Photodegradation Of Organic Pollutants Research Articles

Boosting the Photocatalytic Performance of g-C3N4 through MoS2 Nanotubes with the Cavity Enhancement Effect.

The development of catalysts with high photon utilization efficiency is crucial for enhancing the catalytic performance of photocatalysts. Graphitic carbon nitride (g-C3N4) is a prominent material in the field of photocatalysis. However, it still exhibits drawbacks such as low utilization of visible light and severe recombination of photogenerated carriers. To address these issues, this study employs MoS2 nanotubes (NTs) as cocatalysts and constructs MoS2 NTs/g-C3N4. The MoS2 NTs/g-C3N4 exhibits a significant cavity enhancement effect through multiple light reflections. This results in a broad spectral absorption range and high photon utilization efficiency, while also reducing the recombination of photogenerated carriers. The photocatalyst demonstrates outstanding performance in both photocatalytic hydrogen production and photodegradation of organic pollutants. Specifically, the hydrogen production rate is 1921 μmol·g-1·h-1, which is approximately 2.4 times that of g-C3N4. Furthermore, the photodegradation rate of Rhodamine B reaches 98.6% within 30 min, which is approximately three times higher than that of g-C3N4. Free radical capture experiments confirm that holes (h+) are the primary active species in photodegradation. A plausible photocatalytic mechanism for the catalyst is proposed. This study provides valuable insights into the development of heterojunction photocatalysts with high photon utilization efficiency.

Recent progress of modified CeO2-based materials for photocatalytic environmental remediation and antibacterial activity

The rapid development of industrialization and urbanization has led to serious environmental pollution. As an environmentally friendly and sustainable energy source, solar-driven semiconductor photocatalysis has been widely applied in environmental remediation and antibacterial activity owing to its gentle reaction conditions. The use of CeO2-based nanomaterials in green energy production, CO2 conversion, pollutant degradation, and antibacterial is increasing. The photocatalytic performance of CeO2 can be enhanced by appropriate modification strategies that suppress the rapid recombination of electron-hole pairs. This paper provides a systematic introduction to various modification strategies for CeO2, and reviews the research progress of modified CeO2 materials in photocatalytic CO2 reduction, photocatalytic hydrogen evolution, heavy metal removal, photodegradation of organic pollutants, and antibacterial fields, finally offering perspectives on its future development direction.

Photochemistry of plateau lake-derived dissolved organic matter: Reactive species generation and effects on 17β-estradiol photodegradation

Naturally strong ultraviolet irradiation at high altitudes causes photobleaching of plateau lake DOM (P-DOM) and affects its photochemical activity. However, the photoreactivity of P-DOM has remained unclear under natural photobleaching condition. Here, six P-DOM samples isolated from plateau lakes in Yunnan Province, China as well as two reference DOM as comparisons were used to explore the photogeneration of reactive species (RS) and their effects on 17β-estradiol photodegradation. Compared with SRHA/SRFA, P-DOM has lower aromaticity, average molecular weight, and electron-donating capacity. The quantum yields of triplet state P-DOM (3P-DOM⁎), 1O2, and ∙OH produced in P-DOM solutions were greatly higher than those of reference DOM. The RS quantum yields had positive linear correlations with E2/E3 and SR, whereas were negatively linear correlated with SUVA25. Radical quenching experiments showed that 3P-DOM⁎ was the prominent RS for 17β-estradiol photodegradation, and its contribution exceeded 70% for each of P-DOM. 3P-DOM⁎-mediated photodegradation was mainly attributed to the electron-transfer reactions with an average second-order rate constant of 4.62×109M-1s-1, indicating the strong photoreactivity towards 17β-estradiol. These findings demonstrate that P-DOM is an efficient photosensitizer for RS production, among which 3P-DOM⁎ may play an important role in enhanced photodegradation for organic micropollutants in plateau lake enriched with DOM. Environmental ImplicationDissolved organic matter (DOM) in plateau lakes is a significant component in global DOM pool. Plateau lakes receive stronger natural ultraviolet irradiation relative to plain district, resulting in significantly natural photooxidation of P-DOM, and further affecting its photochemical activity. Considering the strong reactivity, 3P-DOM⁎ is proposed to be a dominant reactive species in the photodegradation of amine and phenolic contaminants in plateau lakes. In addition, ·OH photogeneration ability of P-DOM is great higher than that of the reference DOM with factor of ~ 10, which may act an important role in the photodegradation of refractory organic pollutants in plateau lakes.

Visible light induced S-scheme charge transfer mechanism from Bi12TiO20 to CsPbBr3 for photodegradation of organic pollutants in aqueous solution

This work describes the formation of CsPbBr3/Bi12TiO20 S-scheme heterojunction photocatalysts using 3-mercaptopropionic acid (MPA) passivated CsPbBr3 nanocrystals (CPB) combined with Bi12TiO20 (BTO) nanorods. Under illumination, the charge carriers—undergo a process known as the S-scheme charge transfer, which significantly enhances their redox capability. The most efficient photodegradation of Rhodamine B (RhB) was recorded with the fine-tuned 10 %CPB/BTO composite (degradation rate of 95.35 % within 50 min, kapp = 0.06202 min−1). This improvement is primarily due to the MPA passivation, which increases the stability of the catalyst in aqueous solutions, and the S-scheme heterojunction design, which improves carrier separation and utilisation efficiency.

Transformed construction from type-II WO3/BaTiO3 heterojunction to Z-scheme WO3/Ba0.5Sr0.5TiO3 and WO3/SrTiO3 photocatalytic systems: Enhanced photocatalytic activity and mechanism insight

In this study, type-II heterojunction WO3/BaTiO3 and Z-scheme WO3/SrTiO3 or WO3/Ba0.5Sr0.5TiO3 nanocomposite photocatalysts were constructed for photodegradation of organic pollutants in wastewater under visible light. The photocatalytic performance of three WO3/titanate systems were estimated. Some influencing factors such as molar ratio of WO3 and titanates, light irradiation time, catalyst dose, and initial concentration of organic pollutants on the photocatalytic activity were investigated. The stability and reusability of three WO3/titanates systems were examined. Moreover, the production of some radicals in the three WO3/titanates photocatalytic systems was demonstrated, and the three WO3/titanates photocatalytic reaction mechanisms were compared. The results reveal that the configurations of WO3/titanates photocatalytic systems are transformed from type-II heterojunction WO3/BaTiO3 with lower activity to Z-scheme WO3/SrTiO3 and WO3/Ba0.5Sr0.5TiO3 with higher activity via the change of titanates. The WO3/titanate nanocomposites show higher photocatalytic activity at 3.0:1.0 M ratio of WO3 and titanates, and WO3/Ba0.5Sr0.5TiO3 nanoparticles have superior photocatalytic activity. The order of photocatalytic activity is as follows: WO3/Ba0.5Sr0.5TiO3 > WO3/SrTiO3 > WO3/BaTiO3. Several organic pollutants, such as rhodamine B, methyl parathion, direct brilliant yellow-4R, and methylene blue, can be efficiently degraded using WO3/Ba0.5Sr0.5TiO3 under visible light, and the RhB has higher degradation rate. After four cycles, WO3/titanate nanocomposites still have relatively high stability and reusability. •OH plays a major role in three WO3/titanates photocatalytic degradation. It is expected that the Z-scheme WO3/Ba0.5Sr0.5TiO3 photocatalytic technology creates a good foreground for disposing of dyes and pesticides in water and wastewater.

Experimental and numerical study of photocatalysis in Taylor photoreactors with carbon-quantum-dots/BiOCl as catalysts

A comprehensive CFD model considering the photo radiation, discrete phase dispersion, flow behaviors and photoreactions was built for Taylor‐Couette reactors (TCRs). The carbon quantum dots (CQDs) modified BiOCl composites which were responsive to visible light were synthesized and used as the catalysts for photodegradation of organic pollutants. The degradation kinetic parameters were obtained experimentally. The validated model was used to investigate the effects of the key parameters of TCRs such as rotation speed, light intensity and catalyst properties. The interactions among the photo radiation field, catalyst distribution, flow field, and degradation efficiency were discussed. The results showed the addition of 8 ωt % CQDs/BiOCl enhanced the degradation efficiency to 97% as compared to pure BiOCl, while the catalyst dosage had a limited impact on degradation performance. This work provides engineering insights in the CQDs-based photocatalysis, and the proposed model can serve as an effective tool for the design and scale-up of the TCRs.

Photocatalytic and biological efficacy of Carissa macrocarpa fruit extract-mediated one-pot synthesized ternary metal oxide dual S-scheme heterojunction

Photodegradation of organic pollutants on the surface of greenly synthesized nanomaterials under sunlight irradiation is a viable approach for water purification. Since a little attention has been paid to the green synthesis of ternary nanocomposites, therefore current work has been designed to greenly synthesized dual S-scheme heterojunction using aqueous extract of Carissa macrocarpa fruit. After successful characterization by UV-Visible spectroscopy (UV-Vis.), Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), scanning electrode microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM), Thermogravimetric analysis (TGA), dynamic light scattering (DLS), and zeta potential analysis (ZP), Thermogravimetric analysis and X-ray photoelectron spectroscopy (XPS), the stable nanocomposite was evaluated for its catalytic potential for the photodegradation of three azo dyes, i.e., methylene blue (MB), Congo red (CR), and methyl orange (MO), under sunlight. 91 %, 97 %, and 85 % degradation with rate constant values of 2.03×10−2 min−1, 2.83×10−2 min−1, and 1.64×10−2 min−1 were observed for MB, CR, and MO, respectively, in just 120 minutes of exposure to sunlight. Effect of radical scavengers and flat band positions of NCs were evaluated to propose the mechanism and transfer of electrons and holes to decompose the dyes. The reusability of the catalyst was assessed for five consecutive cycles, which showed only a slight reduction (∼1.09%) in its activity. In addition to their photocatalytic potential, the aqueous extract and the greenly synthesized nanocomposite were also evaluated for their antibacterial potential by the disc diffusion method.

Tactic of A−D−A scheme organic photocatalyst with broad spectral feature of absorption enables photocatalytic performance improvement

Breakthrough in organic pollutant photodegradation is achieved by linking the photocatalysis technology with the excellent photovoltaic nature of bulk heterojunction organic solar cell (BHJ-OSC) active layers. The first pure organic photocatalytic system built to degrade methylene blue (MB)-laden water by associating biochar supporter with active layers, fabricating a subset of organic photocatalysts, it is the first result of A−D−A scheme to date. The champion catalyst C-PM6:TPA-PDI:PIID-ClBF with excellent wide absorption spectra and fine tunable energy level exhibits greater potential in solar harvesting and prolonging charge lifetime, as well as high reusability and no insoluble residuals after treatment. As a result, this strategy both benefits the production of reactive oxygen species and eliminates concerns regarding insoluble residuals, subtly coping with the common disadvantages of most existing photocatalysts. The C-PM6:TPA-PDI:PIID-ClBF successfully degraded MB with a remarkable efficiency of 100 % achieved in 12 min, while also can maintain this high efficiency for up to 100 cycles, as long as the active materials remain active. These findings step forward in developing photocatalysts that are environmentally friendly and affordable, elucidating significant implications of advancing series of BHJ-OSCs-like photocatalysts for the removal of organic pollutants.

CdIn2Se4@chitosan heterojunction nanocomposite with ultrahigh photocatalytic activity under sunlight driven photodegradation of organic pollutants

This research focused on synthesizing a CdIn2Se4@Ch nanocomposite by doping CdIn2Se4 into chitosan using a photolysis assisted ultrasonic process. The aim was to enhance the photodegradation efficiency of ofloxacin and 2,4-dichlorophenoxyacetic acid under sunlight. The synthesized CdIn2Se4@Ch nanocomposite was investigated via different techniques, including XRD, XPS, FTIR, TEM, DSC, TGA, UV–Vis and PL. The study also investigated the influence of various reaction parameters, including the effects of inorganic and organic ions. The synthesized nanocomposite demonstrated exceptional efficiency, achieving 86 % and 95 % removal rates, with corresponding rate constants of 0.025 and 0.047 min-1. This performance surpasses that of CdIn2Se4 by approximately 1.35 and 2.25 times, respectively. The values of COD were decreased to 78 and 86 % for ofloxacin and 2,4-dichlorophenoxyacetic, while the TOC values decreased to 71 and 84 %, respectively, from their premier values. The improvement in performance is associated with the introduction of CdIn2Se4 into chitosan, resulting in the self-integration of Cd into the catalyst. This creates a localized accumulation point for electrons, enhancing the efficiency of charge separation and further reducing the surface charge of chitosan. Experimental evidence suggests that superoxide and hydroxyl radicals play a significant role in the photodegradation of pollutants. Additionally, the nanocomposite exhibits excellent stability and can be reused up to five times, indicating remarkable stability and reusability of the developed photocatalyst.

Intensification of organic pollutant degradation under visible light irradiation using ZnO nanostructured photocatalysts doped with praseodymium

Zinc oxide nanostructures doped with praseodymium (ZnO:Pr) at varying Pr content (0.05 % to 1.0 % w/w) were synthesized using the electrospinning-calcination technique. Comprehensive morphological and structural characterizations were conducted through SEM, XRD, and XPS analyses. In addition, diffuse reflectance and photoluminescence spectroscopy measurements were performed to assess the optical properties of materials. The produced photocatalysts (ZnO:Pr) were then employed for the degradation of methylene blue dye and oxytetracycline under visible-light irradiation. ZnO:Pr(0.1 %) demonstrated the best photocatalytic performance against methylene blue showing a pseudo-first-order rate constant of k = 3.630 × 10-2 min−1. Investigation of oxytetracycline photodegradation with ZnO:Pr(0.1 %) revealed a pseudo-second-order rate constant of ks = 1.165 × 10-1 L mg−1 min−1, resulting in a reaction half-life (τ½) of approximately 1 min under optimal conditions. Total organic carbon and mass spectrometry analyses highlighted mineralization and identified the main reaction intermediates, respectively, for the oxytetracycline photodegradation. The photodegradation mechanism of oxytetracycline was proposed by the photocatalytic degradation measurements in the presence of scavengers such as hydroquinone and isopropanol. These nanostructures exhibited robust photocatalytic activity over multiple cycles, demonstrating excellent stability. This study underlines the promising potential of ZnO:Pr(0.1 %) as an efficient photocatalyst able to intensify the photodegradation of organic pollutants.

Organic pollutants photodegradation increment with use of TiO2 nanotubes decorated with transition metals after pulsed laser treatment

Among various titanium(IV) oxide (TiO2, titania) structures, 1D nanotubes (TiO2 NTs) produced during the two-electrode anodization process, are extensively utilized in sensors or supercapacitors as well as in photo(electro)catalytic water splitting. However, due to wide bandgap and fast electron-hole recombination additional modifications, mostly concerned on materials surface, are required. According to the recent research, TiO2 NTs photo(electro)catalytic characteristic were markedly improved by the combination of surface decoration with transition metal nanoparticles further treated with the laser beam. Nevertheless, until recently, the photocatalytic ability of laser-treated TiO2 NTs for recalcitrant chemicals degradation were hardly described. In this regard, our work focuses on obtaining long, about 7.3 μm TiO2 NTs (L-TiO2 NTs), together with their photoactivity and physicochemical characteristics, as well as their alterations following surface modification utilizing transition metals (tungsten, chromium and nickel) together with laser treatment. Obtained L-TiO2 NTs are characterized by over 13.5 times larger BET surface area in comparison to reference spaced TiO2 NTs with approximately 2 μm length (0.61 m2 g−1 and 0.05 m2 g−1, respectively). This allowed for increasing of the materials photocatalytic activity in both UV–vis and vis light. Additionally, phenol photodegradation reached up to 34% (0.21·10−2 min−1) for tungsten-modified titania after laser annealing at 20 mJ cm2 fluence. The reaction mechanism research revealed that reduction of organic pollutants concentration was primarily caused by superoxide radical anions •O2−. Furthermore, obtained modified L-TiO2 NTs showed remarkable durability without losing their initial activity over ten photocatalytic cycles.

Novel superhydrophobic sponge with flower-like architecture for oily emulsion separation and organic pollutants photodegradation

Design functionalized absorbent materials that fulfillment complex requirements in sophisticated water-treatment fields remains challenging. In this paper, a novel superhydrophobic/superoleophilic sponge with flower-like channel structures and a photodegradation functionality was fabricated via in-situ chelation of zinc oxide (ZnO) and nano-Ag particles. After low surface energy modification with POTS, the as-prepared sponge displayed remarkable superwettability, with a water contact angle (WCA) of 158.8° ± 1.3°. This endowed it with the ultrafast, selective absorption of diverse oils that are 33.9–135.2 times of their own weight. The prepared sponge’s emulsified oil separation efficiency can reach 99.87%, owing to its superhydrophobic/superoleophilic properties and the electrostatic attraction demulsification, guiding effect of ZnO layer crystal plane. Furthermore, the construction of Schottky barrier at the ZnO@Ag interface reduced the recombination rate of photoexcited electrons and electron-holes. Thereby, the prepared sponge’s photodegradation efficiency reached up to 97.07% after 4 h sunlight irradiation. Notably, the stress attenuation of the prepared sponge was only 14.6% after 100 absorption cycles, indicating its excellent mechanical stability. Moreover, the prepared sponge showed excellent environmental tolerance under severe conditions with its WCA stably exceeding 150.0°. Thus, this durable superwetting sponge can be effectively used for oil/water emulsion separation and organic pollutant degradation.

Three-dimensional donor-acceptor conjugated porous polymers based on metal-porphyrin and triazine for highly effective photodegradation of organic pollutants in water

Three-dimensional donor-acceptor (D-A) type conjugated porous polymers (CPPs) was designed and synthesized via imine condensation of copper tetraaminoporphyrin (CuTAPP) as donor and 1,3,5-tris-(4-formyl phenyl) triazine (TFPT) as acceptor, named as CuPT-CPP. The CuPT-CPP possesses a high specific surface area (73.7 m2/g) and excellent photophysical properties. The simultaneous introduction of the organometallic molecules and D-A structures in CuPT-CPP could be broadened the visible-light response range (400–800 nm) and facilitated efficient photogenerated carrier separation and transportation. As heterogeneous photocatalysts, CuPT-CPP has excellent photocatalytic performances under visible light irradiation, leading to excellent model pollutant rhodamine B degradation efficiency up to about 100% in 3 h, it has superb stability and reusability during the photocatalytic processes, and CuPT-CPP also exhibited broad substrate adaptability, which could photocatalytic degradation of methylene blue (MB), methyl orange (MO), and tetracycline hydrochloride (TC). This work indicates that three-dimensional D-A type porphyrin- and triazine-based CuPT-CPP has great potential in the practical application of photocatalysis.

Indirect photodegradation of zinc pyrithione: The effect of chromophoric dissolved organic matter components and seawater factors

Chromophoric dissolved organic matter (CDOM) is the main photosensitizer in seawater. CDOM can absorb solar radiation extensively and generate reactive intermediates (RIs), including singlet oxygen (1O2), hydroxyl radicals (HO·), and CDOM triplet states (3CDOM*), that are favorable for indirect photodegradation of organic pollutants. In the current study, the effect and mechanism of CDOM components on zinc pyrithione (ZnPT) indirect photodegradation were studied. Among the three CDOM isolates (humic acid (JKHA), Suwannee River humic acid (SRHA), and Suwannee River natural organic matter (SRNOM)), JKHA had the highest fluorescence intensity per gram of carbon and the fastest indirect photodegradation rate for ZnPT. Furthermore, the fluorescent components were divided into four terrestrial humic-like components: C1, C2, C3, and C4, by using excitation–emission matrix spectroscopy combined with parallel factor analysis. A notable relationship was found between the four fluorescent components of CDOM and ZnPT indirect photodegradation. The indirect photodegradation rate of ZnPT varied in different types of CDOM solutions, which may be attributed to the different compositions of CDOM. The relative contents of C1 and C4 were significantly higher in JKHA than in the other two CDOMs, and they were the major contributors to the production of 3CDOM* and 1O2, which promoted ZnPT indirect photodegradation. The impact of seawater factors on ZnPT indirect photodegradation was also investigated. The ZnPT indirect photodegradation rate initially decreased and then increased as the pH increased from 5.00 to 11.00. The lowest rate of indirect photodegradation of ZnPT was observed at pH = 9.00. As the salinity was <25‰, in salinity the ZnPT indirect photodegradation rate increased concomitantly with an increase, and pronounced inhibition of ZnPT indirect photodegradation was observed when the salinity was >25‰. Nitrate had a promoting influence on ZnPT indirect photodegradation, whereas HCO3−, halogen ions, and metal ions all inhibited it.

Green fabrication of CuO-egTiO2 composite for photodegradation of organic pollutant under direct visible light illumination

A (CuO-egTiO2) composite coated with copper oxide has been manufactured as a green and facile photocatalyst via Argyreia nervosa leaf extract. The photocatalyst consists of equaixial geometry (egTiO2) particles with copper oxide (CuO) nanocrystals deposited on the TiO2 surface in varying proportions. The structural, morphological, and optical properties of the CuO-egTiO2 photocatalyst nanostructures were inspected via various techniques, through (XRD), (FE-SEM), (DRS), (BET) analysis, (PL) spectra, and (TEM). The results obtained revealed the non-uniform growth of CuO nanocrystals on the surface of TiO2 particles, resembling a (core–shell) structure. The photocatalytic activity of the CuO-egTiO2 nanocomposite was verified in the degradation of Rhodamine B dye (RhB) using an inhomogeneous photocatalytic activation process, with CuO-egTiO2 (10 %) proving to be the most effective photocatalyst under visible light. The effect of the catalyst quantity within concentrations of 0.3–1.8 g/L was studied by exposing aqueous solutions containing the photocatalysts to visible radiation. The dye removal rate was estimated by calculating the remaining concentration, indicating a pseudo-first-order disappearance model with a dye removal percentage of 95.20 %. Additionally, the impact of reactive oxygen species (ROS) types was investigated, The highest photocatalytic degradation rate of 52.16 % was observed when using the inhibitor (EDTA), indicating that the active group contributing to the photocatalytic degradation of RhB is hydroxyl radicals (●OH). At last, in reuse experiments, it was demonstrated that the CuO-egTiO2 (10 %) photocatalyst maintained a remarkable 75.3 % of its initial efficiency even after being recycled for four cycles.

Visible-light-induced photocatalytic degradation of organic contaminants by Silver(I)-loaded N-rich porous organic polymers

Heterogeneous photocatalysts with high activity and reactive free radicals can be used to effectively remove water pollutants in harsh environments, which have attracted considerable attention in the environment chemistry. Here, we designed two conjugated organic porous polymers POPs 1-2 with high redox activity and potential π-electron delocalization. Upon combination with silver(I) nitride salt in solution, two metal-anchoring polymeric catalysts POPs 3-4 were successfully constructed, which possessed a strong electron donating ability as well as a high coplanarity and photoelectron properties. Through the loading of AgNO3, the carrier separation ability was effectively improved and the photocatalytic activity of POPs 3-4 was enhanced because of the surface plasmon resonance (SPR) effect of Ag localized at the polymer surface. The photocatalytic results demonstrated that POPs 3-4 could degrade RhB, MO and TC under visible light irradiation. The photodegradation efficiency reached 82.9% for RhB, 28.6% for Mo and 56.6% for TC with the presence of POP-3, and 76.3% for RhB, 51.1% for Mo and 37.7% for TC with the presence of POP-4, respectively. Furthermore, two porous polymer catalysts showed an excellent reusability in heterogenous conditions, the performance results show that the cycle degradation efficiency has been consistently maintained at over 90%. This demonstrates the robust and reliable performance of the material under repeated test conditions. A plausible photocatalytic mechanism triggered by ROS was proposed for the degradation of organic contaminant. This work on silver(I)-anchored porous organic polymers provided a possibility for development of the highly effective photocatalyst materials towards organic pollutants photodegradation under mild conditions.

Potassium and chlorine co-tuned graphitic carbon nitride for organic pollutants photodegradation: Revealing the effects of cyano groups on O2 evolution

The insufficient active sites and sluggish photogenerated electron migration are hindered the photocatalytic activity of g-C3N4. Herein, we successfully synthesized a K and Cl co-tuned g-C3N4, with cyano groups incorporating (expressed as CN-KCl). The optoelectronic and physicochemical properties of the samples were comprehensively investigated using a combination of characterization techniques and DFT calculations. The results demonstrated that Cl atom replaced sp2-hybridized nitrogen atom, while K atom was doped at the interstitial site. With the synergistic effect of K/Cl atoms, the transfer of photogenerated electrons across layers and lamellae was enhanced. Additionally, the cyano groups not only acted as the most stable adsorption sites for O2, but also served as charge transfer bridge between catalysts and O2, enhancing the activation of O2. This ultimately led to an improvement in the generation of superoxide radicals and contributed to the enhanced photocatalytic activity of CN-KCl.

Recycling of natural and waste materials as supports for green silver nanoparticles as efficient catalysts in photodegradation of organic pollutants

The use of a sustainable technology to synthesize green silver nanoparticles (AgNP) from renewable resources is very appealing. Here, a green protocol for the production AgNP/composites is introduced, via in situ reduction of Ag+ ions on sustainable materials (clays and waste materials) using eucalyptus leaves extract (ELE) as a reducing and stabilizing agent, without the addition of any harmful or expensive organic solvent, surfactant or dangerous compounds. The synthesized AgNP/composites were evaluated as photocatalysts to degrade Indigo Carmine (IC) dye as a model pollutant under visible light. Kaolin and pistachio shells showed to be promising supports for green AgNP, with decolorization efficiency of 85.3(±1.8)% and 48.3(±4.1)%, respectively, after 120 min of irradiation. The best catalytic results were obtained with kaolin as support and so the influence of different synthesis parameters of AgNP/kaolin nanocomposite was evaluated. The catalytic results indicated that increasing the amount of AgNO3 and ELE in the nanocomposites, increased their photocatalytic performance. Nanocomposites synthesized at room temperature showed smaller amount of AgNP and higher decolorization efficiency, compared to those biosynthesized at 50 °C. The evaluation of active species responsible for the photodegradation of IC showed that O2•- and H+ radicals are species involved in the reaction. The AgNP/kaolin showed also to be efficient to degrade both atrazine and sulfamethoxazole after 120 min of irradiation.

Excellent performance of AgVO3@ZIF(Zn, Co) interfacial heterojunction for photodegradation of organic pollutants: Experimental and computational studies

A series of AgVO3@ZIF(Zn, Co) samples were solvothermally prepared, and further evaluated as the photocatalysts for photodegradation of organic pollutants. The inherent characteristics of the as-synthesized composites were determined by some techniques such as XRD, SEM, TG-DTG, XPS, UV-Vis, ESR, and N2-adsorption. Interestingly, the component of the composite constructed with mass ratio of 3:1 (AgVO3@BZIF-3) showed the highest catalytic performance for the degradation of methylene blue (MB). This may be related to the formation of type II heterojunction between AgVO3 and bimetallic ZIF(Zn, Co), which results in MB molecules to be easily adsorbed and degraded on AgVO3@BZIF-3. The results of DFT calculations suggested that the newly-formed O-N bonds linking ZIF structure and AgVO3 crystal surface could promote the charge carriers through the heterostructure interface easily. Moreover, the highest photodegradation efficiency of MB was achieved with 98.20 % when the reaction system was carried out at pH of 5, 3 h and 25 °C in the presence of photocatalyst mass of 30 mg. In addition, various substrates including methyl orange, indole, rofloxacin, methyl blue and tetracycline were respectively investigated under the optimal reaction conditions. Moreover, combined with ESR analysis and free radical capture experiments, superoxide radicals (O2−) was confirmed as the key active species for organic pollutant photodegradation over AgVO3@BZIF-3.

Green synthesis of CuO/Fe2O3/ZnO ternary composite photocatalyst using grape extract for enhanced photodegradation of environmental organic pollutant

This research delves into fabricating a CuO/Fe2O3/ZnO (CFZ) ternary composite photocatalyst, employing grape extract for its eco-conscious synthesis. The method intricately integrates copper acetate, ferric nitrate, and zinc acetate as precursor compounds, harmonizing them with grape extract serving as a green reducing agent. Meticulous microwave treatment and controlled calcination orchestrate the nuanced formation of the desired composite material. The extensive characterization, involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDXS), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) spectroscopy, unveils an array of favorable physical, chemical, and optical attributes conducive to proficient photocatalysis. Notably, CFZ–10mc showcases a narrower bandgap of 1.91 eV, which is pivotal for bolstering electron–hole separation, thereby enhancing its photocatalytic efficacy. Assessment of CFZ's performance in degrading Rhodamine B (RhB) under UV irradiation highlights an impressive 88.8% degradation efficiency within 120 min, accompanied by a kinetic rate constant of 1.81 × 10−2 min−1. Deliberation upon crucial parameters, including photocatalyst dosage, initial RhB pH, and reactor energy consumption, introduces the electrical energy per order (EEO) as a notable efficiency metric. CFZ manifests a substantial reduction in operational costs, estimated to be 18.10 times lower than conventional photolysis, signifying an EEO value of 509.17 kWh m−3 order−1. Optimal operational conditions propose a photocatalyst content of 1.5 g L−1 and an initial RhB pH of 7, fostering the prevalence of the primary active species, •OH. These findings illuminate CFZ's potential in mitigating organic pollutants, underlining its pivotal role in sustainable water remediation. Additionally, practical implementation guidelines for leveraging CFZ's capabilities in real-world applications are presented with care and consideration.