Decomposition Of Organic Compounds Research Articles

Bridging Microbial Functional Traits With Localized Process Rates at Soil Interfaces.

In this review, we introduce microbially-mediated soil processes, players, their functional traits, and their links to processes at biogeochemical interfaces [e.g., rhizosphere, detritusphere, (bio)-pores, and aggregate surfaces]. A conceptual view emphasizes the central role of the rhizosphere in interactions with other biogeochemical interfaces, considering biotic and abiotic dynamic drivers. We discuss the applicability of three groups of traits based on microbial physiology, activity state, and genomic functional traits to reflect microbial growth in soil. The sensitivity and credibility of modern molecular approaches to estimate microbial-specific growth rates require further development. A link between functional traits determined by physiological (e.g., respiration, biomarkers) and genomic (e.g., genome size, number of ribosomal gene copies per genome, expression of catabolic versus biosynthetic genes) approaches is strongly affected by environmental conditions such as carbon, nutrient availability, and ecosystem type. Therefore, we address the role of soil physico-chemical conditions and trophic interactions as drivers of microbially-mediated soil processes at relevant scales for process localization. The strengths and weaknesses of current approaches (destructive, non-destructive, and predictive) for assessing process localization and the corresponding estimates of process rates are linked to the challenges for modeling microbially-mediated processes in heterogeneous soil microhabitats. Finally, we introduce a conceptual self-regulatory mechanism based on the flexible structure of active microbial communities. Microbial taxa best suited to each successional stage of substrate decomposition become dominant and alter the community structure. The rates of decomposition of organic compounds, therefore, are dependent on the functional traits of dominant taxa and microbial strategies, which are selected and driven by the local environment.

Impact of TiO2 Surface Defects on the Mechanism of Acetaldehyde Decomposition under Irradiation of a Fluorescent Lamp

TiO2 was placed in heat-treatment at the temperature of 400–500 °C under flow of hydrogen gas in order to introduce some titania surface defects. It was observed that hole centers in TiO2 were created during its heat treatment up to 450 °C, whereas at 500 °C some Ti3+ electron surface defects appeared. The type of titania surface defects had a great impact on the mechanism of acetaldehyde decomposition under irradiation of artificial visible light. Formation of O•− defects improved both acetaldehyde decomposition and mineralization due to the increased oxidation of adsorbed acetaldehyde molecules by holes. Contrary to that, the presence of electron traps and oxygen vacancies in titania (Ti3+ centers) was detrimental for its photocatalytic properties towards acetaldehyde decomposition. It was proved that transformation of acetaldehyde on the TiO2 with Ti3+ defects proceeded through formation of butene complexes, similar as on rutile-type TiO2. Formed acetic acid, upon further oxidation of butene complexes, was strongly bound with the titania surface and showed high stability under photocatalytic process. Therefore, titania sample heat-treated with H2 at 500 °C showed much lower photocatalytic activity than that prepared at 450 °C. This study indicated the great impact of titania surface defects (hole traps) in the oxidation of acetaldehyde and opposed one in the case of defects in the form of Ti3+ and oxygen vacancies. Oxidation abilities of TiO2 seem to be important in the photocatalytic decomposition of volatile organic compounds (VOCs) such as acetaldehyde.

Quantitative proteome analysis reveals changes of membrane transport proteins in Sedum plumbizincicola under cadmium stress

Sedum plumbizincicola is an herbaceous species tolerant of excessive cadmium accumulation in above-ground tissues. The implications of membrane proteins, especially integrative membrane proteins, in Cd detoxification of plants have received attention in recent years, but a comprehensive profiling of Cd-responsive membrane proteins from Cd hyperaccumulator plants is lacking. In this study, the membrane proteins of root, stem, and leaf tissues of S. plumbizincicola seedlings treated with Cd solution for 0, 1 or 4 days were analyzed by Tandem Mass Tag (TMT) labeling-based proteome quantification (Data are available via ProteomeXchange with identifier PXD025302). Total 3353 proteins with predicted transmembrane helices were identified and quantified in at least one tissue group. 1667 proteins were defined as DAPs (differentially abundant proteins) using fold change >1.5 with p-values <0.05. The number of DAPs involved in metabolism, transport protein, and signal transduction was significantly increased after exposure to Cd, suggesting that the synthesis and decomposition of organic compounds and the transport of ions were actively involved in the Cd tolerance process. The number of up-regulated transport proteins increased significantly from 1-day exposure to 4-day exposure, from 5 to 112, 16 to 42, 18 to 44, in root, stem, and leaf, respectively. Total 352 Cd-regulated transport proteins were identified, including ABC transporters, ion transport proteins, aquaporins, proton pumps, and organic transport proteins. Heterologous expression of SpABCB28, SpMTP5, SpNRAMP5, and SpHMA2 in yeast and subcellular localization showed the Cd-specific transport activity. The results will enhance our understanding of the molecular mechanism of Cd hypertolerance and hyperaccumulation in S. plumbizincicola and will be benefit for future genetic engineering in phytoremediation.

Hydroxyapatites synthesized by different approaches for efficient catalytic decomposition of volatile organic compound

Hydroxyapatites synthesized by different approaches for efficient catalytic decomposition of volatile organic compound

Bacterial Community Analysis and Potential Functions of Core Taxa in Different Parts of the Fungus Cantharellus cibarius.

Cantharellus cibarius is a widely distributed, popular, edible fungus with high nutritional and economic value. However, significant challenges persist in the microbial ecology and artificial cultivation of C. cibarius. Based on the 16S rRNA sequencing data, this study analyzed bacterial community structures and diversity of fruit bodies and rhizomorph parts of C. cibarius and mycosphere samples (collected in the Wudang District, Guiyang, Guizhou Province, China). It explored the composition and function of the core bacterial taxa. The analyzed results showed that the rhizomorph bacterial community structure was similar to mycosphere, but differed from the fruit bodies. Members of the Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium complex had the highest abundance in the fruit bodies. However, they were either absent or low in abundance in the rhizomorphs and mycosphere. At the same time, members of the Burkholderia-Caballeronia-Paraburkholderia complex were abundant in the fruit bodies and rhizomorphs parts of C. cibarius, as well as mycosphere. Through functional annotation of core bacterial taxa, we found that there was an apparent trend of potential functional differentiation of related bacterial communities in the fruit body and rhizomorph: potential functional groups of core bacterial taxa in the fruit bodies centered on nitrogen fixation, nitrogen metabolism, and degradation of aromatic compounds, while those in rhizomorphs focused on aerobic chemoheterotrophy, chemoheterotrophy, defense against soil pathogens, decomposition of complex organic compounds, and uptake of insoluble inorganic compounds. The analysis of functional groups of bacteria with different structures is of great significance to understand that bacteria promote the growth and development of C. cibarius.

First Insights into the Microbiology of Three Antarctic Briny Systems of the Northern Victoria Land

Different polar environments (lakes and glaciers), also in Antarctica, encapsulate brine pools characterized by a unique combination of extreme conditions, mainly in terms of high salinity and low temperature. Since 2014, we have been focusing our attention on the microbiology of brine pockets from three lakes in the Northern Victoria Land (NVL), lying in the Tarn Flat (TF) and Boulder Clay (BC) areas. The microbial communities have been analyzed for community structure by next generation sequencing, extracellular enzyme activities, metabolic potentials, and microbial abundances. In this study, we aim at reconsidering all available data to analyze the influence exerted by environmental parameters on the community composition and activities. Additionally, the prediction of metabolic functions was attempted by the phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt2) tool, highlighting that prokaryotic communities were presumably involved in methane metabolism, aromatic compound biodegradation, and organic compound (proteins, polysaccharides, and phosphates) decomposition. The analyzed cryoenvironments were different in terms of prokaryotic diversity, abundance, and retrieved metabolic pathways. By the analysis of DNA sequences, common operational taxonomic units ranged from 2.2% to 22.0%. The bacterial community was dominated by Bacteroidetes. In both BC and TF brines, sequences of the most thermally tolerant and methanogenic Archaea were detected, some of them related to hyperthermophiles.

Catalytically active membranes for decomposition of organic compounds in aqueous solutions

This work is devoted to the preparation of microfiltration ceramic tubular membranes based on α-Al2O3 with deposited catalytically active layers for use in wastewater treatment processes. Cobalt and manganese oxides were used as the material of the catalytically active layer; deposition was carried out using a mixture of aggregative stable aqueous dispersions of Co3O4 and MnO2 nanoparticles. According to the data of scanning electron microscopy, the thickness of the obtained deposited layers does not exceed 3 μm. X-ray fluorescence analysis confirmed the presence of Mn and Co on the surface of the samples. The resulting membranes with a mass of 10 mg of the deposited layer of the oxide mixture were tested in the methylene blue decomposition reaction in dilute aqueous solutions (1,2 mg/L). The reaction was carried out in a batch reactor at room temperature, complete discoloration of the solution was observed after 180-240 minutes.

Effect of pH on Decomposition of Organic Compounds Using Ozone Microbubble Water

Microbubbles are tiny bubbles with a particle size of 1 - 100 μm. Microbubbles have been reported that the gas dissolving ability is excellent and hydroxyl radical generates when microbubbles collapse in water. On the other hand, ozone is a gas with high oxidation power and eventually decomposes into oxygen. So, ozone is environmentally friendly. Therefore, we thought that ozone microbubbles water, in which ozone is dissolved in microbubbles water, could be used to efficiently decompose persistent organic compounds while being environmentally friendly. In this study, we evaluated the decomposition of phenol, an object subject to wastewater regulation, by ozone water and ozone microbubbles water. At a constant dissolved ozone concentration, we could not confirm the effect of microbubbles in decomposing phenol. Also, under the same conditions, when the pH was changed, the effect of microbubbles could not be confirmed. However, under basic conditions, phenol was decomposed the most because of self-decomposition reaction of ozone. Therefore, the effect of microbubbles could not be confirmed in the phenol degradation by ozone microbubbles in this experiment.

Pulsed Discharge Plasma in High-Pressure Environment for Water Pollutant Degradation and Nanoparticle Synthesis

The application of high-voltage discharge plasma for water pollutant decomposition and the synthesis of nanoparticles under a high-pressure argon gas environment (~4 MPa) was demonstrated. The experiments were carried out in a batch-type system at room temperature with a pulsed DC power supply (15.4 to 18.6 kV) as a discharge plasma source. The results showed that the electrode materials, the pulsed repetition rates, the applied number of pulses, and the applied voltages had a significant effect on the degradation reactions of organic compounds. Furthermore, carbon solid materials from glycine decomposition were generated during the high-voltage discharge plasma treatment under high-pressure conditions, while Raman spectra and the HRTEM images indicated that titanium dioxide with a brookite structure and titanium carbide nanoparticles were also formed under these conditions. It was concluded that this process is applicable in practice and may lead to advanced organic compound decomposition and metal-based nanoparticle synthesis technologies.

Advanced oxidation processes for chlorpyrifos removal from aqueous solution: a systematic review.

Chlorpyrifos (CPF), an organophosphate insecticide, due to its high efficiency and low cost is widely used in the agricultural industry. CPF may lead to lung deficiency, central nervous system damage, developmental and autoimmune disorders. In recent decades, the advanced oxidation processes (AOPs) have been considered in water and wastewater treatment due to their high efficiency in decomposition of organic and inorganic compounds, specially hardly biodegradable or non-biodegradable compounds. In the present review study, the most common AOPs (such as Fenton and Photo-Fenton processes, UV/H2O2 photolysis, UV/TiO2 heterogeneous photo catalysis, electrochemical processes, sonolysis technology, gamma irradiation technology and sulfate-based AOPs) applied for CPF removal from aqueous matrices has been investigated. It can be concluded that the use of AOPs are effective for CPF removal from aqueous media. In addition, Fenton and photocatalytic processes appear to be the most common techniques for CPF degradation.

The impact of environmental water on the potential application of core−shell titania−silica nanospheres as photocatalysts

In this study, the core–shell silica nanospheres modified with titanium dioxide were tested in the photocatalytic decomposition of dyes. The presented data underlines the advantages and shortcomings in the potential application of silica-based catalysts to neutralize organic pollutants. During the photocatalytic reaction in distilled water, catalysts showed decreased efficiency due to a carbon layer deposited on its surface. This finding set an additional goal to investigate the possibility of regenerating the photocatalyst. Studies have shown that the catalyst could be successfully reused following the thermal removal of deposited carbon.Furthermore, the reactivated silica−titania catalysts exhibited comparable photocatalytic performance to the newly made nanomaterial. Surprisingly, catalyst application in the river water eventually resulted in the permanent deactivation of silica−titania nanospheres, which was caused by the interchangeable silica dissolution/precipitation process on the surface of the studied nanomaterial. In environmental water, silica dissolves and precipitates on titanium dioxide’s surface, blocking the interaction between organic compounds and TiO2. The deactivation occurring in the environmental samples is irreversible. In distilled water, the decomposition of organic compounds leads to photocatalysts’ deactivation by forming a carbon layer on their surface. Reactivation of the silica-based photocatalyst after distilled water is achievable by annealing at a high temperature. In light of our findings, the combination of the photocatalytic properties of TiO2 and the silica template shows no prospects in the purification of polluted waste or environmental water.

Effect of Millet Stalks and Shea Nut Shells on Biogas Production

Biogas production undergoes decomposition of organic compounds under anaerobic condition. This present work investigated the yield of biogas production from Shea nut shell and millet stalk and their blends with sheep dung. It was revealed that sheep dung (control) had the highest yield with an average production of 187.8 ml of gas for 102 days followed by sheanut shell - sheep dung blends which had 123.3 ml of gas for 102 days. Millet stalk - sheep dung blends recorded 75.9 ml of gas for 79 days. Shea nut shell and millet stalk presented 31.5 ml of gas for 81 days and 7.1 ml of gas for 48 days respectively while the pH for production ranged from 10.1 to 4.6. The moisture contents recorded for millet stalk, Shea nut shell and sheep dung before and after production were 40%, 45%, 65% and 80%, 65%, 85 respectively, and also the recorded ash contents before and after production were, 35%, 45%, 40% and 85%, 75%, 65%, respectively. It was observed that the blending of Shea nut shell and sheep dung greatly improves biogas yield while Millet stalks alone are good material for biogas production at a reasonable pH and moisture content values.

Oxidative and adsorptive removal of chlorophenols over Fe-, N- and S-multi-doped carbon xerogels

A range of heteroatom-doped carbon gels was studied to identify factors determining the efficiency of oxidative and adsorptive degradation/removal of phenolic compounds from aqueous solutions. Carbon xerogels were obtained via pyrolysis of resorcinol-heterocyclic aldehyde thermosetting resins. By utilizing either nitrogen-, sulfur- or oxygen-bearing heterocycles and impregnating the resins with FeCl3, carbons doped with the selected heteroatoms (N, S, O) and Fe could be obtained. This synthetic approach allows precise control of the doped element(s) amount and type. The efficiency of the chlorophenol removal process was correlated with the texture of the obtained carbon gels (for adsorptive removal), the pH of an aqueous solution and the H2O2 concentration (for oxidative degradation). The coexistence of iron and nitrogen within porous carbons enhances their catalytic properties towards oxidative decomposition of organic compounds via H2O2 activation, while the adsorption capacity for chlorophenols is directly correlated with microporosity and specific surface area values. The extensive mesoporosity and graphitic structure of the Fe and Ncodoped carbons result in efficient oxidative decomposition of the model organic pollutants. Sulfur doping prevented Fe-assisted graphitization during pyrolysis yielding disordered and highly microporous S and Fe codoped materials. The extent of oxidative degradation of chlorophenols decreased with an increasing number of Cl atoms in the phenolic ring. This report shows that Fe and Ncodoped carbons (the so-called FeNC pyrolyzed materials) are more active heterogeneous catalysts for oxidative (chloro)phenol degradation than their nitrogen- and/or iron-free counterparts, showing the importance of simultaneous coexistence of both elements (Fe and N) in the carbon scaffold.

Micellar nanoreactors for organic transformations with a focus on “dehydration” reactions in water: A decade update

Although nature uses the aqueous environment in most of its chemical/biochemical transformations, water as solvent was totally neglected in organic transformations till the end of the last century because of its poor ability to solubilize most of the organic compounds. However, growing environmental concerns make it imperative to replace toxic organic solvents with benign solvents like water. Over the last few decades, the use of catalytic amounts of surfactants in the aqueous media has proved to be the best solution to overcome the problem of insolubility and hydrolytic decomposition of many organic compounds in water. The surfactants form a colloidal, micellar, or other organized phases that serve as “nanoreactors” in aqueous media. The field is called “micellar catalysis” that acts as a greener alternative to conventional organic synthesis. The hydrophobic interior of micelles can successfully accomplish the most challenging task of “dehydration reactions” in water. The last two decades have witnessed enormous contributions of “dehydration reactions” in micellar media. In addition, incredible rate acceleration and selectivities have been observed in micellar media. The technology lends advantages of reusability and easy scalability in the synthetic processes towards setting-up a new dimension of benign chemical transformations. The purpose of the present review to capture the enormous contributions of the last decade on “dehydration reactions” in micellar media including various condensation reactions, formation of acid-derivatives, multicomponent reactions, and the formation of heterocycles to give a comprehensive idea to readers on the development of this field. The review also covers a brief account on micelle-assisted reactions other than dehydrations taking the key and recent contributions of various types of reactions such as cross-coupling reactions, C–H activation, asymmetric catalysis, oxidation-reduction, click chemistry etc.

Atomically Dispersed Y or La on Birnessite-Type MnO2 for the Catalytic Decomposition of Low-Concentration Toluene at Room Temperature.

Room-temperature catalytic decomposition of low-concentration volatile organic compounds (VOCs) in indoor air is an exciting dream to solve their pollution. Herein, two kinds of rare-earth elements (Y and La) were separately doped into birnessite-type MnO2 nanosheets in the form of single atoms by the hydrothermal method. As-synthesized La/MnO2 achieved 100% removal of 10 ppm toluene at 40 °C under the gas hourly space velocity of 60 L g-1 h-1, which was even somewhat better than the single Pt atom-doped MnO2. In addition, La/MnO2 showed the good durability at room temperature for 0.5 ppm toluene removal under the GHSV of 300 L g-1 h-1 and could be effectively regenerated at 105 °C. GC/FID, online-MS and TD-GC/MS analysis demonstrated that only ignorable trace benzene (∼3.4 ppb, < one thousandth of inlet toluene) was generated in the gas phase during catalytic decomposition of 10 ppm toluene at room temperature. This research sheds light on the development of low cost and high activity catalysts for low-concentration VOC oxidation at room temperature.

Catalytic fast pyrolysis of coal tar asphaltene over zeolite catalysts to produce high-grade coal tar: An analytical Py-GC/MS study

Coal tar asphaltene (CTA) is a low-grade fuel with a high content of oxygen, high-viscosity and high-toxicity. Three kinds of zeolite catalysts ZSM-5, HY and USY were used for catalytic fast pyrolysis (CFP) of CTA to upgrade its pyrolysis vapors by using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The effects of the heating rate (1 °C/ms, 5 °C/ms, 10 °C/ms and 20 °C/ms), the pyrolysis time (20 s, 50 s, 80 s and 100 s), the catalyst types and the mass ratio of CTA-to-catalyst (MRCTC, 4:1, 2:1, 1:1 and 1:2) on the pyrolysis product distribution were investigated. Results show that a higher heating rate (20 °C/ms) and a shorter pyrolysis time (20 s) are more beneficial to improve the selectivity of aromatic hydrocarbons (ArHs). Moreover, Compared with the non-CFP of CTA, ZSM-5, HY and USY promote the decomposition of organic oxygen compounds (OOCs) and the generation of light ArHs (L-ArHs, e.g. benzene, toluene, xylene and naphthalene (BTXN)) from polycyclic ArHs (P-ArHs). The highest yield of BTXN has been obtained at the MRCTC of 1:1 over HY, which is 23 times than that obtained from fast pyrolysis of CTA. Viewed as a whole, the catalysis over these catalysts are capable to convert these undesirable pyrolysis products (containing OOCs, P-ArHs or heteroatom compounds) into BTXN through various reactions, and thus to decrease the oxygen content, aromaticity and toxicity of CTA pyrolysis products. Furthermore, the catalytic mechanisms of “Hydrocarbon pool” and “Phenolic pool” were also proposed.

Investigating the souring mechanism in two giant carbonate oil reservoirs, southwestern Iran

In general, a hydrocarbon reservoir with a produced gas stream having more than three parts per million by volume (ppmv) of hydrogen sulfide is considered a sour reservoir. This study aims to present novel ideas on the main souring mechanisms in Bangestan Group, a well-known Mid-Cretaceous hydrocarbon hosting carbonate in Iran, including Ilam, Sarvak, and Kazhdumi formations. Especially, several scenarios are discussed on potential source of H2S in Sarvak Formation and controversial sweetness of the Upper Ilam Reservoir. At first, both of the bacterial or microbial sulfate Reduction (BSR or MSR) and thermochemical sulfate reduction (TSR) mechanisms were rejected based on the reported bottom-hole temperature and lack of anhydrite in rock matrix, respectively. Moreover, the possibility of souring due to migration was disregarded mainly due to the reported constant concentration of H2S over time and among the target oilfield. At the end, thermal decomposition of organic sulfur compounds within the kerogen or crude oil was introduced as the only potential souring mechanism that was further proven through sulfur isotopic analysis. Furthermore, the possibility of H2S absorption in lower horizons of Ilam Formation, and so sweetness of this formation, due to the presence of ferrous minerals was evidenced through detailed petrographic analysis.

Fertilization enhances mineralization of soil carbon and nitrogen pools by regulating the bacterial community and biomass

The stability of soil organic matter is a key predictor of changes in management practices due to the progressive decomposition of organic compounds. However, the dynamics of soil compounds and to what extent the composition of microbes controls the process are still unclear. Black soils from Northeast China without fertilizer (CK), soil treated with chemical fertilizer (NPK), NPK plus maize straw (NPKS), and NPK plus cattle manure (NPKM) were collected and separated into the labile fraction (macroaggregates > 150 μm) and the recalcitrant fraction (microaggregates 150 μm) for a 14-day incubation. The net carbon (C) and net nitrogen (N) mineralization potentials of the labile fraction were 15.87–26.11 and 0.74–1.48 mg kg−1 soil day−1, respectively, which were between 1.4 and 2.3 times higher than those of the recalcitrant fraction. Compared with CK, NPKS and NPKM significantly increased C and N mineralization in the labile fraction but not in the recalcitrant fraction. Boosting regression tree analysis suggested that total nitrogen (TN), microbial biomass nitrogen (MBN), and bacterial abundance accounted for 48.9%, 31.7%, and 14.0% of the total net C mineralization, respectively. Additionally, soil organic carbon (SOC), microbial biomass carbon (MBC), and bacterial abundance accounted for 39.4%, 37.3%, and 22.1% of the total net N mineralization, respectively. Path analysis showed that TN, MBN, and Brevundimonas positively influenced soil net C mineralization. SOC and MBC positively affected soil net N mineralization, whereas unclassified Comamonadaceae had a negative impact. The mineralization of soil C and N was affected by the inputs of external inorganic nutrients and organic materials and was attributed to the bacterial community, in which Brevundimonas positively responded and contributed to mineralization, while unclassified Comamonadaceae responded negatively.

Effects of crude oil on the biological activity of chernozem soils

The article investigates the effect of crude oil on soil microorganisms and the enzymatic activity of chernozem soils. Experiments were carried out on podzolized medium loamy chernozem in the Samara region using high-sulphur crude oil of medium density. Per 1 kg of soil, 10.00 g (1%), 30.00 g (3%) and 50.00 g (5%) of oil were applied. According to the obtained results, the native soil microbiota contains a wide variety of microorganisms capable of oxidizing both individual hydrocarbons and crude oil in general. Bacteria of the Acinetobacter, Bacillus, Mycobacterium, Pseudomonas and Streptomyces genera, filamentous fungi of the Aspergillus and Penicillium genera, as well as Candida yeast showed the greatest activity in the degradation of both individual hydrocarbons and crude oil in general. The soils freshly polluted with oil demonstrated an increase in the number of bacteria that consume organic forms of nitrogen, actinomycetes, fungi and hydro-carbon-oxidizing microorganisms. In addition, a growing trend in the number of autochthonous microorganisms participating in the mineralization of humic substances was observed. Following 3 months of experiments, a decrease in the number of bacteria consuming organic forms of nitrogen and actinomycetes was revealed. The number of fungi showed the most pronounced decrease upon addition of 3 and 5% of oil, while the number of autochthonous microorganisms participating in the mineralization of humic substances and hydrocarbon-oxidizing microorganisms grew with an increase in the degree of oil pollution. Inhibition of various microorganisms by means of physical or toxic action of hydrocarbons contained in crude oil can cause a decrease in the activity of enzymes present in chernozem soils. Oil hydrocarbons inhibit the activity of polyphenol oxidase, catalase, invertase, phosphatase and lipase present in chernozem soils, although slightly stimulating the peroxidase activity. A decrease in the soil humification coefficient indicates that the oxidation of humic substances prevail over the decomposition of organic aromatic compounds into soil humus components, as well as a decrease in soil fertility as a result of its contamination with crude oil hydrocarbons.

Novel noble-metal-free ceramic filter with controlled pore structure for environmental cleaning

We previously reported the complete decomposition of volatile organic compounds (VOCs) on hydroxyapatite (HAp) powder and initially demonstrated the catalytic reaction mechanism, which makes HAp the most promising alternative to conventional noble-metal nanoparticle catalysts for the control of VOC emission and environmental cleaning. To further the practical application of the previous study, we fabricated porous HAp via facile gel-casting assisted direct forming with the aim of developing a new type of ceramic filter. The structural features of the pore, such as pore size and porosity, are selectively controlled by altering the amount of surfactant added and the forming time. The resultant porous HAp was successfully applied as a catalyst filter for VOC decomposition and exhibited performance that was comparable to that of HAp powder. In addition, the correlation between pore structure tailored gas permeability and catalytic performance of HAp filters was also investigated in depth. Instead of a noble-metal nanoparticle catalyst that must be carried by a porous ceramic filter, the superior catalytic activity achieved using the HAp filter itself presents a novel strategy for future VOC decomposition techniques.