Activity For Phenol Degradation Research Articles

Nitrogen-doped carbon aerogel supported SnO2 anode for electrocatalytic degradation of phenol: Enhanced generation of free radicals

To obtain a high-efficiency and low-cost electrocatalytic anode for environmental pollutant degradation, a nitrogen doped graphene aerogel supported tin oxide (SnO2-NGA) composite catalyst was prepared and SnO2-NGA/Ti anode was fabricated. The influence of nitrogen doping content on electrocatalytic activity of the catalysts was investigated. The effects of current density and initial solution pH on degradation efficiency were studied. The SnO2-N3.0GA/Ti anode shows good catalytic activity for phenol degradation. The conversion of phenol and COD removal by SnO2-N3.0GA/Ti reached 83.6% and 61.2% within 4 h when applied current density was 5.00 mA/cm2 and initial pH was 3.0. The SnO2-N3.0GA/Ti electrode has higher specific surface area, and lower charge transfer resistance. The nitrogen atoms doping increased the content of pyridinic N species, which is beneficial for providing more in-situ catalytic active sites and enhancing the production of reactive oxygen species, especially hydroxyl radical (•OH). This work provides a novel strategy for synthesis of electrocatalytic anode with enhanced activity for degradation of refractory organic pollutants in water.

Preparation of a new B-CNTs/PSSF composite catalyst for catalytic wet peroxide oxidation of phenol in structured fixed bed

A new structured catalyst consisting of boron-doped carbon nanotubes growing directly on paper-like stainless steel fibers support (B-CNTs/PSSF) was developed for continuous catalytic wet peroxide oxidation (CWPO) of phenol in a structured fixed bed. Firstly, B-CNTs/PSSF was synthesized by chemical vapor deposition (CVD) with phenyboronic acid as a single precursor and CNTs/PSSF was prepared with camphor for comparison. Secondly, the effects of different deposition temperatures, deposition times, and phenylboronic acid dosages on the morphology and properties of B-CNTs were investigated, respectively. The results verified that under the conditions of deposition temperature of 750 °C, deposition time of 20 min, and phenylboronic acid dosage of 2 g, the B-CNTs/PSSF composite catalyst with uniform growth density, wavy and kinked morphology, abundant oxygen-containing functional groups and defect sites, and boron-doped content of 2.96% was successfully prepared. Then, the performance of B-CNTs/PSSF for continuous CWPO of phenol was evaluated. Catalytic results revealed that the B-CNTs/PSSF showed excellent catalytic activity in phenol degradation within 7 h (phenol conversion reached about 100% and total organic carbon (TOC) conversion was up to 68%). In contrast, the average phenol and TOC conversion of CNTs/PSSF were about 75% and 35%, respectively. It indicated that boron doping endowed CNTs with higher catalytic activity.

Preparation of ceramsite using solid residue from anaerobic digestion of waste activated sludge and its enhancing effect on catalytic ozonation

Anaerobic digestion is an environmentally friendly method for reclaiming waste activated sludge. However, it cannot be overlooked that the solid residue generated from this process can still pose environmental risks and impose economic pressure on society. To mitigate and recycle the solid residue, this study utilized it as a primary raw material for manufacturing ceramsite with potential applications in wastewater treatment. The optimal ratio of solid residue to fly ash was demonstrated to be 6:4 with an additional 15% of clay supplementing the raw ceramsite materials. Furthermore, the optimal sintering process was established as preheating at 300 °C for 25 min followed by sintering at 1085 °C for 10 min, as determined through an L16 (44) Orthogonal test. The prepared ceramsite demonstrated advantageous performance parameters that exceeded the standards outlined in the Chinese industry standard CJ/T 299–2008 for water treatment artificial ceramsite. When utilized in an ozonation system, the ceramsite exhibited remarkable catalytic activity for phenol degradation by promoting the decomposition of molecular O3 into hydroxyl radicals. Additionally, it displayed minimal leaching of heavy metals and lower application costs. These findings emphasize its attractiveness in water and wastewater treatment processes and present a practical strategy for reclaiming this solid residue.

NaOH and temperature-induced formation of Bi-based BixOyBrz photocatalyst for phenol degradation

In this work, Bi-based BixOyBrz photocatalyst including BiOBr, Bi2O3/Bi4O5Br2, BiOBr/Bi4O5Br2 and Bi4O5Br2 were successfully prepared by adding NaOH and controlling reaction temperature. BiOBr/Bi4O5Br2 composite displayed excellent photocatalytic activity for phenol degradation compared with other Bi-based BixOyBrz photocatalyst. Toxicity experiments suggested that low environmental toxicity of BiOBr/Bi4O5Br2 composite for the growth state of Sudangrass seeds and Mung bean seeds. A BiOBr/Bi4O5Br2 S-scheme heterojunction was proposed to explain the photocatalytic degradation mechanism.

Enhancing Photocatalytic Degradation via the Synergetic Effect of Vacancies and Built-In Potential in a BiOCl/BiVO4 p-n Heterojunction.

Photoinduced charge separation and surface reactions are essential for ensuring high quantum efficiency of the photochemical and photophysical processes. BiVO4-based heterojunctions are promising materials for high-performance photocatalysts; however, their photocatalytic performance is significantly lower than the theoretical limit due to the sluggish water oxidation dynamics and rapid recombination of charge carriers on the catalyst surface. To address these issues, oxygen vacancies (OVs) are introduced to a rationally designed BiVO4-based heterojunction using built-in potential and gradient OVs to promote the separation of carriers and increase the photocatalytic activity. The heterojunctions with OVs exhibit a 2-fold increase in the photocatalytic activity for phenol degradation compared with that of pristine BiVO4. Additionally, density functional theory is applied to elucidate the synergistic mechanism of light absorption and charge separation in BiOCl/BiVO4 p-n heterojunction photocatalysts containing vacancies. The obtained results demonstrate a synergistic effect of vacancies and the built-in potential, providing a pathway for defect engineering in photocatalytic processes.

Permanganate activation with Mn oxides at different oxidation states: Insight into the surface-promoted electron transfer mechanism

The development of new strategies to improve the removal of organic pollutants with permanganate (KMnO4) is a hot topic in water treatment. While Mn oxides have been extensively used in Advanced Oxidation Processes through an electron transfer mechanism, the field of KMnO4 activation remains relatively unexplored. Interestingly, this study has discovered that Mn oxides with high oxidation states including γ-MnOOH, α-Mn2O3 and α-MnO2, exhibited excellent performance to degrade phenols and antibiotics in the presence of KMnO4. The MnO4- species initially formed stable complexes with the surface Mn(III/IV) species and showed an increased oxidation potential and electron transfer reactivity, caused by the electron-withdrawing capacity of the Mn species acting as Lewis acids. Conversely, for MnO and γ-Mn3O4 with Mn(II) species, they reacted with KMnO4 to produce cMnO2 with very low activity for phenol degradation. The direct electron transfer mechanism in α-MnO2/KMnO4 system was further confirmed through the inhibiting effect of acetonitrile and the galvanic oxidation process. Moreover, the adaptability and reusability of α-MnO2 in complicated waters indicated its potential for application in water treatment. Overall, the findings shed light on the development of Mn-based catalysts for organic pollutants degradation via KMnO4 activation and understanding of the surface-promoted mechanism.

Reactive seeding growth of cobalt-doped MIL-88B(Fe) on Al2O3 membrane for phenol removal in a photocatalytic membrane reactor

In this study, cobalt-doped MIL-88B(Fe) (xCoMIL-88B(Fe)) was successfully synthesized and grown on an Al2O3 support. The cobalt doping of MIL-88(Fe) not only enhanced its visible-light absorption but also improved free electron–hole pair separation. On adding peroxymonosulfate (PMS), 5CoMIL-88B(Fe) powder demonstrated superior photocatalytic phenol removal than that without the PMS or catalyst. The reactive seeding growth of cobalt-doped MIL-88B(Fe) was employed to prepare a 5CoMIL-88B(Fe) membrane coupled with a filtration module to produce a photocatalytic membrane reactor (PMR). The permeate flux of the photocatalytic membrane reactor (PMR) was approximately 2900–4000 L m−2 h−1 bar−1 (LMH), which demonstrated over 90% phenol removal efficiency and exhibited high stability, reusability, recyclability, and high photocatalytic activity for phenol degradation over 10 cycles utilizing 5CoMIL-88B(Fe)@Al2O3 membrane with PMS. This is the first study to demonstrate a cobalt-doped MIL-88B(Fe) membrane through the reactive seeding method for a PMR system, which is an effective and sustainable process for wastewater treatment.

Synthesis of Bi2S3-TiO2 nanocomposite and its electrochemical and enhanced photocatalytic properties for phenol degradation

Bi2S3-TiO2 nanocomposite with improved visible light photocatalytic activity for phenol degradation was the main focus of the current investigation, which involved solvothermal synthesis. FE-SEM, XRD, and TEM analyses of the Bi2S3-TiO2 nanostructure illustrated the successful synthesis of the Bi2S3-TiO2 nanocomposite. According to electrochemical experiments, the Bi2S3-TiO2 nanocomposite had a low recombination rate toward the TiO2 nanorods and Bi2S3 nanoparticles and a quicker interfacial charge transfer. According to the results of optical analyses, the bandgap energies of TiO2 nanorods, Bi2S3 nanoparticles, and Bi2S3-TiO2 nanocomposite were determined to be 3.15 eV, 1.32 eV, and 2.55 eV, respectively. The results of photocatalytic degradation analyses revealed that TiO2 nanorods, Bi2S3 nanoparticles, and Bi2S3-TiO2 nanocomposite all successfully treated 250 mL of a 50 mg/L phenol solution after being exposed to visible light for 125, 230, and 95 min, respectively. This indicates that the Bi2S3-TiO2 nanocomposite had a rapid rate of photocatalytic degradation because of the synergistic effect of Bi Results of the investigation on the application of Bi2S3-TiO2 nanocomposite for phenol degradation in real-world samples showed that it was capable of treating phenol in industrial wastewater effectively through photocatalytic degradation.

Metal-free and fully recoverable MWCNT/g-C3N4 /chitosan nanocomposite thin film with excellent photocatalytic activity against organic pollutant degradation

The hybrid MWCNTs/g-C3N4/CS (Chitosan) NCTF (Nanocomposites Thin Film) was prepared successfully utilising a simple solution casting approach. The growth of a sheet-like structure of NCTF was predicted by SEM and TEM pictures, and XRD corroborated this. The MWCNTs/g-C3N4/CS NCTF showed better photocatalytic activity in visible light phenol degradation. SEM and TEM investigations indicated that increases in charge segregation, nanotube and nanosheet shape, and other parameters accounted for the improved photocatalytic activity. It is essential to highlight that the MWCNTs/g-C3N4/CS NCTF photocatalyst is an excellent catalyst for eliminating pollutants when exposed to visible light. In the fifth cycle, the photocatalyst can get rid of more than 80% of the phenol. The results of the stability and reusability tests indicate that the catalyst is long-lasting and may be reused on multiple times.

Construction of magnetically recoverable MnZnFe2O4@Ag3PO4 Z-scheme photocatalyst for rapid visible-light-driven phenol degradation.

Visible-light-driven magnetic heterojunction as a promising photocatalysts has received much attention in environmental remediation. In this work, novel Z-scheme heterojunction MnZnFe2O4@Ag3PO4 (MZFO@APO) magnetic photocatalysts with excellent visible-light-driven photocatalytic activity are successfully constructed and characterized. The photocatalytic activity for phenol degradation is measured, and photodegradation mechanism is investigated with EPR, radical trapping experiments, and LC-MS. It turns out that the heterojunction introduced MZFO exhibits good adsorption effect on visible light and the direct Z-scheme bandgap alignment of MZFO and APO significantly improves charge separation and electron transfer, outperforming that of pure APO. MZFO@APO-40% with 40% APO content shows the rapid photodegradation performance, obtaining a 100% removal efficiency of phenol (25mg L-1) after 12-min visible light irradiation, and its kinetic constants are approximately 25.3 and 4.9 times higher than that of P25 TiO2 and pure APO, respectively. Especially, MZFO@APO-40% also possesses a high magnetic separation property and can be efficiently reused for 5 cycles. Additionally, EPR and radical trapping experiments confirm that h+, O2-, and 1O2 are the main active species in the photocatalytic process. Hydroquinone and small molecular organic acids such as maleic acid and oxalic acid are detected by LC-MS, which further indicates that the pathway of phenol degradation involves hydroxylation, open-ring reactions, and mineralization reactions. The novel addition of MZFO in photocatalyst construction has the potential to promote its application in environmental remediation.

Enhancing the Photocatalytic Activity of TiO2/Na2Ti6O13 Composites by Gold for the Photodegradation of Phenol

This study aims to synthesize Au/TiO2/Na2Ti6O13 composites to reduce the occurrence of recombination and increase photocatalytic activity in phenol degradation. Gold was used due to its high stability and strong surface plasmon resonance (SPR) properties which make it operate effectively in the visible light spectrum. The prepared composites were characterized using XRD, SEM, TEM, FTIR, and DRS. The results showed that the composite consisted of rutile TiO2 with a crystal size of 38–40 nm and Na2Ti6O13 with a crystal size of 25 nm. The gold in the composite has a crystallite size of 16–19 nm along with the percentage of gold added. Morphological analysis shows that the composite has the form of inhomogeneous spherical particles with gold spread among composites with sizes less than 20 nm. FTIR analysis showed the presence of Na–O and Ti–O–Ti bonds in the composite. The best composite was 3% Au/TiO2/Na2Ti6O13 which had high crystallinity, small particle size, and bandgap energy of 2.59 eV. Furthermore, it had an efficiency 205% better than without gold. After that, cost estimation is proposed as a large-scale application. This study describes the total cost, break-even analysis, and payback analysis for the commercialization needs of the designed photocatalytic catalyst.

Heteroatom-Doped Hierarchically Porous Biochar for Supercapacitor Application and Phenol Pollutant Remediation.

Biochars are considered as promising materials in energy storage and environmental remediation because of their unique physicochemical properties and low cost. However, the fabrication of multifunctional biochar materials with a well-developed hierarchical porous structure as well as self-doped functionalities via a facile strategy remains a challenge. Herein, we demonstrate a heteroatom-doped porous biochar, prepared by a hydrothermal pretreatment followed by a molten salt activation route. With the creation of a high specific surface area (1501.9 m2/g), a hierarchical porous structure, and the incorporation of oxygen-/nitrogen-functional groups, the as-prepared biochar (BC-24) exhibits great potential for supercapacitor application and organic pollutant elimination. The assembled biochar electrode delivers a specific capacitance of 378 F/g at 0.2 A/g with a good rate capability of 198 F/g at 10 A/g, and excellent cycling stability with 94.5% capacitance retention after 10,000 recycles. Moreover, BC-24 also exhibits superior catalytic activity for phenol degradation through peroxydisulfate (PDS) activation. The phenol (0.2 mM) can be effectively absorbed and then completely degraded within only 25 min over a wide pH range with low catalyst and PDS dosages. More importantly, TOC analysis indicates 81.7% of the phenol is mineralized within 60 min, confirming the effectiveness of the BC-24/PDS system. Quenching experiments and EPR measurements reveal that SO4·− and ·OH as well as 1O2 are involved in the phenol degradation, while the non-radical pathway plays the dominant role. This study provides valuable insights into the preparation of cost-effective carbon materials for supercapacitor application and organic contaminant remediation.

Controlling the charge carriers recombination kinetics on the g-C3N4-BiSI n-n heterojunction with efficient photocatalytic activity in N2 fixation and degradation of MB and phenol

The challenges like the photocatalytic reduction of N2 and elimination of contaminants from the wastewater are accessible by low cost, stable, and visible-light-driven semiconductor-based photocatalysis. A novel g-C3N4/BiSI nanocomposite was synthesized by hydrothermal method and applied for the first time in photocatalytic nitrogen fixation and degradation of methylene blue dye and phenol. The physicochemical features of the photocatalysts were studied by XRD, XPS, FTIR, BET, DRS, FESEM, TEM, EDX mapping, PL, EIS, Mott-Schottky, and photocurrent techniques. Experimental results showed that the production of ammonia in the presence of g-C3N4/BiSI nanocomposite was 1280 μmolL−1g−1, while this values for g-C3N4 and BiSI were 274 μmol g−1 L−1 and 126 μmol g−1 L−1, respectively. Moreover prepared nanocomposite exhibited a higher rate constant in the MB (537.5 × 10−4 min−1) and phenol (353 × 10−4 min−1) degradation compared with the counterparts. The charge separation efficiency obviously improved, which was ascribed to the charges migration between g-C3N4 and BiSI in an n-n heterojunction system. In addition, high specific surface area and strong visible light absorption were identified as other factors affecting photocatalytic performance. This unique heterojunction photocatalyst has wide application prospects in environmental treatment.

Supramolecular photocatalysts as electrons storage: Enhanced photocatalytic degradation activity via interfacial charge transfer effect with Fe (Ⅲ)

Supramolecular photocatalysts based on organic π-conjugate semiconductors have attracted a lot of attention in the field of pollutants photodegradation. However, organic semiconductors also suffer from easy charge recombination which resulted in the low photocatalytic activity. In order to improve the separation of photogenerated charge, interfacial charge transfer (IFCT) on supramolecular photocatalysts of porphyrins (TCPP) and perylenediimide (PDINH) by Fe(III) ions was firstly employed to enhance the photocatalytic activity for degradation organic pollutants such as phenol. The photocatalytic activity of phenol degradation under visible light was significantly improved after introduction of Fe(III) in the system. The rate constant of degradation reaction using supramolecular photocatalysts TCPP/PDINH with Fe(III) can reach up to 42 times that of without Fe(III). The photo-induced electron transfer mechanism and the enhancement of charge separation via interfacial charge transfer interactions were studied and discussed. Supramolecular assemblies based on π-conjugated organic molecules could be used as electrons donors in electron transfer system under irradiation, the reducible metal ion Fe(III) as electron traps can effectively capture electrons and promote the electron-hole separation efficiency. This IFCT was proved to be an effective strategy to improve the photocatalytic oxidation activity of supramolecular photocatalysts.

Growth of crystalline WO3-ZnSe nanocomposites: an approach to optical, electrochemical, and catalytic properties

In this study, novel growth of WO3-ZnSe nanocomposites was carried out by a simple, low-cost hydrothermal process under subcritical conditions and is reported for the first time in just 5 h. The products were characterized in detail by multiform techniques: X-ray diffraction, scanning electron microscopy (SEM), optical studies, and Fourier transform analysis. The influence of ZnSe on the structural, morphological, compositional, optical, and catalytic properties of WO3 is demonstrated. The WO3 metal oxide material is grown in a hexagonal crystal structure with wide-band-gap and has been modified by ZnSe to form a composite nanostructures in the nanoscale range. The electrochemical properties of the prepared materials were studied by cyclic voltammetry, which revealed that the synthesized material exhibited remarkable electrochemical supercapacitive activity. Moreover, the composite nanostructures showed excellent photocatalytic activity for degradation of phenol and almost 93% of phenol was degraded with good recyclability and stability. According to The International Commission on Illumination (CIE), the synthesized nanomaterial shows blue emission and is suitable for blue LEDs.

Tuning surface sites to boost photocatalytic degradation of phenol and ciprofloxacin

There is an urgent demand for tuning the selectivity and activity of the photocatalysts to remove co-existent pollutants simultaneously. Herein, we introduced the surficial activity sites into the bismuth oxybromide (BiOBr), including the Bi/Bi-O defects and hetero Cu atoms, and then the higher photocatalytic activity and selectivity of BiOBr were realized for degradation phenol and ciprofloxacin (CIP). It can be found that the Bi/Bi-O defects played more important role in enhancing the photocatalytic activity for degradation of phenol, while the Cu atoms significantly improved the photocatalytic activity for removing CIP. Moreover, the heterogeneous Cu atoms as the activity sites excited the reaction between phenol and CIP even under dark condition and were beneficial for synchronously removing phenol and CIP. This work provides a feasible way for BiOX photocatalyst to remove co-existent pollutants and may have a practical application.

PH dependent synthesis and characterization of bismuth molybdate nanostructure for photocatalysis degradation of organic pollutants.

Bismuth molybdate (Bi2MoO6) nanostructures has attracted many researches as an advanced photocalysts for the organic contaminants. In this paper, bismuth molybdate Bi2MoO6 nanoparticles were synthesized using a simple hydrothermal method at varied pH (2, 4, 6, 8, and 10) for 15h at 180°C. The results reveal the variation pH precursor solutions have a significant impact on the morphology, phase formations, and photocatalytic activity of samples. The synthesized samples at low pH level were characterized by FESEM analysis revealing Bi2MoO6 nanoplates have formed while gradually convert to Bi2MoO6 spherical nanoparticle at high PH level as shown in energy dispersive X-ray spectroscopy (DES) peaks. The X-ray diffraction patterns reveal characteristic peaks corresponding to mixed phases of Bi2MoO6 and cubic Bi4MoO9 at high pH value. The optical absorption study exhibit Bi2MoO6 nanoplates absorbed visible light with blue shift when compared to the cubic Bi4MoO9 structures. Moreover, the photocatalytic activity results revealed that nanoplates in pH = 4 sample has excellent photocatalytic activity for degradation of rhodamine (RhB), methylene orange (MO), and phenol under visible-light irradiation (λ > 400nm) as well as exhibit the photodegradation 90% of phenol within 300min.

How Do Ionic Liquids Affect the Surface Structure of Titania Photocatalyst? An Electron-Trap Distribution-Analysis Study

Titanium(IV) oxide, titania, photocatalyst particles were prepared from titanium alkoxide in the presence of several kinds of ionic liquids, and it was clarified that a group of samples exhibited photocatalytic activity for phenol degradation under the irradiation of light of wavelength >400 nm higher than those of the other group of samples. Although the conventional structural analytical results could not be related to the activity, electron-trap distribution measured by reversed double-beam photoacoustic spectroscopy suggested that a part of the ionic liquid induced the creation of a surface amorphous layer covered with hydrophobic organic residues to enhance the adsorption of phenol on the surface.

Effects of olive mill waste (OMW) contaminated soil on biochemical biomarkers and reproduction of Dendrobaena veneta.

Olive oil industry is economically important in Mediterranean countries. Disposal of olive mill waste (OMW) presents an environmental concern in those countries due to its high salinity and its high level of polyphenols. In order to reuse OMW, those properties have to change either through the filtration process and addition of adsorbents or by composting. One of the most important organisms in composting of organic wastes is earthworms. However, data on the effects of OMW on earthworms are scarce. The main aim of our study was to investigate whether OMW contaminated soil (OMW CS) causes adverse effects on molecular and organism level in epigeic earthworm Dendrobaena veneta and on microbiological activity. Changes of measured biochemical biomarkers (AChE, CAT, GST, lipids, MDA) varied depending on the quantity of added OMW CS and the exposure duration. Oxidative stress occurred after 7days of exposure, while in most cases enzyme activity recovered after 28days. At the highest ratio of contaminated soil (50%), reproduction was completely inhibited. The second aim was to investigate the impact of earthworms on phenol degradation and microbial activity, indicating an important role in the bioremediation of contaminated soils. Our results show that above a certain quantity an OMW CS has an adverse effect on earthworms, while the impact of earthworms on soil microbial activity was positive but transient. Yet, as the results also imply that earthworms have an impact on phenol degradation, they can be used to help remediation of OMW CS and its subsequent usage in agriculture. However, the quantity of OMW CS that can be safely added should be determined first.

A novel microwave-assisted strategy to fabricate multifunctional photoactive titania-based heterostructures with enhanced activity

TiO2-ZnO heterostructures with multifunctional photoactive properties were prepared using the two-stage microwave method. The presence of a binary crystalline system (anatase – wurtzite) was confirmed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The multifunctional character of the obtained photoactive materials was evaluated in two different processes – photocatalysis and photovoltaics. Photo-oxidation tests proved that the TiO2-ZnO heterostructures demonstrate high photocatalytic activity in phenol degradation. Furthermore, the prepared titania-based heterojunction systems were employed as precursors of the semiconducting layers in the DSSCs working electrodes. The photovoltaic parameters of the cells, assembled with electrodes post-treated with TiCl4 solution, have been tremendously improved by as much as forty-fold. Additionally, the scientific novelty of the work should be emphasized, resulting from the utilization of microwave-assisted synthetic strategy for the first time to prepare highly efficient photoactive materials with significant application potential in both photocatalysis and photovoltaics (DSSC cells).