Cumene Research Articles

Accurate low-dose exposure assessment of benzene and monoaromatic compounds by diffusive sampling: Sampling and analytical method validation according to ISO 23320 for radiello® samplers packed with graphitised charcoal and suitable for thermal desorption

This research was aimed at providing an accurate low-dose benzene exposure assessment method, prospectively suitable to exposure limit values in the low ppb range, such as in the present-day chemical, petrochemical, foundry and pharmaceutical industry. The project addresses the need for a robust and fully validated method of personal exposure measurements considering that the Occupational Exposure Limit Value for benzene will be significantly lowered in the next few years. Diffusive sampling offers a reliable alternative to pumped sampling methods, intrinsic safety in potentially explosive atmospheres, lightness and ease of use. The tested diffusive sampler is radiello® with the RAD145 adsorption substrate. This configuration is packed with graphitised charcoal suitable for thermal desorption and analysis by HRGC-FID or HRGC-MS.The experiments have been conducted following the ISO 23320 standard in the range from 0.005 to 0.1 ppm (16 to 320 µg/m3), yielding a full validation of the sampling and analytical method. The sampler performances have fulfilled all requisites of the ISO 23320 standard, in particular: bias due to the selection of a non-ideal sorbent is lower than 10 % (no significant back diffusion of benzene due to concentration change in the atmosphere); bias due to storage of samples for up to 2 months is lower than 10 %; nominal uptake rate for benzene on RAD145 is 32.3 mL/min; expanded uncertainty of the sampling and analytical method is 22.1 % in the concentration range from 80 to 320 µg/m³. The sampling and analytical method is therefore fit-for-purpose for the personal exposure measurements aimed at testing compliance with lowered occupational exposure limit values for benzene. The method is also fit for short duration exposure monitoring related to specific tasks, and other volatile organic compounds, usually found in the same workplaces, such as aliphatic and aromatic hydrocarbons and some oxygenated compounds, have been also studied. In particular, n-hexane and isopropyl benzene (also known as cumene), whose classification is currently under revision, can be efficiently monitored by this technique.

Low-Temperature Synthesis of Cyano-Rich Modified Surface-Alkalinized Heterojunctions with Directional Charge Transfer for Photocatalytic In Situ Generation and Consumption of Peroxides.

The synthesis of low-temperature poly(heptazine imide) (PHI) presents a significant challenge. In this context, we have developed a novel low-temperature synthesis strategy for PHI in this work. This strategy involves the introduction of Na+ ions, which etch and disrupt the conjugated structure of carbon nitride (CN) during assisted thermal condensation. This disruption leads to the partial decomposition of the heptazine ring structure, resulting in the formation of C≡N functionalities on the CN surface, which are enriched with hydroxyl groups and undergo cyano modification. The formation of heterojunctions between CN and ZnO, which facilitate charge transfer along an immobilization pathway, accelerated charge transfer processes and improved reactant adsorption as well as electron utilization efficiency. The resulting catalyst was employed for the room temperature, atmospheric pressure, and solvent-free photocatalytic selective oxidation of cumene (CM), achieving a cumene conversion rate of 28.7% and a remarkable selectivity of 92.0% toward the desired product, cumene hydroperoxide (CHP). Furthermore, this CHP induced oxidative reactions, as demonstrated by the successful oxidation of benzylamine to imine and the oxidation of sulfide to sulfoxide, both yielding high product yields. Additionally, the utilization of a continuous-flow device significantly reduces the reaction time required for these oxidation processes. This work not only introduces an innovative approach to environmentally friendly, sustainable, clean, and efficient PHI synthesis but also underscores the promising potential and advantages of carbon nitride-based photocatalysts in the realm of sustainable and green organic transformations.

Deep Cracking of Bulky Hydrocarbons into Light Products via Tandem Catalysis over Uniform Interconnected ZSM-5@AlSBA-15 Composites.

Deep cracking of bulky hydrocarbons on zeolite-containing catalysts into light products with high activity, desired selectivity, and long-term stability is demanded but challenging. Herein, the efficient deep cracking of 1,3,5-triisopropylbenzene (TIPB) on intimate ZSM-5@AlSBA-15 composites via tandem catalysis is demonstrated. The rapid aerosol-confined assembly enables the synthesis of the composites composed of a continuous AlSBA-15 matrix decorated with isolated ZSM-5 nanoparticles. The two components at various ZSM-5/AlSBA-15 mass ratios are uniformly mixed with chemically bonded pore walls, interconnected pores, and eliminated external surfaces of nanosized ZSM-5. The typical composite with a ZSM-5/AlSBA-15 mass ratio of 0.25 shows superior performance in TIPB cracking with outstanding activity (≈100% conversion) and deep cracking selectivity (mass of propylene + benzene > 60%) maintained for a long time (> 6h) under a high TIPB flux (2mLh-1), far better (several to tens of times higher) than the single-component and physically mixed catalysts and superior to literature results. The high performance is attributed to the cooperative tandem catalytic process, that is, selective and timely pre-cracking of TIPB to isopropylbenzene (IPB) in AlSBA-15 and subsequently timely diffusion and deep cracking of IPB in nanosized ZSM-5.

Accurate low-dose exposure assessment of benzene and monoaromatic compounds by diffusive sampling: sampling and analytical method validation according to ISO 23320 for radiello® samplers packed with activated charcoal.

The research study aimed at providing an accurate low-dose benzene exposure assessment method, by validating diffusive monitoring techniques for benzene personal exposure measurements at workplaces where benzene concentrations are expected in the low ppb range, such as in the present-day chemical, petrochemical, foundry, and pharmaceutical industry. The project was aimed at addressing the need for a robust and fully validated method to perform personal exposure measurements considering that the occupational exposure limit value for benzene is going to be significantly lowered in the next few years. Diffusive sampling offers a reliable alternative to pumped sampling methods, intrinsic safety in potentially explosive atmospheres, lightness, and ease of use. In this study, the radiello® diffusive sampler, with the packed activated charcoal RAD130 adsorbing substrate [suitable for solvent desorption and analysis by high-resolution gas chromatography-flame ionization detection (HRGC-FID)], was used. The experiments have been conducted following the ISO 23320 standard in the range from 0.005 to 0.1 ppm (16 to 320 μg/m3), yielding a full validation of the sampling and analytical method. The sampler performances have fulfilled all requisites of the ISO 23320 standard, in particular: bias due to the selection of a non-ideal sorbent is lower than 10% (no significant back diffusion of benzene due to concentration change in the atmosphere); bias due to storage of samples for up to 2 months is lower than 10%; nominal uptake rate for benzene on RAD130 is 74.65 mL/min; and expanded uncertainty of the sampling and analytical method is 20.6%. The sampling and analytical method is therefore fit-for-purpose for the personal exposure measurements aimed at testing compliance with occupational exposure limit values for benzene. The method is also fit for short-duration exposure monitoring related to specific tasks, and other volatile organic compounds, usually found in the same workplaces, such as aliphatic and aromatic hydrocarbons and some oxygenated compounds, have also been studied. In particular, n-hexane and isopropyl benzene, whose classification is currently under revision, can be efficiently monitored by this technique.

GIS-based emission inventory of heavy metals from road transport and NMVOCs associated with biomass burning for megacity Delhi

Clean air is an essential requirement for human health and well-being. The rapid evolution in urbanization poses a risk to human health. The significance of robust emission inventory has intensified with scientific advancement in air quality improvement. A comprehensive GIS-based emission inventory of heavy metals and NMVOCs from road transportation, road dust, and biomass burning covering the megacity of Delhi has been prepared in this study for the base year 2018. The emission of heavy metals from biomass burning and road dust was estimated by computing the chemical constituents of PM2.5. The emission of heavy metals from all sources is estimated as 695.202 Mg/year, with Zinc (Zn ∼ 48%) having the highest emissions, followed by Copper (Cu ∼ 21%). The share of road transportation emissions was 78%, followed by resuspended road dust emissions at 4%. The emissions of 23 NMVOCs (1.158 Gg/year) were calculated from biomass burning (fuelwood, agricultural residue, dung cake, and coal) with Dung cake (∼58%) and fuelwood (∼41%) as the major contributors. The maximum emission was ethene (∼29%), and the minimum was isopropyl benzene (∼0.06%). The finding of this study will assist environmental policymakers and stakeholders in developing mitigation methods to reduce emissions and enhance air quality.

Visible Light-Driven Sandwich-like g-C3N4-Catalyzed Oxidation to Produce Cumene Hydroperoxide

Cumene hydroperoxide (CHP) is an important intermediate for the production of phenol, acetone, propylene oxide, and other raw materials in the petrochemical industry. However, due to the high reaction temperature and pressure, the current process for the industrial production of CHP has problems of potential safety hazards and high energy consumption. In this work, carbon nitride (g-C3N4) with a unique sandwich structure was discovered as a photocatalyst. It efficiently activates molecular oxygen in the air, oxidizes cumene (CM) to prepare CHP, and realizes high atom economy transformation at room temperature, atmospheric pressure, and solvent-free conditions. The continuous flow strategy was adopted to improve the gas–liquid mass transfer efficiency and reduce the phenomenon of back-mixing, thereby reducing the decomposition of the products and improving the product selectivity. The conversion rate was the same as that of the batch reaction, reaching 23%. The selectivity of the product CHP increased from 82 to 92%, and the reaction residence time was shortened from 10 h to 70 min. The catalysts have the advantages of high efficiency, easy availability, environmentally friendly, etc., and are recyclable and stable. This work provides a new strategy for establishing green, sustainable, clean, and efficient methods for the preparation of peroxides.

Pollution Characteristics and Risk Assessment of Volatile Organic Compounds in Songhua Lake, China

In order to assess the dangers to human health and the environment from Songhua Lake's volatile organic compounds (VOCs) pollution. A total of 18 VOCs were found in the water samples that were collected at 26 sampling locations in Songhua Lake utilizing the purge and trap technique and gas chromatography-mass spectrometry (GC-MS). Toluene and naphthalene had the highest detection rates among them, reaching 96.15%; trans-1,2-dichloroethylene, 1,2-dichloroethane, and isopropyl benzene had the lowest rates, only 3.85%. The maximum and average concentrations of 1,1-dichloroethane were 20.93 μg/L and 4.16 μg/L, respectively, the maximum concentration of isopropyl benzene was only 0.02 μg/L, and the average concentration was also the lowest. The spatial distribution of VOCs in Song Hua Lake was typically described as "high in the northwest and low in the southeast," with a concentration range of 0.00 to 23.21 μg/L. An examination of the current situation reveals that human activity-related ecological deterioration is the primary cause of the VOCs contamination in Songhua Lake. The results of the risk assessment revealed that there were only moderate ecological risks to aquatic organisms and that the non-carcinogenic and carcinogenic risk indices of Songhua Lake were within the safe range. Additionally, there were no non-carcinogenic or carcinogenic threats to the health of people as a whole.

Catalytic Oxidation of Volatile Organic Compounds Using the Core–Shell Fe2O3-Cenospheric Catalyst in a Fluidised Bed Reactor

The results of selected volatile organic compounds (benzene, n-hexane, isopropanol, and formic acid) catalytic oxidation are presented on Fe2O3 cenospheres in the fluidised bed reactor. The core–shell Fe2O3-cenosphere catalyst was developed by applying an Fe layer on cenospheres by FB-MO-CVD (fluidised bed, metal–organic chemical vapor deposition) and following Fe layer oxidation. The efficiency of the decomposition of VOCs was tested in the range of 200 to 500 °C, using the method based on infrared spectroscopy (FTIR). The research was focused especially on the analysis of incomplete combustion products, such as CO and oxygen compounds. During the oxidation of isopropanol and n-hexane, in addition to carbon monoxide, species such as acetone, formaldehyde, and acetaldehyde were also detected. The oxidation of formic acid proceeded with only a slight emission of carbon monoxide, unexpectedly the oxidation of benzene proceeded in a similar way, and no other products of the incomplete oxidation were detected. In addition, the CO concentration was lower than in the case of conversion of isopropanol and n-hexane. For the presented solution, complete formic acid oxidation is possible at temperatures below 400 °C, and almost complete oxidation to CO2 of isopropyl alcohol, benzene, and n-hexane was achieved at 500 °C. Additionally, the possibility of conducting the autothermal process of oxidation of VOCs in a fluidised bed, provided that heat recuperation is used, was presented.

Visible-light-driven g-C3N4-doped Co catalyzed oxidation of benzylic hydroxylation of alkyl aromatic hydrocarbons

The functionalization of C(sp3)-H bonds of alkyl aromatic hydrocarbons is an important unit reaction in the petrochemical industry. In this work, a g-C3N4-doped Co photocatalyst was found, which can activate molecular oxygen to oxidize alkyl aromatic hydrocarbons benzylic C(sp3)-H bond hydroxylation at room temperature to prepare alcohol compounds. In the batch reaction system, the product can be obtained without additional free radical initiator and solvent, which is suitable for a variety of alkyl aromatic hydrocarbon substrates. In two different continuous flow strategies, no oxygen environment was required. 2-phenyl-2-propanol (BP) was prepared from cumene (CM) as a substrate, with the selectivity of BP can be increased from 89.3 % to 96.8 % and 97.7 %, respectively, and the reaction time can be shortened from 9 h to 100 min and 165 min. This work demonstrates the advantages of highly active carbon nitride-based photocatalysts in the field of green and sustainable chemistry.

Robust control of isopropyl benzene production process using H ∞ loop shaping control scheme

This paper discusses robust control strategy for isopropyl benzene production process using the method of loop shaping H ∞ technology. This cumene production process is a part of phenol plant in HOCL, Kochi. H ∞ control of the propylene concentration is done here. The H ∞ controller is derived from the linearised model of the reactor. The optimal H ∞ controller is obtained by simplifying two algebraic Riccati equations. The proposed PID-like H ∞ controller provides a single tuning parameter which makes the controller design more accurate. The proposed controller has been compared with other robust controllers like H 2 and LQR. The H ∞ controller is found to be superior in a wide frequency range and has a feature of low distortion and good regulating performance. The reactor model has been developed in COMSOL Multiphysics with the parameters obtained from HOCL plant, Kochi. The model extracted is reduced using model order reduction for the controller design.

Exposure to volatile organic compounds and risk perception among workers: An industry-based cross-sectional survey

This study aimed to determine the volatile organic compound (VOC) exposure levels and evaluate the risk perception among integrated circuit assembly and testing workers in Taiwan. Five representative companies were selected as the study population to measure the VOC levels of benzene, toluene, ethanol, acetone, and isopropyl alcohol using 50 stainless steel canisters in 2013. A gas chromatograph with a flame ionization detector was used to analyze the VOC levels, and multiple logistic regression models were used to identify relative factors of risk perception among 210 volunteers using a self-administered questionnaire. Ethanol (median: 465.1 ppbv; range: 64.8–1744.3 ppbv) had the highest concentration compared with isopropyl alcohol (291.6 [171.8–411.4] ppbv), acetone (176.3 [106.8–528.4] ppbv), toluene (171.6 [130.2–240.1] ppbv), and benzene (all below the limit of detection of 6.95 ppbv). Subjects exposed to the total of five VOCs ≥406.5 ppbv had a significantly higher risk perception of health hazards caused by hazardous gas exposure (AOR = 4.17, 95% CI = 1.17–14.93) compared with those exposed to <278.1 ppbv. A significant exposure–response association was identified in the total levels of the five VOCs and risk perception (AOR = 2.03, 95% CI = 1.07–3.85). Workers exposed to higher levels of the total of five VOCs may have higher risk perceptions.

Optical Spectrum Analyzer Integrated Fiber optic Modified nanocrystalline annealed Al[formula omitted]O[formula omitted] cladding for improved evanescent-wave toxic gas detection

To detect toxic gases, a clad modified fiber optic sensor with nanocrystalline Al2O3 is proposed. The cladding of the fiber in the gas sensing region is made of as-prepared and annealed Al2O3 (500 °C & 1200 °C) samples. The sensitivity to poisonous gases such as acetone, isopropyl alcohol, and benzene at ambient temperature is studied using the phenomenon of the evanescent wave absorption. For various gas concentrations (0-50-100––500 ppm), the spectrum characteristics of the fiber optic gas sensor are investigated. The spectral peak intensity of the sensor varies linearly with the acetone concentration. For gas selectivity, the sensor’s properties with isopropyl alcohol and benzene gases are also investigated. Acetone (1200 °C) had a higher sensitivity than isopropyl alcohol and benzene among the three gas vapors. The sensor’s time response characteristics are also presented.

A Dehydrogenative Inverse Electron Demand Diels-Alder Reaction for the Synthesis of Functionalized Pyranones.

An efficient dehydrogenative inverse electron demand Diels-Alder reaction of isopropyl and prenyl benzene derivatives with electron-deficient dienes followed by decarboxylation has been reported for the first time. The much broader substrate scope of dienophiles and electron-deficient dienes led to biologically valuable pyranones in good to excellent yields.

Effect of 1,4-bis(tert-butyl peroxy isopropyl) benzene on the rheological, mechanical, thermal and barrier properties of poly(butylene succinate-co-terephthalate)/poly(lactic acid) blends and blown films

In this article, 1,4-bis(tert-butyl peroxy isopropyl) benzene (BIPB) was used as a reactive compatibilizer to enhance the compatibility between poly(butylene succinate-co-terephthalate) (PBST) and poly(lactic acid) (PLA) to prepare a novel environmentally friendly PBST/PLA-based blown film. Rheological analysis and gel permeation chromatography showed that BIPB reacted with PBST/PLA during melt-blending extrusion. The PBST/PLA blend gradually changed from the typical sea-island phase structure without BIPB towards a homogeneous phase structure with the increase in BIPB concentration, indicating that the compatibility between PBST and PLA improved significantly upon addition of BIPB. Moreover, compared to PBST/PLA blown film, the Young’s modulus, tensile strength, breaking strain, tear strength, and falling dart impact strength of PBST/PLA/BIPB blown film showed great improvement. The PBST/PLA/BIPB blown film could control microenvironmental humidity in the packaging and inhibited mushroom molding and rotting for up to 7 days. In vitro cell experiments showed that the PBST/PLA/BIPB blown film was suitable for mouse fibroblast (L929) cell growth. Thus, the PBST/PLA/BIPB blown film can be used in fields such as biomedical materials, food packaging, and hygienic products.

Preparation of polyphenylsulfone/graphene nanocomposite membrane for the pervaporation separation of cumene from water

AbstractPolyphenylsulfone (PPSU) was applied for the first time in the hydrophobic PV process. Nanocomposite membranes of PPSU/graphene (Gr) nanosheets were prepared and used to separate isopropyl benzene (cumene) from water via pervaporation (PV). Analysis of the mechanical properties of the membranes showed that the tensile strength and Young's modulus had an increasing trend with the incorporation of Gr into PPSU. The water contact angle of the membranes had a rising trend with the addition of Gr, confirming the improved hydrophobicity of membranes. In the PV experiments, the membrane containing 3.5 wt% Gr provided the highest separation factor, which was 4.5‐fold as much as that of the neat PPSU membrane. Cumene separation from water by the PPSU/3.5 wt% Gr membrane was associated with the total flux of 132.73 gMH, the separation factor of 1566.36, and the PSI of 208,124.8 gMH.

Study on Air Pollution Behavior of VOCs with Photochemical Monitoring Stations Using EGARCH Model in Southern Taiwan

This study adopted the exponential generalized autoregressive conditional heteroscedasticity (EGARCH) model to examine the 10 ozone precursors of the highest concentrations among the 54 that were assessed over a number of years at the four photochemical assessment monitoring stations (PAMSs) in the Kaohsiung–Pingtung Area in Taiwan. First, the 10 ozone precursors, which were all volatile organic compounds (VOCs), were analyzed using the factor analyses in multiple statistical analyses that had the most significant impact on the area’s ozone formation: mobile pollution factor, which included 1,2,4-Trimethylbenzene (C9H12), toluene (C7H8), and Isopropyl benzene (C9H12). Then, taking into consideration that the number sequences might be affected by standardized residuals, this study applied the vector autoregressive moving average-EGARCH (VARMA-EGARCH) model to analyze the correlation between the three VOCs under different polluting activities. The VARMA-EGARCH model in this research included dummy variables representing changing points of variance structures in the variance formula to predict the conditional variance. This process proved able to effectively estimate the relevant coefficients of the three VOCs’ dynamic conditions that changed with time. The model also helped to prevent errors from occurring when estimating the conditional variance. Based on the testing results, this study determined the VARMA(2,1)-EGARCH(1,0) as the most suitable model for exploring the correlation between the three VOCs and meteorological phenomena, as well as the interplay between them in regard to interaction and formation. With the most representative of the three, toluene (TU), as the dependent variable and 1,2,4-Trimethylbenzene (TB) and Isopropyl benzene (IB) as the independent variables, this study found it impossible to calculate the TU concentration with TB and IB concentrations in the same period; estimations of TB and IB concentrations with a period of lag time were required because TU was mainly contributed by automobiles and motorcycles in Kaohsiung. TB and IB resulted from other stationary pollution sources in the region besides cars and motorbikes. When TU was evenly distributed and stayed longer in the atmosphere, the TB and IB concentrations were lower, so distribution conditions and concentrations could not be used to effectively estimate the concentration of toluene. This study had to wait until the next period, or when stationary pollution sources started producing TB and IB of higher concentrations during the daytime, in order to estimate the TU concentrations in a better photochemical situation.

Preparation and hydrophobicity modification of poly(vinylidene fluoride‐co‐hexafluoropropylene) membranes for pervaporation separation of volatile organic compound from water

AbstractIn this study, novel nanocomposite membranes were fabricated for the removal of isopropyl benzene, a volatile organic compound (VOC), from water via pervaporation (PV). The membranes were made of poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) copolymer. In order to improve the hydrophobic properties of the membranes, hydrophobic silica nanoparticles that had been surface modified by hexamethyldisilazane were used as the nanofiller in the PV membranes, for the first time. Incorporating hydrophobic silica nanoparticles into PVDF‐HFP and increasing its concentration up to 9 wt% enhanced membrane hydrophobicity. Evaluation of membrane performance in VOC separation from water showed that the membrane containing 9 wt% of silica had the highest VOC separation factor, so that the values of total flux, separation factor, and PV separation index (PSI) were 3.77 g/m2/h; 42,483.81; and 158,788.50 g/m2/h for this membrane, respectively. The separation factor and PSI value of the mentioned membrane were almost 204 and 5 times higher than that of the neat PVDF‐HFP membrane.

New high-fat dairy products with colour attractants

In the present work, the nutritional value of high-fat dairy product - melted butter, which was produced in Ukraine, was characterised. It was shown that, along with the traditional fatty acid compositions, this product had an insufficient concentration of biologically active substances that contributes to storage stability, expands organoleptic characteristics, and prevents main spoilage processes such as rancidity and tallowiness. The appropriate biologically active colouring attractants for improvement of organoleptic and biological properties of melted butter were observed. The formulations of new melted butter-based products were tested by using two individual carotenoids (carotene and xanthophyll); namely chlorophyll and chlorophyll-carotenoid complex additives in a concentration of 3 - 7%. The antioxidant activity of the samples, which was determined volumetrically by the intensity of initiated oxidation of isopropyl benzene, made it possible to establish an increase (4.40 - 6.52 times the period of induction) of oxidation for melted butter variants, with colorants. The study of organoleptic, physico-chemical, and microbiological indicators confirmed the biological stability and safety of the developed high-fat dairy products, thus fulfilling the body requirement for carotenoids, magnesium, and several other biologically active compounds. According to the results, the guaranteed shelf life of the developed melted butter types with colouring attractants of carotenoid and chlorophyll, which met the safety requirements, could be prolonged by 31 - 48%. In conclusion, the present work improved the technical and economic indicators, and confirmed the feasibility of their production.

Highly Selective Separation of Isopropylbenzene and α-Methylstyrene by Nonporous Adaptive Crystals of Perbromoethylated Pillararene via Vapor- and Liquid-Phase Adsorptions

Isopropylbenzene (IPB) and α-methylstyrene (AMS), two members of C9 aromatics, are important in both industrial production and laboratory research, but the separation of IPB/AMS mixtures is still a big challenge. Here, we provide a new strategy to separate IPB and AMS using nonporous adaptive crystals of four pillararenes, perethylated pillar[5]arene, perethylated pillar[6]arene, perbromoethylated pillar[5]arene, and perbromoethylated pillar[6]arene (BrP6). Among them, BrP6 selectively adsorbs IPB from an equal volume mixture of IPB and AMS with >95% purity for solid-vapor phase adsorption and >94% purity for solid-liquid phase adsorption, while the selectivities for the other three pillararenes are unsatisfactory. Single-crystal structural analyses combined with powder X-ray diffraction and differential scanning calorimetry experiments demonstrate that the selectivity arises from the different stabilities of guest-loaded BrP6 crystals. Moreover, the reversible transitions between guest-free and IPB-loaded structures indicate the preeminent recycling performance of BrP6 crystals.

Effects of Origanum vulgare essential oil and its two main components, carvacrol and thymol, on the plant pathogen Botrytis cinerea.

BackgroundBotrytis cinerea causes serious gray mold disease in many plants. This pathogen has developed resistance to many fungicides. Thus, it has become necessary to look for new safe yet effective compounds against B. cinerea.MethodsEssential oils (EOs) from 17 plant species were assayed against B. cinerea, of which Origanum vulgare essential oil (OVEO) showed strong antifungal activity, and accordingly its main components were detected by GC/MS. Further study was conducted on the effects of OVEO, carvacrol and thymol in vitro on mycelium growth and spore germination, mycelium morphology, leakages of cytoplasmic contents, mitochondrial injury and accumulation of reactive oxygen species (ROS) of B. cinerea. The control efficacies of OVEO, carvacrol and thymol on tomato gray mold were evaluated in vivo.ResultsOf all the 17 plant EOs tested, Cinnamomum cassia, Litsea cubeba var. formosana and O. vulgare EOs had the best inhibitory effect on B. cinerea, with 0.5 mg/mL completely inhibiting the mycelium growth of B. cinerea. Twenty-one different compounds of OVEO were identified by gas chromatography–mass spectrometry, and the main chemical components were carvacrol (89.98%), β-caryophyllene (3.34%), thymol (2.39%), α-humulene (1.38%) and 1-methyl-2-propan-2-ylbenzene isopropyl benzene (1.36%). In vitro experiment showed EC50 values of OVEO, carvacrol and thymol were 140.04, 9.09 and 21.32 μg/mL, respectively. Carvacrol and thymol completely inhibited the spore germination of B. cinerea at the concentration of 300 μg/mL while the inhibition rate of OVEO was 80.03%. EC50 of carvacrol and thymol have significantly (P < 0.05) reduced the fresh and dry weight of mycelia. The collapse and damage on B. cinerea mycelia treated with 40 μg/mL of carvacrol and thymol was examined by scanning electron microscope (SEM). Through extracellular conductivity test and fluorescence microscope observation, it was found that carvacrol and thymol led to increase the permeability of target cells, the destruction of mitochondrial membrane and ROS accumulation. In vivo conditions, 1000 μg/mL carvacrol had the best protective and therapeutic effects on tomato gray mold (77.98% and 28.04%, respectively), and the protective effect was significantly higher than that of 400 μg/mL pyrimethanil (43.15%). While the therapeutic and protective effects of 1,000 μg/mL OVEO and thymol were comparable to chemical control.ConclusionsOVEO showed moderate antifungal activity, whereas its main components carvacrol and thymol have great application potential as natural fungicides or lead compounds for commercial fungicides in preventing and controlling plant diseases caused by B. cinerea.