Sb( iii ) adsorption and oxidation on MnO 2 facets: a mechanistic study.

Discharge of high-concentration nitrate wastewater poses significant environmental threats. Conversion of nitrate into ammonia achieves a win-win strategy by both promoting sustainable nitrogen resource recycling and eliminating nitrate pollution. Further oxidation of the generated ammonia by free chlorine can also provide a method for the denitrification of wastewater. This study introduces a self-supported, defective cobalt-based electrocatalyst (V-O-Co3O4@NF) synthesized via the hydrothermal-calcination method. Upon introduction of oxygen vacancies into the Co3O4 spinel structure, its electron transfer efficiency was enhanced, and its electrochemical activity was improved. Electrochemical nitrate reduction reaction (ENRR) tests demonstrate exceptional performance of 99.5% nitrate conversion, 95.4% ammonia selectivity, and 75.2% Faraday efficiency at -0.59 V vs RHE, with a high ammonia yield rate of 3.14 mg cm(-2) h(-1). Mechanistic studies reveal the dominance of atomic H* mediated *NOH pathway in ENRR process. The introduction of oxygen vacancies improves the ENRR activity, suggesting a superior intrinsic ENRR activity of the V-O-Co3O4@NF electrode. The actual coal chemistry industry wastewater treatment confirmed the practicability of the V-O-Co3O4@NF. By coupling cathode ENRR and anode chlorine evolution reaction (CER) processes, complete denitrification is realized in wastewater. This work advances defective cobalt-based catalysts for high-efficiency nitrate reduction, offering a cost-effective alternative to traditional methods.

Nitrate pollution in groundwater poses severe threats to ecosystems and human health, making the electrochemical nitrate reduction reaction (NO3RR) a promising remediation technology. Conductive metal–organic frameworks (cMOFs) with π-d conjugation, dispersed active sites, and tunable structures are ideal candidates for electrocatalysis. Herein, we synthesized a series of cMOFs (M3(HHTP)2, M = Fe, Zn, Cu, Co, Ni) via conjugated coordination between hexahydroxytriphenylene (HHTP) ligands and metal ions and systematically investigated their NO3RR performance. Electrochemical tests revealed that Fe3(HHTP)2 exhibits superior catalytic performance for nitrate reduction, achieving a high NH3 selectivity of 99.5% and a yield rate of 676.4 mg·gcat−1·h−1 at −1.0 V vs. RHE (reversible hydrogen electrode), along with excellent cyclic and structural stability. In situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy identified key intermediates (*NO2, *NH2OH) and proposed the reaction pathway: NO3− → *NO3 → *NO2 → *NO → *NOH → *NH2OH → *NH2 → *NH3. DFT calculations revealed that Fe center exhibited a lower energy barrier for NO3RR compared to other metal ions (Zn, Cu, Co, Ni). This study demonstrates the significant potential of Fe3(HHTP)2 for efficient NO3RR and provides new insights into the structure-function relationship of cMOF-based electrocatalysts.

Designing dimensionally stable anodes with high activity and stability is urgently needed, since they play important roles in the areas of chlorine evolution reaction (CER). In this study, a nitrogen-doped RuO2-TiO2/Ti (NRT) anode with enhanced CER activity and stability is developed via an easy to batch producible way, that is by in-situ modifying the coating solution through the prevalent brush coating method. Nitrogen atoms interstitially doped into the RuO2-TiO2 solid solution lattice, and help to form low valence Ti species (Ti 3 +) and oxygen vacancy active sites. This is accompanied by the decrease of CER overpotential, improvements of electrochemically active surface area and electron transfer ability for NRT electrodes. The Faraday efficiency and accelerated service life of NRT are both about twice that of RuO2-TiO2/Ti anode (RT), while the energy consumption is only half that of RT. Batch production of NRT is achieved, and NRT is applied in a portable electrochemical device, demonstrating superior water disinfection performance that can completely inactivate Candida albicans, Staphylococcus aureus, and Bacillus coli by 5 min electrolysis of tap water, and remain above 99.99 % inactivating rates for up to 400 h of continuous operation. The high activity, long-term stability, as well as batch producible preparation methods enable the NRT electrodes to have great potential in chlorine evolution reaction areas.

Recovering phosphorus (P) from wastewater presents a dual benefit: reducing eutrophication and supplementing finite phosphate rock resources. This study developed an integrated electrochemical fixed-bed reactor filled with siderite and calcite for enhanced P recovery. During operation, H+ and OH- ions generated via electrochemical water splitting dissolve siderite and calcite in situ while simultaneously establishing an optimal pH environment for phosphorus precipitation. By adjusting the current density and feed flow rate, the recovery process can be effectively controlled. Mechanistic investigations revealed that phosphate removal was primarily achieved through Ca-P and Fe-P precipitation, along with the formation of various Fe-Ca-P complexes. The proposed system combines the advantages of in situ electrochemical acid and alkali generation with the cost-effectiveness of natural mineral materials. It also aligns with the technical requirements of sewage treatment plants, offering a compact process and minimal chemical usage. With its flexibility and controllability, this electrochemical system holds promising potential for on-site treatment and phosphorus recovery in decentralized wastewater treatment applications.

Antimony (Sb) contamination from mining and industrial activities poses a major environmental concern. Manganese dioxide (MnO2) exhibits strong potential for Sb removal from aqueous solutions through adsorption and redox processes. The surface reactivity of MnO2 facets critically governs interfacial Sb(iii) reactions; however, the structural and mechanistic controls underlying facet-dependent reactivity remain unclear. This study investigates Sb(iii) adsorption and oxidation on three MnO2 nanomaterials with distinct exposed facets, delta-001, alpha-310, and alpha-110, to elucidate surface structure-dependent mechanisms. Sb(iii) adsorption followed the Langmuir isotherm, with maximum capacities of 153.9, 107.3, and 70.1 mg g(-1) for delta-001, alpha-310, and alpha-110, respectively. The oxidation of Sb(iii) to Sb(v) followed the order alpha-310 (13.2%) > alpha-110 (10.0%) > delta-001 (2.5%). ATR-FTIR analysis showed that Sb(iii) forms inner-sphere surface complexes whose structures evolve during adsorption and transformation. XPS results revealed that Sb(iii) oxidation is coupled with Mn reduction, controlled by facet-dependent Mn(iii)/Mn(iv) and O-ads/O-lat ratios. XRD confirmed mineral transformations from MnO2 to MnO(OH) and Mn3O4. EPR measurements demonstrated that Mn(ii)/Mn(iv) species play key roles in Sb(iii) adsorption and oxidation. Overall, the three MnO2 facets exhibited distinct Sb(iii) adsorption and oxidation behaviors. These findings provide new mechanistic insights into facet-dependent redox processes and enhance predictive understanding of Sb transformation at mineral surfaces.

Considering the potential eutrophication risk of phosphonate and scarcity of phosphorus resources, the oxidation of organically-bound phosphorus to orthophosphate (ortho-P) is an important prerequisite for high-value phosphorus recovery. This study investigated efficiency and mechanism of different categories of phosphonates oxidation to ortho-P by classical Fenton and practical electrochlorination Fenton-like processes. The target phosphonates included two categories: nitrogen-free phosphonates (NF-PPs), i.e. 2-phosphonobutane-1,2,4tricarboxylic acid (PBTC) and 1-Hydroxyethane-1,1-diphosphonic acid (HEDP), and aminophosphonates (APPs), i.e. Nitrilotris(methylene phosphonic acid) (NTMP) and diethylenetriamine penta(methylene phosphonic acid) (DTPMP). The results showed that ortho-P conversion for both NF-PPs and A-PPs by classical Fenton process were below 35 %, even though the content of Fe(II) and H2O2 were high enough to neglect the influence of phosphonate-Fe(II) complexation on Fenton reaction initiation. While electrochlorination Fenton-like process greatly enhanced ortho-P conversion of HEDP, NTMP and DTPMP. Potent oxidation relied on generation of HClO, FeIVO2+, and 1O2 rather than HO center dot. In particular, PBTC failed to decompose effectively by electrochlorination Fenton-like process possibly due to chlorine resistance. The non-N-element group was inferred to serve as a decisive role in phosphonates decomposition. This study provided the first systematic description of oxidation rules and mechanism characteristics of diverse phosphonates under classical Fenton and electrochlorination Fenton-like treatment.

Recovering phosphorus (P) from wastewater presents a dual benefit: reducing eutrophication and supplementing finite phosphate rock resources. This study developed an integrated electrochemical fixed-bed reactor filled with siderite and calcite for enhanced P recovery. During operation, H + and OH − ions generated via electrochemical water splitting dissolve siderite and calcite in situ, while simultaneously establishing an optimal pH environment for phosphorus precipitation. By adjusting the current density and feed flow rate, the recovery process can be effectively controlled. Mechanistic investigations revealed that phosphate removal was primarily achieved through Ca–P and Fe–P precipitation, along with the formation of various Fe–Ca–P complexes. The proposed system combines the advantages of in situ electrochemical acid and alkali generation with the cost-effectiveness of natural mineral materials. It also aligns with the technical requirements of sewage treatment plants, offering a compact process and minimal chemical usage. With its flexibility and controllability, this electrochemical system holds promising potential for on-site treatment and phosphorus recovery in decentralized wastewater treatment applications.

Fe electrocoagulation (Fe-EC) is efficient for the removal of phosphate (PO43--P). The fate of Ca2+, Mg2+, and PO43--P during the Fe-EC process is unclear, resulting in the difficulty for mitigating the cathodic scaling. After Fe-EC treatment for 10 min at 10 mA/cm(2), PO43--P was mainly distributed in the sediment (>90 %). Ca and Mg was mainly distributed in the solution (54 % - 97 %), followed by in the sediment (2 % - 44 %) and on the cathode (0 % - 6 %). Although only a small amount of Ca and Mg was precipitated on the cathode, with a long term operation, cathodic scaling would still occur. The precipitation of Ca on the cathode was mainly caused by the presence of HCO3- with other precipitates which directly precipitated with OH- as crystal seeds, because the precipitation of CaCO3 did not depend on the local pH near the cathode. The precipitation of Mg on the cathode was mainly caused by a lower applied current, because Mg(OH)(2) which formed on the cathode would be prevented by H-2 evolution with a higher current. Accordingly, the strategies for preventing cathode scaling are proposed. The precipitation of Ca can be prevented by increasing the current both with HCO3- and crystal seeds, and by increasing the current only with PO43--P. It is hard to prevent the precipitation of Ca by controlling the current only with HCO3-. The precipitation of Mg can be prevented by increasing the current. With the initial concentrations of PO43--P, HCO3-, Ca2+, and Mg2+ in the real wastewater 1.0 mg/L, 48 mg/L, 150 mg/L, and 30 mg/L, respectively, the amounts of Ca and Mg deposited on the cathode were much less at 10 mA/cm(2) (5.8 +/- 2.9 mg/L, 1.1 +/- 0.3 mg/L) than those at 1 mA/cm(2) (28.6 +/- 4.6 mg/L, 5.0 +/- 0.4 mg/L). With the above controlling strategies, the cathode scaling can be alleviated under different water quality conditions.

Electrochemical hydrogenation utilizing reactive hydrogen (H*) derived from water dissociation offers a sustainable route for chemical synthesis and environmental remediation. However, besides the sluggish generation of H*, its utilization efficiency, and consequently the overall electrochemical hydrogenation performance, is limited by competing hydrogen evolution and barrier interfacial H* transfer. Here, using combined theoretical and in situ spectroscopic–electrochemical analyses, we demonstrate that nitrogen vacancy (N V )‐rich Fe 2 N surfaces serve as highly efficient catalytic sites for generating and stabilizing H* for subsequent reactions. During water dissociation, the resulting OH species adopt a bridging μ 2 ‐configuration between adjacent Fe atoms and undergo facile desorption, overcoming a known rate‐limiting step. Simultaneously, H* is stabilized at nitrogen sites in the form of N‐H moieties with high recombination energy barriers, creating an effective H* reservoir. This mechanism guides the application of Fe 2 N‐N V as a simple yet highly active catalyst for nitrate reduction, achieving over 94% Faradaic efficiency and NH 3 selectivity. Furthermore, the accumulated H* on Fe 2 N‐N V enables tandem hydrogenation with cocatalysts such as cobalt ensembles (Co n ), extending its utility to coupled electrochemical hydrogenation.

Cu-organic complexes with highly stable structures and resistance to be removed by conventional methods in electroplating wastewater cause worldwide attention due to their potential threat to the aquatic environment, however, they also represent a valuable heavy metal resource. In this work, an electrochemical system based on Ti/Sn-SbO2/Ni-Sn-SbO2/SiOx (ATO/NATO/SiOx) anode combined with dual cathodes (stainless steel (SS) and activated carbon fiber (ACF) cathodes) was developed to efficiently decomplex Cu-EDTA, a typically refractory Cu-organic complex, and simultaneously recover Cu. The process mainly utilizes the synergistic effect between the in situ generated O3 by ATO/NATO/SiOx anode and the H2O2 generated by ACF cathode to boost the generation of center dot OH, thus achieving efficient Cu-EDTA decomposition. The dual-cathode system achieved 95.75 % removal of Cu-EDTA within 120 min, while 92.25 % of Cu was recovered. Meanwhile, Cu was mainly deposited as Cu2O and Cu at the SS cathode, and CuO at the ACF cathode. Major intermediates of Cu-EDTA degradation were analyzed and a possible degradation pathway was proposed. Additionally, the application potential of the system was also evaluated in the presence of various anions.

Green and agent-free treatment and resource recovery of widespread heavy metal complexes (HMCs) remains a major challenge in wastewater treatment. To address this, we establish an electrochemical ozone production (EOP) system, wherein a new strategy for designing a multilayer heterogeneous anode to facilitate the EOP process is proposed for efficient Cu-EDTA degradation and Cu recovery. Results demonstrated that among various metal (Ta, Ti, Si, and Sb) oxide coatings, SiOx-modified ATO/NATO (A/N/SiOx) anodes could significantly enhance the current efficiency of ozone generation by increasing the overpotential of the oxygen evolution reaction. Remarkably, 98.8 % of Cu-EDTA was removed by the A/N/SiOx anode within 120 min at 10 mA/cm(2) and pH = 2.2, with corresponding k(obs) of 0.035 min(-1), while 92.9 % of Cu was recovered by the stainless steel cathode. Cu-EDTA degradation intermediates could also serve as the catalyst to activate O-3 during the EOP process, which further generates (OH)-O-center dot and O-2(center dot-), attacking the metal-organic bonds of Cu-organic complexes and leading to successive breakage following CuO > CO > CN > -OH > CO > COOH > OCO bonds, thereby enabling self-enhanced decomplexation and Cu recovery. The established system showed excellent performance for treating various metal complexes as well as real electroplating wastewater, indicating its potential feasibility for resourceful treatment of HMCs.

The electrochemical oxygen reduction reaction (ORR) to generate H2O2 provides a compelling path for direct H2O2 generation and on-site applications. However, it is still challenging to create noble-metal-free electrocatalysts with strong activity and H2O2 selectivity. Here, a Co- and N- modified Mo2C catalyst (Co,N-Mo2C) was developed, attaining a high selectivity of H2O2 of 92-95 % in acidic electrolyte within the range of 0.1 to 0.5 VRHE. The Co,N-Mo2C catalyst immobilized on carbon felt (CF) exhibits high H2O2 faradaic efficiency (92-94 %) from 0.1 to 0.5 VRHE, and the Co,N-Mo2C/CF can generate 1093.7 mmol & sdot;g- 1 of H2O2 with a faradaic efficiency above 89 % at 0.1 VRHE over 24 h in acidic electrolyte. The pyridinic N in Co,N-Mo2C can create Lewis base sites that promotes the O2 adsorption on Co,N-Mo2C. Results of density functional theory elucidated that the partially substituted Co0 in Co,N-Mo2C can preserve the O-O bond of adsorbed *OOH and promote further protonation of *OOH to H2O2. This work offers an innovative approach to creating highly selective two-electron ORR electrocatalysts for on-site H2O2 generation.

Heavy metals that are readily chelated with coexisting organic ligands in industrial wastewaters impose threats to environment and human health but are also valuable metal resources. Traditional treatment methods generally require additional chemicals and generate secondary contaminants. Here, a reagent-free dual-cathode electrochemical system was proposed for the efficient destruction of Cu-organic complexes and synchronous cathodic recovery of Cu, whereby in situ production of H2O2 at carbon aerogel (CA) cathode was coupled with the reduction of Cu(II) to Cu(I) and finally to Cu(0) at Ti cathode. The intermediate Cu(II) complexes enabled the self-reinforced degradation owing to their higher activities toward •OH generation by activating H2O2 in contrast to initial Cu-ethylenediaminetetraacetic acid (Cu-EDTA). The enhanced production of Cu(I) by Ti cathode facilitated both •OH and Cu(III) formation, and the copper redox cycle was realized in the self-reinforced system, maintaining its sustainable catalytic activity. The energy cost of the dual-cathode system is 0.011 kWh/g for decomplexation and 0.057 kWh/g for Cu recovery, which is much lower than single Ti or CA cathode system. This established process provides a prospective approach for cost-effective destruction of chelating metal complexes and metal resources recovery from heavy metal wastewaters.

Heavy metal complexes from the industrial wastewater induce risks for the humans and ecosystems, yet are valuable metal resources. For energy saving and emission reduction goals, the simultaneous decomplexation and recovery of metal resources is the ideal disposal of wastewater with heavy metal complexes. Herein, a self-catalytic decomplexation scheme is developed via an electrochemical ozone production (EOP) system to achieve efficient decomplexation and Cu recovery. The EOP system could achieve 94.36% decomplexation of Cu-TEPA, which is a typical complex in catalyst industrial wastewater, and 86.52% recovery of Cu within 60 min at a current density of 10 mA/cm2. The O3 and •OH generated at the anode would first attack Cu-TEPA to produce Cu-organic nitrogen intermediates, which further catalyze O3 to generate •OH, thus self-enhancing the decomposition process in the EOP system. The released Cu2+ was gradually reduced to Cu+ and finally deposited as Cu2O and Cu to the stainless steel cathode. The technological feasibility was confirmed with other Cu-complexes such as Cu-EDTA and Cu-citrate, and the actual Cu-TEPA-containing industrial wastewater. The results provide new insights regarding the application of EOP in the simultaneous treatment of heavy metal complex wastewater and resource recovery.

Electrocoagulation (EC) is promising for the removal of chemical and microbial contaminants. Although the removal of pathogens from wastewater is efficient by conventional Fe-EC in the presence of dissolved oxygen (DO), the non-inactivated pathogens in the sediment still have a risk. Herein, the inactivation of Escherichia coli (E. coli) with the mixed-valent iron nanoparticles, magnetite and green rust (GR), in-situ generated from Fe-EC process in the absence of DO was investigated. The inactivation efficiency was significantly higher with magnetite (4.7 log cells) and GR (3.2 log cells) compared with FeOOH (0.7-1.7 log cells) generated at 50 mA in 10 min. The unstable in-situ generated magnetite with positive charges was prone to adsorb onto E. coli, damaging the cell membrane, inactivating the bacteria. The unstable in-situ generated GR was prone to coagulate with E. coli, delivering Fe2+ into the cell and inducing the generation of endogenous ROS, inactivating the bacteria. Fe-EC in the absence of DO was proved to be efficient for the inactivation of E. coli (4.2-4.3 log cells) in real wastewater. These findings identified the ignored inactivation effect and mechanism of E. coli with magnetite and GR generated in situ from Fe-EC process, which will provide theoretical support for real applications.

Several Covid-19 infection events have been reportedin restaurantand food-processing factory scenarios. To block the transmission ofwaterborne pathogens and protect human's safety, it is urgentto take action for the purification and disinfection of restaurantwastewater. Considering the requirement of restaurant wastewater treatmenttechnology, such as limited spaces, low capital cost, simple to operate,and high efficiency, an integrated electro-coagulation (EC) and electro-oxidation(EO) process was put forward. The lab-scale system treatment resultsillustrated that the composition of restaurant wastewater underwentsignificant changes. The chemical oxygen demand value decreased from1680 to 344 mg/L. Total phosphate, total nitrogen, suspended solids,petroleum, animal fat and vegetable oils, and anionic surfactantsachieved a distinct decrease. Moreover, the removal of Escherichia coli and Phi6 illustratedthe satisfactory disinfection performance of the EC-EO system.The acute toxicity of the EC-EO effluent was reduced comparedto that of raw wastewater. Comparing the results of EC treatment withEO treatment, the EC process provided more significant contributionsto the purification and disinfection of wastewater than the EO process.The oxidants generated in the EO process would ensure the residualpurification and disinfection performance through the long sewer pipe.The physical-chemical parameters and disinfection performancesof the field-scale EC-EO system met the requirement of "Wastewaterquality standards for discharge to municipal sewers-GB/T 31962-2015".However, a certain amount of disinfectant byproducts were formed inthe effluent. Moreover, the techno-economic analysis further illustratedthe feasibility of the integrated EC-EO system for the purificationand disinfection of restaurant wastewater.

Photoelectrocatalysis is effective for the oxidation of ammonium (NH4+) due to the ability to produce oxidizing species such as center dot OH and Cl center dot. Compared to center dot OH and Cl center dot, ClO center dot is a more robust species capable of oxidizing NH4+, which can be produced by the combination of center dot OH and Cl center dot with free chlorine. However, the conventional photoelectrochemical (PEC) systems generally prefer to produce Cl center dot for NH4+ oxidation due to the lack of sufficient HOCl. Herein, a UV-driven PEC system consisting of TiO2/Ru-IrO2 bifacial electrode has been constructed for the enhanced ClO center dot generation for NH4+ oxidation. Large amounts of HOCl can be generated at the Ru-IrO2 interface, which can be further activated by UV irradiation to generate Cl center dot and center dot OH, and then rapidly react with HOCl to generate ClO center dot. The Cl center dot and center dot OH generated at the TiO2 interface could also react with HOCl, further accelerating the generation of ClO center dot. Under UV irradiation, the oxidation rate of TiO2/Ru-IrO2 was 6.7 times than TiO2, 1.5 times than Ru-IrO2, and even 1.24 times than the sum of individual TiO2 and Ru-IrO2. In addition, the bifacial electrode achieved highly efficient NH4+ oxidation for the treatment of actual wastewater, eliminating 81.0 mg L-1 of NH4+ in 120 min with a TN removal rate of 98.4%. The UV-driven PEC system with TiO2/Ru-IrO2 bifacial electrode is a promising potential technology for NH4+ oxidation due to its ability to rapidly produce ClO center dot and oxidize NH4+ to N-2 without the addition of chemical reagents.

The electroreduction of nitrate to ammonia is particularly important in mitigating environmental pollution and obtaining value-added products. Although non-toxic and inexpensive iron-based materials are expected to be a promising catalyst for electrochemical nitrate reduction, ensuring their sustained high activity and inhibiting spontaneous corrosion requires the implementation of complex design. Here we report an economical self-corrosion approach that utilizes Ni 2+ ions in wastewater to control the formation of NiFe layered double hydroxide active phase on iron surface, resulting in high nitrate conversion (97.2%) and ammonia selectivity (90.3%). Coupling nitrate reduction with acid absorption, the conversion from NO 3 − to (NH 4 ) 2 SO 4 (s) for applications such as acting as fertilizer are achieved. This distinctive ‘waste-to-treasure’ perspective not only challenges the conventional belief that corrosion diminishes active phase but also notably improves catalytic efficiency while harnessing valuable resources from wastewater, offering a practical method for converting nitrate to useful ammonia products.

Carbon aerogel (CA) cathode was adopted to an undivided-chamber photoelectrocatalytic system with TiO2 nanotube arrays (TNA) photoanode to enhance the oxidation of hypophosphite (H2PO2-) and simultaneous recovery of metallic nickel (Ni). Both the efficiencies of H2PO2- oxidation and Ni recovery were significantly enhanced after replacing Ti or carbon fiber paper cathode with CA cathode. With 1.0 mM H2PO2- and 1.0 mM Ni2+, the ratio of PO43- production increased from similar to 41% or similar to 54% to similar to 100%, and the ratio of Ni recovery increased from similar to 20% or similar to 37% to similar to 93% within 180 min at 3.0 V. H2PO2- was finally oxidized to PO43- by center dot OH radicals, which was speculated to be generated from UV/H2O2 and bound on TNA photoanode. Meanwhile, Ni2+ was eventually electro-reduced to metallic Ni by a two-electron reduction reaction. The efficiencies of H2PO2- oxidation and Ni recovery were favored at higher cell voltage, faintly acid conditions and larger H2PO2- concentration. The stability of this system exhibited that the ratio of PO43- production increased significantly in each cycle, which was attributed to the increase of H2O2 in-situ-generation via CA cathode caused by deposition of metallic Ni. Finally, the treatment of actual electroless nickel plating effluents was demonstrated.