Bisphenol A Degradation Research Articles

Selective pollutant degradation with a novel persulfate activation cell resistant to environmental interference

The activation of persulfate by heterogeneous catalysts is susceptible to background matrices present in wastewater, resulting in reduced catalytic efficiency during practical applications. Herein, a persulfate activation cell (PAC) is developed by spatially separating pollutants and persulfate into two independent chambers. The CuCoNi-NF catalyst is fabricated and utilized as the electrode of the PAC. The performance of the PAC is compared with a mixed persulfate activation system (PAM) concerning cyclic degradation of various phenolic pollutants and in the presence of different environmental matrices. The results indicate that phenol pollutants such as bisphenol A (BPA) can be degraded in the PAC via transferring electrons to persulfate. The PAC exhibits superior stability compared to the PAM during six cyclic BPA degradation experiments, with BPA degradation rate constant decreasing by 16.7% for PAC and 81.9% for PAM. Over the 192-hour continuous operation period, the PAC attains a BPA removal efficiency of 88.8 ± 5.6%, a TOC removal efficiency of 74.0 ± 4.6%., and a current output of 0.24 ± 0.04 mA. Furthermore, environmental matrices such as cations, anions, humic acid, and natural water environments demonstrate a slight enhancing effect on BPA degradation in the PAC while conversely displaying inhibition in the PAM. High solution conductivity benefits BPA degradation in the PAC by reducing internal resistance. The pH level of the environment (pH 6–9) has minimal impact on the degradation of BPA in the PAC. The pollutants begin to degrade in PAC when the anode potential reaches their oxidation potential, and the stable potential difference between the anode and cathode ensures the continuous oxidation of the pollutants. Our work proposes a novel persulfate activation strategy that can effectively degrade target pollutants by resisting environmental interferences.

Fe-N-C Catalyst Derived from MOFs with Enhanced Catalytic Performance for Selective Oxidation of Emerging Contaminants

Fe-N-C/peroxymonosulfate (PMS) systems have demonstrated selective oxidation of pollutants, but the underlying mechanism and reasons for variability remain unclear. In this work, we synthesized a highly active Fe-N-C catalyst derived from MOFs using a pyrolysis protection strategy. We assessed its catalytic activity by employing PMS as an activator for pollutant degradation. The presence of Fe-Nx sites favored the catalytic performance of FeMIL-N-C, exhibiting 23 times higher activity compared to N-C. Moreover, we investigated the degradation performance and mechanism of the FeMIL-N-C/PMS system through both experimental and theoretical analyses, focusing on pollutants with diverse electronic structures, namely bisphenol A (BPA) and atrazine (ATZ)N-C. Our findings revealed that the degradation of ATZ primarily follows the free radical pathway, whereas BPA degradation is dominated by electron transfer pathways. Specifically, pollutants with a low LUMO- HOMO energy gap (BPA) can be degraded via the FeMIL-N-C/PMS system through the electron transfer pathway. Conversely, pollutants with a high LUMO-HOMO energy gap (ATZ) exhibit limited electron donation and predominantly undergo degradation through the free radical pathway. This work introduces novel insights into the mechanisms underlying the selective oxidation of pollutants, facilitating a deeper understanding of effective pollutant removal strategies.

Production of reactive species during UV photolysis of chlorite for the transformation of micropollutants in simulated drinking water

Chlorite (ClO2−) is a dominant product during chlorine dioxide (ClO2) disinfection. This study investigated the mechanism for UV photolysis of ClO2− and the production of reactive species. The apparent quantum yield of ClO2− is 1.21 ∼ 1.29 mol einstein−1 by UV photolysis at 254 nm at pH 7. UV photolysis primarily transforms ClO2− to ClO2, and then to HOCl/OCl−, ClO3− and Cl−. Both ClO2 and HOCl/OCl− are major reactive chlorine species, which maximum concentrations are 8.4 and 11.0 μM, respectively, at 50 μM ClO2− and pH 7. Meanwhile, hydroxyl radical (HO) and chlorine atom (Cl) are also formed with the concentrations of 3.1 × 10−14 and 7.8 × 10−15 M, respectively. The abatement of structurally diverse pharmaceuticals and personal care products (PPCPs) by UV/ClO2− is compound specific, depending on their reactivity toward ClO2, HOCl/OCl− and HO. The first-order rate constants of PPCPs primarily relying on ClO2 and HOCl/OCl− range from 0.043 to 1.533 min−1 and from 0.240 to 2.071 min−1, respectively, while those relying on HO range from 0.012 to 0.020 min−1. As for phenolics, phenol and bisphenol A (BPA) are completely removed within 15 min and ClO2 plays a dominant role. Natural organic matter (NOM) inhibits the degradation of phenol and BPA in UV/ClO2−, while chloride and bicarbonate shows slight impacts. The transformation pathways of BPA in the UV/ClO2− system initiate with electron transfer, and then hydroxylation, carbonylation, chlorination, and coupling reactions. The formation of disinfection byproducts (DBPs) and total organic chlorine (TOCl) is not significant during UV/ClO2− treatment, and over 90% TOCl are unknown DBPs. This study improves the understanding of the water chemistry of UV photolysis of ClO2−.

Pulsed gas–liquid discharge plasma catalytic degradation of bisphenol A over graphene/CdS: process parameters optimization and O3 activation mechanism analysis

In the present work, pulsed gas–liquid hybrid discharge plasma coupled with graphene/CdS catalyst was evaluated to eliminate bisphenol A (BPA) in wastewater. The optimization of a series of process parameters was performed in terms of BPA degradation performance. The experimental results demonstrated that nearly 90% of BPA (20 mg l−1) in the synthetic wastewater (pH = 7.5, σ = 10 μS m−1) was degraded by the plasma catalytic system over 0.2 g l−1 graphene/CdS at 19 kV with a 4 l min−1 air flow rate and 10 mm electrode gap within 60 min. The BPA removal rate increased with increasing the discharge voltage and decreasing the initial BPA concentration or solution conductivity. Nevertheless, either too high or too low an air flow rate, electrode gap, catalyst dosage or initial solution pH would lead to a decrease in BPA degradation. Moreover, optical emission spectroscopy was used to gain information on short-lived reactive species formed from the pulsed gas–liquid hybrid discharge plasma system. The results indicated the existence of several highly oxidative free radicals such as ·O and ·OH. Finally, the activation pathway of O3 on the catalyst surface was analyzed by density functional theory.

Stable and recyclable FeS-CMC-based peroxydisulfate activation for effective bisphenol A reduction: performance and mechanism

In this study, a novel material, iron sulfide modified by sodium carboxymethyl cellulose (FeS-CMC), was successfully synthetized for peroxydisulfate (PDS) activation to remove bisphenol A (BPA). Characterization results showed that FeS-CMC had more attachment sites for PDS activation due to its higher specific surface area. A stronger negative potential contributed to preventing nanoparticles from reuniting in the reaction and improving the interparticle electrostatic interactions of the materials. Fourier transform infrared spectrometer (FTIR) analysis of FeS-CMC suggested that the coordination of the ligand for combining sodium carboxymethyl cellulose (CMC) with FeS was monodentate. A total of 98.4% BPA was decomposed by the FeS-CMC/PDS system after 20 min under optimized conditions (pH = 3.60, [FeS-CMC] = 0.05 g/L and [PDS] = 0.88 mM). The isoelectric point (pHpzc) of FeS-CMC is 5.20, and FeS-CMC contributed to reducing BPA under acidic conditions but showed a negative effect under basic conditions. The presence of HCO3−, NO3− and HA inhibited BPA degradation by FeS-CMC/PDS, while excess Cl− accelerated the reaction. FeS-CMC exhibited excellent performance in oxidation resistance with a final removal degree of 95.0%, while FeS was only 20.0%. Furthermore, FeS-CMC showed excellent reusability and still reached 90.2% after triple reusability experiments. The study confirmed that the homogeneous reaction was the primary part of the system. Surface-bound Fe(II) and S (-II) were found to be the major electron donors during activation, and the reduction of S (-II) contributed to the cycle of Fe(III)/Fe(II). Sulfate radicals (SO4•−), hydroxyl radicals (•OH), superoxide radicals (O2•−) and singlet oxygen (1O2) were produced at the surface of FeS-CMC and accelerated the decomposition of BPA. This study offered a theoretical basis for improving the oxidation resistance and reusability of iron-based materials in the presence of advanced oxidation processes.

Continuous degradation of plasticizer bisphenol A by catalytic Cu(FexAl2-x)O4@sediment ceramic membranes combined with peroxymonosulfate activation

The Cu(FexAl2-x)O4-embeded sediment ceramic membranes (CuFeAl@SCMs) were fabricated by the low-temperature sintering technology and further employed in a dead-end filtration device for continuous bisphenol A (BPA) degradation with peroxymonosulfate (PMS) activation. Results showed that using river sediment as precursor decreased the fabrication temperature for ceramic membranes (900 °C). The Al-doping Cu(FexAl2-x)O4 spinel solid solution was the predominant product phase, and the membrane with 42 wt% spinel content (CuFeAl@SCM-42) exhibited the highest BPA degradation efficiency (98.3%). SO4∙- and ∙OH were identified as the involved and primary reactive oxygen species (ROS). The density functional theory (DFT) calculations illustrated the forming mechanisms of SO4∙- and ∙OH. Furthermore, the DFT results confirmed that Al doping could enhance the adsorption energy and the electron transfer rate between the spinel and PMS, which encouraged PMS activation for BPA degradation. The outstanding performance of BPA degradation was observed in different pH, PMS content, transmembrane pressure, anions, natural organic matter (NOM) and water matrices, which revealed the excellent practicability, stability and recyclability of the prepared CuFeAl@SCM-42 in complex water environment. Therefore, this study demonstrated the possibility of using dredged river sediment to fabricate the superior catalytic ceramic membranes for wastewater treatment under a low-temperature sintering scheme.

Adsorption and catalytic degradation of bisphenol A and p-chlorophenol by magnetic carbon nanotubes

Phenolic compounds are common industrial pollutants that seriously endangers water ecology and human health. Therefore, the development of efficient and recyclable adsorbents is of importance for wastewater treatment. In this research, HCNTs/Fe3O4 composites were constructed using co-precipitation way by loading magnetic Fe3O4 particles onto hydroxylated multi-walled carbon nanotubes (MWCNTs), showing excellent adsorption capacity for Bisphenol A (BPA) and p-chlorophenol (p-CP), and excellent catalytic ability of activating potassium persulphate (KPS) for degradation of BPA and p-CP. The adsorption capacity and catalytic degradation potential were evaluated for the removal of BPA and p-CP from solutions. The results showed that the adsorption took only 1 h to reach equilibrium and HCNTs/Fe3O4 had maximum adsorption capacities of 113 mg g−1 for BPA and 41.6 mg g−1 for p-CP at 303 K, respectively. The adsorption of BPA fitted well using the Langmuir, Temkin and Freundlich models while the adsorption of p-CP fitted well using the Freundlich and Temkin models. BPA adsorption on HCNTs/Fe3O4 was dominated by π-π stacking and hydrogen bonding forces. The adsorption included both the mono-molecular layer adsorption on the adsorbent surface and the multi-molecular layer adsorption on the non-uniform surface. The adsorption of p-CP on HCNTs/Fe3O4 was a multi-molecular layer adsorption on a dissimilar surface. The adsorption was controlled by forces such as π-π stacking, hydrogen bonding, partition effect and molecular sieve effect. Moreover, KPS was added to the adsorption system to initiate a heterogeneous Fenton-like catalytic degradation. Over a wide pH range (4–10), 90% of the aqueous BPA solution and 88% of the p-CP solution were degraded in 3 and 2 h, respectively. After three adsorption-regeneration or degradation cycles, the removal of BPA and p-CP remained up to 88% and 66%, indicating that HCNTs/Fe3O4 composite is cost-effective, stable and highly efficient to remove BPA and p-CP from solution.

Activation of peroxymonosulfate by a magnetic Co doped NiFe2O4 catalyst for efficient Bisphenol A degradation in water

BackgroundSulfate radicals-based advanced oxidation process (AOPs) were considered to be an effective process for treating organic wastewater. However, the difficult separation of catalysts and the toxicity of metal ions may cause secondary pollution. A new efficient and separable heterogeneous catalyst is desirable to be explored. MethodsMagnetic porous Co-doped NiFe2O4 (CoxNi1-xFe2O4, x = 0, 0.05, 0.2 and 0.5), prepared by a simple sol-gel method, were used as heterogeneous catalysts for the removal of Bisphenol A (BPA) in aqueous solution by the generation of strong oxidizing radicals and reactive oxygen species from activating peroxymonosulfate (PMS). Significant findingsCo addition increased the saturation magnetism of the catalyst and decreased the redox preparation temperature. Increasing the amount of Co-doping resulted in a pronounced enhancement of BPA removal, which the removal rate increased by 33.6% with Co-doping amount from 0 to 0.2. The hydroxyl groups on the catalyst surface plays a vital role in activating PMS, and the main reactive species for BPA degradation was determined as sulfate radical (SO4•-) and singlet oxygen (1O2) in Co0.2Ni0.8Fe2O4/PMS system. The conversion of Ni2+/Ni3+, Co2+/Co3+, and O2-/O2 for maintaining Co0.2Ni0.8Fe2O4 charge balance, PMS was activated simultaneously.

Catalytic degradation of bisphenol A by heterogeneous bimetal composite carbon in the PMS and H2O2 systems: Performance and mechanism

Bisphenol A (BPA) has caused adverse effects on human health and natural environment as a poisonous endocrine disrupting chemical. In this study, the bimetal composite carbon material (Co&Ni/C) with carbon nanotubes was fabricated for BPA degradation by the catalytic pyrolysis method. The dense carbon nanotubes were observed on the carbon surface with a specific surface area of up to 265.68 m2/g. The cobalt oxide and nickel oxide were distributed evenly causing more catalytic sites. The factors affecting catalytic efficiency for degrading BPA by the peroxymonosulfate (PMS) and hydrogen peroxide (H2O2) systems were investigated and compared systematically. The Co&Ni/C showed better catalytic performance with a BPA degradation rate of nearly 80%–100% in the Co&Ni/C-PMS process. However, BPA was difficult to be removed completely by H2O2 with a mineralization efficiency below 40% under most reaction conditions. The different degradation pathways and mechanisms under the oxidation of SO4•− and HO• were also discussed respectively, and the intermediate reactions included radical adduct formation, hydroxylation, skeleton oxidation rearrangement, dehydration and ring cleavage. It was proved that the stable Co&Ni/C possessed good reusability for remaining 77% removal rate of BPA after a 4-stage adsorption-degradation reaction. This paper revealed that the synthetic Co&Ni/C was hopeful as the adsorption material with efficient catalytic activity to provide new insight into BPA in-situ degradation.

Propuesta de ruta de degradación del BPA durante la reacción del ozono

Endocrine-disrupting compounds (EDC) are present in surface water bodies that supply water to the population. One of them is bisphenol A (BPA), which is listed as a carcinogen. This research addresses its degradation through the ozone reaction and presents a likely pathway established by analyzing products and degradation products using gas chromatography-mass spectrometry (GC-MS). BPA degradation was carried out under pseudo-first-order conditions, where liquid phase ozone was the limiting reactive, in doses of ≈2.29 × 10-4 M and BPA doses of 1.25 × 10-4, 17.5 × 10-4, and 35.0 × 10-4 M, looking to have molar ratios [BPA]> [O3]; the oxidation reaction was carried out in a stopped-flow system that allows obtaining results in the order of seconds. The degradation pathway obtained shows the rupture of one of the benzene rings, decreasing the phenolic toxicity of the BPA compound. The proposed pathway can contribute to the understanding of the degradation of BPA in the environment and tertiary treatment processes with the use of ozone. Likewise, it is intended to contribute with new data to the issues of drinking water treatment to offer safe water to the population.

Coupling of Fe-N-C single atom catalyst and ferrocene-modified graphitic carbon nitride as an efficient photocatalyst for removal of pollutants from water

Graphitic carbon nitride (CN) is a promising photocatalyst in wastewater treatment field; however, CN suffers from sluggish photogenerated charge separation. Herein, a single atom catalyst (Fe-N-C) coupled with ferrocene-functionalized CN (CN-Fc) heterostructured composite (FCF-0.05) with superior photocatalytic activity was fabricated. Bisphenol A (BPA) can be removed completely over FCF-0.05/PMS/Vis system within 60 min, the corresponding apparent rate constant (k) was 24 times and 10 times higher than those of CN/Vis and CN/PMS/Vis systems, respectively, which was derived from the efficiently charge separation since generated interfacial heterojunction. Moreover, FCF-0.05/PMS/Vis system exhibited high stability and superior catalytic activity in real water and outdoor environment. Furthermore, the BPA degradation mechanism and pathway have been identified by combination experimental (quench testing, electron paramagnetic resonance and liquid chromatography-mass spectrometry techniques) and density functional theory (DFT) calculations method, providing insight of synthesis of cost-effective photocatalyst with outstanding catalytic activity.

Activation of persulfate by MIL-100(Fe) coated with perylene diimide heterojunction photocatalyst for efficient removal of Bisphenol A in visible light

A new MIL-100(Fe) coated with perylene diimide (MIL-100(Fe)/PDI) heterojunction photocatalytic materials prepared by solution impregnation method. The composite material significantly promoted removal rate for Bisphenol A(BPA) under the MIL-100(Fe)/PDI/Persulfate (PS)/Visible light (Vis) system. The 0.4 g/L MIL-100(Fe)/PDI composite and 8 mM PS achieved 100% degradation of BPA at natural pH. On the MIL-100(Fe)/PDI/PS/Vis system, the kinetic rate constant of the reaction(k) was 0.08714 min−1. The enhanced degradation performance may be attributed to the transport of photo-generated electrons from PDI to MIL-100 (Fe). And this photocatalytic promotes more reactive oxygen species are produced, leading to a greatly accelerated activation of PS to produce highly reactive SO4•−. The free radical quenching assays indicated that h+, SO4•− and •OH play a dominating role. This study presents a new viewpoint for constructing heterojunction photocatalysts of Fe-based MOFs, which provides an effective way for the PS/Vis system to remove organic pollutants, and provides a new direction for building a good eco-friendly system.

Heterogeneous and Photosensitized Oxidative Degradation Kinetics of the Plastic Additive Bisphenol-A in Sea Spray Aerosol Mimics.

Plastics have become ubiquitous in the world's oceans, and recent work indicates that they can transfer from the ocean to the atmosphere in sea spray aerosol (SSA). Hazardous chemical residues in plastics, including bisphenol-A (BPA), represent a sizable fraction of consumer plastics and have been measured consistently in air over both terrestrial and marine environments. However, the chemical lifetimes of BPA and mechanisms by which plastic residues degrade with respect to photochemical and heterogeneous oxidation processes in aerosols are unknown. Here, we present the photosensitized and OH-initiated heterogeneous oxidation kinetics of BPA in the aerosol phase consisting of pure-component BPA and internal mixtures of BPA, NaCl, and dissolved photosensitizing organic matter. We found that photosensitizers enhanced BPA degradation in binary-component BPA + photosensitizer aerosol mixtures when irradiated in the absence of OH. OH-initiated degradation of BPA was enhanced in the presence of NaCl with and without photosensitizing species. We attribute this enhanced degradation to greater mobility and thus reaction probability between BPA, OH, and reactive chlorine species (RCS) formed through reaction between OH and dissolved Cl- in the more liquid-like aerosol matrix in the presence of NaCl. Addition of the photosensitizers in the ternary-component BPA + NaCl + photosensitizer aerosol led to no enhancement in the degradation of BPA following light exposure compared to the binary-component BPA + NaCl aerosol. This was attributed to quenching of triplet state formation by dissolved Cl- in the less viscous aqueous aerosol mixtures containing NaCl. Based upon measured second-order heterogeneous reaction rates, the estimated lifetime of BPA with respect to heterogeneous oxidation by OH is one week in the presence of NaCl compared to 20 days in the absence of NaCl. This work highlights the important heterogeneous and photosensitized reactions and the role of phase state, which affect the lifetimes of hazardous plastic pollutants in SSA with implications for understanding pollutant transport and exposure risks in coastal marine environments.

Regulatable construction of 3D/2D cubic In2O3/copper doped g-C3N4 heterojunction with boost photocatalytic degradation of BPA

In this work, a 3D/2D cubic In2O3/Copper doped graphitic carbon nitride (Cu-CN), heterojunction photocatalysts were synthesized using hydrothermal process and further applied to study its photocatalytic properties for bisphenol-A (BPA) degradation. The cubic three-dimensional In2O3 disperse on the surface of Cu-CN two-dimensional sheet was studied by TEM and XRD. The resulting composites of In2O3/Cu-CN, show the highest photocatalytic activity for 15%-In2O3/Cu-CN at optimized ratio under the visible-light irradiation. As compared to both pure Cu-CN and/or In2O3, the optimized composites of In2O3/Cu-CN show 5–7 fold improvement for the degradation of BPA. Specifically, In2O3/Cu-CN with a In2O3/Cu ratio of 15% displays a kinetic value of 0.01/min, whereas pure Cu-CN and In2O3 have a kinetic value of 0.002/min and 0.0015/min, respectively. The significant enhancement of the photocatalytic behaviour of the heterojunction is attributed to the regulated In2O3/Cu-CN, that not only promotes the separation of photo-induced electrons and electron-hole efficiently, but also the transformation of heterojunction interface via the band position in between the Cu-CN and In2O3. Furthermore, the improvement mechanism of achievable activity is discussed in details. Moreover, 15%-In2O3/Cu-CN also exhibits a good stability and photocatalytic activity as verified through four recycling responses. It is evidenced that the superoxide (•O2−) and holes (h+) play a crucial role as reactive species for the photocatalytic degradation of BPA. This study provides a new opportunity for the preparation of metal oxide/Cu-CN, heterojunction photocatalysts, which has promising application prospects in wastewater treatment and pollution controlling.

N-doped biochar mediated peroxydisulfate activation for selective degradation of bisphenol A: The key role of potential difference-driven electron transfer mechanism

N-doped biochar has emerged as a promising material for peroxydisulfate (PDS) activation to degrade organic pollutants; however, its reaction mechanism remains elusive. In this study, we synthesized N-doped piggery biogas residue biochar (NBRBC) and investigated an NBRBC-mediated PDS activation system for contaminants degradation. The experimental results show that the NBRBC/PDS system exhibits superior activity for selective degradation of bisphenol A (BPA) via an electron transfer pathway (ETP) but does not work for the degradation of bisphenol S (BPS) and hexafluorobisphenol A (BPAF). Density functional theory (DFT) calculations indicate that the removal efficiencies of contaminants are highly related to the potential difference (EPD) between the highest occupied molecular orbitals (HOMOs) of contaminants and the lowest unoccupied molecular orbital (LUMO) of the NBRBC/PDS system (R2 = 0.9568). Contaminants with low EPD (e.g., BPA) were more easily degraded via ETP, while the oxidation of high EPD contaminants (e.g., BPS, BPAF) was inert to ETP. In addition, N-doping process endowed NBRBC with superior PDS activation activity by lowering the EHOMO−ELUMO gap of the NBRBC/PDS system, thereby accelerating electron transfer. Graphitic carbon, pyridinic N and graphitic N are regarded as the predominant active sites. Our NBRBC/PDS system also possessed resistance to the interference of water matrix and efficient mineralization capacity during BPA degradation. This work further clarified the in-depth mechanism of PDS activation over N-doped biochar catalysts, unraveled the mysterious selective degradation behavior of the NBRBC/PDS system toward BPA, and provides a novel perspective for developing a “fit-for-purpose” strategy for organic wastewater purification.

Facile synthesis of novel Z-scheme GO-modified ternary composite as photocatalyst for enhanced degradation of bisphenol-A under sunlight

BackgroundPhotocatalytic degradation using sunlight as a light source has attracted increasing attention because of low operating cost, high degradation efficiency, and environmental friendliness. Metal oxide decorated graphene oxide-based composites as Z-scheme photocatalysts are highly efficient in degrading bisphenol-A (BPA), but such studies are scarce. MethodsThis work employed a facile and green synthesis route for Z-scheme GO-modified ternary composite (ZnO/GO/Mn2O3) photocatalyst. FTIR, FESEM, RAMAN spectra, EDX, BET, XRD, UV–Vis DRS, and PL spectra characterized the synthesized materials. Significant findingsThe results indicate that the catalyst's bandgap energy and surface area were 1.69 eV and 75.35 m2/g. The synthesized ZnO/GO/Mn2O3 composite degrade BPA under sunlight irradiation and completely degraded within 20 min reaction time, pH 7, and using 10 mg/100 mL catalyst dosage. Free radical capturing experiments established that the dominant reactive species for degradation were •O2− and h+ having 95.16 and 91.23% degradation efficiency. The kinetic study show that the pseudo-first-order best presents the kinetic model, and the rate constant (0.201 min−1) was 22.22, 14.28, and 4.08 times higher than Mn2O3, GO, and ZnO/GO, respectively. The enhanced catalytic activity occurred due to the development of an efficient Z-scheme heterojunction, which facilitates the separation of charge carriers, thereby increasing the number of reactive species in the solution. The recycling experiments showed only 10.85% degradation was reduced after five consecutive cycles. Finally, a plausible BPA degradation mechanism was proposed.

Bi3O4Br/Ti3C2 Schottky junction with enhanced active species generation for boosting visible-light photodegradation bisphenol A activity

Enhanced photocatalytic active species generation is an important strategy for tuning its visible-light photocatalytic activity, which is highly related to the separation and transfer of photogenerated charge carriers. In this study, we successfully prepared a novel Bi3O4Br/Ti3C2 two-dimensional/two-dimensional (2D/2D) Schottky junction with special interfacial charge transfer channel via in-situ growth of Bi3O4Br on the surface of ultrathin Ti3C2. The relevant characterization results indicated that Bi3O4Br/Ti3C2 had a stable structure and tight interface binding, which shortened the distance of charge transfer, promoted the separation of photogenerated electron-hole pairs, and then enhanced the generation of active species. Therefore, the optimized photodegradation activity and TOC removal efficiency of Bi3O4Br/Ti3C2 on Bisphenol A (BPA) could reach 91.26% and 70.97% within 60 min visible-light irradiation, respectively. Furthermore, intermediate products and BPA degradation pathways were determined. This work provides a new protocol for the construction of 2D/2D heterojunction photocatalytic systems and regulating photocatalytic active species generation by electronic effective transporting.

Mo and N co-doped iron biochar materials activating peroxymonosulfate for enhanced degradation of bisphenol A: Mechanism discussion and practical application

Mo and N co-doped iron biochar material (Fe/Mox-NC) was prepared through one-pot calcination method with anhydrous iron chloride, ammonium molybdate, and cherry stone powder as precursors. The composite can effectively catalyze activation of peroxymonosulfate (PMS) for organic pollutants degradation, and the removal rate of 20 mg/L bisphenol A (BPA) reaches 99.08% in 30 min in the presence of 0.1 g/L Fe/Mo0.1-NC and 1 g/L PMS. Electrochemical analysis indicates that appropriate doped Mo and N can improve the electron transfer performance of the composite, which enhances the PMS activation property for BPA degradation. Quenching experiments and electron paramagnetic resonance analysis both demonstrated that the Fe/Mo0.1-NC/PMS system generated SO4•−, •OH and 1O2, which involved in BPA degradation. Moreover, a galvanic oxidation process had shown that there existed nonradical pathway which relied on electron transfer. The degradation pathway is proposed by measuring the intermediate products with HPLC-HRMS/MS. Through the exploration of the reaction mechanism, low-valence molybdenum ions can promote the cycle of Fe2+/Fe3+, and the pyridine-N and graphitic-N contained in Fe/Mo0.1-NC can catalyze activation of PMS together with Fe2+. The designed membrane filtration device revealed the feasibility of the composite in dynamic process, which was great significant for actual operation of water treatment. Furthermore, the Fe/Mo0.1-NC/PMS system could effectively decompose organic pollutants in the effluent from sewage treatment plant, achieving 82.6% of total organic carbon removal rate. This study not only prepared a novel heteroatom doped Fe-biochar material for PMS activation to degrade organic pollutants, but also deepened the reaction mechanism and explored its applicability for advanced treatment of real wastewater.

Molten-salt assisted synthesis of polymeric carbon nitride-based photocatalyst for enhanced photocatalytic activity under green light irradiation

The co-condensation of dicyandiamide and aminobenzonitrile (ABN) followed by post-calcination in NaCl-KCl molten salt can endow the Polymeric Carbon Nitride (PCN) with enhanced electron delocalization and defects (-CN and nitrogen defects), leading to extended optical absorption range and improved separation rate of photogenerated carriers. As a consequence, the active-optimized DCN-NaK-90ABN accounts for 76 times promotion than DCN in photodegradation of bisphenol A (BPA) under visible light. More importantly, the photocatalytic activity is demonstrated by the significantly enhanced degradation of BPA and H2 production under λ > 500 nm, which are much better than those of most previously reported PCN-based photocatalysts. Furthermore, the theoretical calculations certify the validity of proposed structure and explain the reactive mechanism combing with the experimental results. Our findings shed light on a new pathway for designing the efficient photocatalysts to capture the long wavelength solar power.

Role of Silica on Clay-Catalyzed Ozonation for Total Mineralization of Bisphenol-A.

Catalytic ozonation for the total mineralization of bisphenol-A (BPA) from aqueous solution was investigated in the presence of various silica-based catalysts such as mesoporous silica, acid-activated bentonite (HMt) and montmorillonite-rich materials (Mt) ion-exchanged with Na+ and Fe2+ cations (NaMt and Fe(II)Mt). The effects of the catalyst surface were studied by correlating the hydrophilic character and catalyst dispersion in the aqueous media to the silica content and BPA conversion. To the best of our knowledge, this approach has barely been tackled so far. Acid-activated and iron-free clay catalysts produced complete BPA degradation in short ozonation times. The catalytic activity was found to strongly depend on the hydrophilic character, which, in turn, depends on the Si content. Catalyst interactions with water and BPA appear to promote hydrophobic adsorption in high Si catalysts. These findings are of great importance because they allow tailoring silica-containing catalyst properties for specific features of the waters to be treated.