Ethylene Removal Research Articles

Removal of Ethylene and Secondary Organic Aerosols Using UV-C254 + 185 nm with TiO2 Catalyst

ABSTRACTIn this investigation we evaluated the feasibility and effectiveness of ozone-producing UV (254 + 185 nm) irradiation and a TiO2 photocatalyst for degradation of ethylene, which is strongly hydrophobic and does not decompose easily in a humid environment. Tests were performed in a photoreactor (V = 0.55 L) under UV irradiation at various wavelengths (365, 254 and 254 + 185 nm), relative humidities (RH 86%), atmospheres (pure N2 and air), residence times (11–33 sec), initial ethylene concentrations in the range of 25–105 ppmv and TiO2 contact areas (86.4–259 cm2) with presumably ambient pressure and temperature. The experimental results demonstrated that the use of TiO2 under 254 + 185 nm UV irradiation significantly enhanced the photodegradation of ethylene compared to the case of UV irradiation alone, due to the synergistic effect of photochemical oxidation in the gas phase and photocatalytic oxidation on the TiO2 surface. Photodegradation induced with 254 + 185 nm UV irradiation was compared with photodegradation induced with UV irradiation at wavelengths of 365 and 254 nm. The highest conversion and mineralization levels were obtained with 254 + 185 nm UV irradiation among the three tested UV sources. Moreover, irradiating with 254 +185 nm light generated secondary organic aerosols (SOA) via gas-to-particle conversion of organic compounds in the air stream. The results indicate that the concentration of generated SOAs decreased in the presence of the TiO2 catalyst, and thus that TiO2 may be used to effectively control the emissions of undesirable SOAs. In an application test, for photocatalytic oxidation with 254 + 185 nm UV irradiation, corresponding to a flow rate of 0.5 L/min, and an initial concentration of 34 ppmv, over 90% of the inlet ethylene could be degraded.

Biofiltration of a mixture of ethylene, ammonia, n-butanol, and acetone gases

This study describes cleaning of a waste gas stream using bench scale biofilters (BFs) or biotrickling filters (BTFs). The gas stream contained a mixture of acetone, n-butanol, methane, ethylene, and ammonia, and was diverted uniformly to six biofilters and four biotrickling filters. The biofilters were packed with either perlite (BF-P), polyurethane foam (BF-F), or a mixture of compost, wood chips, and straw (BF-C), whereas the biotrickling filters contained either perlite (BTF-P) or polyurethane foam (BTF-F). Experimental results showed that both BFs and BTFs packed with various media were able to achieve complete removal of highly soluble compounds such as acetone, n-butanol, and ammonia of which the dimensionless Henry’s constants (H) are less than 0.01. Methane was not removed due to its extreme insolubility (H>30). However, the ethylene (H≈9) removal efficiencies depended on trickle water flow rates, media surface areas, and ammonia gas levels.

A Comparative Study of Ethylene Growth Response Kinetics in Eudicots and Monocots Reveals a Role for Gibberellin in Growth Inhibition and Recovery

Time-lapse imaging of dark-grown Arabidopsis (Arabidopsis thaliana) hypocotyls has revealed new aspects about ethylene signaling. This study expands upon these results by examining ethylene growth response kinetics of seedlings of several plant species. Although the response kinetics varied between the eudicots studied, all had prolonged growth inhibition for as long as ethylene was present. In contrast, with continued application of ethylene, white millet (Panicum miliaceum) seedlings had a rapid and transient growth inhibition response, rice (Oryza sativa 'Nipponbare') seedlings had a slow onset of growth stimulation, and barley (Hordeum vulgare) had a transient growth inhibition response followed, after a delay, by a prolonged inhibition response. Growth stimulation in rice correlated with a decrease in the levels of rice ETHYLENE INSENSTIVE3-LIKE2 (OsEIL2) and an increase in rice F-BOX DOMAIN AND LRR CONTAINING PROTEIN7 transcripts. The gibberellin (GA) biosynthesis inhibitor paclobutrazol caused millet seedlings to have a prolonged growth inhibition response when ethylene was applied. A transient ethylene growth inhibition response has previously been reported for Arabidopsis ethylene insensitive3-1 (ein3-1) eil1-1 double mutants. Paclobutrazol caused these mutants to have a prolonged response to ethylene, whereas constitutive GA signaling in this background eliminated ethylene responses. Sensitivity to paclobutrazol inversely correlated with the levels of EIN3 in Arabidopsis. Wild-type Arabidopsis seedlings treated with paclobutrazol and mutants deficient in GA levels or signaling had a delayed growth recovery after ethylene removal. It is interesting to note that ethylene caused alterations in gene expression that are predicted to increase GA levels in the ein3-1 eil1-1 seedlings. These results indicate that ethylene affects GA levels leading to modulation of ethylene growth inhibition kinetics.

CURRENT DPA AND ETHOXYQUIN SITUATION AND ALTERNATIVES TO SUPERFICIAL SCALD CONTROL IN APPLES AND PEARS

Regulations governing the use of chemicals to control diseases and disorders of apples and pears in storage are becoming increasingly stringent, especially in European Union (EU) countries. The European Commission (EC) is currently conducting a review of the active ingredients (AI) of chemicals used in food production under EC Council Directive 91/414. DPA is under a review process and research is being conducting to address the concerns raised in the review. Ethoxyquin is also excluded from the list of AI in Annex I. Commercial supporters have recently come forward so this AI is also now under review. In light of the potential change in regulations, and the concern of fruit packers who market in EU, a survey of international researchers, suppliers and packers was conducted. The aim was to assess the situation in each fruit growing region, to determine which alternatives to antioxidants are being evaluated, gauge the perception about the acceptability of fruit treated with 1-methlycyclopropene (1-MCP) and learn how much packers of different regions are concerned about scald control. The respondents concerned about potential ban on antioxidants are from the countries that export to EU, especially from pear producing regions. Of all the alternatives mentioned by researchers consulted, the ones related to storage under controlled atmosphere (ultra-low oxygen, initial low oxygen stress, and dynamic controlled atmosphere) and 1-MCP are considered as the only sustainable technology to replace DPA. Other alternatives mentioned were ethylene removal, resistant cultivars, inhibition of phospholipase D and combined strategies. Regarding the use of 1-MCP, researchers report that it is a good alternative to current chemicals for control storage scald in apples. Although 1-MCP application to pears provides control of storage scald as well as the reduction in senescent scald, ripening may be inhibited after storage. Researchers are attempting to induce ripening in a number of ways including simultaneous application of 1-MCP and ethylene, conditioning through high temperatures, among others.

Manejo do etileno em ameixas 'Laetitia' armazenadas sob atmosferas controlada e modificada ativa

O objetivo deste trabalho foi avaliar o efeito de condições de atmosfera controlada (AC) e atmosfera modificada (AM) ativa (filme PEBD de 40 µm, com duas perfurações de 1,0 mm de diâmetro), associadas ao manejo do etileno, sobre a manutenção da qualidade em ameixas 'Laetitia'. Os tratamentos avaliados consistiram no armazenamento refrigerado (60 dias a 0,5±0,1ºC) em: atmosfera refrigerada (AR; 21,0 kPa O2 + <0,03 kPa CO2); AM; AM + baixo etileno (BE); AC; e AC + 1-MCP (1,0 µL L-1). As pressões parciais de O2 + CO2 (kPa) foram de 1,0 + 1,0 e 2,5 + <0,1, em AC e AM, respectivamente. Os frutos armazenados em AC, independentemente do tratamento com 1-MCP, apresentaram retardo no amadurecimento, quando comparados aos frutos em AR. Contudo, os melhores resultados para a manutenção da textura da polpa e da acidez titulável foram obtidos em AC + 1-MCP. Os tratamentos não interferiram para a incidência de podridões, rachaduras e degenerescência da fruta. Frutos dos tratamentos AM + BE e AC + 1-MCP apresentaram menor escurecimento da polpa e maior aceitabilidade quanto à cor e ao sabor na análise sensorial em relação àqueles armazenados em AR.

Application of High-Voltage Electrostatic Equipment to Ethylene Removal

Ethylene is hazardous to the shelf life of fruits and vegetables. To extend shelf life, the accumulation of ethylene should be prevented. High-voltage electrostatic fields have been found to contribute to the removal of ethylene. To develop high-voltage electrostatic equipment for a storage room, the effects of electrode shape, initial ethylene concentration (IEC), and electrode voltage (EV) on high-voltage electrostatic equipment performance were studied. The ethylene removal rate of the needle–needle electrode was significantly higher than that of the needle–plate electrode. When the EV was -17 KV and the IEC was 200 ppm, ethylene in the gases of the exit-tube could not be detected after 3–5 s. A mathematical model for the removal efficiency, IEC, and EV was established. The results can contribute to the development of an ethylene cleaner for storage rooms for fresh fruits and vegetables in commercial establishments.

Ethylene removal evaluation and bacterial community analysis of vermicompost as biofilter material

Biofiltration of ethylene provides an environmentally friendly and economically beneficial option relative to physical/chemical removal, where selection of appropriate bed material is crucial. Here the vermicompost with indigenous microorganisms as bed material was evaluated for ethylene removal through batch test and biofilter experiment. Temporal and spatial dynamics of bacterial community in the vermicompost-biofilter under different ethylene loads were characterized by culture and denaturing gradient gel electrophoresis (DGGE) methods. The results showed that ethylene was effectively degraded by the vermicompost under conditions of 25–50% moisture content and 25–35 °C temperature. The vermicompost-biofilter achieved nearly 100% ethylene removal up to an inlet load of 11 mg m −3 h −1. Local nitrogen lack of the vermicompost in the biofilter was observed over operation time, but the change of pH was slight. DGGE analysis demonstrated that the bacterial abundance and community structure of vermicompost-biofilter varied with the height of biofilter under different ethylene loads. Pseudomonads and Actinobacteria were predominant in the biofilter throughout the whole experiment.

Ethylene Receptor ETHYLENE RECEPTOR1 Domain Requirements for Ethylene Responses in Arabidopsis Seedlings

Ethylene influences many processes in Arabidopsis (Arabidopsis thaliana) through the action of five receptor isoforms. We used high-resolution, time-lapse imaging of dark-grown Arabidopsis seedlings to better understand the roles of each isoform in the regulation of growth in air, ethylene-stimulated nutations, and growth recovery after ethylene removal. We found that ETHYLENE RECEPTOR1 (ETR1) is both necessary and sufficient for nutations. Transgene constructs in which the ETR1 promoter was used to drive expression of cDNAs for each of the five receptor isoforms were transferred into etr1-6;etr2-3;ein4-4 triple loss-of-function mutants that have constitutive growth inhibition in air, fail to nutate in ethylene, and take longer to recover a normal growth rate when ethylene is removed. The patterns of rescue show that ETR1, ETR2, and ETHYLENE INSENSITIVE4 (EIN4) have the prominent roles in rapid growth recovery after removal of ethylene whereas ETR1 was the sole isoform that rescued nutations. ETR1 histidine kinase activity and phosphotransfer through the receiver domain are not required to rescue nutations. However, REVERSION TO SENSITIVITY1 modulates ethylene-stimulated nutations but does not modulate the rate of growth recovery after ethylene removal. Several chimeric receptor transgene constructs where domains of EIN4 were swapped into ETR1 were also introduced into the triple mutant. The pattern of phenotype rescue by the chimeric receptors used in this study supports a model where a receptor with a receiver domain is required for normal growth recovery and that nutations specifically require the full-length ETR1 receptor.

Performance of CaX Zeolite for Separation of C2H6, C2H4, and CH4 by Adsorption Process; Capacity, Selectivity, and Dynamic Adsorption Measurements

Adsorption-based process for removal of ethane and ethylene, as the main products of oxidative coupling methane reaction from unreacted methane is discussed. The adsorption equilibrium of methane, ethane, and ethylene was determined experimentally on CaX, the calcium cation exchanged NaX zeolite, by the volumetric measurements in a high pressure setup at three different temperatures. The adsorption isotherms were well modeled by the extended Langmuir-Freundlich isotherm and the adsorbed capacity, adsorption constants, and surface heterogeneity parameter were determined by regression of the model to the isothermal experiments. The results indicated that CaX zeolite would be a selective adsorbent for the separation of ethane, ethylene, and methane from each other at moderate temperatures and pressures. The breakthrough curves of gases were determined in a dynamic adsorption experiment of the gaseous mixture in a fixed bed of CaX zeolites for a feed with similar molar composition of OCM hydrocarbon product. Significant difference of breakthrough times was observed for methane, ethane, and ethylene. It is concluded that construction of an adsorption unit from CaX zeolites at the OCM reactor downstream would be economic and useful for the separation of methane from the C2 products.

Ethylene removal efficiency and bacterial community diversity of a natural zeolite biofilter

To establish an economical and environmentally friendly technology for ethylene removal from horticultural facilities and industrial point sources, a bench-scale natural zeolite biofiltration system was developed in this study. The system was evaluated for its performance in removing ethylene from an artificially contaminated air stream and characterized for its bacterial diversity under varied ethylene concentrations, and in different spatial stages of the filter. The biofilter enabled to approximately 100% remove ethylene at loading rates of 0.26-3.76 g m(-3) h(-1) when operated with inoculum containing enriched ethylene-degrading bacteria. The bacterial diversity and abundance varied with the height of the biofilter. Moreover, the occurrence and predominance of specific bacterial species varied with the concentrations of ethylene introduced into the biofilter, as observed by PCR-DGGE methods. Phylogenetic analysis indicated that the biofilter system supported a diverse community of ethylene-degrading bacteria, with high similarity to species in the classes Betaproteobacteria, Gammaproteobacteria, Bacilli, and Actinobacteria.

Selective Removal of Ethylene, a Deposit Precursor, from a “Dirty” Synthesis Gas Stream via Gas-Phase Partial Oxidation

A fundamental issue in the gasification of biomass is that in addition to the desired synthesis gas product (a mixture of H(2) and CO), the gasifier effluent contains other undesirable products that need to be removed before any further downstream processing can occur. This work assesses the potential to selectively remove hydrocarbons from a synthesis gas stream via gas-phase partial oxidation. Specifically, the partial oxidation of methane-doped, ethylene-doped, and methane/ethylene-doped model synthesis gas mixtures has been investigated at ambient pressures over a temperature range of 760-910 degrees C and at residence times ranging from 0.4 to 2.4 s using a tubular flow reactor. For the synthesis gas mixtures that contain either methane or ethylene, the addition of oxygen substantially reduces the hydrocarbon concentration while only a small reduction in the hydrogen concentration is observed. For the synthesis gas mixtures doped with both methane and ethylene, the addition of oxygen preferentially removes ethylene while the concentrations of methane and hydrogen remain relatively unaffected. These results are compared to the predictions of a plug flow model using a reaction mechanism that is designed to describe the pyrolysis and partial oxidation of small hydrocarbon species. The agreement between the experimental observations and the model predictions is quite good, allowing us to explore the underlying chemistry that leads to the hydrocarbon selective oxidation. The implications of these results are briefly discussed in terms of using synthesis gas to produce liquid fuels and electrical power via a solid oxide fuel cell.

Effects of 1-MCP and ethylene on expression of three CAD genes and lignification in stems of harvested Tsai Tai ( Brassicachinensis)

Tsai Tai ( Brassica chinensis) is produced mainly in China but also consumed overseas. The stems of Tsai Tai are subject to toughening due to lignification. Cinnamyl alcohol dehydrogenase ( CAD) is a key enzyme involved in lignin biosynthesis. Three full-length CAD cDNAs were isolated, encoding proteins of 288, 323, and 323 amino acids, respectively. Sequence analysis showed that they share a highly conserved putative NAD/NADP(H)-binding site at the amino terminus. All the three BcCAD genes responded to 1-MCP and ethylene within 2 h. Ethylene up-regulated expression of BcCAD1- 1 and BcCAD2, while 1-MCP down-regulated them. Ethylene increased yellow leaves and stem lignin, and 1-MCP decreased them. These results suggest ethylene is involved in lignin growth in Tsai Tai, and induced expression of BcCAD1- 1 and BcCAD2 could contribute to lignification. They also suggest removal of ethylene and application of 1-MCP could extend shelf-life and knockout of certain CAD genes could produce lines that store well.

MANIPULATING THE RIPENING OF IMPORTED AVOCADO 'HASS' FRUIT DURING COLD STORAGE USING E+® ETHYLENE REMOVER OR 1-METHYLCYCLOPROPENE (1-MCP)

Increased ethylene production is associated with development of quality characteristics of climacteric fruit and also with loss of storage potential. The removal of ethylene and/or inhibition of the effect of ethylene in stored environments is fundamental to maintaining postharvest quality of climacteric produce. A wide range of approaches has been used to minimise the effect of ethylene on fruit. A former study by Terry et al. (2007) demonstrated that a newly developed palladium (Pd)-promoted material was capable of removing ethylene at cool temperatures to sub-physiologically active levels. Whilst 1-methylcyclopropene (1-MCP) acts by blocking the action of ethylene, the Pd-promoted scavenger rapidly removes ethylene from an environment. Hence, the aim of this study was to compare the efficacy of 1-MCP vs. Pd-promoted material (e+ ® Ethylene Remover) to extend storage life and maintain postharvest quality of avocado (Persea americana Mill.) 'Mass' fruit during 26 d storage at 5°C. The e+ ® Ethylene Remover effectively removed both exogenously administered and endogenously produced (i.e., fruit-derived) ethylene to sub-physiologically active levels within 24h. Accordingly, a delay in ethylene-induced softening and colour development was observed but e+ ® Ethylene Remover did not completely disrupt subsequent ripening. Inhibition of ethylene-induced ripening was also observed for 1-MCP, despite the presence of ethylene within storage atmosphere being well above physiologically active levels. There was no main treatment effect on the fatty acid composition of mesocarp lipids. Sugars content measured in response to treatments is discussed. This study suggests that e+ ® Ethylene Remover has the potential to be used commercially and possibly to overcome problems associated with disruption of normal ripening, which are often observed when using 1-MCP.

Effects of ethylene on somatic embryogenesis and galanthamine content in Leucojum aestivum L. cultures

The influence of ethylene on in vitro morphogenesis of Leucojum aestivum and galanthamine accumulation was studied. Calli were cultivated on Murashige and Skoog (MS) medium supplemented with 25 μM 4-amino-3,5,6-trichloropicolinic acid (picloram) and 0.5 μM benzyladenine (BA). During incubation under these conditions, callus cultures produced ethylene (9.5 nL/g fresh weight: F.W.) whereas no ethylene was found in somatic embryos cultivated on medium supplemented with 0.5 μM α-naphthalene acetic acid (NAA) and 5 μM zeatin. Application of the precursor of ethylene 1-aminocyclopropane-1-carboxylic acid (ACC) increased ethylene production in both cultures, and decreased callus growth by a factor of 1.2, whereas callus growth was enhanced by a factor of 1.1 in the presence of an inhibitor of ethylene silver nitrate (AgNO3) or by a factor of 1.2 with an absorbent potassium permanganate (KMnO4). ACC enhanced the induction of somatic embryos and the development of globular embryos. Removal of ethylene by KMnO4 during somatic embryogenesis led to the development of plants with greater length. Silver thiosulphate (STS) induced galanthamine production in callus cultures (0.1% dry weight), whereas ACC induced galanthamine production in somatic embryo cultures (2% dry weight).

Fatty acid and sugar composition of avocado, cv. Hass, in response to treatment with an ethylene scavenger or 1-methylcyclopropene to extend storage life

This study reports on the effect of 1-methylcyclopropene (1-MCP) and a newly developed palladium (Pd)-promoted ethylene scavenger (e + ® Ethylene Remover) on changes in firmness, colour, fatty acids and sugar content of early and late season avocado ( Persea americana Mill.), cv. Hass, during storage at 5 °C and subsequent ripening at 20 °C. The e + ® Ethylene Remover effectively delayed ripening of avocado stored at 5 °C. 1-MCP was more effective at inhibiting ripening, but, in contrast to e + ® Ethylene Remover, it impaired subsequent ripening. Fatty acid profile of late season fruit remained unchanged in response to treatments or storage time, whilst that of early season fruit was slightly, yet significantly, different according to treatments and storage time. Substantial amounts of perseitol were found in all fruit. In contrast, mannoheptulose was only present at high concentration in early season fruit whilst it was quasi-absent in late season fruit. Where ripening was inhibited in response to 1-MCP treatment, significantly more mannoheptulose and better maintenance of perseitol was found vs. controls. Similarly, but to a lesser extent and concomitant with trends in firmness retention and colour changes, e + ® Ethylene Remover led to greater maintenance of mannoheptulose and perseitol than that of controls. This is the first piece of research comparing effects of ethylene removal vs. ethylene action blocking on physical and biochemical changes in avocado cv. Hass and supports the view that C7 sugar metabolism could be an important feature of the avocado fruit-ripening process.

Ethylene removal using biotrickling filters: Part I. Experimental description

The control of liquid flow is one of the most significant factors that affect operation of biotrickling filters. This study evaluated removal of ethylene (C 2H 4) using biotrickling filters at various liquid recirculation flow rates. Perlite and glass beads were utilized as media in eight and two reactors, respectively. Trickle liquid recirculation flow rates ranging from 2.7 to 26 L h −1 (velocity of 0.4–3.7 m h −1) were used. Two perlite reactors were operated with the liquid being recirculated intermittently for 10 min every hour at a recirculation flow velocity of 13 L h −1 (velocity of 1.9 m h −1). Inlet gas contained about 30 mg m −3 of C 2H 4 and 0–40 mg m −3 of ammonia (NH 3). The results showed that C 2H 4 removal efficiencies increased as time elapsed, but the increasing rate of C 2H 4 removal was different based on the reactor types. One of the two perlite biotrickling filters with low liquid recirculation flow exibited a high C 2H 4 removal up to 90%, but other biotrickling filters reached only about 40–70% of C 2H 4 removal efficiency, due to either a relatively high mass transfer limitation or poor distribution of nutrients. This study denotes that a trickle liquid flow over 0.8 m h −1 (5.4 L h −1) had a significant detrimental effect on ethylene removal due to high mass transfer limitation that suppresses microbial growth for ethylene degradation. Therefore, the perlite biotrickling filters with flow rates as low as 0.4 m h −1 (2.7 L h −1) can gave the best performance in high ethylene removal.

Ethylene removal using biotrickling filters: part II. Parameter estimation and mathematical simulation

Mathematical models of biofiltration often encounter uncertain parameters characterizing mass transfer, microbial degradation, biofilm growth, and biofilm detachment. The genetic algorithm, which is one of the most reliable methods for optimization although it has rarely been addressed in biofiltration models up to now, was utilized to estimate the unknown parameters using given experimental data. This study combined genetic algorithm and biofiltration equations to obtain simulated ethylene (C 2H 4) removal efficiencies with estimated parameters. Sensitivity analysis of each parameter was assessed to observe the significance of each parameter. As a result, the simulation well characterized C 2H 4 removal efficiencies for most of the reactors. The large difference in removal efficiencies among reactors could be mostly explained using the mass transfer parameters. Perlite biotrickling filters with low continuous liquid flow tended to increase C 2H 4 removal efficiencies, due to a large active surface area of biofilm facilitating C 2H 4 transfer from the gas to the biofilm phase. Conversely, most of the other reactors underwent relatively low C 2H 4 removal because of high liquid flow that generated a severe mass transfer limitation. The low C 2H 4 removal in the biofilters with discontinuous liquid recirculation flow, in spite of the lowest liquid flow rate was, probably caused by a low active microbial growth condition.

Endogenous ethylene in indirect somatic embryogenesis of Medicago sativa L.

Ethylene biosynthesis during different phases of somatic embryogenesis in Medicago sativa L. cv. Rangelander using two regeneration protocols, RPI and RPII, was studied. The highest ethylene production was detected during callus growth on induction medium in both regeneration protocols. Significantly less ethylene was produced by embryogenic suspension than by callus (RPII). Developing embryos synthesized higher amounts of ethylene than mature embryos. Production of ethylene was strongly limited by the availability of 1-aminocyclopropane-1-carboxylic acid and also by ACC-oxidase activity. However, removal of ethylene from culture vessels’ atmosphere using KMnO4 or HgClO4 had no significant effect on callus growth, somatic embryo induction and development. Reducing of ethylene biosynthesis by aminoethoxyvinylglycine substantially decreased somatic embryo production and adversely affected their development, indicating ethylene requirement during proliferation and differentiation but not induction.

O tratamento pré-colheita com AVG, aliado à absorção do etileno durante o armazenamento refrigerado, preserva a qualidade de maçãs 'Gala'

O manejo do estádio de maturação na colheita e a remoção do etileno no ambiente de armazenamento são estratégias importantes na preservação da qualidade pós-colheita de maçãs. O presente trabalho teve por objetivo avaliar a ação combinada do manejo da maturação na colheita, através da pulverização pré-colheita com aminoetoxivinilglicina (AVG), com a utilização de sachê contendo absorvedor de etileno à base de permanganato de potássio (KMnO4), na preservação da qualidade pós-colheita de maçãs 'Gala'. Frutos dos tratamentos envolvendo combinações de doses de AVG (0; 62,5; 125 e 250 mg L-1) e datas de colheita (0; 5; 10 e 14 dias após o início da colheita comercial) foram acondicionados em caixas, envoltos em filme de polietileno de alta densidade (30µm), sem (controle) ou com a inclusão de um sachê de KMnO4, e armazenados por dois meses em câmara fria convencional (0±0,5ºC/90-95% de UR) e mais sete dias em condição ambiente (20±4ºC/70-80% de UR). A pulverização pré-colheita com AVG retardou substancialmente a maturação dos frutos na colheita, bem como o amadurecimento durante o armazenamento refrigerado em mais de uma semana em condição ambiente. O armazenamento refrigerado com a utilização de sachê de KMnO4 retardou o amadurecimento, avaliado imediatamente após a remoção da câmara fria, expressa em maiores valores de firmeza de polpa e de ângulo 'hue' (hº) no lado verde (menos exposto à luz), em frutos tratados com AVG nas doses de 125 e 250 mg L-1 e colhidos antecipadamente. Todavia, após uma semana de armazenamento em condição ambiente, o emprego de sachê de KMnO4 retardou o amadurecimento de frutos colhidos tardiamente e tratados com AVG nas doses >62,5 mg L-1. Os resultados obtidos mostram que o tratamento pré-colheita com AVG permite retardar a data de colheita e preservar a qualidade durante o armazenamento pós-colheita de maçãs 'Gala', com a utilização de sachê de KMnO4.

Adsorption Equilibrium Parameters of Trace Impurities

Atmospheric air contains various trace impurities which include oxides of nitrogen, carbon, sulphur, and light hydrocarbons. Prior to cryogenic distillation of air to produce oxygen, nitrogen, and argon, these trace impurities have to be removed since many of these compounds constitute a safety hazard in the plant. In this study, adsorption has been considered for their removal and adsorption behavior of ethylene, acetylene, nitrous oxide, acetonitrile, methyl tert-butyl ether, methyl sulfoxide, dimethyl sulfoxide, and methanol have been studied in the Henry's Law low concentration region with several different adsorbents. Adsorption equilibrium parameters have been determined with samples of Alcan pure alumina, Alcan alumina/13X composites Actiguard 600/650PC, CABSORB Chabazite, Ceca13X, and Clinoptilolite by using the concentration pulse chromatographic technique. Heat of adsorption values and van't Hoff plots have been presented.