Natural Sunlight Irradiation Research Articles

Sunlight assisted highly efficient desorption of ammonia by redox graphene hybrid metal–organic framework photothermal conversion adsorbents

The capture, storage and release of NH3 play a pivotal role in sustainable energy applications. However, to simultaneously achieve high adsorption capacity and low energy desorption remains a challenge. In this work, a novel class of hybrid materials with photothermal conversion performance have been developed by doping redox graphene and metal–organic framework of MOF-303(Al). It is found that the optimized rGO@MOF-303(Al)-8% exhibits high NH3 uptake (17.0 mmol g−1) at 25.0 °C and 1.0 bar and exceptional photothermal conversion performance. Under the irradiation of simulated sunlight, its temperature can be raised to about 75 °C in 10 min. Even under direct natural sunlight irradiation, a stable equilibrium temperature of 53 °C may be achieved. Based on this excellent photothermal conversion performance, we investigated the desorption behavior of ammonia under visible light irradiation for the first time. We found that due to the breakdown of hydrogen bonds of NH3 and N-N, N–H sites of rGO@MOF-303(Al)-8% caused by the rapid rise of temperature, approximately 68% of NH3 could be effectively desorbed in 2-hour irradiation under ambient conditions. In addition, the optimized adsorbent demonstrated remarkable cycling stability. After undergoing 10 cycles, high adsorption capacity and efficient light-induced desorption of NH3 were still maintained Thus, the present study provides a novel concept for high-capacity adsorption and low-energy desorption of NH3 and other industrial gases.

Kinetics of the photocatalytic degradation of methylene blue under natural sunlight irradiation using nanocatalysts Ce3+ and Mg2+ co-doped CaFeO3−δ

Kinetics of the photocatalytic degradation of methylene blue under natural sunlight irradiation using nanocatalysts Ce3+ and Mg2+ co-doped CaFeO3−δ

Synergistic effect of Fe doping and oxygen vacancy in AgIO3 for effectively degrading organic pollutants under natural sunlight

In this work, a series of hydrogenated Fe-doped AgIO3 (FAI-x) catalysts are synthesized for photodegrading diverse azo dyes and antibiotics. Under the irradiation of natural sunlight with a light intensity of ∼60 mW/cm2, the optimum FAI-10 exhibits a considerable rate constant for decomposing methyl orange (MO) of 0.067 min−1, about 7.4 times higher than that of AgIO3 (0.009 min−1), and 24.6% and 83.8% of MO can be decomposed over AgIO3 and FAI-10 after irradiation for 40 min. In the amplification photodegradation experiments with using 0.5 g catalyst and 400 mL MO dye solution (10 mg/L), FAI-10 possesses greatly higher photoreactivity to common semiconductors (ZnO, TiO2, In2O3 and Bi2MoO6), and the photodegradation rates over FAI-10 are 92%. Particularly, the FAI-10 shows superior stability, the activity of which remains unaltered after 8 continuous cycles. Foreign ions and water bodies have slight effect on the activity of FAI-10, but the MO degradation rates are decreased by adjusting pH values, especially when pH = 11 because of the strong electrostatic repulsion between MO and FAI-10. FAI-10 can also effectively decompose another azo dye (rhodamine B (RhB)) and diverse antibiotics (sulflsoxazole (SOX), chlortetracycline hydrochloride (CTC), tetracycline hydrochloride (TC) and ofloxacin (OFX)). The activity enhancement mechanism of FAI-10 has been systemically investigated and is ascribed to the promoted photo-absorption, charge separation and transfer efficiency, and affinity of organic pollutants, owing to the synergistic effect of Fe doping and oxygen vacancy (Ov). The photocatalytic mechanisms and process for decomposing MO are verified and proposed based on radical trapping experiments and liquid chromatography-mass spectrometry (LC-MS). This work opens an avenue for the fabrication of effective photocatalysts toward water purification.

Photodegradation of anthelmintic drugs under natural sunlight and simulated irradiation: kinetics, mechanisms, transformation products, and toxicity.

Albendazole (ALB) and bithionol (BIT) are two anthelmintic drugs (ADs) with high consumption from benzimidazole group and diphenylsulfide group, respectively. However, information on the transformation of the two anthelmintics under environmental condition is scare. Therefore, in the present study, we investigated the natural attenuation of the two ADs in the aquatic environment, including biodegradation, hydrolysis, and direct and indirect photodegradation. The direct photodegradation occupied a vast portion among other degradation pathways of the two ADs in natural water, with near-surface summer half-lives of 0.272-0.387h and 0.110-0.520h for ALB and BIT, respectively. Suspended particles in water were found to facilitate the photodegradation of the two ADs. Study on the indirect photodegradation demonstrated the positive roles of singlet oxygen (1O2) and excited triplet dissolved organic matter (3DOM*) in the photolysis of the two ADs, whereas the hydroxyl radical (•OH) affected little on the overall photodegradation procedures of ALB due to the scavenging effect of HCO3-. Dual effects of DO, DOM, HCO3-, NO3-, and NO2- on the photodegradation of ALB and BIT were perceived. Transformation intermediates (TIs) of the two ADs during photodegradation were analyzed by UHPLC-QTOF-MS. Six TIs of ALB were identified, including a broad-spectrum fungicide carbendazim and another common AD ricobendazole. Two TIs of BIT yielded from dechlorination were also detected. Probable transformation mechanism and predicted aquatic ecotoxicity based on the identified TIs were unveiled.

Enhanced performance of dual-functional ZIF-8/red phosphorus photocatalysts for concurrent degradation of organic dyes and hydrogen generation under natural solar light irradiation.

Herein, zeolitic imidazole framework (ZIF)-8/red phosphorus photocatalysts were prepared via a solvothermal method for simultaneous organic dye degradation and hydrogen (H2) generation. The 5 wt% ZIF-8/RP photocatalyst achieved the highest H2 generation rate of 822.5 μmol h-1 g-1 and 92% rhodamine dye degradation under natural sunlight irradiation. This approach offers an effective strategy to replace costly and toxic traditional electron donors with organic dye pollutants for H2 generation.

Use of zinc oxide nanorods in the photocatalytic degradation activity of tricosane hydrocarbon from produced water under visible light irradiations

The research work aims to synthesize and study the characterizations of ZnO nanorods (ZnO NRs) used in the photocatalytic process under visible region for the oxidation and degradation of tricosane an organic compound present in produced water (PW). The degradation of tricosane was achieved at 66 % under the solar simulator and 61 % under natural sunlight irradiation determined by the GC-MS/MS. Whereas the degradation was 7.5 % without ZnO NR under a solar simulator and 5.7 % in direct sunlight. The degradation follows pseudo first-order photocatalytic degradation kinetics with rate constant (k) of 0.2285 min−1 under solar simulator, and k = 0.1602 min−1 under sunlight irradiations. Photocatalytic degradation is more efficient at 6.64 pH when subjected to solar simulator, and 6.87 pH when exposed to sunlight irradiations. The TOC has reduced to 59 % and 57 % respectively. The presence of effects of salts and heavy metal compounds under visible light irradiation played a prominent role in the activity of the photocatalytic, which contributed to raising the efficiency rate of tricosane degradation. The tricosane removal rate reached 75.6 % and 83.5 % in the presence of salts CaSO4 and MgSO4, while about 71.8 % and 68.6 % were achieved in the presence of heavy metals CuSO4 and FeSO4, respectively.

Synthesis of core-shell structured silver-polypyrrole nanocomposite for cost effective photocatalytic degradation of methylene blue under natural sunlight

In this article, we report synthesis of silver-polypyrrole(Ag-PPy) nanocomposites using simple interfacial polymerization method to be applied for photocatalytic degradation of cationic dye Methylene blue (MB) under natural Sunlight. Ag-PPy nanocomposites are synthesized by varying the concentrations (5 mM, 15 mM and 20 mM) of silver nitrate. Field emission scanning electron microscopy (FESEM) show that the particle size of Ag-PPy nanocomposites increases from 200 nm to 450 nm with increasing concentration of silver from 5 mM to 20 mM. Transmission electron microscopy (FETEM) indicates the formation of core shell structure of the nanocomposites with silver at the core. UV–Visible spectra (UV–Vis) show a remarkable broad peak at around 252 nm. The X- ray diffraction spectra (XRD) show characteristic peaks at 2θ = 27.7°,32.1°,46.1°,76.2° for diffraction planes (226),(264),(200) and (311) of FCC structure of silver respectively. FTIR spectra indicates the crosslinking of silver with PPy in the nanocomposite. The photocatalytic activity of the as prepared Ag-PPy nanocatalysts is evaluated by 66 % of degradation of MB dye under natural sunlight irradiation within 3 h.

Design and fabrication of graphitic carbon nitride incorporated nickel selenide hybrid composite for effective degradation of organic pollutants under UV and natural sunlight irradiations

Addressing the challenge of developing a visible-light-driven photocatalyst with robust redox capabilities for organic pollutant degradation in environmental remediation, this study presents a novel hybrid composite. The composite was synthesized using g-C3N4 and NiSe2 through an ultrasonication-assisted hydrothermal method. Notably, the energy gap of this hybrid composite decreased from 2.72 to 2.30 eV as the g-C3N4 concentration ranged from 0 wt% to 30 wt%, as per the Kubelka–Munk theory. The surface area of the hybrid composite stood out at 31.2 m2/g, surpassing pristine NiSe2 (18.9 m2/g) and g-C3N4 (15.2 m2/g), as confirmed by BET analysis. The photocatalytic prowess of NiSe2/g-C3N4 composites was systematically investigated for the degradation of Reactive Blue 5 (RB 5) and Reactive Violet 5 (RV 5). Notably, the compositions with 30 % g-C3N4 incorporated into NiSe2 exhibited the highest degradation rates (86.4 % for RB 5 and 89.4 % for RV 5) and rate constants (0.0093 min−1 for RB 5 and 0.0095 min−1 for RV 5) during the degradation processes. Furthermore, the incorporation of g-C3N4 into NiSe2 not only elevated the surface area but also improved the separation rate of photogenerated electrons and holes. This enhancement significantly enhanced the visible-light-driven photodegradation performance of RB 5 and RV 5. The study also proposes a mechanism to explain the impact of graphitic carbon nitride concentration on photocatalytic performance. This research contributes to the development of advanced photocatalysts for eco-friendly pollutant degradation and provides insights into their composition-performance relationships.

Solar photoactive magnesium substituted copper ferrite photocatalysts for Rose Bengal treatment

In the present investigation, we have reported solar photo active, cost effective and magnetically recoverable magnesium substituted copper ferrites successfully prepared by simple co-precipitation method. The prepared materials were characterized for structural and microstructural analysis using PXRD, SEM, EDS, FT-IR and UV–Visible spectroscopy. It was observed that, when copper introduces into magnesium ferrite system light absorption shifted to visible region, this is due to formation of metastable energy levels just below the conduction band of magnesium ferrites. As a result an MgCuFe2O4 catalyst exhibits excellent efficiency under solar light irradiation. These catalysts are stable for longer period even after many runs and magnetically separable. Based on the analysis result these nanomaterials can be used as potential environmental and energy applications under natural sunlight irradiation.

CuO/ZnO Type-II heterojunction modified by rGO nanosheets for improved photocatalytic mineralization of antibiotics

In the present work, CuO/ZnO type-II heterojunction was modified by graphene oxide nanosheets for excellent photocatalytic mineralization of antibiotics under artificial UV light and natural sunlight. For this purpose, CuO/ZnO heterojunction-graphene oxide nanocomposites were synthesized via a facile refluxing method in aqueous media. The synthesized nanocomposites were characterized through diverse characterization techniques such as XRD, FT- IR, Raman, SEM, TEM, and UV–Vis DRS to determine their structural, morphological, and optical properties. XRD analysis confirmed the monoclinic CuO and hexagonal wurtzite ZnO phase in bare CuO/ZnO heterojunction and different CuO/ZnO heterojunction-graphene oxide nanocomposites as well. The optical band gap was found in the range of 3.06–3.19 eV for different nanocomposites. The photocatalytic activity of the bare heterojunction and nanocomposites was performed against the degradation of ciprofloxacin under the irradiation of artificial UV and natural sunlight as well. The highest degradation % of ciprofloxacin was achieved at 96.27 % and 76.44 % under artificial UV and natural sunlight within 120 min, respectively over CuO/ZnO heterojunction with 3 wt% of graphene oxide. The outstanding photocatalytic performance of CuO/ZnO heterojunction-graphene oxide (3 wt%) owing to the high adsorption capacity and synergism between CuO/ZnO and graphene oxide caused the improved separation of charge species resulting higher production rate of reactive oxygen species and prompt degradation of ciprofloxacin.

Interfacial modulation of α-Ag1.82Cu0.09WO4 with high active BiOClxI1−x for boosting photocatalytic activity and degradation of emerging contaminants under direct sunlight

Removal of organic contaminants in wastewater using sunlight-driven photocatalysts has received significant attention in recent years. However, the rational design of photocatalysts to attain high light absorption, lower charge carrier recombination with efficient photocatalytic activity and good recycling capability is crucial for the practical photocatalysis process. Herein, solid-state Z-scheme BiOCl0.6I0.4/α-Ag1.82Cu0.09WO4 heterojunction is synthesized by assembling hierarchical 3D-BiOCl0.6I0.4 nanoflowers on cube-like 3D-α-Ag1.82Cu0.09WO4 surface through a hydrothermal method. A wide range of characterization techniques confirms the successful synthesis of BiOClxI1−x (0 ≤ x ≤ 1.0), α-Ag1.82Cu0.09WO4 and BiOCl0.6I0.4/α-Ag1.82Cu0.09WO4 binary composites. The TC antibiotic removal efficiency of 30 wt% BiOCl0.6I0.4/α-Ag1.82Cu0.09WO4 binary composite reaches 95.91% within 120 min under natural sunlight irradiation and the rate constant is 1.81 and 3.33 times higher than the pristine BiOCl0.6I0.4 and α-Ag1.82Cu0.09WO4, respectively. The optimized binary heterojunction exhibits excellent photocatalytic performance for toxic pollutants like MB (η = 97.27%) and RhB (η = 95.75%) under direct sunlight irradiation. The favorable photocatalytic activity of binary heterojunction is ascribed to enhancing the sunlight absorption range, the tight contact interface and the effective separation of electron/hole pairs. Notably, 30 wt% BiOCl0.6I0.4/α-Ag1.82Cu0.09WO4 binary composite exhibits attractive recycling ability and good photostability for prolonged sunlight irradiation. Furthermore, the total organic carbon results also confirm that the 30 wt% BiOCl0.6I0.4/α-Ag1.82Cu0.09WO4 efficiently mineralized the model pollutants (TC antibiotic, MB and RhB) into other unharmful compounds under sunlight irradiation. In summary, this work offers an effective strategy to prepare solid-state Z-scheme heterojunction with favorable photocatalytic activity, which can increase wastewater purification efficiency.

Potential positive effects of natural sunlight on a biological system for landfill leachate treatment

AbstractActivated sludge filtration performance is a significant mean to evaluate membrane fouling trend for wastewater treatment. Here the impact of sunlight irradiation on activated sludge filtration performance and microbial communities in sequencing batch reactors (SBRs) when treating raw landfill leachate were studied. The sludge in photic SBR (i.e., SBR exposed to natural sunlight) exhibited better filtration performance compared to dark SBR (i.e., SBR unexposed to sunlight). The removal efficiency of COD and NH4+‐N in the photic SBR were slightly higher than those in the dark SBR. The contents of the extracellular polymeric substances (EPSs) of sludge in both SBRs initially increased and then decreased. However, in the later period, the sludge filtration performance worsened due to the fungal activity in the dark SBR. Natural sunlight irradiation promoted sludge filtration performance by affecting the microorganism structure in the photic SBR. The bacterial genus Thauera was dominant in the photic SBR (39.35%), whereas Planktosalinus and Ottowia were dominant in the dark SBR (16.84% and 12.55%, respectively). Natural sunlight irradiation had a prominent effect on the fungal diversity in the system, and filamentous bulking caused by the fungi genus Trichosporon’s proliferation was observed in the dark SBR but not in the photic SBR, which also increased the polysaccharide content.

Uncovering the role of unsaturated coordination defects in manganese oxides for concentrated solar-heating photothermal OVOCs oxidation: Experimental and DFT explorations

In this study, we innovatively develop a concentrated photothermal catalysis (CPTC) system with a cost-effective solar concentrator to efficaciously achieve light-to-heat conversion, and combine a defect engineering strategy to design Mn3O4-based catalysts with unsaturated coordination defects (O and Mn atoms) for solar-heating photothermal ethyl acetate oxidation without additional artificial-energy input. As a result, Mn3O4-3 exhibits outstanding photothermal catalytic performance for ethyl acetate and other OVOCs oxidation under weak simulated sunlight even natural sunlight irradiation. The enriched unsaturated defects in Mn3O4-3 with lower Mn-O and Mn-Mn coordination numbers not only improve the concentration of surface reactive species (Mn4+ and Oads), but also regulate the energy-band structure to further promote the light absorption capacity and charge separation. Experimental and theoretical evidences demonstrate that the generation of abundant Mn defects is conducive to the ethyl acetate dissociation/hydrolysis into key intermediates, while the existence of more O vacancies synergistically facilitates the O2 dissociation toward highly reactive O* participating in the deep oxidation of key intermediates. Moreover, in-situ DRIFTS and DFT results reveal the reaction pathway expansion (Pathway I and II) of photothermal ethyl acetate oxidation on manganese oxides under sunlight irradiation. This work provides an attractive CPTC technology for VOCs removal in energy and environmental application.

Solar light-driven photocatalysis by Co doped SnS nanoparticles towards degradation of noxious organic pollutant: Mechanism and toxicity assessment

Tin Sulphide (SnS), one of the main sulfide compounds, has generated a great deal of interest because of its distinctive properties and diverse applications. Pure and Cobalt (Co) doped tin Sulphide (SnS) nanoparticles (NPs) have been synthesized by a facile co-precipitation approach. The synthesized nanoparticles were characterized using various characterization techniques such as X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), Raman, UV-Vis Spectroscopy, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) studies were used to investigate and confirmed the crystalline, optical, and morphological features of nanoparticles. Under the irradiation of natural sunlight, the synthesised nanoparticles effectively performed as a visible light-activated catalyst for the degradation of Crystal violet (CV) and Bromophenol blue (BP) dyes. A 7% of Co-doped SnS catalyst showed excellent photodegradation efficiency of 95.5% and 93.0% for CV and BP, respectively. Rate constant values of 0.066 and 0.059 min−1 are estimated for CV and BP degradation, respectively. The higher photocatalytic activity might be attributed to Co doping, with the doped Co then playing a substantial role in lowering bandgap and boosting charge carriers, superoxide radical, and hydroxyl radical production, which prevents recombination and thus improves the efficiency and stability of the photocatalyst. Additionally, the toxicity of Vigna radiata seeds that are readily available commercially is evaluated using the treated, untreated dye solution, and control solutions.

Mechanical Effects of Elastic Crystals Driven by Natural Sunlight and Force

AbstractFlexible crystals that can capture solar energy and convert it into mechanical energy are promising for a wide range of applications such as information storage and actuators, but obtaining them remains a challenge. Herein, an elastic crystal of a barbiturate derivative was found to be an excellent candidate, demonstrating plastic bending behavior under natural sunlight irradiation. 1H NMR and high‐resolution mass spectrum data of microcrystals before and after light irradiation demonstrated that light‐induced [2+2] cycloaddition was the driving force for the photomechanical effects. Interestingly, the crystals retained elastic bending even after light irradiation. This is the first report of flexible crystals that can be driven by natural sunlight and that have both photomechanical properties and elasticity. Furthermore, regulation of the passive light output direction of the crystals and transport of objects by applying mechanical forces and light was demonstrated.

Mechanical Effects of Elastic Crystals Driven by Natural Sunlight and Force.

Flexible crystals that can capture solar energy and convert it into mechanical energy are promising for a wide range of applications such as information storage and actuators, but obtaining them remains a challenge. Herein, an elastic crystal of a barbiturate derivative was found to be an excellent candidate, demonstrating plastic bending behavior under natural sunlight irradiation. 1 H NMR and high-resolution mass spectrum data of microcrystals before and after light irradiation demonstrated that light-induced [2+2] cycloaddition was the driving force for the photomechanical effects. Interestingly, the crystals retained elastic bending even after light irradiation. This is the first report of flexible crystals that can be driven by natural sunlight and that have both photomechanical properties and elasticity. Furthermore, regulation of the passive light output direction of the crystals and transport of objects by applying mechanical forces and light was demonstrated.

Nacre-inspired fabrication of robust and flexible photothermal protective films using a coordination-crosslinking self-assembly strategy

Multifunctional photothermal protective films are novel photothermal-conversion materials that efficiently harvest and utilize solar energy. They also require excellent stability and durability. However, the poor toughness, loose structure, and weak shielding performance of these films limit their applications in photothermal conversion and metal protection. Inspired by the delicate microstructure of nacre, which exhibits excellent strength and barrier protection performance, a coordination-crosslinking self-assembly strategy is proposed herein that realizes a bio-phytic acid–silane–graphene oxide (bio-PSGO) metal-protective film with nacre-mimetic structures. The self-assembled bio-PSGO film exhibits good flexibility, excellent photothermal-conversion efficiency (93.9 %), outstanding protective performance, and water-desalination ability under natural sunlight irradiation. The coordination-crosslinking self-assembly process is simple and spontaneous, and it quickly assembles a complete thin film in an aqueous system. Nacre-like structured bio-PSGO films are easily obtained on the surfaces of metal substrates, such as iron, copper, zinc, magnesium, aluminum, and nickel. Metal ions released from metal materials promote the self-assembly of films via coordination crosslinking with PSGO nanosheets; meanwhile, the thermally conductive metal materials quickly transfer the heat generated in the photothermal-conversion process, synergistically improving the photothermal efficiency of the system. The proposed strategy designs robust and flexible materials that simulate the lamellar microstructure of nacre, which can be applied in flexible wearable devices and sensors, energy supply, metal protection, seawater desalination, solar thermal de-icing, and aerospace technologies.

Degradation of Paracetamol in Distilled and Drinking Water via Ag/ZnO Photocatalysis under UV and Natural Sunlight

The present study demonstrates the synthesis and application of Ag/ZnO powder films (thickness of 4 μm) as photocatalysts for natural sunlight and ultraviolet (UV, 315–400 nm) irradiation. The synthesis procedure is simple and eco-friendly, based on the photo-fixation of silver ions onto commercial ZnO powder via UV illumination for the first time. The photocatalytic efficiency of the newly developed films is evaluated through degradation of paracetamol in distilled and drinking water. Our experimental evidences show that the Ag/ZnO nanostructure films are more active than pristine ZnO films in the photodegradation process. Namely, the photocatalytic efficiency of the films modified with 10−2 M concentration of silver ions achieve the highest degradation (D) percentages for paracetamol in both types of water (Ddistilled = 80.97%, Ddrinking = 82.5%) under natural sunlight. Under UV exposure, the degradation percentages are slightly lower but still higher than those achieved by pure ZnO films (Ddistilled = 53.13%, Ddrinking = 61.87%). It is found that the photocatalytic activity grows in direct proportion to the concentration of Ag+ ions: ZnO < Ag 10−4/ZnO < Ag 10−3/ZnO < Ag 10−2/ZnO. Scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance and photoluminescence spectroscopy are used to characterize the as-prepared ZnO and Ag/ZnO nanostructures. The improved photocatalytic performance of the Ag/ZnO films is mostly attributed to the combination of excited electron transfer from ZnO to Ag and the inhibition of photogenerated electron–hole pair recombination. Furthermore, Ag/ZnO nanostructure films can retain their photocatalytic activity after three cycles of use, highlighting their potential practical application for the treatment of pharmaceutical wastewater in real-world scenarios where natural sunlight is often more readily available than artificial UV light.

N-doped carbon/TiO2 composites with enhanced photocatalytic performance for the removal of organic pollutants

A nitrogen doped carbon (NC) material, obtained via the camphor combustion technique, was used to develop a TiO2 based visible light photocatalyst. Various physical and analytical techniques were used to characterize the structural, morphological and photocatalytic study of the obtained catalyst. The results illustrate that N-doped carbon/TiO2 composites (NCT) exhibit NC spheroids embedded on the surface of 3D flower-like hierarchical TiO2 microspheres composed of 1D nanorods. The presence of C-N, C-C, N-Ti-O and Ti-O-C was successfully confirmed by the FTIR study. The UV–vis absorption spectra revealed the energy bandgap between 2.4 and 2.8 eV, confirming the enhanced visible light absorption ability for the NCT samples with increased wt% of N-doped carbon. The NCT sample has achieved 86% photodegradation of methyl orange in an aqueous solution within 25 min under mercury light irradiation and 85% within 10 min under natural sunlight irradiation. In addition, NCT3 composite degrades 30% of BPA (20 ppm) within 210 min under mercury light irradiation. The enhanced catalytic activity of the composite material was ascribed due to the high surface area, large pore size and high pore. Also, the high absorption in the visible range and efficient charge transfer of the charge carriers were credited for the enhanced photocatalytic activity of the NCT3 sample.

Solar/periodate-triggered rapid inactivation of Microcystis aeruginosa by interrupting the Calvin-Benson cycle

Frequent outbreak of cyanobacteria is a serious problem for drinking water treatment. The microcystins released from Microcystis aeruginosa (M. aeruginosa) could cause irreversible damage to human health. Catalyst-free solar/periodate (PI) system has recently presented great potential for bacterial inactivation, whereas the application potential and underlying mechanisms of the effective M. aeruginosa control remain unclear. Our work delineated the key role of ROS that inactivating/harmless disposing M. aeruginosa in the simulated sunlight (SSL)/PI system. Singlet oxygen may specifically cause DNA damage but maintain membrane integrity, preventing the risk of microcystins leakage. The SSL/PI 300 μM system could also effectively inhibit M. aeruginosa recovery for >7 days and completely degrade microcystin-LR (50.0 μg/L) within 30 min. Non-targeted metabolomic analysis suggested that the SSL/PI system inactivated M. aeruginosa mainly by interrupting the Calvin-Benson cycle, which damaged the metabolic flux of glycolysis and its downstream pathways such as the oxidative PPP pathway and glutathione metabolism. Furthermore, the activated PI system exhibited an even better algal inhibition under natural sunlight irradiation, evidenced by the seriously damaged cell membrane of M. aeruginosa. Overall, this study reported the comprehensive mechanisms of algal control and application potentials of solar/PI systems. The findings facilitated the development of emerging algicidal technology and its application in controlling environmental harmful algae.