Search

Treatment of municipal wastewater (MWW) is one of the potential challenges in developing/underdeveloping countries. The present work demonstrates treatment of MWW using the irradiation effect of ultrasound (US) and light-emitting diode ultraviolet (UVC). The process was further intensified using the combined effect of irradiation with H2O2/O3. MWW consisted of elevated pathogen concentrations of Enterobacter aerogenes, Escherichia coli, and other coliforms with a total coliform concentration of 12 × 103CFU/mL. The efficiency of processes was analyzed on complete inactivation of total coliform, pseudo-first-order kinetic rate constant, synergy analysis, COD removal, and process economics. Nearly complete elimination of pathogen was observed for the US+UVC effect in 20 min, whereas 83 and 98.6% of removal were observed for US and UVC effects, respectively. Further combination of US and UVC with H2O2showed an enhanced inactivation rate for total coliforms. The least treatment time of 10 min was required for US–UVC–H2O2for complete inactivation with a pseudo-first-order kinetic rate constant of 3.56 ± 0.3 min–1. The synergy coefficient for UVC–H2O2(1.9) was much higher as compared with other effects. The operational cost for the UVC–H2O2process was 12.6 times higher than that for the UVC–O3process, with a synergy coefficient of 1.1. Synergy of US/UVC with H2O2/O3reduced the initial oxidant requirement. It was reduced by 50% compared to nonsynergy studies. Based on process analysis, UVC–O3was observed as the most suitable combination for the inactivation of pathogens present in MWW with a COD removal of 91.1% and an operational cost of 0.3$/m3. The synergy of UVC–O3has potential beneficial effects to overcome the limitation of individual processes and development of large-scale processes.

Artificial photosynthesis, which mimics the natural process used by plants, offers a promising strategy for harnessing solar energy to produce valuable fuels. One intriguing approach is the photocatalyst-enzyme attached system, where a photocatalyst captures light energy and transfers it to an enzyme to drive specific chemical reactions. This study describes the synthesis of a novel photocatalyst (MWCNTCEBr) formed by coupling multiwall carbon nanotubes (MWCNTs) with a dye ethidium bromide (EBr) via a condensation reaction. The resulting photocatalyst exhibits excellent charge separation and migration abilities, leading to enhanced photocatalytic activity. Notably, MWCNTCEBr photocatalyst successfully converts α-Ketoglutarate to L-Glutamate (81.9%) and photo-regeneration of NADH (76.20%) under the influence of solar radiation. Therefore, the study demonstrates the development and the application of MWCNTCEBr photocatalyst for impressive NADH regeneration and bio-transformation.

Covalent organic frameworks (COFs) have developed as highly crystalline porous organic materials with promising applications in gas adsorption and separation, catalysis, energy storage, and solar cells. It is highly valued due to the suitability of the optical band gap as well as its excellent light-harvesting capability. Therefore, herein we report on the newly in-situ prepared highly efficient polymeric framework as a photocatalyst (Me-CAFs), which is melem (Me) covalently coupled with 2, 6-diamino anthraquinone (A). The melem covalently coupled 2,6-diamino anthraquinone framework (Me-CAFs) photocatalyst follows the Z-scheme to mimic half of the natural photosynthesis with an organometallic complex as an electron shuttle. Herein, our research offers an integrated method for combining the light-harvesting photocatalytic system for NADH regeneration cofactors with the anchoring electron mediator.

Graphical Abstract:

Oxidation reactions are required in the chemical industry to manufacture a variety of fine compounds. However, chemists continue to have challenges with the selectivity of oxidized compounds, which must be addressed. In the current study, highly effective organic acid fuchsin (AF) was infused with boron-enriched graphitic carbon nitride (Ben-g-C3N4), resulting in an AF-Infused-Ben-g-C3N4nanocomposite photocatalyst via condensation method. The nanocomposite activity was tested for benzylamine oxidation processes. The heterojunction increased charge carrier separation, increasing imine yields by up to 99% while maintaining > 99% selectivity. Up to five cycles, the reaction yields with the recovered photocatalyst remained reasonably similar to those with the fresh photocatalyst, with no loss of photocatalytic activity or leaching of the acid fuchsin content. The physicochemical parameters of the heterojunction were also identified and investigated. The outstanding photocatalytic activity of AF-Infused-Ben-g-C3N4nanocomposite photocatalyst and one-pot two reactions has a wide range and may be extended to other organic transformations.

[Display omitted]

Melem (M) is an emergent metal‐free material due to its nature abundance and easy preparation. Synergetic escalation of band gap generation and charge transfer of M to increase solar chemical synthesis ability remains a hot challenging topic yet. Herein, we designed first time in‐situ prepared sulfur‐doped covalent melem‐based frameworks (S‐CMFs) photocatalyst for NAD(P)H regeneration and 1,3‐oxathiolane‐2‐thiones production under solar light irradiation. S‐CMFs photocatalyst shows excellent photocatalytic stability and activity over the pristine CMFs and M. The presence of sulfur in frameworks drastically improved the photocatalytic efficiency of S‐CMFs due to its unique properties such as enhanced the solar light adsorption ability, molar extinction coefficient, slow charge recombination, fast charge separation and transportation of solar light to generate electrons‐holes. Hence, S‐CMFs photocatalyst has a vital role in the regeneration of NADH and NADPH with 54.84 and 51.05 % catalytic efficiencies and ~ 99 % for yields and selectivity of 1,3‐oxathiolane‐2‐thiones under solar light. This study demonstrates that the Z‐scheme hetero junction and photocatalytic reaction using S‐CMFs would be a suitable route for the production of solar fuel via artificial photosynthetic system.

Covalent organic frameworks (COFs) exhibit excellent characteristics in the optoelectronic and photocatalytic areas. The broad demand for highly efficient flexible clothes enhances the investigation of multifarious COFs materials. Currently, COFs have materialized as future generation flexible clothes layered materials with previously designed π‐π stacking skeletons and extremely efficient ordered structures, which are more fascinated for countering their photocatalytic characteristics. Still, COFs are generally formed as solid materials because of direction‐dependent growth which make them unpredictable to integrate into flexible clothes. Here, by choosing tetraamino‐benzoquinone (T) and N,N'‐di‐(4‐benzoic acid)‐perylene‐3,4,9,10‐tetracarboxylic acid diimide (BP) monomers with photocatalytic activity, ornately designed sun‐light‐responsive COFs with well‐ordered donor and acceptor moieties are in situsynthesized on flexible activated carbon cloth (fACC), eventually forming TBPCOF‐fACC structures. Ultra‐responsive photocatalyst is fruitfully fabricated with the TBPCOF‐fACC structure and showed an excellent selective C‐S arylation performance with high yields (99 %) at ambient temperature. The research presents new plans for constructions of advanced light harvesting functional flexible clothes with programmable COFs material, covering the technique for a creation of highly improved applications in photocatalytic and various areas. The TBPCOF‐fACC based humidity sensor shows the average sensitivity as 1.58 MΩ/%RH along with calculated response and recovery time as 15 s and 55 s respectively. The sensor has 96.20 % repeatability and shows long term stability.

Selective radical‐radical coupling of terminal alkynes and thiol has been broadly used in chemical synthesis, providing plausible entries to the formation of anti‐Markovnikov products. Because of the selective control and Kharasch effect, the formation of Markovnikov products still remains an immense challenge. Herein, we designed a covalent organic polymer, poly(naphthalene 1,4,5,8‐tetracarboxylic dianhydrideimide‐benzoquinone) through in situ polymerization on activated flexible carbon cloth to function as a light harvester material for selective Markovnikov radical‐radical coupling of terminal alkynes and thiol. Mechanistic explorations verified that cross‐coupling between radical of terminal alkynes and thiol might be the key route in this organic transformation, such as C—S bond formation. This selective radical‐radical Markovnikov of cross‐coupling protocol provide an opportunity to assist the synthesis of valuable vinyl sulfide. Additionally, the synthesized material has been explored as liquefied petroleum gas (LPG) sensor for 0.5, 1.0, 1.5, and 2.0 vol% LPG, respectively. At 2.0 vol% LPG, it shows maximum sensor response as 635.29. Least response and recovery times are 2.44 and 1.0 s, respectively. A newly designed highly efficient solar light active covalent organic polymer, poly(naphthalene 1,4,5,8‐tetracarboxylic dianhydrideimide‐benzoquinone) through in situ polymerization on activated flexible carbon cloth (PNIB‐AFCC) photocatalyst is used for selective radical‐radical cross coupling of terminal alkynes and thiol. This selective radical‐radical Markovnikov of cross‐coupling reaction has been providing an opportunity to aid the solar chemical synthesis. Additionally, this PNIB‐AFCC photocatalyst is proven as an excellent liquefied petroleum gas sensor with better response and recovery time.

In artificial photosynthesis process the photocatalyst‐enzyme attached system is a best strategy to utilize solar energy for solar chemical/fuels production. Herein, we prepared a solar light active graphene‐based photocatalyst received by the covalent attachment of 9‐aminoanthracene (AA) chromophore with chemically converted graphene (CCG) for highly efficient 1,4‐NADH regeneration (79.9 %) and conversion of α‐ketoglutarate (α‐KG) in to L‐glutamate (L‐GM) (88.3 %) in 2 hrs. The present result is a benchmark example of highly selective solar light active enzyme based artificial photosynthetic system for selective formation of L‐GM from α‐KG.

Graphitic carbon nitride (g-C3N4) is a promising two-dimensional semiconducting material that has shown potential for various applications in the field of photocatalysts due to its thermal stability and excellent electronic properties. However, pristine g-C3N4has a wide optical band gap, which limits the active absorption of solar light in the spectral region below 420 nm. One way to improve the optical character is by doping with a sulfur heteroatom to make sulfur-doped g-C3N4(S-g-C3N4), which has a smaller band gap relative to the pristine g-C3N4. Herein, we have developed a new type of S-g-C3N4composite incorporating eosin-Y (EY–S-g-C3N4) by employing the co-polymerization approach between eosin-Y (EY) and S-g-C3N4. In this composite, eosin-Y moieties act as external photosensitizing groups. The optical characteristics of EY–S-g-C3N4were investigated using density functional theory, various optical spectroscopies, and various imaging techniques. From those characterizations, it was found that the appearance of the charge-transfer state in the low band gap regime improved the light-harvesting ability relative to the g-C3N4and S-g-C3N4. The use of the EY–S-g-C3N4photocatalyst for the regeneration of NADH and NADPH showed quite excellent efficiencies of 64.38% and 81.14%, respectively. In addition, it showed the high conversion efficiency of sulfide to sulfoxide with an yield of 99.6%. This research highlights the potential application of the EY–S-g-C3N4composite in the field of organic transformation based on photoinduced conversion.

[Display omitted]

The consumption of carbon dioxide (CO2) for direct solar fuel productions and synthesis of fine solar chemicals are gaining leading significance due to the shortage of fossil-fuel and global warming worldwide. Therefore, herein, we report the synthesis and development of solar light harvesting bamboo-shape magnesium tetraphenyl porphyrin based framework (Mg-TPPBF) photocatalyst. The development of Mg-TPPBF photocatalyst-biocatalyst bonded system as a solar light harvesting photocatalyst functions in a extremely efficient manner, increasing to high regeneration of NADH (73.9%), followed by its utilization in exclusive amount of formic acid (HCOOH) production (197.2 μmol) from CO2. The Mg-TPPBF photocatalyst also enables in consecutive C-S/C-N bonds formation with high yield (~96–99%) and selectivity (~97–99%) under solar light with excellent reusability. The current research work highlights the enlargement and application of Mg-TPPBF photocatalyst for direct solar fuel production from CO2and fine solar chemical synthesis.

Due to the pharmaceutical, biological, physical, and chemical properties of fluorinated compounds and 1,4-NADH/NADPH, these species have attracted a lot of attention from researchers across the chemical society. Despite their crucial significance, present methods of regenerating cofactors (1,4-NADH/NADPH) as well as inserting fluorine into organic compounds suffer from ruthless drawbacks. Herein, we designed a highly efficient S-gC3N4@Fe2O3/LC photocatalyst, and its in situ generations were accomplished by calcinations of Fe2O3, melamine (M), thiophenol (T), and lignin carbon (LC). The Fe2O3part performs similar to an additional light harvester, gifting utmost photo-generated electrons, whereas the carbon part bridges a “thoroughfare” to make easy electron transfer from Fe2O3to S-gC3N4(Schemes 1 and 2). Therefore, the newly designed S-gC3N4@Fe2O3/LC photocatalyst is more efficient for the generation and regeneration of the C(sp3)–F bond and 1,4-NADH/NADPH due to its surface active sites and defects.

ABSTRACTAscorbate peroxidase from Leishmania major(LmAPX) is one of the key enzymes for scavenging of reactive oxygen species generated from the mitochondrial respiratory chain. We have investigated whether mitochondrial LmAPX has any role in oxidative stress-induced apoptosis. The measurement of reduced glutathione (GSH) and protein carbonyl contents in cellular homogenates indicates that overexpression of LmAPX protects Leishmaniacells against depletion of GSH and oxidative damage of proteins by H2O2or camptothecin (CPT) treatment. Confocal microscopy and fluorescence spectroscopy data have revealed that the intracellular elevation of Ca2+attained by the LmAPX-overexpressing cells was always below that attained in control cells. Flow cytometry assay data and confocal microscopy observation strongly suggest that LmAPX overexpression protects cells from H2O2-induced mitochondrial membrane depolarization as well as ATP decrease. Western blot data suggest that overexpression of LmAPX shields against H2O2- or CPT-induced cytochrome cand endonuclease G release from mitochondria and subsequently their accumulation in the cytoplasm. Caspase activity assay by flow cytometry shows a lower level of caspase-like protease activity in LmAPX-overexpressing cells under apoptotic stimuli. The data on phosphatidylserine exposed on the cell surface and DNA fragmentation results show that overexpression of LmAPX renders the Leishmaniacells more resistant to apoptosis provoked by H2O2or CPT treatment. Taken together, these results indicate that constitutive overexpression of LmAPX in the mitochondria of L. majorprevents cells from the deleterious effects of oxidative stress, that is, mitochondrial dysfunction and cellular death.

Ascorbate peroxidase from Leishmania major (LmAPX) is one of the key enzymes for scavenging of reactive oxygen species generated from the mitochondrial respiratory chain. We have investigated whether mitochondrial LmAPX has any role in oxidative stress-induced apoptosis. The measurement of reduced glutathione (GSH) and protein carbonyl contents in cellular homogenates indicates that overexpression of LmAPX protects Leishmania cells against depletion of GSH and oxidative damage of proteins by H2O2or camptothecin (CPT) treatment. Confocal microscopy and fluorescence spectroscopy data have revealed that the intracellular elevation of Ca2+attained by the LmAPX-overexpressing cells was always below that attained in control cells. Flow cytometry assay data and confocal microscopy observation strongly suggest that LmAPX overexpression protects cells from H2O2-induced mitochondrial membrane depolarization as well as ATP decrease. Western blot data suggest that overexpression of LmAPX shields against H2O2- or CPT-induced cytochrome c and endonuclease G release from mitochondria and subsequently their accumulation in the cytoplasm. Caspase activity assay by flow cytometry shows a lower level of caspase-like protease activity in LmAPX-overexpressing cells under apoptotic stimuli. The data on phosphatidylserine exposed on the cell surface and DNA fragmentation results show that overexpression of LmAPX renders the Leishmania cells more resistant to apoptosis provoked by H2O2or CPT treatment. Taken together, these results indicate that constitutive overexpression of LmAPX in the mitochondria of L. major prevents cells from the deleterious effects of oxidative stress, that is, mitochondrial dysfunction and cellular death.