Ozonation and ozone-enhanced photocatalysis for VOC removal from air streams: Process optimization, synergy and mechanism assessment

A comprehensive review and perspective research in technology integration for the treatment of gaseous volatile organic compounds

Volatile organic compounds (VOCs) are harmful pollutants emitted from industrial processes. They pose a risk to human health and ecosystems, even at low concentrations. Controlling VOCs is crucial for good air quality. This review aims to provide a comprehensive understanding of the various methods used for controlling VOC abatement. The advancement of mono-functional treatment techniques, including recovery such as absorption, adsorption, condensation, and membrane separation, and destruction-based methods such as natural degradation methods, advanced oxidation processes, and reduction methods were discussed. Among these methods, advanced oxidation processes are considered the most effective for removing toxic VOCs, despite some drawbacks such as costly chemicals, rigorous reaction conditions, and the formation of secondary chemicals. Standalone technologies are generally not sufficient and do not perform satisfactorily for the removal of hazardous air pollutants due to the generation of innocuous end products. However, every integration technique complements superiority and overcomes the challenges of standalone technologies. For instance, by using catalytic oxidation, catalytic ozonation, non-thermal plasma, and photocatalysis pretreatments, the amount of bioaerosols released from the bioreactor can be significantly reduced, leading to effective conversion rates for non-polar compounds, and opening new perspectives towards promising techniques with countless benefits. Interestingly, the three-stage processes have shown efficient decomposition performance for polar VOCs, excellent recoverability for nonpolar VOCs, and promising potential applications in atmospheric purification. Furthermore, the review also reports on the evolution of mathematical and artificial neural network modeling for VOC removal performance. The article critically analyzes the synergistic effects and advantages of integration. The authors hope that this article will be helpful in deciding on the appropriate strategy for controlling interested VOCs.

Investigation of photocatalytic-proxone process performance in the degradation of toluene and ethyl benzene from polluted air

In this study, toluene and ethylbenzene were degraded in the photocatalytic-proxone process using BiOI@NH₂-MIL125(Ti)/Zeolite nanocomposite. The simultaneous presence of ozone and hydrogen peroxide is known as the proxone process. Nanocomposite Synthesis was carried out using the solvothermal method. Inlet airflow, ozone concentrations, H₂O₂ concentrations, relative humidity, and initial pollutants concentrations were studied. The nanocomposite was successfully synthesized based on FT-IR, BET, XRD, FESEM, EDS element mapping, UV-Vis spectra and TEM analysis. A flow rate of 0.1 L min^-1, 0.3 mg min^-1 of ozone, 150 ppm of hydrogen peroxide, 45% relative humidity, and 50 ppmv of pollutants were found to be optimal operating conditions. Both pollutants were degraded in excess of 95% under these conditions. For toluene and ethylbenzene, the synergistic of mechanisms effect coefficients were 1.56 and 1.76, respectively. It remained above 95% efficiency 7 times in the hybrid process and had good stability. Photocatalytic-proxone processes were evaluated for stability over 180 min. The remaining ozone levels in the process was insignificant (0.01 mg min^-1). The CO₂ and CO production in the photocatalytic-proxone process were 58.4, 5.7 ppm for toluene and 53.7, and 5.5 ppm for ethylbenzene respectively. Oxygen gas promoted and nitrogen gas had an inhibitory effect on the effective removal of pollutants. During the pollutants oxidation, various organic intermediates were identified.

Revelation of contributing mechanism of reactive oxygen species in photocatalytic ozonation heterocyclization of gaseous hexane isomers

The reactive oxygen species (ROS) involved photocatalytic ozonation of gaseous n-hexane to heterocyclic compounds has been recently reported. However, whether such heterocyclization reaction happens on other alkanes and what is the contributing mechanism of ROS to the heterocyclic compound formation are still unclear. In present study, photocatalytic ozonation of three n-hexane's isomers (i.e. 2-methypentane, 3-methylpentane and 2,3-dimethylbutane) on Cu₂O-CuO/TiO₂-foam ceramic was investigated. Within reaction period, 2-methylpentane and 3-methylpentane not only showed higher average degradation efficiency than 2,3-dimethylbutane, but also separately converted to interfacial heterocyclic compounds of 5,5-dimethyldihydro-2(3H)-furanone and 4,5-dimethyl-4,5-dihydro-2(3H)-furanone. Enough reaction time, optimum experimental atmosphere and shorter light wavelength benefited the formation of heterocyclization products. None of O₃, ¹O₂, electron and hole directly contributed to the heterocyclic compound formation. While ^•O₂^- dominated the production of the heterocyclic compound under the dry reaction atmosphere and ^•OH showed more important role than ^•O₂^- in the heterocyclic compound formation under the moist reaction atmosphere. Theoretical calculation confirmed that ^•OH or ^•O₂^- induced heterocyclization reaction of alkane was exothermic, while the former reaction released 0.47 eV higher energy than the later reaction. The findings provide a comprehensive understanding of contributing roles of ROS in heterocyclization reaction of alkanes, and are helpful for effective elimination of industrial alkanes by advanced oxidation methods.

Optimization of photothermal conversion and catalytic sites for photo-assisted-catalytic degradation of volatile organic compounds

Solar energy conversion is a promising strategy to enhance the elimination of volatile organic compounds (VOCs) and minimize power consumption. Herein, non-noble metal WC@WO₃ as cocatalyst was composited with CeO₂ to optimize photochemical and photothermal conversion for the catalytic ozonation of toluene and acetone. The photothermal conversion efficiencies of visible and infrared lights on 20%WC@WO₃-CeO₂ were 2.2 and 10.4 times higher than those on CeO₂, respectively, which indicates that the equilibrium temperature of the catalyst remarkably increased under full-spectrum light irradiation. Moreover, WC@WO₃ transferred electrons to CeO₂ in 20%WC@WO₃-CeO₂ and thus remarkably improved the activity of catalytic sites. The synergy factor of light and O₃ on 20%WC@WO₃-CeO₂ was 5.8, and the reaction rate of toluene and acetone reached 9274.5 and 35779.0 mg/(m³∙min), respectively. This work provides a low-cost and high-efficient catalyst for the utilization of solar energy for VOC control.

Novel monolithic catalysts for VOCs removal: A review on preparation, carrier and energy supply

Volatile organic compounds (VOCs) are considered the culprit of secondary air pollution such as ozone, secondary organic aerosols, and photochemical smog. Among various technologies, catalytic oxidation is considered a promising method for the post-treatment of VOCs. Researchers are sparing no effort to develop novel catalysts to meet the requirements of the catalytic process. Compared with the powdered or granular catalysts, the monolithic catalysts have the advantages of low pressure drop, high utilization of active phases, and excellent mechanical properties. This review summarized the new design of monolithic catalysts (including new preparation methods, new supports, and new energy supply methods) for the post-treatment of VOCs. It addressed the advantages of the new designs in detail, and the scope of applicability for each new monolithic catalyst was also highlighted. Finally, the highly required future development trends of monolithic catalysts for VOCs catalytic oxidation are recommended. We expect this work can inspire and guide researchers from both academic and industrial communities, and help pave the way for breakthroughs in fundamental research and industrial applications in this field.

Efficient degradation of VOCs using semi-coke activated carbon loaded ternary Z-scheme heterojunction photocatalyst BiVO4-BiPO4-g-C3N4 under visible light irradiation

The coal chemical industry generates large amounts of solid waste and volatile organic compounds (VOCs). In this study, the solid waste semi-coke powder obtained in the semi-coke production process was used as a raw material to prepare high-specific surface area semi-coke activated carbon (SAC) by a carbonization and activation process, and a ternary z-scheme heterojunction photocatalyst with high catalytic performance was loaded for synergistic treatment by adsorption and photodegradation to achieve waste treatment with waste. The prepared semi-coke activated carbon has a specific surface area of 619.27 m² g^-1, which can achieve effective adsorption of VOCs. The ternary z-scheme heterojunction photocatalyst BiPO₄-BiVO₄-g-C₃N₄ (PVCN) was supported on a semi-coke activated carbon substrate by a one-step sol-gel method. Based on the synergistic effect of adsorption and photocatalysis, the obtained PVCN/SAC material can degrade toluene by 85.6% within 130 minutes under simulated sunlight irradiation, which is 2.43 times that of pure photocatalyst. The rate of degrading toluene can be increased by 4.43 times. Capture experiments showed that superoxide radicals (_˙O₂^-) and hydroxyl radicals (_˙OH) were the key active species in the degradation pathway. Even after five cycles, the material maintained 81.6% of the degradation performance. In this work, we deeply investigate the mechanism of semi-coke activated carbon as a matrix for enhancing photocatalytic degradation performance. The findings of this work provide new insights into the efficient degradation of VOCs and provide a good theoretical basis for the development of high-performance photocatalysts.

A review of volatile organic compounds (VOCs) degradation by vacuum ultraviolet (VUV) catalytic oxidation

Volatile organic compounds (VOCs), one of the most important gaseous air pollutants, are getting more and more attention, and a lot of technologies have been studied and applied to eliminate VOCs emissions. Advanced oxidation processes (AOPs) are considered as one of the most promising techniques used for the degradation of VOCs. Vacuum ultraviolet (VUV) catalytic oxidation system is a typical composite AOPs system involving several processes such as VUV photodegradation, photocatalytic oxidation (PCO), ozone catalytic oxidation (OZCO) and their combinations. VUV based catalytic oxidation processes have been intensively studied for degrading VOCs. This review summarizes the recent studies on the use of VUV catalytic oxidation for degrading VOCs. All the processes involved in VUV catalytic oxidation and their combinations have been reviewed. Studies of VOCs degradation by VUV catalytic oxidation can be generally divided into two aspects: developments of catalysts and mechanistic studies. Principles of different processes, strategies of catalyst development and reaction mechanism are summarized in this review. Two directions of prospective future work were also proposed.

Modulate the metal support interactions to optimize the surface-interface features of Pt/CeO2 catalysts for enhancing the toluene oxidation

Metal support interactions modulation is one of the effective strategies to enhance the catalytic performance. Herein, we reported that modulating metal support interactions by switching the strength (CO, H₂, NH₃) and temperature (200, 300, 400 °C) of reducing gases is a facile way to improve the catalytic performance of Pt/CeO₂ for toluene oxidation. The distinct reduction treatments will stepwise enhance the reducibility, ratio of Pt⁰ and oxygen vacancy concentration, which dominated the activity. The metal support interactions modulation can significantly affect toluene deep oxidation (from benzoate to formate or monodentate carbonate) via enhancing the mobility of surface/lattice oxygen and activation ability towards O₂ molecules, since the main activation sites for O₂ molecules expand from Pt⁰ sites to oxygen vacancies and Pt⁰ sites with temperature increasing.

Mixing in the NETmix Reactor

NETmix is a static mixing reactor composed of a network of mixing chambers interconnected by channels. The repetitive mixing pattern inside the reactor enables the use of reduced geometries to represent the NETmix network, such as the ExtendedNUB model, used in this work. Mixing in NETmix is based on the impingement of jets, issuing from channels. Inside the chambers, the jets are engulfed by dynamic vortices which can be quantified using Lagrangian techniques. Batch Lagrangian Mixing Simulation (BLMS) is based on successive injections of particles to measure the fraction of the fluids at the outlet of the mixing chambers. The distribution of the outlet fraction of particles indicates that it is possible to have nearly perfect mixing inside the NETmix chambers, depending on the dimensions of the channels and chambers. The NETmix design is here optimized in relation to the chamber diameter to channel width ratio, D/d. Results from BLMS show that best performance in NETmix occurs for 6.65≤D/d≤6.85.

Adsorption performance and kinetic study of hierarchical porous Fe-based MOFs for toluene removal

In light of the promising merits of large surface area, uniform pore size, and tunable functional groups, metal-organic frameworks (MOFs) have great potential to be utilized for adsorbing volatile organic compounds (VOCs). In this study, three Fe-based MOFs, MIL-100(Fe), MIL-101(Fe), and MIL-53(Fe), were synthesized systematically and used to adsorb a typical VOC, toluene. Static adsorption, dynamic breakthrough curves, and adsorption kinetics were conducted to assess the adsorption performance. Additionally, the surface functional groups, pore structure, and morphology were systematically characterized by means of XRD, SEM, XPS, FTIR and N₂ adsorption-desorption analyses to reveal the cause of the difference in adsorption of these Fe-based MOFs. The results revealed that the maximum equilibrium adsorption capacity of 663 mg/g was achieved by MIL-100(Fe) with the highest specific surface area and pore volume. The dynamic adsorption of toluene on MIL-100(Fe) was in accordance with the pseudo-first order kinetic model and the Langmuir isothermal model. The formed π-π stacking interaction between organic ligands and the benzene ring in the MIL-100(Fe) cluster is the primary adsorption mechanism based on XPS analysis. Moreover, MIL-100(Fe) was easily regenerated via microwave irradiation with a negligible adsorption capacity decrease after three cycles. This work highlights the feasibility of hierarchical porous Fe-based MOFs as toluene adsorbents and promotes the application of MOFs in the field of pollution control.

Photocatalytic oxidation technology for indoor air pollutants elimination: A review

As more people are spending the majority of their daily lives indoors, indoor air quality has been acknowledged as an important factor influencing human health, with increasing research attention in recent decades. Indoor air pollutants (IAPs), such as volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), can cause acute irritation and chronic diseases. Photocatalytic oxidation (PCO) technology is an efficient approach for eliminating IAPs. In this review, the development of PCO technology was explained and discussed to promote future development of PCO technology for IAP elimination. First, the health effects and the measured concentrations of typical VOCs and SVOCs in indoor environments worldwide were briefly introduced. Subsequently, the development and limitations of some typical photocatalytic reactors (including packed-bed reactors, monolithic reactors, optical fiber reactors, and microreactors) were summarized and compared. Then, the influences of operating parameters (including initial concentration of contaminants, relative humidity, space velocity, light source and intensity, catalyst support materials, and immobilization method) and the degradation pathways as well as intermediates of PCO technology were elucidated. Finally, the possible challenges and future development directions regarding PCO technology for IAP elimination were critically proposed and addressed.

Highly efficient adsorptive removal of toluene using silicon-modified activated carbon with improved fire resistance

Activated carbons (ACs) are widely applied in the removal of volatile organic compounds (VOCs) emitted from industrial processes, because of their high adsorption capacity, low cost and reusability. Their poor thermal stability under oxidative conditions is a limiting factor and often leads to fire risk in real applications. Here, Si-modification was performed over a wood-derived AC material, and a series of modified ACs with different Si/C mass ratios (0.1-0.9) were prepared via a hydrothermal route. Physicochemical characteristics of Si/C samples was examined by XRD, SEM, TEM, XPS, FTIR and N₂-physisorption measurements. As compared to pristine AC, Si-modified ACs showed enhanced fire resistance, and an increase of ignition temperature by 79 ℃ was achieved at a Si/C mass ratio of 0.9. A combination of TEM, XPS and FTIR characterization suggests that the formation of amorphous SiO₂ nanoparticles and SiC species on the surface was responsible for the enhanced fire resistance of Si-modified ACs. By increasing microporosity, Si-modification also significantly improved the adsorption capacity of toluene as a model VOC molecule. Static and dynamic adsorption experiments were performed to understand the adsorption kinetics of the Si-modified ACs. Reusability tests showed that the desorption rate of the modified AC remained at nearly 80% even after five cycles of repeated adsorption-desorption, indicating that the modified AC has a great potential for industrial applications.

A Critical Review on Removal of Gaseous Pollutants Using Sulfate Radical-based Advanced Oxidation Technologies

Excessive emissions of gaseous pollutants such as SO₂, NO_x, heavy metals (Hg, As, etc.), H₂S, VOCs, etc. have triggered a series of environmental pollution incidents. Sulfate radical (SO₄•^-)-based advanced oxidation technologies (AOTs) are one of the most promising gaseous pollutants removal technologies because they can not only produce active free radicals with strong oxidation ability to simultaneously degrade most of gaseous pollutants, but also their reaction processes are environmentally friendly. However, so far, the special review focusing on gaseous pollutants removal using SO₄•^--based AOTs is not reported. This review reports the latest advances in removal of gaseous pollutants (e.g., SO₂, NO_x, Hg, As, H₂S, and VOCs) using SO₄•^--based AOTs. The performance, mechanism, active species identification and advantages/disadvantages of these removal technologies using SO₄•^--based AOTs are reviewed. The existing challenges and further research suggestions are also commented. Results show that SO₄•^--based AOTs possess good development potential in gaseous pollutant control field due to simple reagent transportation and storage, low product post-treatment requirements and strong degradation ability of refractory pollutants. Each SO₄•^--based AOT possesses its own advantages and disadvantages in terms of removal performance, cost, reliability, and product post-treatment. Low free radical yield, poor removal capacity, unclear removal mechanism/contribution of active species, unreliable technology and high cost are still the main problems in this field. The combined use of multiactivation technologies is one of the promising strategies to overcome these defects since it may make up for the shortcomings of independent technology. In order to improve free radical yield and pollutant removal capacity, enhancement of mass transfer and optimization design of reactor are critical issues. Comprehensive consideration of catalytic materials, removal chemistry, mass transfer and reactor is the promising route to solve these problems. In order to clarify removal mechanism, it is essential to select suitable free radical sacrificial agents, probes and spin trapping agents, which possess high selectivity for target specie, high solubility in water, and little effect on activity of catalyst itself and mass transfer/diffusion parameters. In order to further reduce investment and operating costs, it is necessary to carry out the related studies on simultaneous removal of more gaseous pollutants.

Toluene degradation by heterogeneous photocatalysis assisted with ozone in a tubular reactor: analysis over the reactor length

Volatile organic compounds (VOCs) are atmospheric pollutants that can affect human healthy and intensify some environmental problems. Among different techniques to degrade VOCs, heterogeneous photocatalysis has been highlighted. The aim of this research was to obtain high toluene degradation using heterogeneous photocatalysis in the ozone presence (TiO₂/O₃/UV) and analyze VOC degradation over the reactor length comparing with ozone concentration also over the reactor length. Ozone concentration has influence on toluene degradation; 75% of VOC degradation was reached with 69.0 mgL^-1 of O₃ meanwhile a degradation of 91% was obtained with 96.2 mgL^-1 of O₃. Toluene degradation reached a plateau over reactor length at flowrate of 565 mL min^-1, which indicates the reactor was oversized in this case. However, it was not observed at 1425 mL min^-1. In addition, it was evaluated that O₃ concentration and toluene reaction rate decreased over the reactor length.

Toward Scaling-Up Photocatalytic Process for Multiphase Environmental Applications

Recently, we have witnessed a booming development of composites and multi-dopant metal oxides to be employed as novel photocatalysts. Yet the practical application of photocatalysis for environmental purposes is still elusive. Concerns about the unknown fate and toxicity of nanoparticles, unsatisfactory performance in real conditions, mass transfer limitations and durability issues have so far discouraged investments in full-scale applications of photocatalysis. Herein, we provide a critical overview of the main challenges that are limiting large-scale application of photocatalysis in air and water/wastewater purification. We then discuss the main approaches reported in the literature to tackle these shortcomings, such as the design of photocatalytic reactors that retain the photocatalyst, the study of degradation of micropollutants in different water matrices, and the development of gas-phase reactors with optimized contact time and irradiation. Furthermore, we provide a critical analysis of research–practice gaps such as treatment of real water and air samples, degradation of pollutants with actual environmental concentrations, photocatalyst deactivation, and cost and environmental life-cycle assessment.

Photocatalytic Oxidation of PLA/TiO2-Composite Films for Indoor Air Purification

Non-decomposable plastic has been replaced with polylactic acid, which is a biodegradable aliphatic polyester stationary phase, in composite films embedded with a TiO₂ photocatalyst for mitigation of indoor air pollution. PLA has superior properties relative to those of other biopolymers, such as a relatively high melting point, crystallinity, and rigidity. This study aimed to incorporate TiO₂-anatase into PLA for use as a photocatalyst using the blown film method. Photocatalytic oxidation, an advanced oxidative process, has been recognized as an economical technique providing convenience and efficiency with indoor air treatment. Therefore, the use of new environmentally friendly biodegradable polymers provides an alternative way to address the severe environmental concerns caused by non-decomposable plastics. UV-vis spectrophotometry and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) were used to observe the dispersibility and mixing capacity of the TiO₂-anatase PLA matrix. TiO₂ dosages were 5, 10, and 15% (wt/wt), and they were incorporated with a twin-screw extruder. SEM-EDX images demonstrated the homogeneity of TiO₂ distribution in the PLA matrix. The energy band gaps of TiO₂ in the PLA/TiO₂-composite films were between 3.14 and 3.22 eV. The relationship between the photocatalytic oxidation rate and the TiO₂ dosage in the PLA/TiO₂-composite films was determined. A prototype reactor model is geared toward the development of air purifiers for indoor air conditioning. Rate constants for benzene degradation were obtained using first-order kinetics to find rate constants matching experimental findings. In the PLA/TiO₂-composite film, the TiO₂-anatase photocatalyst was able to degrade 5 ppm benzene. This work contributes to the use of ecoefficient photocatalytic oxidation.

Efficient Photocatalytic Degradation of Gaseous Benzene and Toluene over Novel Hybrid PIL@TiO2/m-GO Composites

In this work, the PIL (poly ionic liquid)@TiO2 composite was designed with two polymerized ionic liquid concentrations (low and high) and evaluated for pollutant degradation activity for benzene and toluene. The results showed that PIL (low)@TiO2 composite was more active than PIL (high)@TiO2 composites. The photodegradation rate of benzene and toluene pollutants by PIL (low)@TiO2 and PIL (high)@TiO2 composites was obtained as 86% and 74%, and 59% and 46%, respectively, under optimized conditions. The bandgap of TiO2 was markedly lowered (3.2 eV to 2.2 eV) due to the formation of PIL (low)@TiO2 composite. Besides, graphene oxide (GO) was used to grow the nano-photocatalysts’ specific surface area. The as-synthesized PIL (low)@TiO2@GO composite showed higher efficiency for benzene and toluene degradation which corresponds to 91% and 83%, respectively. The resultant novel hybrid photocatalyst (PIL@TiO2/m-GO) was prepared and appropriately characterized for their microstructural, morphology, and catalytic properties. Among the studied photocatalysts, the PIL (low)@TiO2@m-GO composite exhibits the highest activity in the degradation of benzene (97%) and toluene (97%). The ultimate bandgap of the composite reached 2.1 eV. Our results showed that the as-prepared composites hold an essential role for future considerations over organic pollutants.

Insights into efficient removal of gaseous p-xylene using cerium-doped ZnO nanoparticles through photocatalytic oxidation

Novel Ce-doped ZnO exhibited excellent photocatalytic activity for decomposing VOCs under VUV light.

Promotional removal of oxygenated VOC over manganese-based multi oxides from spent lithium-ions manganate batteries: Modification with Fe, Bi and Ce dopants

In this work, cathode materials of spent lithium-ions manganate batteries are recovered as the precursor of manganese-based oxides catalysts and furthermore, different amount of Fe, Bi, Ce are introduced to modify their properties. A series of MnOx(MS)-X Fe, MnOx(MS)-X Bi and MnOx(MS)-X Ce samples with crystal phase of Mn₅O₈ are synthesized using combustion method and then the catalytic behavior and physicochemical properties of prepared catalysts are investigated. Compared to binary MnOx-5% Fe, MnOx-15% Bi and MnOx-10% Ce samples, multi MnOx(MS)-5% Fe, MnOx(MS)-15 Bi and MnOx(MS)-10% Ce catalysts display enhanced catalytic performance significantly in the removal of oxygenated VOC, which could be attributed to larger specific surface area, higher concentration of surface active oxygen species and Mn⁴⁺ ions and better reducibility at low temperature. In-situ DRIFTS results imply that main oxygen-containing functional groups such as carbonyl (-C=O), carboxyl (-COO), hydroxyl (-OH) can be observed during VOC oxidation and by comparison, it can be found that gas-phase O₂ plays a crucial role in facilitating the further oxidation of by-products into CO₂. In addition, TD/GC-MS results point out that the main by-products are formaldehyde; 2-propanol, 1-methoxy-; ethanol, 2-methoxy-, acetate; 2-ethoxyethyl acetate; acetic acid during VOC oxidation.

Utilization of edible fungi residues towards synthesis of high-performance porous carbon for effective sorption of Cl-VOCs

Edible fungi residues are natural fungi etching feedstock that provide loose structure with multidimensional framework. These advantages help KOH to penetrate rigid cytoderm into innermost space and attain porous carbon with high porosity. Utilization of edible fungi residue not only avoids artificial operation of fungal inoculation and culture steps, but also provides new method for waste disposal. As expected, carbon derived from three fungi residues attains excellent porosity. The highest surface area reaches 3463.3 m²/g, which is approximately 2 and 6 times higher than original biomass (1630.7 m²/g) and commercial carbon (691.1 m²/g), respectively. Filiform structures derived from hyphae growth contribute to pores formation. Coprinus comatus fungi residue as optimal raw material obtains hierarchical pore channel with dominant micropores (76%) and natural nitrogen doping (1.28 at.%). The highest DCM and CB adsorption capacities attain 716.9 and 641.7 mg/g, respectively, which are 13 and 6 times higher than that of commercial carbon. The positive effects from fungi growth improve DCM adsorption particularly. DCM adsorption over fungi residues derived carbon is twice higher than original biomass carbon. Competitive adsorption, recyclability, surface variations and desorption components after saturated adsorption are fully investigated for practical application. The present study provides a new insight for developing high-value technology for synthesizing Cl-VOCs adsorbents using edible fungi residues.

A Cataluminescence Sensor Based on NiO Nanoparticles for Sensitive Detection of Acetaldehyde

Sensitive and selective detection of harmful gas is an important task in environmental monitoring. In this work, a gas sensor based on cataluminescence (CTL) for detection of acetaldehyde was designed by using nano-NiO as the sensing material. The sensor shows sensitive response to acetaldehyde at a relatively low working temperature of 200 °C. The linear range of CTL intensity versus acetaldehyde concentration is 0.02–2.5 mg/L, with a limit of detection of 0.006 mg/L at a signal-to-noise ratio of three. Mechanism study shows that electronically excited CO₂ is the excited intermediate for CTL emission during the catalytic oxidation of acetaldehyde on the NiO surface. The proposed sensor has promising application in monitoring acetaldehyde in residential buildings and in the workplace.

The synergistic effect of Ag/AgCl@ZIF-8 modified g-C3N4 composite and peroxymonosulfate for the enhanced visible-light photocatalytic degradation of levofloxacin

In this work, a series of Ag/AgCl@ZIF-8 modified g-C₃N₄ composites were synthesized and used to degrade levofloxacin (LVFX) in water under visible light irradiation with the assistant of peroxymonosulfate (PMS). The morphologies and physicochemical properties of the materials were characterized by SEM, TEM, XRD, XPS, FTIR, and DRS technologies. The results of photocatalytic experiments showed that in the presence of PMS, the degradation rate of LVFX reached 87.3% in 60min. Furthermore, factors affecting photocatalytic efficiency such as the concentration of PMS, photocatalyst dosage and different pH values were investigated. The degradation products of LVFX were analyzed by LC-MS and the degradation pathway was inferred. Active species trapping experiments indicated that O₂^-, h⁺ and SO₄^- played important roles in the degradation process in the presence of PMS and the possible degradation mechanism was put forward. This work provides a photocatalyst system that is beneficial to the separation of photogenerated carriers and demonstrates the great potential of PMS-assisted photocatalysis in the purification of organic pollutants.