic and Fenton-based properties, copper and cobalt ferrites (CuFe2O4 and CoFe2O4) have been considered promising catalysts as they are magnetic, thus being potentially easy to implement in wastewaters treatment plants (WWTPs). However, the activation mechanism of PS by these ferrites still exhibits some discrepancies in the literature where different reactive species, either radical ROS, non-radical ROS or activated surface complexes, have been reported.

In this work, we have used a comprehensive approach to elucidate activation mechanism of PMS and PDS using CuFe2O4 and CoFe2O4. Along with scavenging experiments to determine the role and contribution of reactive species, we have employed advanced spectroscopic techniques like XPS and EPR to identify the PS activation routes. In addition, the degradation pathways of different persistent and emerging pollutants have been investigated to provide insights into the degradation mechanism. Finally, to highlight the relevance and applicability of our findings, we have tested these SR-AOP in effluents collected at municipal WWTPs, so the activation of PS by transition metal ferrites could be a viable technology to integrate WWTPs as an additional treatment.