Organic Dispersion Research Articles

Ongoing increases in dissolved organic carbon are sustained by decreases in ionic strength rather than decreased acidity in waters recovering from acidic deposition

Dissolved organic carbon (DOC) has received considerable attention in freshwater research, particularly since the early 2000s when increasing trends became apparent. However, remaining questions need to be resolved to address future effects of DOC on surface waters. This study was undertaken to determine (1) the relative importance of acidity and ionic strength in driving DOC increases in waters recovering from acidification and (2) the role played by long-term acid rain effects on soil. Data obtained from temporal and spatial monitoring of 142 headwater streams throughout the Adirondack region of New York (USA) were used to evaluate chemical relationships involving DOC. Year-round monitoring of three streams of differing acidification status were combined with intermittent stream surveys during spring snowmelt throughout this 24,243 km2 region that is recovering from acidification of soils and surface waters.Despite acidic deposition decreases reaching levels estimated for the early 1900s, DOC concentrations exhibited linear increases from the early 2000s through 2019. Ionic strength or conductivity showed consistent inverse relationships with DOC in all data comparisons from 2004‐05 to 2018‐19. In contrast, relationships between pH and DOC did not support increasing pH as an important factor in DOC increases. Inconsistent relationships between pH and DOC were due to strongly acidic organic acids that remain unprotonated throughout the pH range of these waters and limited weak-acid deprotonation below pH 6.2. Decreasing ionic strength increases DOC solubility by expanding the diffuse double layer, which fosters disaggregation of organic matter and dispersion of colloids. This affect controlled DOC solubilization below a pH of approximately 6.2. Distinguishing between ionic strength and pH effects is important because further large reductions in acidic deposition are not expected but continued soil-water dilution is likely from soil-Ca2+ depletion and the decreasing rate of Ca2+ leaching by SO42− and NO3−, which are still being released from soil organic matter.

MXene-based ultra-thin film for terahertz radiation shielding

We have successfully fabricated Ti-based MXenes flakes, Ti3C2Tx, by chemical etching, then prepared it as an organic dispersion and finally spin-coated it on polyimide plastic substrate for terahertz wave shielding. The shielding effectivity of the 12 μm ultra-thin film can reach up to 17 dB measured by the terahertz time-domain spectra. We can attribute the excellent phenomenon to the intrinsic absorption of triple-layered Ti3C2, due to the similar double-peak type refraction curves, which have been respectively observed from the experimental samples and the simulation ones. High conductivity and strong THz absorption indicate the Ti3C2Tx MXene is the absorptive electromagnetic shielding material. Comparing with other kinds of THz shielding materials, the Ti-based MXenes might be a potential candidate for the next generation of ultra-thin and lightweight THz shielding.

First-principles investigation of phosphate ester and carboxylic acid on BaTiO3 surfaces with stoichiometric terminations

Phosphate ester and carboxylic acid are common anchoring groups for organic dispersants which are used in BaTiO3 suspension processes for multi-layered ceramic capacitors (MLCCs). However, the adsorption behaviors and the structure sensitivity of phosphate ester and carboxylic acid on BaTiO3 surfaces at the molecular-level remain largely unknown and thus require a systematic study. In this report, we theoretically investigate adsorption of those molecules on the BaTiO3 surfaces using Density Functional Theory (DFT). Our study includes three low-index facets of BaTiO3: the BaTiO3(001), (011), and (111) surfaces with the stoichiometric terminations. Also, to model phosphate ester and carboxylic acid, we employ methyl dihydrogen phosphate (CH3OPO3H2) and acetic acid (CH3COOH) in our simulation. Our DFT result reveals that BaTiO3(011)-BaTiO is the most active surface for molecular and dissociative adsorption of phosphate ester and carboxylic acid compared to other surfaces. Also, the saturated coverages of phosphate ester and carboxylic acid on the BaTiO3(011)-BaTiO surface are 0.5 ML (monolayer), respectively, based on the grand potential analysis. These findings reveal the role of the BaTiO3 facets and terminations for adsorption of phosphate ester and carboxylic acid. Thus, we believe that our DFT result will be a building block for understanding on the interaction of tetragonal BaTiO3 with relevant dispersants which are utilized in MLCC applications.

Air-assisted liquid-liquid micro-extraction based on the solidification of a floating organic droplet for the determination of three strobilurin fungicides in water samples

ABSTRACT A simple, fast, air-assisted liquid-liquid micro-extraction technique using the solidification of a floating organic droplet method was developed for the extraction of three strobilurin fungicides in water samples before analysis by high-performance liquid chromatography equipped with a diode array detector (HPLC-DAD). In this method, a low-density solvent (1-dodecanol) was used as the extraction solvent. Fine extraction solvent droplets were rapidly formed and dispersed into the water samples through air-pumping by syringe rather than an organic disperser solvent. The extractant droplets with its freezing point near room temperature could be gathered from the top of the water sample after solidification in anice bath. Under optimal extraction conditions (200 μL of 1-dodecanol, four extraction cycles, 150 mg of NaCl), good linearities were obtained with correlation coefficients exceeding 0.996 and the limits of detection varied between 0.73 and 8.49 ng mL−1. The practical applicability of the proposed method was verified by the determination of three strobilurin fungicide contents in tap water, river water, well water and seawater. Extraction recoveries were between 75.3% and 98.3% with relative standard deviations ranging from 1.2% to 8.5%.The results prove that the method has promising applications for low-cost, accurate and rapid determination of strobilurin fungicides in water samples.

PH-triggered intracellular release of doxorubicin by a poly(glycidyl methacrylate)-based double-shell magnetic nanocarrier.

Two core-double-shell pH-sensitive nanocarriers were fabricated using Fe3O4 as magnetic core, poly(glycidyl methacrylate-PEG) and salep dialdehyde as the first and the second shell, and doxorubicin as the hydrophobic anticancer drug. Two nanocarriers were different in the drug loading steps. The interaction between the first and the second shell assumed to be pH-sensitive via acetal cross linkages. The structure of nanocarriers, organic shell loading, magnetic responsibility, morphology, size, dispersibility, and drug loading content were investigated by IR, NMR, TG, VSM, XRD, DLS, HRTEM and UV-Vis analyses. The long-term drug release profiles of both nanocarriers showed that the drug loading before cross-linking between the first and second shell led to a more pH-sensitive nanocarrier exhibiting higher control on DOX release. Cellular toxicity assay (MTT) showed that DOX-free nanocarrier is biocompatible having cell viability greater than 80% for HEK-293 and MCF-7 cell lines. Besides, high cytotoxic effect observed for drug-loaded nanocarrier on MCF-7 cancer cells. Cellular uptake analysis showed that the nanocarrier is able to transport DOX into the cytoplasm and perinuclear regions of MCF-7 cells. In vitro hemolysis and coagulation assays demonstrated high blood compatibility of nanocarrier. The results also suggested that low concentration of nanocarrier have a great potential as a contrast agent in magnetic resonance imaging (MRI).

Polymeric Carbon Nitride Armored Centimeter-Wide Organic Droplets in Water for All-Liquid Heterophase Emission Technology.

High potential of emission chemistry has been visualized in many fields, from sensors and imaging to displays. In general, conjugated polymers are the top rankers for such chemistry, despite the fact that they bring solubility problems, high expenses, toxicity and demanding synthesis. Metal-free polymeric semiconductor graphitic carbon nitride (g-CN) has been an attractive candidate for visible light-induced photocatalysis, and its emission properties have been optimized and explored recently. Herein, we present modified g-CN nanoparticles as organodispersible conjugated polymer materials to be utilized in a heterophase emission systems. The injection of a g-CN organic dispersion in aqueous polymer solution not only provides retention of the shape by Pickering stabilization of g-CN, but high intensity emission is also obtained. The heterophase all-liquid emission display can be further modified by the addition of simple conjugated organic molecules to the initial g-CN dispersion, which provides a platform for multicolor emission. We believe that such shape-tailored and stabilized liquid–liquid multicolor emission systems are intriguing for sensing, displays and photonics.

Preparation and Characteristics of Titanium Silicate Filler for Functional Materials

During the interaction of titanite with hydrochloric acid, a composite titanosilicate precipitate (TSP) of the composition TiO2 ⋅ (1.1–1.15) SiO2 ⋅ (0.8–0.85) H2O consisting of two phases is isolated—crystalline titanium dioxide of rutile modification and silica. It has been found that, during high-temperature treatment (850°C), particles of the hydrated precipitate condense with an increase in crystallinity and a decrease in Ssp almost twofold compared to freshly precipitated TSP, without sintering of particles and formation of new phases. Particles of the resulting composition are agglomerates of fragments of a fairly regular shape, which is characteristic of crystalline particles of titanium dioxide, the surface of which is coated with an amorphous silica shell. The study of the samples using an electron microscope and a laser analyzer showed that 90% of the particles are represented by a fairly narrow fraction 0.4–1 μm in size. The morphological properties of the particles of the composition, as well as its technical characteristics, including the ability to give a matte surface to transparent organic dispersions, allow one to conclude the prospects of its use as an effective filler in the manufacture of adhesives and sealants with dielectric properties and increased heat resistance. In addition, such a filler may find application in the manufacture of other functional materials.

Efficient Syntheses of 2D Materials from Soft Layered Composites Guided by Yield Prediction Model: Potential of Experiment‐Oriented Materials Informatics

AbstractExfoliation is a common route to synthesize 2D materials such as monolayered and few‐layered nanosheets. However, it is not easy to control the breaking‐down process. This work shows a new exfoliation strategy for generation of nanosheets from soft layered composites in high yield. Soft layered composites of inorganic hosts and organic guests are exfoliated into nanosheets in organic dispersion media. A simple yield prediction model is constructed on small‐scale experimental data by sparse modeling, a data‐scientific approach, combined with chemical perspective. The prediction model indicates the guest–medium combinations enabling high‐ and low‐yield syntheses of the nanosheets. The high‐ and low‐yield syntheses are actually achieved on different types of layered transition metal oxides in a minimum number of experiments. The number of experiments is reduced by 94%. The experimental optimization realizes further improvement of the yield, namely, shortening the exfoliation time. The present strategies can be applied to obtain a variety of 2D materials through exfoliation. Moreover, the present work suggests that combination of small experimental data, data‐scientific approach, and chemical perspective, i.e., experiment‐oriented materials informatics, has potentials for acceleration of materials design.

Controlling the Structures, Flexibility, Conductivity Stability of Three-Dimensional Conductive Networks of Silver Nanoparticles/Carbon-Based Nanomaterials with Nanodispersion and their Application in Wearable Electronic Sensors.

This research has successfully synthesized highly flexible and conductive nanohybrid electrode films. Nanodispersion and stabilization of silver nanoparticles (AgNPs) were achieved via non-covalent adsorption and with an organic polymeric dispersant and inorganic carbon-based nanomaterials—nano-carbon black (CB), carbon nanotubes (CNT), and graphene oxide (GO). The new polymeric dispersant—polyisobutylene-b-poly(oxyethylene)-b-polyisobutylene (PIB-POE-PIB) triblock copolymer—could stabilize AgNPs. Simultaneously, this stabilization was conducted through the addition of mixed organic/inorganic dispersants based on zero- (0D), one- (1D), and two-dimensional (2D) nanomaterials, namely CB, CNT, and GO. Furthermore, the dispersion solution was evenly coated/mixed onto polymeric substrates, and the products were heated. As a result, highly conductive thin-film materials (with a surface electrical resistance of approximately 10−2 Ω/sq) were eventually acquired. The results indicated that 2D carbon-based nanomaterials (GO) could stabilize AgNPs more effectively during their reductNion and, hence, generate particles with the smallest sizes, as the COO− functional groups of GO are evenly distributed. The optimal AgNPs/PIB-POE-PIB/GO ratio was 20:20:1. Furthermore, the flexible electrode layers were successfully manufactured and applied in wearable electronic sensors to generate electrocardiograms (ECGs). ECGs were, thereafter, successfully obtained.

Broadband free space impedance in Co2Z hexaferrites by substitution of high valency heavy transition metal ions for miniaturized RF devices

Polycrystalline samples of Z-type hexaferrites, having nominal compositions Ba3Co2+xFe24−2xMxO41, where M = Ir, Hf, or Mo and x = 0 and 0.05, were processed via ceramic protocols in pursuit of low magnetic and dielectric losses, as well as equivalent permittivity and permeability over the VHF–UHF band. Fine process control was conducted to ensure optimal magnetic properties. Organic dispersants, i.e., isobutylene and maleic anhydride, were employed to achieve maximum densities. Crystallographic structure, characterized by x-ray diffraction, revealed that the dopants did not adversely affect the crystal structure and phase purity of the Z-type hexaferrite. An increase in permeability and size reduction factor is shown to be linearly proportional to the ionic radii of the dopants. This trend is consistent with local bonding distortions giving rise to increased exchange energy (J) as predicted by the Goodenough–Kanamori–Anderson rules and superexchange theory. We posit that these distortions increase the magnetocrystalline anisotropy energy affecting the frequency dependent complex permeability. For Mo doping of x = 0.05, a bandwidth of 400 MHz exists at a center frequency of 650 MHz where the permittivity and permeability are very nearly equal, i.e., Z = 377 ± 5 Ω. These results give rise to low loss, i.e., tan δε/ε′ = 0.0006 and tan δμ/μ′ = 0.038 at 650 MHz, with considerable size reduction (×9). The miniaturization and optimized performance of magnetodielectric materials for antenna at VHF–UHF frequencies using cost-effective and volumetric processing methodologies are demonstrated.

Dispersants’ influence on the effectiveness of oxidation of soot catalysed with liquid dispersions of iron nano-compounds

Four light heating oil combustion modifiers were synthesised, containing iron compounds on +3 oxidation state. Combustion modifiers were liquid dispersions of iron nano-compounds. Four different organic dispersants were used in the synthesis: prop-2-enoic acid, 10-undecenoic acid, olein and dodecenyl succinic acid and isopropan alcohol semi-ester. The stability of synthesised substances was determined visually and using the Dynamic Light Scattering technique. Modifiers were introduced to a light heating oil, which was next burned, controlling the emission of harmful components originating from this process. The obtained PM, CO, and CHx concentrations were compared with values obtained for a light heating oil without modifiers. The modifiers obtained with olein (N3) and dodecenyl succinic acid and isopropan alcohol semi-ester (N4) showed high stability and high efficiency in the process of soot oxidation. Poorly stable modifiers (N1, N2) showed weak catalytic properties. Fuel containing the N3 modifier showed a reduction in PM emissions of about 30 %, unburned hydrocarbons by almost 70 %, and carbon monoxide by 55 %.

Facile preparation of a polymer-ZnO composite colloid as an electron transport layer and its effects on inverted polymer solar cells

A polymer-ZnO colloidal solution was prepared as the organic-inorganic composite electron transport layer of inverted polymer solar cells (i-PSCs) by successive modification of ZnO particles with organic dispersant and polyethyleneimine (PEI), which offers an alternative to previously used complicated processes such as high temperature annealing or multi-layer coatings. The modification of ZnO surfaces with 2-(2-methoxyethoxy) acetic acid (MEA) provides colloidal stability and prevents aggregation of ZnO particles after adding PEI into the ZnO colloidal solution. The amount of incorporated PEI was increased to ~10 wt%, and the cell performance parameters of Jsc and fill factor (FF) were enhanced proportional to PEI content because of its contribution in decreasing the work function of ZnO ETL. By fabrication of i-PSCs with the modified ZnO ETL, the power conversion efficiency (PCE) was increased by ~40% from 5.10% to 7.51% in the ITO/ETL/PV-D4610:PC60BM/MoO3/Ag structure. The multi-functionalized ZnO ETL provides a more facile process for preparation of an organic-inorganic composite ETL to improve the performance of i-PSCs.

Fabrication of bacteriochlorin shell/gold core nanoparticles for the sensitive determination of trichlosan using differential pulse voltammetry

The triclosan contamination in daily life has attracted great attention, and there is rare electroanalytical assay based on π-system dyes. In this work, a facile preparation and electroanalytical application of an organic dispersion containing bacteriochlorin dyes (LS11) and gold nanoparticles (AuNPs) was proposed. The organic-inorganic hybrid nanocomposites were characterized by transmission electron microscope (TEM) showing a core–shell structure with a uniform layer of dye molecules. The as-prepared nanocomposites were successfully coated onto glassy carbon electrodes, and the surface characteristics of the top most layer of the modified electrodes were examined by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and water contact angle experiments. The nanocomposite film-modified electrodes exhibited good electrochemical activity towards oxidation of triclosan. The oxidation of adsorbed triclosan occurred at a reduced overpotential, and the anodic current responses under a pre-concentration step prior to the potential scan were used for quantitative analysis. A good linear relationship from 0.01 μM to 0.5 μM was obtained using differential pulse voltammetry. The sensitivity and detection limit (S/N = 3) were 23.69 μA μM−1 and 0.03 μM, respectively. The proposed assay was applied to detect triclosan in two personal hygiene products using standard addition method, and the results showed good recoveries that ranged from 96.6% to 101.5% and from 99.3% to 103.8% for a toothpaste sample and a hand wash sample, respectively. A reference HPLC-UV method was used to evaluate the proposed electroanalytical method, and a good agreement was achieved.

Improvement of Sintering Performance of Nanosilver Paste by Tin Doping

Nanosilver paste, an interconnect solder, is a common choice in the electronics packaging industry. However, higher sintering temperature and lower sintering strength limit its application. At present, doped nanosilver paste has been studied for use in chip interconnection. In order to improve the sintering properties and shear strength of nanosilver paste, we have developed a new tin-doped nanosilver paste (referred to as silver tin paste), and according to the decomposition temperature of the organic dispersant in the slurry, a corresponding sintering process with a maximum temperature of 300°C was developed. The product after sintering of the silver tin paste is a mixture of a solid solution of Ag and an Ag3Sn phase. Among them, the hard and brittle phase Ag3Sn diffuse distribution in the silver matrix for strengthening, and the solid solution of Ag acts as a replacement solid solution strengthening. As the content of doped Sn increases, the sintering strength increases remarkably. When the Sn content is 5%, the joint shear strength reaches the highest value of 50 MPa. When it exceeds 5%, the sintering strength gradually decreases, which may be caused by the excessive formation of the intermetallic compound IMC as the dopant content increases. This new tin-doped nanosilver technology has the characteristics of low-temperature sintering and high-temperature service, so it is expected to be widely used in semiconductor power devices.

Facile Fabrication of Flexible Electrodes and Immobilization of Silver Nanoparticles on Nanoscale Silicate Platelets to Form Highly Conductive Nanohybrid Films for Wearable Electronic Devices.

This study investigated films with remarkably high electrical conductivity after they were easily prepared from organic/inorganic nanohybrid solutions containing an organic polymeric dispersant and two-dimensional nanoscale silicate platelets as the inorganic stabilizer dispersed with silver nanoparticles. Transmission electron microscopy shows that the production of silver nanoparticles synthesized by the in situ chemical reduction of AgNO3 in an aqueous solution by N,N-dimethylformamide results in an average silver nanoparticle diameter of circa 20 nm. Thin films of silver nanoparticles were prepared on a 1-μm-thick film with a low sheet resistance of 8.24 × 10−4 Ω/sq, achieved through the surface migration of silver nanoparticles and prepared by sintering at 300 °C to form an interconnected network. This was achieved with a silver nanoparticle content of 5 wt%, using nanoscale silicate platelets/polyoxyethylene-segmented polyimide/AgNO3 at a weight ratio of 1:10:35. During sintering, the color of the hybrid film changed from gold to milky white, suggesting the migration of silver nanoparticles and the formation of an interconnected network. The results show promise for the fabrication of novel silver-based electrocardiogram electrodes and a flexible wireless electrocardiogram measurement system for wearable electronics.

Nonpolar Organic Dispersion of 2D Ti3C2Tx MXene Flakes via Simultaneous Interfacial Chemical Grafting and Phase Transfer Method.

Herein, we demonstrate a simple and versatile way for preparing stable Ti3C2Tx MXene dispersions in nonpolar organic solvents through a simultaneous interfacial chemical grafting reaction and phase transfer method. Alkylphosphonic acid ligands were chemically grafted on the hydroxyl terminal groups of Ti3C2Tx flakes at the liquid-liquid interface between water and water-immiscible organic medium to form a covalent Ti-O-P bond via interfacial nucleophilic addition and sequential condensation reaction at room temperature; the surface-functionalized Ti3C2Tx flakes concurrently migrated from the aqueous phase to the organic phase. Unlike conventional surface chemical modification methods that require many complex and tedious steps, this is a simple and easy process for fabricating a Ti3C2Tx organic dispersion in various organic solvents, from highly polar to nonpolar. The nonpolar Ti3C2Tx dispersion in chloroform also exhibits strong oxidation resistance and stable long-term storage. This approach provides an opportunity for preparing MXene nanocomposites with nonpolar polymeric matrices that are soluble in organic media for future applications such as stretchable electrode.

Wettability Reversal of Hydrophobic Pigment Particles Comprising Nanoscale Organosilane Shells: Concentrated Aqueous Dispersions and Corrosion-Resistant Waterborne Coatings.

We demonstrate the synthesis of polysiloxane-modified inorganic-oxide nanoparticles comprising a TiO2-based pigment (Ti-Pure R-706), which undergo drastic wettability reversal from a hydrophilic wet state to a hydrophobic state upon drying. Furthermore, the dry hydrophobic pigment particles can be reversibly converted back to a hydrophilic form by the application of high shear aqueous milling. Our synthetic approach involves first condensing the cross-linking monomer CH3Si(OH)3 onto the surface of Ti-Pure R-706 at pH 9.5 ± 0.2 in an aqueous suspension. After drying this surface-modified material in the presence of a polyanionic dispersant so as to preserve the primary particle size via dynamic light scattering, it is trimethylsilyl-capped with (CH3)3SiOH, which consumes some residual Si-OH functionalities, and washed to remove all dispersant and excess reagents. Transmission electron microscopy demonstrates a ∼6 nm polysiloxane coating uniformly surrounding the surface of the pigment particle. A 70 wt % (37 vol %) concentrated aqueous slurry of the hydrophobically modified pigment particles prepared in the absence of dispersant exhibits rheological characteristics that are nearly the same as an aqueous dispersion of native unmodified hydrophilic Ti-Pure R-706 comprising an optimal amount of the organic anionic dispersant. It is also possible to synthesize dispersions without the use of an added surfactant and/or dispersant at even higher solid concentrations of up to 75 wt % (43 vol %) in water, conditions at which even the hydrophilic native Ti-Pure R-706 oxide pigment yields a gel-like paste in the absence of a dispersant. Films prepared by drying an aqueous suspension of these pigment particles exhibited a hydrophobic contact angle of ∼125°. When acrylic-based waterborne coatings were prepared comprising these surface-modified Ti Pure R-706 pigments, they showed excellent corrosion protection of a mild steel substrate. These data point to a wettability reversal in which the particles change from hydrophobic to hydrophilic upon high-shear aqueous milling and vice versa upon drying. 29Si CP/MAS NMR spectroscopy highlights the importance of flexibility of the polysiloxane coating for achieving this wettability reversal, a result that emphasizes the importance of surface reconstruction.

Flexible dispersive liquid–liquid microextraction for on-site sample pre-concentration

ABSTRACT In recent years, more and more interest has been focused on the on-site sample preparation. Dispersive liquid–liquid microextractions without centrifugation or toxic organic solvent were developed and proved suitable for on-site extraction. In this study, a flexible dispersive liquid–liquid microextraction was developed for on-site water sample pre-concentration. A device containing a phase separation filter was prepared. By means of the phase separation filter packed with hydrophobic nonwoven polypropylene fibre, extraction phase and aqueous phase of the emulsified system were separated by manual filtration, which avoided the electric devices usually required in dispersive liquid–liquid microextractions. Combining the device with ionic liquid-based in situ dispersive liquid–liquid microextraction, a totally electricity-free procedure was developed. During the procedure, the extraction phase 1-hexyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide was formed through an ion exchange reaction, and then separated with water by filtration. After filtration, the extraction phase was eluted and submitted to high-performance liquid chromatography-variable wavelength detector for analysis. Parameters affecting the extraction performance were investigated and optimised. The optimised procedure achieved extraction recoveries of 75–89%. The intra-device, inter-device, intra-day and inter-day relative standard deviations were less than 4.6%. Good linearity (r2 > 0.9992) was obtained over the calibration range from 2 to 1000 µg L−1. The limits of detection of the method were in the range of 0.41–0.65 µg L−1. Because electric devices and organic dispersants are not required, the present approach is proved green, fast, and extremely flexible for on-site preparation of water sample. The proposed device is also expected to make other dispersive liquid–liquid microextractions transform into the on-site procedure.

Investigation of natural resilience capacity of soil features affected by low severity ground wildfire after three years in Mediterranean forest ecosystem

Wildfires are one of the succession dynamics in the ecosystem, however forest ecosystems have natural resilience capacity to combat with natural disturbance regimes depend on local ecologic properties. This study was conducted to evaluate natural resilience capacity status of the soil’s physical, chemical and hydrological features exposed to low severity ground wildfire after three years in the Bulutoglu village, Kahramanmaras. Particle size distribution, soil reaction (pH), electrical conductivity (EC), organic matter content (OM), dispersion ratio (DR), moisture content (MC), field capacity (FC), colloid/moisture equivalent (CM), particle density (PD), bulk density (BD) and porosity ratio (PR) analysis were performed on two groups of soils (burned and unburned counterpart). The environmental sensitivity index (ESI) include soil, vegetation, climate, and management quality of the study area was determined by MEDALUS methodology. According to the results, there is no environmental sensitivity in the study area. It was determined that the negative effects of soil properties improved significantly after three years from the wildfire except for the PR and BD values. There was no statistically significant difference between the analyzed two soil samples groups. It was concluded that the difference between the bulk density and porosity ratios is not only due to the effects of the fire but also with grazing pressure, especially on the unburned area. According to the results, the burned area suffered from low severity ground wildfire has substantially been naturally rehabilitated itself within three years. Environmentally sensitivity (ESI) of the study area was a play an important role in the recovery of soil features. Additionally recommended avoiding some activities that will compress the soil for increasing natural resilience capacity after a wildfire.

PLASMA-CHEMICAL TECHNOLOGY OF STABILIZATION OF COMPOSITION WATER-COAL FUEL ON THE BASIS OF ORGAN-CONTAINING WASTE WATER

Industrial and domestic waste water containing waste lubricants, cooling suspensions, waste from the food, alcohol and pulp and paper industries contain fuel residues, solvents, fats, dyes and other organic compounds. Large volumes and multi-component composition of such waste complicate and cost more water purification. Disinfection of such waters using adsorption, membrane or catalytic technologies requires the cost of scarce materials and expensive equipment, as well as leading to the formation of secondary man-made wastes in the form of waste adsorbents, catalysts, membranes, etc.
 A promising option is the use of organ-containing sewage in formulations of composite water-coal fuel. At the same time, organic substances of sewage during the combustion of technological equipment allocate additional heat, which allows improving the energy characteristics of the fuel. The possibility of using plasmochemical technology for the stabilization of composite aqueous-coal fuel on the basis of organ-containing wastewater has been investigated. Organic dispersion media used waste after purification of fusel oil and wastewater after the washing of parts for technical purposes. Electrokinetic and rheological properties of composite aqueous-coal fuel have been studied. It has been established that the previous plasmochemical conversion of organo-containing wastewater, which is used as a dispersion medium for composite water-coal fuel, makes it possible to improve its operational properties. The growth of sedimentation stability and the optimization of effective viscosity are achieved both by increasing the electrostatic repulsion of the suspension particles with an increased ξ-potential and by achieving the bimodal composition of the disperse phase.
 There is also a significant increase in the absolute values of ξ - the potential reached in the alkaline medium (pH = 10) 55-64 mV for anthracite coal. Accordingly, electrostatic repulsion of coal particles increases and improves in the viscosity in the modified samples is (1.1-1.25 Pa·s) and sedimentation stability (28-36 hours). The sedimentation stability of the fuel obtained is significantly improved in comparison with conventional suspensions of coal in organ-containing wastewater and reaches 28 to 36 hours without the addition of stabilizers. In addition, highly dispersed additives increase the reactivity of the composite aqueous-coal fuel contributes to increasing the caloricity and completeness of the burning of slurry fuel.