Effect Of Electron Acceptors Research Articles

Site Effect of Electron Acceptors on Ultralong Organic Room-Temperature Phosphorescence.

Herein, we successfully observe the site effect of electron acceptors on ultralong organic room-temperature phosphorescence (UORTP) in the case of 7H-benzo[c]carbazole (BCz) derivatives: cyanophenyl on the nitrogen site can promote intersystem crossing (ISC) efficiency and enhance phosphorescence intensity by facilitating n-π* transitions but make a slight change to the phosphorescence wavelength; cyanophenyl on the naphthalene site can cause a remarkable red shift of phosphorescence wavelength by reducing the T1 energy level of BCz derivatives and also enhance phosphorescence intensity by promoting ISC but weaken phosphorescence intensity by lowering the molecular symmetry. Three BCz derivatives (1-BCzPhCN, 2-BCzPhCN, and 3-BCzPhCN) with the electron acceptor cyanophenyl at different sites (nitrogen site and naphthalene site) were synthesized through a combination of the nucleophilic substitution reaction and the Suzuki coupling reaction. The phosphorescence properties of 1-BCzPhCN, 2-BCzPhCN, and 3-BCzPhCN in toluene solution, in a copolymerized MMA film, and in a PVA film were measured and analyzed. 1-BCzPhCN emits intrinsic green ultralong phosphorescence at ∼500, ∼536, and ∼580 nm, while 2-BCzPhCN and 3-BCzPhCN give out intrinsic yellow ultralong phosphorescence with a red shift of 27 and 40 nm, showing that cyanophenyl on the naphthalene site leads to a remarkable red shift of the intrinsic phosphorescence wavelength, but cyanophenyl on the nitrogen site makes a slight difference to the intrinsic phosphorescence wavelength. Under the same condition, the phosphorescence intensity is usually ranked as 1-BCzPhCN/3-BCzPhCN > 2-BCzPhCN, demonstrating that cyanophenyl on the nitrogen site promotes ISC and enhances phosphorescence intensity, but cyanophenyl on the naphthalene site reduces molecular symmetry and accelerates nonradiative dissipation. Time-dependent density functional theory calculations verify that cyanophenyl on the naphthalene site shifts the phosphorescence wavelength by reducing the T1 energy level, and cyanophenyl on the nitrogen site facilitates n-π* transitions to strengthen the phosphorescence intensity. Moreover, three BCz derivatives were doped into DMAP and BBP, separately. The BCz derivatives exhibited different phosphorescence colors and shifts due to interactions with the host materials. We believe this work will give an insight into the structure-property relationship of organic phosphorescence molecules and pave a way for design of colorful UORTP materials.

Comparative analysis of the influence of BpfA and BpfG on biofilm development and current density in Shewanella oneidensis under oxic, fumarate- and anode-respiring conditions.

Biofilm formation by Shewanella oneidensis has been extensively studied under oxic conditions; however, relatively little is known about biofilm formation under anoxic conditions and how biofilm architecture and composition can positively influence current generation in bioelectrochemical systems. In this study, we utilized a recently developed microfluidic biofilm analysis setup with automated 3D imaging to investigate the effects of extracellular electron acceptors and synthetic modifications to the extracellular polymeric matrix on biofilm formation. Our results with the wild type strain demonstrate robust biofilm formation even under anoxic conditions when fumarate is used as the electron acceptor. However, this pattern shifts when a graphite electrode is employed as the electron acceptor, resulting in biofilm formation falling below the detection limit of the optical coherence tomography imaging system. To manipulate biofilm formation, we aimed to express BpfG with a single amino acid substitution in the catalytic center (C116S) and to overexpress bpfA. Our analyses indicate that, under oxic conditions, overarching mechanisms predominantly influence biofilm development, rather than the specific mutations we investigated. Under anoxic conditions, the bpfG mutation led to a quantitative increase in biofilm formation, but both strains exhibited significant qualitative changes in biofilm architecture compared to the controls. When an anode was used as the sole electron acceptor, both the bpfA and bpfG mutations positively impacted mean current density, yielding a 1.8-fold increase for each mutation.

Effect of electron acceptors on electricity production and desalination of caspian sea water using microbial desalination cells

ABSTRACT The Microbial Desalination Cell (MDC) stands out as an innovative and a sustainable technology for both renewable energy generation and water treatment. The choice of electron acceptor significantly influences the efficiency of electricity flow. This study focuses on exploring the MDC performance under different conditions, including variations in cathode electron acceptors, initial pH levels, and hydraulic retention time (HRT). The investigation assesses simultaneous reduction of TDS and power generation from Caspian Sea water, a prominent saline water source in northern Iran, in both open-circuit (OC) and closed-circuit (CC) modes. The findings reveal that sodium hypochlorite, potassium permanganate, and potassium bromate as catholyte achieved TDS reduction rates of 84%, 77%, and 72%, respectively, under CC conditions at pH 5. Furthermore, it was observed that increasing HRT and pH levels lead to a decrease in desalination efficiency and power generation. Notably, the study highlights that the maximum power density was attained using permanganate, hypochlorite, and bromate as catholyte in both OC and CC configurations. By showcasing the adaptability of MDC performance with different cathode electron acceptors under varying conditions, this research offers valuable insights for optimizing MDC efficiency when treating real saline water sources.

Aromaticity of tropylium derivatives: When and why might captodative structures be preferred over the isomeric push‐pull structures?

AbstractAn intriguing question in the general problem of aromaticity is whether captodative aromatic systems with the donor and acceptor substituents at the same carbon of the CC bond can be more stable than the π‐conjugated push‐pull counterparts? The analysis of electronic, magnetic, and structural criteria of aromaticity showed that for conventional organic substituents XO, TfN, (NC)2C, (NO2)2C, Tf2C, the push‐pull tropylidene derivatives [tropylium]+CHCHX− are expectedly more stable than their captodative isomers [tropylium]+C(X−)CH2, with the lowest ΔE for the most strong acceptor Tf2C. A different behavior is observed for XMHlg3 (MB, Al; HlgF, Cl). They are not only structurally and magnetically most aromatic in both series but show the inverse stability of the push‐pull and captodative isomers, the latter being more stable by up to 10 kcal/mol (in gas).The difference between the MHlg3 groups and conventional organic groups is that in the latter the electron density is transferred to the π‐system of the substituent, while the former can accept it only to the σ*(CM) orbital. Thus, when the electron donor and acceptor effects are separated between the σ and π systems, captodative isomers can be more stable than their push‐pull isomers with more extended conjugation.

Enhancing perhydrobenzyltoluene dehydrogenation performance with Co, Mo and Mn metal oxides: A comparative study with Pt/Al2O3 catalyst

In this study, the influence of incorporating Co, Mo and Mn oxides into Pt/Al2O3 catalyst on the dehydrogenation performance of Liquid organic Hydrogen Carrier (LOHCs) is investigated. A notable positive impact on the dehydrogenation process was observed, resulting in enhanced catalytic performance. This effect is associated with improved product desorption and a significant reduction in the by-product formation like methylfluorene. Particularly, the electron-acceptor effect exhibited by molybdenum, emerge as the key factor in enhancing catalytic performance. This effect allowed for the reduction of platinum content without compromising the productivity and selectivity and representing a significant advancement in catalyst design. These findings highlight the potential for Mo-based catalysts to serve as a promising alternatives to Pt-based catalysts in LOHC dehydrogenation processes.

Radical-mediated oxidative desulfurization of dibenzothiophene in a chromophore-enhanced photocatalytic system

This study presents a refined photocatalytic oxidative desulfurization (PODS) approach, leveraging a chromophore-enhanced system specifically designed for the selective degradation of dibenzothiophene (DBT). Employing a ruthenium-based complex (RuL) as a model sensitizer that can be activated by visible light, the system catalytically decomposes peroxydisulfate (S2O82−) into highly reactive radical species, key agents in facilitating efficient sulfur oxidation. In this system, the oxidative degradation of DBT proceeds through a well-defined pathway, sequentially transforming DBT into its sulfoxide (DBT-O) and subsequently into its sulfone (DBT-O2) derivatives, achieving nearly complete conversion to DBT-O2. The electron transfer dynamics within this photocatalytic system are examined through a concentration-dependent decrease in photoluminescence. Moreover, the effects of various electron donors and acceptors on the system’s catalytic activity, as well as the influence of structural modifications of the ruthenium sensitizer are investigated. Comparative evaluations with an alternative 9,10-dicyanoanthracene (DCA)-sensitized system underscore the superior efficiency and selectivity of the sulfate and/or hydroxyl radicals generated in the RuL/S2O82− system. Unlike the superoxide radicals produced in the DCA-sensitized system, the radicals generated in the RuL/S2O82− system exhibit significantly enhanced kinetics for DBT oxidation. The RuL/S2O82− photocatalytic system operates effectively under milder conditions without requiring hydrogen, positioning it as a promising alternative for sulfur removal and potentially contributing to more environmentally sustainable and economically viable fuel processing technologies.

Exploring electron donor and acceptor effects: DFT analysis of ESIPT/GSIPT in 2-(oxazolinyl)-phenols for photophysical and luminophore enhancement.

Understanding excited-state intramolecular proton transfer (ESIPT) is essential for designing organic molecules to enhance photophysical and luminophore properties in the development of optoelectronic devices. In this context, an attempt has been made to understand the impact of substituents on the ESIPT process of 2-(oxazolinyl)-phenol. Electron donating (EDG: -NH2, -OCH3, and -CH3) and electron withdrawing (EWG: -Cl, -Br, -COOH, -CF3, -CN, and -NO2) substitutions have been computationally designed and screened through density functional theory (DFT) and time-dependent density-functional theory (TDDFT) calculations. Furthermore, the ground state intramolecular proton transfer and ESIPT mechanisms of these designed luminophores are explored using the transition state theory. The results reveal that molecules with EDG show higher absorption and emission peaks than molecules with EWG and also indicate that the mobility of charge carriers in 2-(oxazolinyl)-phenol derivatives is significantly influenced by substituents. We found that the EWGs decrease the reorganization energy and increase the vertical ionization potential and electron affinity values, as well as the highest occupied molecular orbital-lowest unoccupied molecular orbital gap, compared to the EDG substituted molecules. Significantly, the excited state (S1) of the keto emission (K) form shows notably larger values for the EDG substitutions. The intersystem crossing pathway efficiency weakens with reduced spin-orbit coupling matrix element in the enol form with electron-donating substituents and vice versa in the keto form during S1-T3 transitions. Our research links intramolecular proton transfers and triplet generation, making these substituted molecules appealing for optoelectronic devices. Introducing EDGs, such as -NH2, boosts the ESIPT reaction in 2-(oxazolinyl)-phenol. This study guides designing ESIPT emitters with unique photophysical properties.

1H NMR SPECTRAL CHARACTERISTICS OF PYRIDO[1,2-A]BENZIMIDAZOLE AND ITS DERIVATIVES

A systematic study of proton NMR spectra of pyrido[1,2-a]benzimidazole and 65 of its mono-, di- and poly-substituted derivatives with substituents in the pyridine and/or benzene fragment was carried out. The choice of certain structures is related to the great practical significance, as well as the complexity of interpreting their 1H NMR spectra. As a result of the research, a number of general patterns of arrangement (characteristic ranges) on the scale of chemical shifts of signals of hydrogen atoms associated with the nucleus of the studied heterocycles have been established. In the 1H NMR spectrum of pyrido[1,2-a]benzimidazole and most of its derivatives, the H1 signal of the pyridine cycle associated with a carbon atom was released in the weakest field, which experienced a strong electron acceptor effect of the nodal endocyclic nitrogen atom. The signal of another heteroaromatic proton H2 was usually detected in the strongest field region of the spectrum. The H8 signal had the smallest chemical shift among the aromatic protons. As the analysis of 1D 1H NOE spectra of a series of pyrido[1,2-a]benzimidazoles showed, this position of the heterocycle was the reaction center for the introduction of an electrophilic particle under SEAr reaction conditions. The H9 signal was detected in a weaker field relative to other aromatic protons. The influence of the electronic nature of the substituent and its position in the condensed heterocycle on the distribution of the electron density in the molecule has been established. It is concluded that the transmission of electronic effects of substituents in pyrido[1,2-a]benzimidazoles differs from benzoid systems. A number of controversial proton signals were attributed by means of 1H-1H NOESY and 1H-15N HMBC spectroscopy. The conducted studies will allow to use the data of 1H NMR spectroscopy to determine potential reaction centers in pyrido[1,2-a]benzimidazoles and other similar condensed pyridine derivatives with a nodal nitrogen atom. For citation: Begunov R.S., Fakhrutdinov A.N., Sokolov A.A., Savina L.I., Bashkov N.E. 1H NMR spectral characteristics of pyrido[1,2-a]benzimidazole and its derivativese. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 5. P. 43-53. DOI: 10.6060/ivkkt.20246705.6971.

Influence of acetate-to-butyrate ratio on carbon chain elongation in anaerobic fermentation

This study investigated the effect of electron acceptor (EA) distribution (acetate to butyrate ratio) on the carbon chain elongation (CCE) process. The results showed that the higher content of butyrate in the initial material led to the higher production of caproate. The maximum production of caproate was 3.74 ± 0.30 g·L−1, which was obtained when only butyrate was added as EA. Little caproate but much butyrate was produced where only acetate was added as EA. This indicated that CCE bacteria preferentially selected acetate as the EA to produce butyrate, and butyrate could be selected as EA to produce caproate only when the acetate content was much lower than butyrate. Unclassified_f_Dysgonomonadaceae, Massilibacterium, and Seramator were the predominant bacteria. Functional enzyme analysis showed that high butyrate content strengthened the fatty acid biosynthesis pathway and reverse β-oxidization pathway. The findings showed the importance of butyrate in CCE for caproate production.

Unravelling substrate availability and redox interactions on methane production in peat soils of China

AbstractThe availability of electron acceptors (EAs) in peatlands determines the potential of methane (CH4) formation under waterlogged conditions. Previous studies suggested that EAs can suppress CH4 production based on Gibbs free energy under the Redox Ladder Theory. However, growing evidence challenges this theory, raising the question of how the coupling of soil substrates with EAs influences CH4 emissions. To answer this key question, peat soils were collected across different climatic zones with different degrees of soil degradation. Anoxic incubation experiments were set up, and continuous addition of SO42−, Fe3+ and humic acid (HA) at different concentrations was followed by characterization of dissolved organic matter using fluorescence spectroscopy. Results suggest that low concentrations of SO42− (1000 μmol L−1), Fe3+ (100 μmol L−1) and HA (30 mgC L−1) promoted CH4 production in most of the peat soils. With the addition of SO42− and HA, increased CH4 emissions were attributed to the facilitation of dissolved organic carbon and increased quinone‐like component C1, which increased the substrate availability for methanogenesis. Furthermore, strengthened microbial activity as indicated by fluorescence component C2 led to higher CH4 production under Fe3+ treatments. On the other hand, at high concentrations of SO42− (5000 μmol L−1), Fe3+ (500 μmol L−1) and HA (50 mgC L−1), CH4 emissions rapidly decreased by 70.65 ± 1.57% to 96.25 ± 0.45% compared to control group without EAs addition, accompanied by increased δ13C‐CH4 signatures indicating the outweighed CH4 production under anaerobic oxidation of methane (AOM) when coupling with reduced EAs. The effect of EAs on CH4 emissions in peat soils could also be related to lability and characteristics of natural organic matter. Our results suggest that the CH4 production in waterlogged peatlands could be facilitated by regulating organic substrates at low EAs concentrations, but excessive EAs will reduce net CH4 emissions through AOM. The valuable discovery of CH4 production and oxidation processes provides insights for mitigating methane emissions from peatlands and regulating global climate change.

Effect of electron acceptors on product selectivity and carbon flux in carbon chain elongation with Megasphaera hexanoica

Megasphaera hexanoica is a bacterial strain following the reverse β-oxidation pathway to synthesize caproate (CA) using lactate (LA) as an electron donor (ED) and acetate (AA) or butyrate (BA) as electron acceptors (EA). Differences in the type and concentration of EA lead to distinctions in product distribution and energy bifurcation of carbon fluxes in ED pathways, thereby affecting CA production. In this study, the effect of various ratios of AA, BA, and AA+BA as EA on carbon flux and CA specific titer during the carbon chain elongation in M. hexanoica was explored. The results indicated that the maximum levels of CA were 18.81 mM and 31.48 mM when the molar ratios of LA/AA and LA/BA were 10:1 and 3:1, respectively. Meanwhile, when AA and BA were used as combined EA (LA, AA, and BA molar amounts of 100, 23, and 77 mM), a maximum CA production of 39.45 mM was obtained. Further analysis revealed that the combined EA exhibited a CA production carbon flux of 49 % (4.3 % and 19.5 % higher compared to AA or BA, respectively) and a CA production specific titer of 45.24 mol (80.89 % and 58.51 % higher compared to AA or BA, respectively), indicating that the effective carbon utilization rate and CA production efficiency were greatly improved. Finally, a scaled-up experiment was conducted in a 1.2 L (working volume) automated bioreactor, implying high biomass (optical density at 600 nm or OD600 = 1.809) and a slight decrease in CA production (28.45 mM). A decrease in H2 production (4.11 g/m3) and an increase in CO2 production (0.632 g/m3) demonstrated the appropriate metabolic adaptation of M. hexanoica to environmental changes such as stirring shear.

Effects of electron acceptors and donors on anaerobic biodegradation of PAHs in marine sediments

Polycyclic aromatic hydrocarbons (PAHs) are typical organic pollutants accumulated in the environment. PAHs' bioremediation in sediments can be promoted by adding electron acceptor (EA) and electron donor (ED). Bicarbonate and sulfate were chosen as two EAs, and acetate and lactate were selected as two EDs. Six groups of amendments were added into the sediments to access their role in the anaerobic biodegradation of five PAHs, containing phenanthrene, anthracene, fluoranthene, pyrene, and benzo[a]pyrene. The concentrations of PAHs, EAs and EDs, electron transport system activity, and microbial diversity were analyzed during 126-day biodegradation in serum bottles. The HA group (bicarbonate and acetate) achieved the maximum PAH degradation efficiency of 89.67 %, followed by the SL group (sulfate and lactate) with 87.10 %. As the main PAHs degrading bacteria, the abundance of Marinobacter in H group was 8.62 %, and the addition of acetate significantly increased the abundance of Marinobacter in the HA group by 75.65 %.

Unveiling the electron-acceptor effect in selenium-doped Cu-N-C catalyst with atomically dispersed active sites for boosting Hg0 oxidation

M-N-C catalysts have considerable potential in the fields of catalysis, such as highly polluting gaseous elemental mercury (Hg0) oxidation. However, the direct application of these kinds of catalysts for mercury removal is stymied by their low catalytic efficiency. Heteroatom-doping in M-N-C catalysts has been proposed as a powerful strategy to the promote catalytic of Hg0, but the origin of boosting catalytic activity is still elusive. Herein, it is disclosed that selenium doping induces an obvious electron-acceptor effect for accelerating the Hg0 catalytic oxidation. The model selenium-doped Cu-N-C catalyst with atomically dispersed active sites was verified by various characterization methods, such as SEM-EDS and scanning transmission electron microscopy. The optimal Cu-NC-Se with Cu/Se ratio of 1:1 exhibited the best Hg0 removal performance, over 8-fold enhancement in their Hg0 oxidation capacities than raw selenium-free Cu-NC. At the optimal reaction temperature of 90 °C, Cu-NC-Se achieved an average Hg0 removal rate of 92.44% within 60 min under single pure N2 atmosphere. As for the influence of flue gas components, the presence of O2 promoted the removal of mercury in Cu-NC-Se, whereas CO2, NO and SO2 served as slight inhibitors. Even after five cycles of the experiment, the average mercury oxidization efficiency was still remained at 88.5%, showing that Cu-NC-Se can be reused with good maintenance of the catalytic activity and atomic dispersion of Cu and Se in the structure. The unsaturated Cu sites connected with pyridinic N on the carbon matrix can serve preferential adsorption to Hg0 and doped selenium. Meanwhile, the selenium doping accelerated Hg0 adsorption and accept sufficient electrons for promoting Hg0 oxidation to forming stable HgSe, which is also corroborated by the theoretical analysis results based on density functional theory. This work not only provides an alternative facile synthetic strategy for developing heteroatom-doping atomically dispersed M-N-C catalysts, but also represents a significant advance for deepening the understanding of the Hg0 catalytic oxidation mechanism on M-N-C catalyst.

Squaric Acid Core Substituted Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells: Effect of Electron Acceptors on Their Photovoltaic Performance

The design and development of sensitizing dyes possessing wide-wavelength photon harvesting encompassing visible to near-infrared (NIR) wavelength regions are unavoidable for increasing the overall efficiency of dye-sensitized solar cells (DSSCs). In this study, three far-red-sensitive squaraine sensitizers were designed computationally, synthesized, and characterized, aiming towards their suitability as a potential sensitizer for DSSCs. It has been found that the incorporation of an electron acceptor moiety in the central squaraine core brought about a red shift in the absorption maximum (λmax) and the emergence of a secondary absorption band in the blue region, thus broadening the photon-harvesting window. In addition, it also lowered the dye’s HOMO energy level enabling a facile regeneration of the photo-excited dye, which improved the photovoltaic performance of SQ-223, exhibiting a photoconversion efficiency (PCE) of 4.67%. Thereafter, to address the issue of wide-wavelength photon harvesting, DSSCs were fabricated by co-adsorbing two complementary dyes SQ-223 and D-131 in various molar ratios. The DSSC fabricated with D-131 and SQ-223 in 9:1 molar ratio displayed the best photovoltaic performance with a PCE of 5.81%, a significantly higher PCE when compared to corresponding individual dye-based DSSCs containing D-131 (3.94%) and SQ-223 (4.67%).

Evaluation of the decolorization potential of azo dyes by aerobic granular sludge

This study assessed the azo dye decolorization potential by aerobic granular sludge (AGS), particularly investigating the effects of different electron donor substrates, redox mediators, dye structures, and alternative electron acceptors. Additionally, the stability and performance of an AGS reactor were evaluated during the treatment of a synthetic azo dye-containing effluent in the absence and presence of a redox mediator. Propionate and anthraquinone-2-sulfonate (AQS) were the best substrate (k1 1.1–1.9-fold higher) and redox mediator (k1 1.4-fold higher), respectively, for Reactive Black 5 (RB5) decolorization. AQS (50 μM) had a greater impact on Reactive Orange 16 (k1 = 15.60 h−1) than on Reactive Red 120 (k1 = 0.48 h−1) and RB5 (k1 = 7.92 h−1). Nitrate and sulfate (100 and 200 mg·L−1) inhibited dye reduction (decreasing k1 from 5.52 to 0.72 and 2.40 h−1, respectively), possibly because they compete with the dye for the electrons in the environment. However, AQS minimized their impact on this process (except for nitrate at 200 mg·L−1). In the reactor, RB5 and AQS did not alter the physical characteristics of AGS and its ability to remove organic matter and nutrients. Finally, the effect of AQS on decolorization was not so intense, increasing only ∼15%.

Insights into adsorption and high photocatalytic oxidation of ciprofloxacin under visible light by intra-molecular Donor-Acceptor like p-n isotype heterojunction: Performance and mechanism

Antibiotics, e.g. ciprofloxacin (CIP) are frequently detected in natural waters and sewage, however, the conventional sewage treatment techniques presents a great challenge for efficient removal them due to the inhibition of bacterial proliferation. Herein, the intra-molecular Donor-Acceptor like p-n isotype heterojunction of phosphorus and boron co-doped hollow tubular g-C3N4 (xB-PCN) was synthesized for high-efficiency visible light photocatalytic degradation of CIP. The Mott-Schottky curves showed that the xB-PCN exhibited both p and n-type conductivities, which probably because the doped boron has electron acceptor effect and the NH/NH2 groups could act as electron donors. This unique property enables xB-PCN to have excellent charge generation, separation and transfer ability for the highly efficient photodegradation of CIP, reaching 87.56% of decomposition efficiency within 1 h with the apparent rate constant (0.01151 min−1) of 6.85 times that of PCN. Furthermore, the 3B-PCN maintained high degradation percentage in tap water (84.63%) and aquaculture wastewater (78.41%). The results of LC-MS and TOC showed that CIP was gradually mineralized and the degradation pathways were proposed. Based on the radical trapping experiments and ESR characterization, the reactive oxygen species involved in the degradation of CIP were checked. This work offers a promising approach for treating antibiotics polluted water based on a metal-free conjugated polymeric g-C3N4.

Photo-Oxidation of Organic Dye by Fe2O3 Nanoparticles: Catalyst, Electron Acceptor, and Polyurethane Membrane (PU-Fe2O3) Effects

The textile industry’s discharges have long been regarded as severe water pollution. The photocatalytic degradation of dyes using semiconductors is one of the crucial methods. The present study efficiently used the mechanical method to synthesize Iron oxide Nanoparticles. XRD, FT-IR, UV-Vis DRS, and Raman analyses were performed to analyze the structural and optical. From the data provided by XRD and Raman data, we believed that the as-synthesized Iron oxide was pure hematite (α-Fe2O3) with a hexagonal structure. Additionally, the EDS results show that the synthesized material is pure. By adjusting specific parameters, including the dye concentration, the catalyst dosage, the pH, and the oxidizing agent such as H2O2 and K2S2O8, the degradation of eosin yellowish using Fe2O3 as a photocatalyst has been discussed. Additionally, the kinetics of eosin yellowish degradation has been studied. A study was also conducted using Fe2O3 nanoparticles attached to polyurethane polymer (PU) to investigate its photocatalytic activity on methylene blue, methyl orange, and indigo carmine. In 30 minutes, nearly 90% of the dyes had degraded. The total organic carbon (TOC) analysis confirmed this result.

Cu(II) and Cr(VI) Removal in Tandem with Electricity Generation via Dual-Chamber Microbial Fuel Cells

Microbial fuel cells (MFCs) have shown great advantages in electricity production, heavy metal removal, and energy recovery. However, the impact and mechanism of conflicting effects of numerous electron acceptors on heavy metal removal remain unknown. The effects of different initial heavy metal concentrations, cathodic dissolved oxygen, and electrode materials on the electricity generation and heavy metal removal efficiencies of Cu(II) and Cr(VI) were investigated in this study. When the initial concentration of Cr(VI) increased from 10 mg/L to 150 mg/L, the maximum voltage, coulomb efficiency, and maximum power density declined from 99 to 44 mV, 28.63% to 18.97%, and 14.29 to 0.62 mW/m2, and the removal efficiencies of Cu(II) and Cr(VI) decreased dramatically from 98.34% and 99.92% to 67.09% and 37.06%, respectively. Under anaerobic cathodic conditions, the removal efficiency and removal rate of Cu(II) and Cr(VI) were lower than those under aerobic conditions. When the cathode electrode was titanium sheet and graphite plate, the coulomb efficiency and maximum power density increased to 38.18%, 50.71%, 33.95 mW/m2, and 62.23 mW/m2. The removal efficiency and removal rates of Cu(II) and Cr(VI) were significantly increased to 98.09%, 86.13%, and 0.47, 0.50 mg/(L h) with a graphite plate, respectively. The pH of the cathode varied considerably greater as the MFC current increased. Cu(II) and Cr(VI) were removed and reduced to elemental Cu, Cu2O, and its oxides as well as Cr(OH)3 and Cr2O3 precipitates on the cathode electrode by cathodic bioelectrochemical reduction.

β-Functionalized palladium(II) porphyrins: Facile synthesis, structural, spectral, and electrochemical redox properties

Two [Formula: see text]-substituted Pd(II) porphyrins, (PdTPP(NO[Formula: see text]Ph2 and PdTPP(Ph)[Formula: see text], were synthesized and characterized by various spectroscopic techniques, and their spectral and electrochemical redox properties were investigated with respect to PdTPP. The single-crystal X-ray structure of PdTPP(NO[Formula: see text]-Ph2 revealed saddle-shape conformation of the macrocyclic core of porphyrin. DFT studies revealed nonplanar saddle shape conformation of PdTPP(Ph)4 with an average deviation of [Formula: see text]-pyrrole carbon atoms from the porphyrin mean plane ([Formula: see text]C[Formula: see text] = ± 0.751 Å) and also 24 core atoms ([Formula: see text]24 = ± 0.368 Å) as compared to PdTPP(NO[Formula: see text]Ph2 ([Formula: see text]C[Formula: see text] = 0.649 Å and [Formula: see text]24 = ± 0.317 Å) due to more [Formula: see text]-pyrrole substitution. Both PdTPP(NO[Formula: see text]Ph2 and PdTPP(Ph)4 exhibited 13-19 nm and 49-59 nm red-shift in the Soret and Q[Formula: see text] bands as compared to PdTPP, respectively. PdTPP(NO[Formula: see text]Ph2 exhibited a very high dipole moment (7.32 D) as compared to PdTPP(Ph)4 (0.239 D) due to the “push-pull” effect of electron donor (phenyl) and acceptor (-NO[Formula: see text] groups at the [Formula: see text]-pyrrole positions of the macrocycle. The redox potentials of PdTPP(NO[Formula: see text]Ph2 anodically shifted ([Formula: see text]E = 0.2-0.4V) as compared to PdTPP and PdTPP(Ph)4 due to the presence of [Formula: see text]-phenyl groups and the strong electron-withdrawing effect of the nitro group. Hence the HOMO-LUMO energy gap of PdTPP(NO[Formula: see text]Ph2 decreased by 0.20 V and 0.28 V as compared to PdTPP(Ph)4 and PdTPP, respectively.

Performance comparison of photocatalysts for degradation of organic pollutants using experimental studies supported with DFT and fundamental characterization

The effect of different metal supported TiO2 catalysts on the photocatalytic degradation of p-Nitrophenol (PNP) was investigated experimentally and supported by Density Functional Theory (DFT) approach. Process optimization studies were carried out using the best performing catalyst and the effect of different electron acceptors was also investigated. Degradation was strongly influenced by operating parameters and oxidants with efficacy as H2O2 > K2S2O8 > air. DFT simulations confirmed higher electrostatic potential in presence of hydroxyl radicals explaining the higher degradation. Overall, this work clearly establishes the effectiveness of electron acceptors in maximizing PNP degradation and explains the interaction of organic pollutants with different radicals.