Degradation Of Acetaldehyde Research Articles

Impact of Condensed Tannin and Sulfur Dioxide Addition on Acetaldehyde Accumulation and Anthocyanin Profile of Vitis vinifera L. Cv. Cabernet Sauvignon Wines During Alcoholic Fermentation

Acetaldehyde is a key carbonyl by-product during red wine alcoholic fermentation; it is reactive and takes part in certain reactions involving anthocyanin. The aim of this study was to investigate the influence of SO2 and condensed tannin on the acetaldehyde accumulation of Saccharomyces cerevisiae (S. cerevisiae) during alcoholic fermentation and the ripple effect on wine anthocyanin. In this study, six sets of Cabernet Sauvignon alcoholic fermentation with two different sulfur levels (HS and LS) were carried out by adding exogenous condensed tannins before fermentation (T0) in the acetaldehyde rise period (TA) of S. cerevisiae and at the end of fermentation (TE), separately. The acetaldehyde evolution was identified during fermentation and anthocyanin was analyzed comparatively. The results showed that HS treatment slowed down the degradation of acetaldehyde, while tannins accelerated the degradation of acetaldehyde during alcoholic fermentation, especially TA wines. Furthermore, TA wines possessed a unique anthocyanin profile after fermentation regardless of SO2 level compared with other wines. These results suggest that acetaldehyde-mediated anthocyanin polymerization most likely occurs timely at the acetaldehyde production phase of S. cerevisiae during alcoholic fermentation, and managing tannin addition time during production could be used to regulate the anthocyanin profile.

A novel ZnO-TiO2-Bi2WO6/Carboxymethyl chitosan composite with high antimicrobial activity and visible-light catalytic degradation of ethylene towards banana preservation in hot and humid environments

In order to solve the problem of significantly shortened storage time of bananas in hot and humid environment (e.g., 30 °C and 90 % relative humidity), this paper reports the preparation of ZnO-TiO2-Bi2WO6 (ZTB) ternary heterojunction antimicrobial photocatalysts composite carboxymethyl chitosan film (ZTB/CMCS). ZTB were prepared by hydrothermal method and composited with CMCS by surface deposition method to construct ZTB/CMCS edible nano-preservation film. It is noteworthy that the ZTB/CMCS composite film exhibited excellent antibacterial efficiency (>99.99 %) against E. coli and S. aureus suspensions (106 CFU/mL) after 24 h of incubation at 37 °C. Time-resolved photoluminescence (TRPL) spectroscopy showed that the incorporation of Zinc oxide nanoparticles (ZnO NPs) into the ZTB structure led to a decrease in fluorescence lifetime. Moreover, the interfacial interaction between ZnO and TiO2/Bi2WO6 inhibited the recombination of photogenerated electron-hole pairs, promoting carrier separation and improving photocatalytic activity. The combination of high antibacterial activity, photocatalytic degradation of ethylene and inhibition of gas exchange provided multiple protections for fruit preservation. Therefore, this work provides a novel, effective and safe method for prolonging the preservation of bananas in hot and humid environments.

Highly efficient degradation of ethanol, acetaldehyde, and ethyl acetate removal by bio-trickling filter reactors with various fillers

This study investigates the purification performance of bio-trickling filters (BTFs) using different media to treat ethanol, acetaldehyde, and ethyl acetate in kitchen waste malodorous gases. The media compared included a custom composite medium, pine bark, hollow polyhedral spheres, and ceramic particles. Over 25 days, the composite medium outperformed the traditional media, achieving removal rates of 90.13 % for ethanol, 63.89 % for acetaldehyde, and 82.56 % for ethyl acetate during the biofilm initiation phase, with the others below 60 %. Even under low empty bed residence time and high inlet concentrations, the maximum elimination capacity for ethanol, acetaldehyde, and ethyl acetate was 8.34–14.70 g/m3·h, 9.55–15.06 g/m3·h, and 6.18–10.45 g/m3·h. Kinetic analysis showed the Michaelis-Menten model fit well, indicating enhanced removal potential. High-throughput of 16S rDNA sequencing identified dominant microorganisms like Enterobacteriaceae (13.89 %), Stenotrophomonas (29.23 %), and Acinetobacter (4.09 %) in the composite medium, which thrived even at high pollutant concentrations. Principal component analysis (PCA) demonstrated differences in the microbial composition of the custom composite medium compared to traditional media under varying inlet concentrations and loads. This study provides technical support for the treatment of complex malodorous gas mixtures.

Effect of NH2-functionalization of MIL-125 on photocatalytic degradation of o-xylene and acetaldehyde

Ligand functionalization of metal organic framework (MOF) is a great important strategy to enhance the various properties of pristine materials. In this study, MIL-125 with different extents of NH2-functionalization were synthesized by solvothermal method. The photocatalytic degradation efficiency of the optimal sample for o-xylene and acetaldehyde were 88 % and 49 %, respectively, which were much improved compared to pristine MIL-125 (56 % for o-xylene and 3 % for acetaldehyde). Compared to pristine MIL-125, NH2-functionlized MIL-125 were more easily photoexcited to form photogenerated carriers, which facilitated the formation of more OH and O2− radicals under visible light irradiation. In addition, NH2 groups as the adsorption site interacted with o-xylene and acetaldehyde by the H-bonding and the Lewis acid-base effect, respectively. The above results contribute to a deep understanding of the influence of ligand functionalization of MOF on the photocatalytic degradation of VOCs.

Multiple Roles of Anions on the Degradation Efficiency and Mineralization Pathway of Recalcitrant Acetaldehyde by Vacuum Ultraviolet (185 nm) Oxidation.

Vacuum-UV (185 nm, VUV) is widely applied to polish reverse osmosis permeate (ROP), such as the production of electronics-grade ultrapure water. In this study, the VUV oxidation of acetaldehyde, a common carbonyl in ROP, was found to be influenced by anions even at low concentrations. Interestingly, the influencing extent and mechanism varied depending on the anions. Bicarbonate minimally affected the VUV-photon absorption and •OH consumption, but at 5000 μg-C·L-1, it decreased the degradation of acetaldehyde by 58.7% possibly by scavenging organic radicals or other radical chain reactions. Nitrate strongly competed for VUV-photon absorption and •OH scavenging through the formation of nitrite, and at 500 μg-N·L-1, it decreased the removal rate of acetaldehyde degradation by 71.2% and the mineralization rate of dissolved organic carbon by 53.4%. Chloride competed for VUV-photon absorption and also generated reactive chlorine species, which did not affect acetaldehyde degradation but influenced the formation of organic byproducts. The radical chain reactions or activation of anions under VUV irradiation could compensate for the decrease in oxidation performance and need further investigation. In real ROPs, the VUV oxidation of acetaldehyde remained efficient, but mineralization was hindered due to nitrate and chloride anions. This study deepens the understanding of the photochemistry and feasibility of VUV in water with low concentrations of anions.

In-situ electrospinning PVB/Camellia oil/ZnO-TiO2 nanofibrous membranes with synergistic antibacterial and degradation of ethylene applied in fruit preservation

This work utilizes a handheld electrospinning device to prepare a novel nanofibrous composite membrane in situ for packaging freshness. It can realize pick-and-pack and is easy to operate. The nanofibrous membrane is based on PVB as the matrix material, adding Camellia oil (CO) and ZnO-TiO2 composite nanoparticles (ZT) as the active material. The antimicrobial property of the CO and the photocatalytic activity of the nanoparticles give the material good antimicrobial and ethylene degradation functions. Meanwhile, this nanofibrous membrane has good mechanical properties, suitable moisture permeability and good optical properties. The nanofibrous membrane are suitable for both climacteric and non- climacteric fruits. Its use as a cling film extends the shelf life of strawberries by 4 days and significantly slows the ripening of small tomatoes. Therefore, this nanofibrous membrane has great potential for application in the field of fruit preservation.

Photocatalytic films with high ethylene degradation efficiency for strawberry preservation

The preservation of fruits has always been a research hotspot. In this research, titanium dioxide(TiO2) exhibiting diffraction peaks characteristic of both anatase and rutile phases was synthesized. Subsequently, photocatalytic films loaded with the TiO2 were fabricated using a twin-screw extruder combined with an extrusion casting technique. The films demonstrated a highest ethylene photocatalytic degradation efficiency of 88.57 %. The addition of TiO2 significantly enhanced the hydrophilicity of the films, with a maximum increase of 8.08 %. The tensile strength and elongation at break of the films were also improved. The optical properties, barrier properties and mechanical properties revealed that the film may make contributions to slowing down light aging, reducing weight loss of strawberries and increasing the load-bearing property. Furthermore, fresh-keeping experiment proved that the photocatalytic films could markedly slow down the appearance change, reduce weight loss and TBARS accumulation while decelerating the decline of TSS and antioxidant capacity in strawberries.

Oxygen-deficient WO3 for stable visible-light photocatalytic degradation of acetaldehyde within a wide humidity range

Indoor VOCs pollution has attracted broad attention for its harm to mankind’s health recent years. Photocatalytic degradation of indoor VOCs holds great prospects in addressing these health concerns in daily life. However, traditional photocatalysts have a large recombination rate of charge carriers and a decrease of the photocatalytic degradation efficiency under high relative humidity. Herein, uniform tungsten oxide nanoparticles with enriched oxygen vacancies (WO3-U) were synthesized by a direct annealing method with urea addition, which exhibited superior performance in the visible-light photocatalysis. The reaction rate constant value of photocatalytic acetaldehyde degradation over WO3-U catalyst was above 3 times higher than that of pristine WO3 sample. More importantly, the WO3-U catalyst maintained stable and excellent photocatalytic performance at relative humidity range of 25–100 %. Except for the enhanced photogenerated charges separation, abundant oxygen vacancies could effectively accelerate O2 activation to generate •O2−, which accounted mainly for the initial conversion of acetaldehyde. Then the subsequent transformation of •O2− into •OH to promoted the final mineralization of acetaldehyde. In addition, the presence of oxygen vacancies also facilitated H2O dissociation to form surface hydroxyl groups, which increased the adsorption of acetaldehyde, resulting in the consistent photocatalytic performance of WO3-U catalyst within a wide humidity range. This work provides guidelines to design visible-light responsive photocatalysts with efficient activity at high humidity conditions for indoor VOCs degradation.

Novel kinetic modeling of photocatalytic degradation of ethanol and acetaldehyde in air by commercial and reduced ZnO: Effect of oxygen vacancies and humidity

A comprehensive kinetic model has been developed to address the factors and processes governing the photocatalytic removal of gaseous ethanol by using ZnO loaded in a prototype air purifier. This model simultaneously tracks the concentrations of ethanol and acetaldehyde (as its primary oxidation product) in both gas phase and on the catalyst surface. It accounts for reversible adsorption of both compounds to assign kinetic reaction parameters for different degradation pathways. The effects of oxygen vacancies on the catalyst have been validated through the comparative assessment on the catalytic performance of commercial ZnO before and after the reduction pre-treatment (10% H2/Ar gas at 500 °C). The influence of humidity has also been assessed by partitioning the concentrations of water molecules across the gas phase and catalyst surface interface. Given the significant impact of adsorption on photocatalytic processes, the beginning phases of all experiments (15 min in the dark) are integrated into the model. Results showcase a notable decrease in the adsorption removal of ethanol and acetaldehyde with an increase in relative humidity from 5% to 75%. The estimated number of active sites, as determined by the model, increases from 7.34 10−6 in commercial ZnO to 8.86 10−6 mol gcat−1 in reduced ZnO. Furthermore, the model predicts that the reaction occurs predominantly on the catalyst surface while only 14% in the gas phase. By using quantum yield calculations, the optimal humidity level for photocatalytic degradation is identified as 25% with the highest quantum yield of 6.98 10−3 (commercial ZnO) and 10.41 10−3 molecules photon−1 (reduced ZnO) catalysts.

Time-resolved spectroscopic investigation for the practical application of a photocatalytic air purifier

The photocatalytic efficiency for removing volatile organic compounds (VOCs) is significantly influenced by operational parameters like humidity and flow velocity, exhibiting notable and inconsistent fluctuations in both lab-scale and large-scale demonstrations. In this study, operando spectroscopy and isotope analysis were employed to investigate the correlation between humidity levels and degradation of gaseous acetaldehyde using TiO2 photocatalysts, aiming to demonstrate the scaling-up of photocatalytic air purifier. It was observed that rate constants for the mineralization of acetaldehyde rapidly decreased by 30% as relative humidity increased from 25% to 80% in the flow system (with an air velocity, v = 0.78 m/s). However, batch system showed smaller change with only a 10% reduction of the rate constant. Humidity fluctuations were more pronounced under high-speed conditions and were amplified in air purifier (v = 3.8 m/s). Time-resolved operando spectroscopy using an 13C isotope of acetaldehyde revealed that humidity’s distinct role in dark adsorption and photocatalytic reactions. Water was found to inhibit the formation of crotonaldehyde during aldol condensation reaction in dark condition. Moreover, water suppressed photocatalytic mineralization by inhibiting acetate oxidation to formate. These findings provide valuable insights for improving realistic air purification processes, underscoring the importance of identifying key intermediates and controlling humidity to enhance the selectivity of gaseous pollutant oxidation reactions.

Prolonging banana shelf life through visible light-induced ethylene scavenging using manganese-decorated TiO2 via KMnO4 reduction

Apart from being a good source of nutrition, bananas are also an essential worldwide commodity. However, bananas exhibit fast ripening and low shelf life, especially after artificial ripening. TiO2 can act as an ethylene scavenger through photocatalytic degradation of ethylene. In this work, Mn-decorated TiO2 was synthesized through MnO4- reduction on the surface of P25 TiO2. The aim is to prolong the shelf life of artificially ripened bananas. Based on characterization results, we found that Mn decoration increased absorption of visible light, with the interaction between TiO2 and Mn predicted to be a type I heterojunction. The photocatalytic activity was tested by ethylene photodegradation. It was found that TiO2/Mn was able to partially oxidize ethylene to formic acid under visible light. Furthermore, bananas stored in a fruit storage chamber with TiO2/Mn showed a 2-day delay in color change. This confirms that TiO2/Mn can be used as an ethylene scavenger.

Efficient ethylene degradation in storage bananas by Bi–Mn catalyst at room temperature

There has been growing interest in removing ethylene (C2H4) from fresh fruit packaging to prevent its detrimental effects on fruit quality. Thus, creating innovative, efficient, and simple catalysts capable of degrading C2H4 at room temperature is imperative for fruit preservation. We demonstrated that the bismuth-manganese (Bi–Mn) catalysts, synthesized using the stepwise hydrothermal method, can degrade up to 40% of 50 ppm C2H4 in 6 h at room temperature. Doping with the Bi element resulted in an irregular broccoli-like catalyst with a specific surface area of up to 71.66 m2/g more surface Mn vacancies, a higher Mn3+/Mn4+ ratio, and increased oxygen adsorption capacity. The catalyst extended banana shelf life by 3–5 days, unprecedentedly maintaining the overall sensory quality at the desired level. The catalyst was effective in reducing ethylene production by 45.2% at 25 °C storage. Banana respiration rates were also effectively reduced by 17.2% and 38.2% after 5 days of storage. The catalyst efficiently controlled banana respiration and ripening during storage, offering an effective method for banana preservation and ripening.

Electrochemical Removal of Gaseous Acetaldehyde Using Ag-Hg Bimetallic Catalyst with a Liquid-Free Electrolyte

Electrochemical methods have been widely used to remove gaseous pollutants that are dissolved in liquids. However, there have been no significant attempt made to remove gaseous pollutants in their gas state, especially through electrochemical method. In this study, we attempted to remove gaseous acetaldehyde (AA) through electro-oxidation using an Ag-Hg bimetallic catalyst coated on a Ni foam electrode at a gas–solid interface. The interface was induced by a semi-solid agar gel in a membrane-divided electrolytic cell. We confirmed the formation of Ag-Hg on the Ni foam electrode through X-ray photoelectron spectroscopy and scanning electron microscopy. We also found that the semi-solid gel was a suitable solid electrolyte, as evidenced by the absence of discernible redox peaks in cyclic voltammetry analysis and the high charge transfer resistance in electrochemical impedance analysis. Under inlet conditions of 15 ppm with a flow rate of 200 mL min−1, we could achieve up to 80% AA degradation. This was due to the effective transfer of electrons in the presence of the semi-solid gel, which was eight times higher than that obtained in the zero-gap method. In continuous operation of the electrochemical reactor with a single-pass of AA, we consistently achieved a removal capacity of 169.81 mg cm−2 h−1 over a 1-h period in an Ar atmosphere. These results demonstrate the practical applicability of this electrochemical system developed using a liquid-free electrolyte and a bimetallic catalyst for the electrode.

Improved photocatalytic performance of acetaldehyde degradation via crystal plane regulation on truncated octahedral CeO2

Improved photocatalytic performance of acetaldehyde degradation via crystal plane regulation on truncated octahedral CeO2

Enhanced Degradation of Ethylene in Thermo-Photocatalytic Process Using TiO2/Nickel Foam.

The photocatalytic decomposition of ethylene was performed under UV-LED irradiation in the presence of nanocrystalline TiO2 (anatase, 15 nm) supported on porous nickel foam. The process was conducted in a high-temperature chamber with regulated temperature from ambient to 125 °C, under a flow of reacted gas (ethylene in synthetic air, 50 ppm, flow rate of 20 mL/min), with simultaneous FTIR measurements of the sample surface. Ethylene was decomposed with a higher efficiency at elevated temperatures, with a maximum of 28% at 100-125 °C. The nickel foam used as support for TiO2 enhanced ethylene decomposition at a temperature of 50 °C. However, at 50 °C, the stability of ethylene decomposition was not maintained in the following reaction run, but it was at 100 °C. Photocatalytic measurements conducted in the presence of certain radical scavengers indicated that a higher efficiency of ethylene decomposition was obtained due to the improved separation of charge carriers and the increased formation of superoxide anionic radicals, which were formed at the interface of the thermally activated nickel foam and TiO2.

Impact of thermal ethylene degradation in zeolite-templated carbon synthesis

Which is the best temperature for the synthesis of Zeolite-Templated Carbons (ZTCs)? This is the question which will be foregrounded in the present article. ZTCs were achieved using ethylene on protonic beta zeolite at different synthesis temperatures comprised between 490 and 890 °C. By comparing the results achieved from TGA, nitrogen physisorption at 77 K, XRD and XPS, an optimal ZTC synthesis temperature could be determined. For low temperature synthesis (i.e. 490 °C), textural defects arise in the carbon network, possibly related to the low reactivity of ethylene. At temperatures above 700 °C thermally induced ethylene transformation was evidenced, leading to the development of carbon species on the external surface of the zeolite and hence to the generation of composite materials. Below 700 °C, ZTC formation exclusively proceeds through a zeolite acid-site catalyzed mechanism, whilst with increasing temperature the thermally induced ethylene transformation path gains impact. We further prove that ZTC/turbostratic carbon composites can be achieved through a purely thermally induced ethylene transformation path by using an all-silica beta zeolite as template.

Synergistic effect of multiple reactive oxygen species via orbital-reconstructed tungsten for indoor acetaldehyde photocatalytic oxidation

The visible-light photocatalytic elimination of indoor acetaldehyde, a prevalent volatile organic compound, remains a significant challenge. Despite that tungsten oxide photocatalysts emerge as promising catalysts for acetaldehyde degradation indoors, their energy band structure often limits the removal performance by favoring the generation of a single reactive oxygen species. Herein, we showed a 5d orbital-reconstructed tungsten-based photocatalyst induced by g-C3N4 support, notably enhancing acetaldehyde elimination under visible light. Experimental and theoretical findings demonstrated that the 5d orbital reconstruction induced an upward shift in the unoccupied orbital of tungsten site, thereby facilitating the generation of superoxide radicals. Furthermore, hydroxy radicals can efficiently convert acetaldehyde into acetic acid, followed by the rapid elimination of acetic acid intermediates. This synergistic effect among multiple oxygen species significantly amplifies acetaldehyde elimination indoors, and offers new insights into the interactions between reactive species and pollutants in photocatalytic environmental applications.

Construction of photocatalytic coating for alleviating the shriveling of postharvest fruit cucumber after simulated transportation

The shriveling of fruit cucumber was commonly occurred during supply chain, photocatalyst exposed to UV light can endow the coatings with ethylene removal capacity to reduce the respiration of fruit and water loss. The study developed a novel photodynamic technology responsive photocatalytic coating with exceptional ultraviolet (UV) photocatalytic degradation of ethylene ability to decay the shriveling of postharvest fruit cucumber during supply chain. This coating involved the integration of Carbon dots (CDs)-loaded nano ZnO and the skillful selection of pullulan (Pul) and apple pectin (AP) matrix. The CDs/ZnO coatings boasted an impressive array of photocatalytic degradation of ethylene and adhesion properties, including high ethylene removal rates of 32.04 % in 60 min UV light stimulation. The decrease of cell-wall strength, degradation of the cell wall polysaccharides and water loss resulted in cucumber shriveling. Compared with CK sample, after UV-CDs/ZnO coating treatment, the higher firmness and cell wall polysaccharides were found in cucumbers with lower cell wall degrading enzymes activities, weight loss and water movement, which was associated with the decrease of respiration and ethylene accumulation. The UV-CDs/ZnO coatings possessed promising potential for alleviating the shriveling of postharvest fruit cucumber and applications in fruits preservation in the future.

Cellulose nanocrystals reinforced chitosan/titanium dioxide bionanocomposite with enhanced interfacial compatibility: Fabrication, characterization, and application in fresh-cut apple slices

This research aimed to investigate the feasibility of using a bionanocomposite made of chitosan, CNC, and TiO2 nanoparticles to package freshly sliced apples. At the outset, the effect of varying concentrations of CNC (1, 5, and 10 %) and TiO2 (1, 3, and 5 %) on the mechanical, thermal, and water sensitivity characteristics of the chitosan bionanocomposite was studied. Among different combinations, the bionanocomposite containing 10 % CNC and 3 % TiO2 displayed significant enhancements compared to neat chitosan film. Notably, it exhibited a substantial increase in tensile strength (78.2 %), glass transition temperature (26.7 %), and melting temperature (30.0 %) compared to neat chitosan film. Additionally, it demonstrated reduced WVP (27.8 %), FWS (44.4 %), and SR (50.7 %). These improvements were attributed to the synergistic interactions among chitosan, CNC, and TiO2 nanoparticles through hydrogen and oxygen bonding, corroborated by spectral changes in the material. The photocatalytic degradation of ethylene and microbes by UV-A (intermittent) activated TiO2 contained in the developed bionanocomposite was confirmed by the retention of acceptable quality and radical scavenging activity (70 % retention) of fresh-cut apple slices up to 11 days. The developed bionanocomposite can thus preserve the quality of ethylene-producing horticultural produce.

A novel Z-scheme heterojunction Fe-BDC/TiO2 for efficient photocatalytic degradation of acetaldehyde

Constructing heterojunction structures is considered one of the effective methods to improve the activity of photocatalysts. A novel Z-Scheme heterojunction Fe-BDC/TiO2 was designed and synthesized by amorphous gel Fe-BDC and TiO2 nanoparticles with electrostatic self-assembly method. The introduction of Fe-BDC has been proved to expand the light absorption range and promote the separation and transfer of interface photo generated electrons and holes. Thus, the photocatalytic degradation efficiency of acetaldehyde by 5% Fe-BDC/TiO2 sample is 2.3 times than that of pure TiO2 sample. And the reaction rate is 2.5 times than that of pure TiO2 sample. The free radical capture experiment shows that O2− played a more important role in the degradation of acetaldehyde. In addition, in situ infrared analysis further reveals the surface species of the photocatalysts during adsorption and degradation processes. The acetaldehyde degradation route of Fe-BDC/TiO2 has been speculated. ‘1These findings provide valuable references for the design of metal oxide semiconductor/Fe based MOF heterojunctions and the efficient degradation of aldehyde VOCs.