Photocatalytic Degradation Of Bisphenol Research Articles

TiO2–Cu7S4 modified with a carbazole-based conjugated porous polymer for adsorption and photocatalytic degradation of bisphenol A

Adsorption-photocatalytic degradation of organic pollutants in water is an advantageous method for environmental purification. Herein, a feasible strategy is developed to construct a novel dual S-scheme heterojunctions Cu7S4–TiO2-conjugated polymer with a donor–acceptor structure. There are abundant adsorption active sites for adsorption in the porous structure of the composites, which can rapidly capture pollutants through hydrogen bonding and π-π interactions. In addition, the dual S-scheme heterojunctions effectively improve carrier separation while maintaining a strong redox ability. Thus, the optimized 1.5% CST-130 catalysts can adsorb 71% of 20 ppm BPA in 15 min and completely remove it within 30 min with high adsorption capacity and photodegradation efficiency. Therefore, this study provides a new inspiration for synergistic adsorption and degradation of BPA and the construction of dual S-scheme heterojunction.

Rational fabrication of Z-scheme heterojunction ZnFe2O4-seed@TpTt-COF for the visible-light-driven photocatalytic degradation of bisphenol A in food waste leachate boosted by primitive humic acid

Herein, we proposed a method by pre-embedding organic covalent organic framework TpTt-COF(TpTt) (consisting of the electron donor 1,3,5-triazine-2,4,6-triamine (Tt) and electron acceptor 2,4,6-triformylphloroglucinol (Tp) aldehyde) within inorganic ZnFe2O4 core to serve as seed for the in-situ grafting of organic TpTt shell tightly. The as-formed ZnFe2O4-seed@TpTt-COF (Z-S@TpTt) core–shell structure exhibited visible-light-driven photocatalytic degradation of BPA effectively. This may stem from the rationally tuned energy band structure of ZnFe2O4-seed via TpTt pre-anchoring, thus enabled a Z-scheme electron transfer way within the heterojunction to broaden the light adsorption, accelerate the charge transfer and maintain their thermodynamic redox capacity. More strikingly, humic acid (HA) in the actual wastewater (food waste leachate (FWL), where BPA highly frequently presented) could even boost the photocatalytic degradation of BPA. Comprehensive characterizations and DFT calculations revealed that HA acts as a critical “electron shuttle” to further promote the separation of electron-hole pairs via the formation of an EDA complex with the Z-S@TpTt. The gathered electrons on CB of ZnFe2O4-seed and holes on VB of TpTt may generate more •O2– and 1O2, thus the improved performance of Z-S@TpTt core–shell heterojunction in BPA degradation was achieved. Besides the promoted catalytical activity, the convenient separation ability and extraordinary chemical/thermal stability inherited from the magnetic core and the COF shell also enabled robust reuse of Z-S@TpTt heterojunction in FWL. All of these properties endowed Z-S@TpTt heterojunction with the practical application potential to remove BPA in an economical and environment-friendly way, which is also compatible with the “waste control by waste” strategy today.

Peak-like three-dimensional CoFe2O4/carbon nanotube decorated bamboo fabrics for simultaneous solar-thermal evaporation of water and photocatalytic degradation of bisphenol A

Catalytic CoFe2O4 and solar-thermal carbon nanotube decorated bamboo fabrics (CCBF) are fabricated for integrating efficient solar steam generation from wastewater with catalytic degradation of its organic contaminants. Thanks to the numerous porous channels and polar groups of bamboo fabric and the efficient solar-thermal energy conversion of black carbon nanotubes, the porous and hydrophilic CCBF exhibits fast upward transport of water, efficient solar light absorption, and high solar-thermal energy conversion efficiency. The decorated CoFe2O4 not only enhances the solar-thermal energy conversion efficiency of CCBF but also activates potassium peroxymonosulfate to generate abundant highly active species for catalytic degradation of bisphenol A (BPA). Furthermore, folding the CCBF into a peak-like 3D evaporator can enhance solar energy utilization, and gain environmental energy for promoting solar-thermal water evaporation and catalytic degradation performances. The 3D CCBF evaporator achieves a water evaporation rate of 2.72 kg m–2 h–1 under 1-sun irradiation. Meanwhile, 100% of the BPA in the seawater can be degraded within 10 min. An exceptional high purification efficiency of 27.72 kg m–2 h–1 is achieved with the 3D evaporator during a long-term treatment of BPA-containing seawater under 1-sun irradiation. This work demonstrates efficient purification of seawater/wastewater with both metal ions and organic pollutants by simultaneous solar-thermal evaporation of water and catalytic degradation of organic pollutants.

Photocatalytic Applications of Polypyrrole/Polythiophene Co‐Oligomers for the Degradation of Bisphenol A

AbstractWith a view to explore the photocatalytic effect of conjugated oligomers against pollutants, the present work reports ultrasound‐assisted polymerization of pyrrole, thiophene and their oligomers in mol ratios of 80/20, 50/50, and 20/80. The synthesized oligomers were characterized using FTIR, UV‐Vis, and SEM. The co‐oligomers showed band gap values ranging between 2.6 eV–2.9 eV, higher than pristine polypyrrole (PPy) and polythiophene (PTh). The photocatalytic degradation of Bisphenol A was carried out under UV irradiation. Maximum degradation of 86 % within a span of 120 min was reported using PPy/PTh‐80/20 as photocatalyst. A tentative degradation pathway and mechanism of degradation were proposed based on the LCMS data and radical scavenging studies. The studies showed good photocatalytic properties of organic photocatalysts as compared to inorganic metal oxide‐based photocatalysts in terms of higher degradation efficiency attained in a short span of 120 min even for higher concentrations of BPA.

Applicability of NH2-MOF235(Fe)-derived α-Fe2O3/ZnO photocatalyst synthesized by the microwave-assisted method in the degradation of a mixture of phenolic compounds

The NH2-MOF235(Fe)-derived α-Fe2O3-X%/ZnO (X = 15, 20, and 25 wt%) composites were successfully synthesized by microwave-assisted method followed by calcination at 450 °C. The materials were evaluated on the photocatalytic degradation of bisphenol A (BPA), 4-tert-butylphenol (4tBP), and 4-tert-octylphenol (4tOP) mixture (5 mg/L, each) under solar simulated radiation. The synthesized materials were characterized by XRD, FTIR, N2 physisorption analysis, SEM-EDS, XPS, and electrochemical assays. The NH2-MOF235(Fe)-derived α-Fe2O3 incorporation during the ZnO synthesis led to an increase in the specific surface area, improved light absorption in the visible region of the spectrum, and efficient separation of photogenerated charges. Based on the face-centered central composite experimental design matrix and RSM (response surface methodology), the optimal conditions for mineralization of the endocrine-disrupting compound mixture (42.52%) were reached using α-Fe2O3-15%/ZnO photocatalyst at pH 7.0 in 330 min (600 kJ m−2 of accumulated radiation). Moreover, 85.33, 92.82, and 92.72% degradation percentages were obtained for 4tBP, 4tOP, and BPA, respectively. Acetic acid and 2,4-di-tert-butylphenol were the main detected by-products at the end of the treatment. The α-Fe2O3-15%/ZnO material was stable for three reuse cycles for the photocatalytic degradation of the endocrine-disrupting compounds mixture. The scavenger study showed that the O2●- followed by the ●OH radical and photogenerated h+ were the main reactive species involved in the degradation of the contaminants mixture. The Vibrio fischeri assay showed that the obtained effluent was non-toxic. NH2-MOF235(Fe)-derived α-Fe2O3 improves the properties of ZnO, resulting in a promising material to eliminate BPA, 4tBP, and 4tOP mixture from aqueous samples.

Photocatalytic degradation of bisphenol A by temperature-sensitive magnetic hydrogel with enhanced service life

Easy diffusion and low reusability limit the practicality of photocatalysts. In this study, a hollow sphere (HS) heterojunction was synthesized based on oxygen-doped carbon nitride (OCN) and layered double hydroxides (LDHs). A thermosensitive HS hydrogel (HS Gel) was prepared by mixing HS with N-isopropylacrylamide. Bisphenol A (BPA), being widely manufactured and used in commercial and domestical products and its high toxicity, was chosen as the target pollutant to demonstrate the photocatalytic ability and practicality of the HS Gel. HS Gel presented effective BPA degradation (95% degradation in 70 mins, 4.2 × 10−2 min−1 of kobs) at ambient temperature which is much better than kobs = 1.8 × 10−2 min−1 of OCN and kobs = 0.08 × 10−2 min−1 of LDH), and increased by two-fold the recycling service life (retention of >80% degradation efficiency after 13 usage cycles) compared to other carbon-based photocatalysts (retention of >80% degradation efficiency after 5–6 usage cycles). This is due to its multifunctional characteristics (magnetic property and thermal sensitivity). Under ambient temperature, the hydrophilic HS Gel swelled in the aqueous solution, which promoted the photocatalytic reaction between HS and BPA in the gel state. After the reaction, the HS Gel was subjected to shrinkage by high temperature heating to enhance the mechanical strength for recovery. The magnetic recovery was realized by the paramagnetic properties of layered double oxide to reduce environmental interference. Detailed studies of HS gel related to enhanced service life were conducted including structural changes, catalyst leaking and magnetic changing. A new kind of type Ӏ plus Z-scheme mechanism was also proposed based on the Kubelka-Munk equation, UV diffuse reflectance spectroscopy and Mott-Schotty technique.

Photocatalytic degradation of bisphenol A in aqueous solution using TiO2/clinoptilolite hybrid photocatalyst.

Photocatalytic degradation of bisphenol A (BPA) was investigated using commercial TiO2 P25 nanoparticles supported on natural zeolite clinoptilolite (Cli). Employing ultrasound assisted solid-state dispersion method hybrid photocatalyst containing 20 wt% of TiO2, marked TCli-20, was prepared. The structural, morphological and surface properties, and particle size distribution of TCli-20 were studied by X-ray powder diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, atomic force microscopy, Brunner-Emmet-Teller method and laser diffraction. The results revealed a successful loading of TiO2 P25 nanoparticles on Cli surface and the preservation of both zeolitic structure and optical properties of TiO2. The influence of catalyst dose, pH value and the addition of hydrogen peroxide (H2O2) was evaluated. The optimal reaction conditions were 2g/L of catalyst at near-neutral conditions (pH = 6.4) for complete BPA (5mg/L) photodegradation after 180min of exposure to simulated solar light. The addition of H2O2 was beneficial for the degradation process and led to the removal of BPA after 120min of irradiation. BPA removal (60% for 180min of irradiation) was reduced when TCli-20 was tested in bottled drinking water due to the presence of bicarbonate ions which acted as scavengers for hydroxyl radicals. Even though the photocatalytic activity of TCli-20 decreased after several cycles of usage, 70% of BPA was still successfully degraded during the fourth cycle. The reusability study showed easy separation, stability and good photocatalytic ability of investigated cost-effective hybrid photocatalyst.

Photocatalytic degradation of bisphenol A and energy storage capability of novel MoO3/ZnO/GO under visible light irradiation

Photocatalytic degradation of bisphenol A and energy storage capability of novel MoO3/ZnO/GO under visible light irradiation

Photocatalytic Degradation of Bisphenol A by TiO2 Mineralized Using a Polystyrene‐Peptide Template

AbstractBiomineralization is an environment‐friendly strategy for producing inorganic materials, where nitrogen‐doped particles of controlled size can be synthesized. A peptide‐mediated biomineralization was investigated to produce TiO2 particles with enhanced photocatalytic activity. The heptapeptide, HKKPSKS, verified previously as exhibiting TiO2 mineralizing activity, was immobilized on the surface of functionalized polystyrene (PS) bead through N‐ethyl‐N‐(3‐dimethylamino‐propyl) carbodiimide hydrochloride‐N‐hydroxy‐succinimide (EDC−NHS) coupling, so that it acted as the nucleus to trigger TiO2 precipitation on its surface in ambient condition. During the calcination of PS−peptide−TiO2, the PS−peptide template both allowed the formation of porous‐structured particles, and generated nitrogen‐doped crystalline mixed phase (anatase/rutile) TiO2. More than 86 % of bisphenol A (BPA) was decomposed in the presence of optimally calcined TiO2 under visible light in 2 h, whereas commercial P25 catalyst degraded 48 % of BPA. After five cycles of repeated reactions for BPA degradation, the photocatalytic activity of TiO2 decreased by less than 10 %.

Photocatalytic degradation of bisphenol A by GO-TiO2 nanocomposite under ultraviolet light: synthesis, effect of parameters and mineralisation

ABSTRACT In this study, titanium dioxide nanoparticles (TiO 2 ) were loaded on graphene oxide (GO) by hydrothermal method and used as a photocatalyst for the degradation of bisphenol A (BPA). The optimum photocatalytic conditions were evaluated by studying the effect of operating parameters such as initial pH, photocatalyst dosage, radiation intensity, and initial BPA concentration. Under optimal conditions, 88.9% BPA degradation and 65% BPA mineralisation were obtained after 60 min of UV radiation. The presence of anions such as chloride, nitrate, carbonate, and bicarbonate in the reaction reactor significantly reduced the degradation efficiency and the constant kinetic rate by producing reactive species with weaker oxidation potential. The kinetic rate emphasised that the integrated TiO2 and GO nanoparticles have a high degradation activity (0.31 min−1) in the presence of UV compared to the alone process of UV (0.003 min−1) and adsorption (0.007 min−1). The radical trapping experiments showed that h+, •OH, O2 •-, and e− are present in the reaction system, and the h+ and •OH species play a major role in the degradation process. The system energy consumption for different concentrations of BPA (10–100 mg/L) was in the range of 23.06–99.96 kWh/m3. The reusability results showed that the activity of GO-TiO2 in the degradation of BPA did not change significantly even after five cycles, which indicates its excellent photocatalytic stability. To evaluate the performance of GO-TiO2, the photocatalytic activation, oxidants such as H2O2, persulphate, and peroxymonosulfate were evaluated, and the results showed complete degradation of the contaminant at low concentrations of oxidants. The performance of the system for BPA removal in various real solutions such as drinking water, raw water, and treated wastewater was found to be 85.52, 79.52%, and 55.65%, respectively. Based on comparative experiments and trapping of reactive species, the photocatalytic degradation mechanism of BPA by GO-TiO2/UV was proposed.

Photocatalytic degradation of bisphenol A using O-doped dual g-C3N4 under visible light irradiation

Oxygen-doped dual precursor carbon nitride (CN-U10.3M1.7 + AF5) with ammonium formate (AF), which has both characteristics of melamine-derived carbon nitride (CN-M) and urea-derived carbon nitride (CN-U) was prepared by simple one-step heat treatment. CN-U10.3M1.7 + AF5 promotes electron-hole pair separation, controls the bandgap energy, and increases the surface area. The bandgap is controlled from 3.0 to 1.5 eV. The separation of photogenerated electron-hole pairs was efficiently promoted. The surface area was controlled from 11.6 to 91.3 m2 / g. The CN-M / CN-U photocatalyst decomposed about 20% of 5 ppm bisphenol A (BPA) in 90 min under visible light (λ ≧ 420 nm). This result is higher than when only CN-M (10%) and CN-U (15%) are used. In addition, oxygen doping significantly improves the photocatalytic activity of CN-M, CN-U, and CN-M / CN-U. The photocatalytic activity of the optimized oxygen-doped CN-M / CN-U showed a degradation efficiency of 75% in 90 min.

One-step construction of Ti-In bimetallic MOFs to improve synergistic effect of adsorption and photocatalytic degradation of bisphenol A

The key to efficient treatment of organic pollutants in water is to improve their mass transfer efficiency and reaction efficiency. Herein, a one-step construction of new metal-organic frameworks (MOFs) using 4, 4′, 4″, 4″-(pyrene-1, 3, 6, 8-tetrayl) tetra-benzoic acid as a photosensitizer ligand and Ti-In as bimetallic centers has been constructed. The results exhibited that increased specific surface area was obtained by Ti-In-MOF(1:1), which improved the adsorption performance of 50 ppm bisphenol A to 38% and facilitated it complete degradation upon light irradiation in 20 min, being much faster than that of single In/Ti-MOFs. For Ti-In-MOF(1:1), the In-MOF parts enhanced the adsorption capability, meanwhile the Ti-MOF parts based on infinite Ti-O chains realized the effective separation of photogenerated carriers. A synergistic role of adsorption and degradation achieved rapid mass transfer and excellent catalytic degradation performance. This investigation will provide a novel MOF construction strategy for efficient catalytic application in environmental pollutants.

Photocatalytic degradation of bisphenol A over Co-BiOCl/biochar hybrid catalysts: Properties, efficiency and mechanism

In our research, Co-BiOCl/biochar hybrid catalysts were successfully combined using a facile hydrothermal process and applied in the degradation of bisphenol A (BPA) under vacuum ultraviolet/ultraviolet (VUV/UV) irradiation. The results showed that the biochar loading and cobalt (Co) doping strategies enhanced the catalytic efficiency of BiOCl for the removal of BPA (93.8%) via a narrower band gap, a stronger ultraviolet response, and higher electron/hole (e−/h+) pairs separation. According to the first-principles calculations, the energy band gap of Co-BiOCl was 1.47 eV, which was 1.19 eV lower than that of BiOCl (2.66 eV). Under the optimum operating conditions, a BPA elimination rate of over 90% was achieved in 90 min even after five cyclic experiments were performed. This implied the synthetic Co-BiOCl/biochar catalyst presented optimized photocatalytic activity and stability. Furthermore, trapping experiments demonstrated that hydroxyl radicals (OH), photogenerated holes (h+), superoxide radicals (O2−), and hydrated electrons (eaq−) were the main participating species in BPA degradation by the Co-BiOCl/biochar catalyst under VUV/UV illumination. Significantly, LC-MS was used to propose a probable BPA degradation pathway. Moreover, the photocatalytic mechanism of the Co-BiOCl/biochar catalysts for BPA degradation under VUV/UV illumination was also investigated by the first-principles calculations.

Photocatalytic degradation of bisphenol a from aqueous solution using bismuth ferric magnetic nanoparticle: synthesis, characterization and response surface methodology-central composite design modeling.

Bisphenol A (BPA), as endocrine-disrupting compound (EDC), is extensively used as an important chemical in the synthesis of polycarbonate polymers and epoxy resins. BPA absorption into the body can result in the development of metabolic disorders such as low sex-specific neurodevelopment, immune toxicity, neurotoxicity and interference of cellular pathway. Therefore, the presence of BPA in the body and the environment can create hazards that must reach standards before being discharged into the environment. In this study, bismuth ferric nanomagnetic (BFO NMPs) were successfully synthesized via sol-gel method and developed as photocatalysts for BPA removal under visible light irradiation. FE-SEM, TEM, PL, XRD, UV-Vis DRS, VSM, EDX, and FTIR were used to characterize the BFO NMPs. RSM model (R2 = 0.9745) showed a good correlation between experimental and predicted removal efficiency of BPA. The investigation of four independent variables indicated that pH had the most significant positive effect on the degradation of BPA. Under optimal conditions (pH = 4.042, catalyst dose = 7.617mg, contact time = 122.742min and BPA concentration = 15.065mg/L), maximum degradation was calculated to be 98.7%. After five recycles, the removal of BPA remained >82%, which indicated the proper ability to reuse the catalyst. In conclusion, it can be stated like BPA, the prepared BFO NMPs is a promising photocatalyst for practical application in organic pollutant decomposition.

Photocatalytic degradation of bisphenol A on BiOI nanostructured films under visible LED light irradiation

Bismuth oxyiodide (BiOI) films were prepared through the Layer-by-Layer (LbL) method for the first time using powdery BiOI microstructures previously synthesized by a solvothermal method. BiOI films and powdery samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and UV–vis diffuse reflectance spectroscopy. The chemical composition and morphology of the powdery BiOI microstructures was not affected by the deposition process. The photocatalytic activity of prepared BiOI films and powdery samples was evaluated in the degradation of bisphenol A under white LED (Light emitting diode) light irradiation. The BiOI film composed by 1 layer (BiOI-1) of BiOI flower-like microspheres exhibited the highest photocatalytic activity in comparison with BiOI as powder and BiOI films composed by 3 (BiOI-3) and 5 layers (BiOI-5). The probable reasons for the highest photocatalytic performance of BiOI-1 may be related to its larger surface area, morphological characteristics, and fractal geometry. The results obtained in this work demonstrate that the LbL method can be a suitable technique to fabricate BiOI films with photocatalytic properties for water treatment.

Construction of dual Z-scheme Bi2WO6/g-C3N4/black phosphorus quantum dots composites for effective bisphenol A degradation

In this work, a novel dual Z-scheme Bi2WO6/g-C3N4/black phosphorus quantum dots (Bi2WO6/g-C3N4/BPQDs) composites were fabricated and utilized towards photocatalytic degradation of bisphenol A (BPA) under visible-light irradiation. Optimizing the content of g-C3N4 and BPQDs in Bi2WO6/g-C3N4/BPQDs composites to a suitable mass ratio can enhance the visible-light harvesting capacity and increase the charge separation efficiency and the transfer rate of excited-state electrons and holes, resulting in much higher photocatalytic activity for BPA degradation (95.6%, at 20 mg/L in 120 min) than that of Bi2WO6 (63.7%), g-C3N4 (25.0%), BPQDs (8.5%), and Bi2WO6/g-C3N4 (79.6%), respectively. Radical trapping experiments indicated that photogenerated holes (h+) and superoxide radicals (•O2−) played crucial roles in photocatalytic BPA degradation. Further, the possible degradation pathway and photocatalytic mechanism was proposed by analyzing the BPA intermediates. This work also demonstrated that the Bi2WO6/g-C3N4/BPQDs as effective photocatalysts was stable and have promising potential to remove environmental contaminants from real water samples.

Effects of hydrothermal parameters on the physicochemical property and photocatalytic degradation of bisphenol A of Ti-based TiO2 nanomaterials

Effects of hydrothermal parameters on morphology, crystal structure, light absorption, separation efficiency of photo-generated charge carriers, and photocatalytic removal of Bisphenol A (BPA) of Ti-based TiO2 nanomaterials were systematically investigated. Through changing hydrothermal parameters, TiO2 nanobelts, TiO2 nanosheets and TiO2 nanowires were prepared. With increasing NaOH concentration, hydrothermal temperature, and hydrothermal time, more TiO2 with (101) crystal plane grew on Ti substrate, resulting in higher crystallinity. The UV-light absorption enhanced with increasing NaOH concentration, but decreased with improving hydrothermal temperature, hydrothermal time, and HCl concentration. Variation of UV-light absorption was mainly affected by morphology, and UV-light absorption of TiO2 nanomaterials with different morphologies was arranged in order of nanobelts > nanosheets > nanowires. The hydrothermal growth of TiO2 nanomaterials on Ti plate conformed to Ostwald ripening mechanism. Variation trend of photo-generated current was consistent with that of BPA degradation, they both first increased and then decreased within investigated range. The optimal NaOH concentration, hydrothermal temperature, hydrothermal time, and HCl washing concentration were 1 M, 170℃, 28 h, and 0.1 M, respectively. Under this condition, Ti-based TiO2 nanosheets exhibited the highest BPA removal efficiency (92.7%), which was due to highly ordered nanosheet structure, good crystallinity, appropriate UV-light absorption and high separation efficiency of electron-hole pairs.

Construction of a novel Ag/Ag3PO4/MIL-68(In)-NH2 plasmonic heterojunction photocatalyst for high-efficiency photocatalysis

To boost the visible light catalytic performance of typical metal-organic frameworks (MOFs) materials (MIL-68(In)-NH2), a novel stable Z-scheme Ag/Ag3PO4/MIL-68(In)-NH2 plasmonic photocatalyst was constructed by electrostatic attraction, co-precipitation reaction, and in-situ photoreduction reaction methods for the first time. The photocatalytic activities of the photocatalysts are systematically explored by the photocatalytic degradation of bisphenol A (BPA) and reduction of Cr(VI) under visible light. Ag/Ag3PO4/MIL-68(In)-NH2 displays the best photocatalytic performance among the as-prepared photocatalysts. The rate constant of BPA degradation on Ag/Ag3PO4/MIL-68(In)-NH2 is 0.09655 min−1, which is better than many reported photocatalytic materials. It also achieved a maximum rate constant of 0.02074 min−1 for Cr(VI) reduction. The boosted photocatalytic performance is due to the improved absorption caused by localized surface plasmon resonance (LSPR), effective interface charge transfer and separation, and more reactive sites provided by the large specific surface area. Besides, the photocatalytic degradation pathway of BPA is concluded according to GC-MS analysis. Finally, a more reasonable Z-scheme mechanism is speculated and verified through a series of characterizations and simulations, such as time-resolved photoluminescence spectroscopy (TRPL), electron spin resonance (ESR), and finite difference time domain (FDTD) method.

Influence of aqueous chloride and bromide ions on bisphenol A degradation efficiency with zinc oxide nanoparticles

Zinc oxide (ZnO) nanoparticles (NPs) have been widely investigated for applications in photocatalytic degradation of organic pollutants in wastewater. Despite the advantages of robust ZnO material, its photocatalytic activity is greatly affected by environmental factors. Halogen ions are commonly found in wastewater, which directly affect the pollutant aggregation and sedimentation, therefore it is necessary to discuss their effect on the photocatalytic degradation. The current study assesses the halogen ions effect on the photocatalytic degradation of bisphenol A (BPA) using different dosage of sodium chloride (NaCl) and sodium bromide (NaBr). The microstructural characterization of ZnO NPs was conducted by transmission electron microscopy and hydrodynamic size was analyzed through dynamic light scattering. The effective BPA degradation with ZnO NPs was observed and pseudo-first-order kinetics was calculated. The increase of ZnO NPs dosage from 10 to 100 mg L− 1 enhanced the degradation rate constant of BPA up to 0.089 min− 1 (14.8 folds). In order to evaluate the role halogen ions to degrade BPA, NaBr and NaCl were used. The degradation rate was reduced to 0.0034 min− 1 after the addition of NaBr due to the increase in hydrodynamic particle size, thereby restricting the light adsorption capacity. Noteworthy, upon addition of NaCl up to 500 mM concentration, only a slight decrease on BPA degradation rate was observed. Therefore, this study unveils the role of chloride ions as an effective medium for BPA degradation by ZnO NPs, without aggregation, and provides a novel platform for the treatment of organic pollutants in saline water.

Photocatalytic Degradation of Bisphenol A (BPA) Present in Aqueous Solution Using g-C3N4 Nanosheets Under Solar Light Irradiation

A graphite-like carbon nitride (g-C3N4) nanosheet sample was synthesized from a melamine precursor by a method of simple direct heating in a semi-closed system followed by thermal oxidation etching at 550 °C for 12 h. The sample was labelled as (g-C3N412h) and was systematically characterized. Moreover, the results were then compared with a pristine g-C3N4 sample for the degradation of Bisphenol A (BPA) present in water. Bisphenol A (BPA) is an endocrine disruptor. It is known that the BPA is one of the most harmful organic materials and that it does not degrade easily in the environment. It was therefore selected as a target to test the photocatalytic activity of prepared carbon nitride nanosheets under direct solar irradiation. The results showed the structure of the g-C3N4 nanosheets when the sample had been treated for a longer time compared to the regular treatment time. The optical band gap results remained the same, indicating the existence of a g-C3N4 backbone structure. However, the XPS and FTIR spectra showed some modification on g-C3N4 after longer etching treatment time such as the C-H, CO and N pyridinic structure. The photocatalytic degradation of Bisphenol A by the g-C3N4 nanosheets under solar irradiation was much better (around 60%) than that with the g-C3N43h bulk sample (around 30%). This enhanced photocatalytic activity can be attributed to multiple factors such as the smaller particle size, rich carbon surface and high surface area exhibited by the g-C3N4 nanosheets. This further indicates that g-C3N4 can be used with solar irradiation to treat wastewater containing endocrine disruptor chemicals.