Mass Loss Of Samples Research Articles

Cavitation Wear of Basalt-Based Glass Ceramic.

This paper examines the possibility of using basalt-based glass ceramics for construction of structural parts of equipment in metallurgy and mining. An ultrasonic vibration method with a stationary sample pursuant to the ASTM G32 standard was used to evaluate the possibility of the glass ceramic samples application in such operating conditions. As the starting material for synthesis of samples, olivine–pyroxene basalt from the locality Vrelo–Kopaonik Mountain (Serbia) was used. In order to obtain pre-determined structure and properties of basalt-based glass ceramics, raw material preparation methods through the sample crushing, grinding, and mechanical activation processes have been examined together with sample synthesis by means of melting, casting, and thermal treatment applied for the samples concerned. The mass loss of samples in function of the cavitation time was monitored. Sample surface degradation level was quantified using the image analysis. During the test, changes in sample morphology were monitored by means of the scanning electronic microscopy method. The results showed that basalt-based glass ceramics are highly resistant to cavitation wear and can be used in similar exploitation conditions as a substitute for other metal materials.

The impact of bromine- and phosphorous-based flame retardants on flame stability and heat feedback from laminar wall flames

To develop new, efficient flame retardants, it is critical to understand the controlling mechanisms by which they impact material flammability. Our research group has developed a systematic methodology to assess the flammability of polymeric materials through microscale combustion calorimetry (MCC) and bench-scale experimental measurement of flame heat feedback and material burning behavior during vertical burning and upward flame spread. In this work, that experimental framework is used to quantify the mechanisms of action of bromine- and phosphorous-based flame retardants. Here, a series of experiments was conducted in which flame heat transfer and sample mass loss rate were measured as a flame spread over 7 cm tall, 5 cm wide glass-fiber-reinforced poly (butylene terephthalate) (PBT) samples manufactured with increasing amounts (12, 16, and 24 wt %) of the brominated flame retardant, poly (pentabromobenzyl acrylate). In an additional series of tests, similar measurements were obtained for PBT samples manufactured with increasing amounts (8, 12, 16, and 20 wt %) of the phosphorous-based flame retardant, aluminum diethyl-phosphinate (trade name: Exolit OP 1230). These tests allow for the study of the impact of flame retardants on key features of the system including: peak flame heat flux, flame stability, and condensed phase decomposition behaviors (i.e., charring). Current measurements identify an optimal loading concentration of Exolit OP 1230 for the PBT samples tested in this work, identify each flame retardant's impacts on char yield and heat of combustion, and indicate that bromine- and phosphorous-based flame retardants (at least at the concentrations tested here) can affect wall flame stability and gas phase combustion efficiency but do not affect flame to surface heat transfer in the continuous region of wall flames. These measurements allow for greater understanding of tightly coupled condensed- and gas-phase processes that control flame spread and material burning behavior, thus providing a quantitative connection between material composition and the controlling mechanisms of fire growth.

PERFORMANCE EVALUATION OF VARIOUS CONCRETE MIXES SUBJECTED TO SULFURIC ACID

Concrete is an essential structural material that has long been used for the construction of buildings, bridges, tanks, pavements and variety of the other types of structures. Due to its physical properties and economical use, concrete is used extensively in the country's infrastructure. In the Oil and Gas sector, concrete infrastructures are more challenging structures, which are exposed to a highly aggressive environment. A special type of reinforced concrete structure exposed to different forms of sulfur attack is the sulfur storage structure, typically referred to as "Sulfur Pit". Sulfur Pit is an essential part of oil and gas processing facilities, where the sulfur after extraction from the hydrocarbons in Sulfur Recovery Units is stored and maintained in the liquid phase at temperatures ranging from 130 °C to 160 °C. The gas sweeting process results in the formation of acid gas consisting of H2S, water vapor in addition to residual sulfuric acid. Reinforced concrete exposed to this environment is subject to deterioration and corrosion of the reinforcing steel. This paper presents the experimental investigation of four different concrete mixes exposed to 5% sulfuric acid at ambient temperature. These mixes include normal OPC, sulfate resistant (Type V) cement, and two mixes with supplementary cementitious materials blast furnace slag (GGBFS) and Class-F fly ash. The investigation is focused on mechanical properties and mass loss of the concrete samples.

Installation for the implementation of the supercritical fluid extraction regeneration of nickel-molybdenum catalyst

The process of supercritical fluid extraction recovery of the catalyst at pressures of 10, 20 MPa and temperatures of 343, 373, 433, 473 K with pure supercritical carbon dioxide on the original device has been implemented. An increase in pressure and temperature has a positive effect on the catalyst regeneration process. With increasing pressure increases the density of CO2, and, consequently, its dissolving ability. With increasing temperature, the pressure of saturated vapors of compaction products increases and, as a result, their concentration in CO2 increases. In order to increase the efficiency of the supercritical CO2-extraction process for the regeneration of catalyst samples, carbon dioxide modification with various additives (chloroform, dimethylsulfoxide, acetone, ethanol, and non-polar inert with respect to the catalyst composition hexane) was used. Modification of supercritical carbon dioxide with ethanol and hexane at a temperature of 473 K and a pressure of 20 MPa led to an increase in the mass loss of catalyst samples by 12 and 14%, respectively, which indicate the removal of deactivating substances during regeneration by the method of supercritical fluid extraction.

INFLUENCE OF STEEL 09G2S HEAT TREATMENT METHOD FOR ITS CORROSION RESISTANCE

Background Due to high strength, mechanical properties in different temperature ranges, the use of steel 09G2S is wide. After heat treatment, this steel acquires various properties, and as a result it is used in mechanical engineering and other areas of industry. For example, pipelines for various liquids and gases transportation, different machine parts, steam boilers, oil-field equipment, and tanks are made of it. Aims and Objectives The aim of the work is to determine the effect of heat treatment of steel 09G2S on its corrosion resistance. To achieve this aim the following tasks were solved: 1. to conduct heat treatment of steel 09G2S; 2. to determine the value of the hardness of the samples after heat treatment according to the Rockwell method; 3. to determine the depth and mass indicators of corrosion using gravimetric studies. Results Heat treatment of steel 09G2S was performed. After heating to a certain temperature and cooling, it resulted in change in the structure of the metal and in change in its mechanical and physical properties. In order to increase the hardness of steel, hardening was performed followed by tempering. After quenching, an increase in the hardness of steel 09G2S was found. Hardness is the most important characteristic of the mechanical properties of materials. To determine the hardness, one sample was selected after quenching, as well as five samples after tempering. The hardness of the samples was determined by the Rockwell method. At least three measurements were performed on each sample. As a result, it was found that the maximum value of hardness is observed after quenching and subsequent tempering at 100 °C, the minimum value at a tempering temperature of 500 °C. The corrosion rate by the gravimetric method was determined by the mass loss of metal samples during their stay in the test medium. To assess the corrosiveness of the environment on the studied samples, mass and deep corrosion indicators were determined. The maximum corrosion rate is observed during quenching and subsequent tempering at a temperature of 300 °C, the minimum - at a tempering temperature of 500 °C.

Comparative Study on Pyrolysis of Wet and Dry Torrefied Beech Wood and Wheat Straw

This study compares the influences of wet and dry torrefaction on pyrolysis behaviors of beech wood and wheat straw. These two types of torrefaction were compared at similar mass loss of samples. F...

Preparation and stereolithography 3D printing of ultralight and ultrastrong ZrOC porous ceramics

Porous ZrOC ceramics with octet truss structure have been successfully obtained based on Digital Light Processing (DLP) 3D printing and polymer-derived ceramic technology. Zr-based photosensitive resin with low viscosity and high photosensitivity was synthesized to prepare the octet truss structures. The transition process from resin to ceramic was verified through tests on phase composition, morphology and thermodynamic properties. Linear shrinkage and mass loss of the as-prepared samples reached approximately up to 79% and 42%, respectively. Nanocrystallines of t-ZrO2 of about 15 nm diameter was found to exist stably under 1200 °C. The three-dimensional reconstructed micro-CT images showed that the porosity of octet truss structure reached 55.49%. This helps acquire ultralight and ultrastrong ceramics with greatly improved specific stiffness which is superior to that of most materials within the scope of comparable density. This work provides the possibility to expand the available ceramic precursors (Ti, Al, Ni, etc) for 3D printing and excavate its potential applications.

The corrosion effect on supports used in underground mining operations generated by low-rank salt-bearing coals: the Central Anatolia case

The formations containing soluble salt structures are located on the upper sections of underground coal beds in Central Anatolia Region, where ground waters infiltrate into coal seams through faults and with other environmental factors that result in corrosion danger upon machinery/equipment employed within mining operations. In order to define the corrosion rates of steel component samples, tests performed with bore water representing regional underground hydrosphere, mine water for mining conditions, and pure water for control purposes. The corrosion mechanisms were implemented according to “Standard Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens-ASTM G1-03 (2011),” and the microscopic images of steel surfaces have been examined ASTM G1-03, (2011). At the end of experiments, support steel sample mass loss is defined as lowest for bore water and highest for mine water and pure water. The rates of corrosion for bore water is 0.010, mine water 0.182, and pure water 0.180 (mm/year). Evidently, actual underground water corrosiveness is assessed as high; therefore, suggestions are developed for the mining enterprises to take into consideration for safe and secure operation in such environment.

Autogenous and drying shrinkage of alkali‐activated slag mortars

AbstractShrinkage of alkali‐activated slag (AAS) cement is a critical issue for its industrial application. This study investigated the mechanisms and effectiveness of shrinkage‐reducing agent (SRA) and magnesia expansive agent on reducing autogenous and drying shrinkage of AAS mortars that were activated by liquid sodium silicate (LSS) solution with modulus (SiO2/Na2O molar ratio) of 0‐1.5. The results showed that the autogenous shrinkage of AAS mortars increased with the increase of LSS modulus from 0 to 0.5, then decreased as modulus increased up to 1.5. The drying shrinkage consistently increased with the increase in the modulus of LSS. The oxyalkylene alcohol‐based SRA could significantly reduce the autogenous and drying shrinkage of AAS mortars while the magnesia expensive agent was comparatively less effective. The autogenous shrinkage of AAS mortars was inversely proportional to the internal relative humidity, while the drying shrinkage was more related to the mass loss of samples. Mathematical models were established to describe the autogenous and drying shrinkage behavior of AAS mortars.

Durability Assessment of Western Juniper from Five Different Growing Regions

The relationship between extractives content and resistance to fungal attack was examined in heartwood samples of western juniper (Juniperus occidentalis) collected from across the growing range. Mass losses of juniper samples exposed to Trametes versicolor were generally low and indicated that this species would be classified as highly durable, while mass losses for samples exposed to Gloeophyllum trabeum were higher and suggested that juniper heartwood was slightly less resistant to this fungus. Extractives levels were generally poorly correlated with decay resistance, but there were substantial differences in extractives content between samples from different geographic areas. The results suggest the need for further evaluation of a wider range of samples to better determine the relationship between extractives and decay resistance.

Wood decomposition is more rapid on than off termite mounds in an African savanna

AbstractDecomposition is important for nutrient cycling and the dynamics of soil organic matter. The factors that influence local decomposition rates in savannas dominated by Macrotermes mounds remain uncertain. Here, we experimentally assessed the effects of macro‐ and micro‐detritivores, active and inactive mounds, and vegetation cover on wood decomposition rates for eight common woody plant species in Lake Mburo National Park, in Uganda. Five pairs of Macrotermes mounds, one active and one inactive per pair, were selected. Each mound provided two sample locations, one, the most shaded (with canopy cover), and one, the most open (without canopy cover) edge of mound. In addition, for each mound pair, one additional sample location was located off‐mound, in an open level area between the mounds. After one, three, and 12 months, protected (wrapped in 1‐mm mesh fiber‐glass excluding macrodetritivores) and unprotected wood samples from each location were retrieved, brushed clean, oven‐dried, and weighed. After 12 months, mean percentage mass loss was four times higher for unprotected than protected wood samples across all species located on mound sites (when decomposition in shaded and open microhabitats was combined). Mean percentage mass loss across all species combined was 1.2 times higher on active than inactive mounds. Across all mounds, decomposition was on average 1.1 times more rapid in the shaded than open mound parts. These differences were more pronounced on inactive mounds (1.3 times more rapid in the shaded than open parts). Percentage mass loss was markedly lower off‐mound (12.6 ± 0.8%) than on active (25.9 ± 1.5%) or inactive mounds (19.7 ± 1.2%). Proportional mass loss for unprotected wood decreased with increasing wood density, but proportional mass loss of protected wood samples was not detectably influenced by wood density. Our study highlights the strong and locally contingent influence of termite mounds, termite activity, vegetation, and their interactions on wood decomposition rates within a savanna landscape. Furthermore, variation in per‐species wood decomposition rates, including the negative correlation with wood density, depends on accessibility to macrodetritivores.

The Impact of Bromine- and Phosphorous-Based Flame Retardants on Flame Stability and Heat Feedback from Laminar Wall Flames

Flame retardants are widely used to improve the resistance and response of combustible materials to fire. Unfortunately, widespread bioaccumulation of brominated flame retardants has evoked growing concern with regards to the environmental hazards that flame retardants pose, thus industry is moving towards developing safer and equally effective alternatives. To develop new, efficient flame retardants, it is critical to understand the exact mechanisms by which they inhibit flaming combustion. Our research group has developed a systematic methodology to assess the flammability of polymeric materials through microscale combustion calorimetry (MCC) and experimental measurement of flame heat feedback and material burning behavior during upward flame spread. In this work, that experimental framework is used to quantify the mechanisms of action of bromine- and phosphorous-based flame retardants. Here, a series of experiments was conducted in which flame heat transfer and sample mass loss rate were measured as a flame spread over 7 cm tall, 5 cm wide glass-reinforced poly(butylene terephthalate) (PBT) samples manufactured with increasing amounts (12, 16, and 24 wt %) of the brominated flame retardant, poly(pentabromobenzyl acrylate). In an additional series of tests, similar measurements were obtained for PBT samples manufactured with increasing amounts (8, 12, 16, and 20 wt %) of the phosphorous-based flame retardant, aluminum diethyl-phosphinate (trade name: Exolit OP 1230). These tests allow for the study of the impact of flame retardants on key features of the system including: peak flame heat flux, flame stability, and condensed phase decomposition behaviors (i.e. charring). Current measurements identify an optimal loading concentration of Exolit OP 1230 for the PBT samples tested in this work, identify each flame retardant’s impacts on char yield and heat of combustion, and indicate that bromine- and phosphorous-based flame retardants (at least at the concentrations tested here) do not affect flame to surface heat transfer in the continuous region of wall flames and do not have a significant effect on flame stability at ignition. These measurements allow for greater understanding of tightly coupled condensed- and gas-phase processes that control flame spread and material burning behavior, thus providing a quantitative connection between material composition and the controlling mechanisms of fire growth.

Erosion-Resistant Enhancement of Anti-oxidation Coatings in Hypersonic Flows of Air Plasma

The problems of creating aircraft are connected to the development of new heat-resistant thermal materials. The paper analyses the possible increase in durability of heat-resistant coatings to erosion in hypersonic streams of air plasma. To achieve this goal, granulation of obtained powders was studied on Fritsch Analysette 22 Micro Tec Plus using the laser diffraction method. The study was conducted using powders of technical silicon KR00, titanium PTOM-1, molybdenum PM 99.95, amorphous boron B-99A, yttrium metal ITM-1. It is established that the absence of films based on amorphous silica leads to an increase in catalyticity of coatings surface in regard to reactions of heterogeneous recombination of dissociated and partially ionized air and consequently to additional heating of the surface. The authors defined rational levels of SiCw in coatings of the Si–TiSi $$_2$$ –MoSi $$_2$$ –B–Y–SiCw system—up to 15 mass%. In the course of the experiment, there was a decline in the average level of erosion and decrease in deviations from the mean mass loss of samples with coatings, modified by SiCw whisker, compared to basic coatings of respective compositions.

Investigation of the films based on the uronate polysaccharides by the method of differential scanning calorimetry

In this paper, the problem of studying of the films properties on the basis of uronate polysaccharides (sodium alginate and pectin low-esterified amidated), created on the principle of ionotropic gelation with the participation of calcium ions, has being considered. The purpose of the study is to determine the patterns of films formation based on the composition of the uronate polysaccharides, to determine their properties when heated and conditions of destruction or combustion. The thermophysical properties of the films in the temperature range 20–500°C were controlled by the method of differential scanning calorimetry in the dynamic mode. The temperature at which the loss of external and internal moisture is occurring have been determined. The temperatures when films are subjected to destruction have been founded. Thus, the mass loss of samples was noted in the following temperature ranges: 52–100°С and 40–100°С; the maximum moisture loss was noted at 83 and 85°C for specimens with a total concentration of uronate polysaccharides 2% and 3% respectively. Maximum external moisture losses were 6% and 9%; intra-linked moisture – 28.5 and 29% respectively. Complete disintegration of polymers occurs after 300 and 310°C for specimens with a total concentration of uronate polysaccharides 2% and 3% respectively. The investigation of the destraction temperatures of the above systems allows us to predict the principle of heat treatment of semi-finished products contained in films, created on the basis of the reaction of ionotropic gelation of polysaccharides and calcium ions.

Edible film-forming coating with CO2-extracts of plants for meat products

In this work, a film-forming coating for natural semi-finished pork meat has been developed, which has barrier properties against microbial flora and free oxygen radicals. Polysaccharides such as agar, gelatin, cornstarch, and citrus pectin were used as components of a film-forming coating, as well as CO2-extracts of parsley and ginger. It has been found that the most effective is a coating with the following composition: agar – 0.25%, citrus pectin – 0.5%, citric acid – 0.5%, CO2-extract of parsley or CO2-extract of ginger – 0.1%. This coating prolongs the shelf life of natural semi-finished pork meat at a storage temperature (–1…+1)°С for 2 days compared with the traditional technology.Studying the effect of the film-forming coating developed on the organoleptic properties of meat has shown that on the 7th day of storage at a temperature (–1…+1)°С, there were no signs of spoilage like putrid smell, greenish stain, and sliminess that were observed in the samples without coating. The study of the effect of the coating on the microbiological parameters of the meat has shown that the best microbiologcal stability that does not exceed the allowable values after 7 days of storage at a storage temperature (–1…+1)°C is that of the sample covered with the film-forming coating with a CO2-extract of parsley. The study of the effect of the film-forming coating on the physical and chemical properties of meat has shown that peroxide number of its fat content is lower by 0.007% of iodine, and the acid number of its fat content is 0.39 mg KOH/kg of fat lower compared to the values of these parameters in the meat samples without coating. Besides, during storage, the mass loss in the meat samples covered with the coating developed was about 6 % less, thus reducing drying loss.

Surface Contaminants on Ni-Rich Cathode Active Materials: Influence of the Storage Conditions

Ni-rich cathode materials like NCM811 (Li1+x(Ni0.8Co0.1Mn0.1)1-xO2) are promising candidates for reaching the energy density targets of Li-Ion batteries for automotive applications [1]. However, these materials show a rapid performance decrease when stored under ambient conditions [2]. The performance decrease is often related to the formation of surface impurities containing M-CO3 and M-OH groups on the surface of the cathode active material [2, 3, 4]. In this work, we investigate the influence of different storage parameters on the formation of surface contaminants on Ni-rich cathode materials using TGA-MS and XPS. First, we store the cathode material (NCM622) under the following conditions: (i) pristine, meaning the material as-received and stored in an argon-filled glovebox; (ii) wet, which is stored 7 days under air at a relative humidity of ~85%; and, (iii) wet without O2 at a relative humidity of ~85%. The last storage condition is realized by working under argon atmosphere. Afterwards, TGA-MS analysis with a novel analysis protocol is performed in order to deconvolute the release of physisorbed water from the evolution of water and CO2 produced by the thermal decomposition of mixed transition metal hydroxides and carbonates, predominantly NiCO3 • x Ni(OH)2 • y H2O on the surface of the cathode material. The protocol contains a temperature hold phase at 25 °C, then a heat ramp (10K/min) to 120 °C with a hold at this temperature for 30 minutes, followed by a second temperature ramp to 450 °C and a final hold at this temperature (see panel 1, Figure 1). In Figure 1 (panel 2), the weight loss of the NCM samples is shown. When the samples are stored for 7 days at an RH of 85%, the surface contaminants, especially Ni hydroxide species, decompose when going to 450°C, accompanied by the release of H2O (m/z = 18 from coupled MS shown in panel 3, Figure 1). The weight loss equals to 1.2 wt.%. When the pristine as-received sample is analyzed, only a very small amount of surface contaminants (< 0.1 wt.%) is present. Surprisingly, when the material is stored under an argon atmosphere which is saturated with H2O, no Ni hydroxide species do form on the surface of the cathode material, as there is nearly no weight loss when going from 120 to 450 °C. This is confirmed by the MS analysis where no water is detected. In our contribution we will compare the extent of surface contaminants formation as a function of Ni-content (NCM111, NCM622, and NCM811). Furthermore, we investigate the effect of the presence and absence of CO2 on the formation of surface contaminants. We will support our measurements by XPS and FTIR measurements in order to detect eventually formed LiOH and Li2CO3 on the surface of the cathode active materials. Figure 1: TGA-MS analysis of NCM622 samples stored (i) in a glovebox under argon atmosphere, (ii) stored under air at RH~85%, and, (iii) stored in a water-saturated argon atmosphere. Panel 1 shows the TGA profile, panel 2 shows the mass loss of the different samples, and in panel 3 the mass traces of H2O (m/z = 18) are plotted.

Inhibition of fungi with wood extractives and natural durability of five Cameroonian wood species

The natural durability of five Cameroonians wood samples was evaluated using the European standard EN 350-1 with a slight modification. The capacity of extracts to inhibit the fungal growth was evaluated at different concentrations with propiconazole (a commercial fungicide for wood) as standard. Scanning Electron Microscopy (SEM) of wood blocks was carried out before and after extraction in different solvents. Unextracted and extracted wood blocks were exposed to fungal attack, with beech as a reference wood. Results showed that mass losses of non-extracted samples ranged from 0.1 to 59% and those of extracted samples from 3% to 40%. Before extraction, all wood samples under study were classified as very resistant to fungi attack (class 1) with respect to the standard. After extraction, some of the wood samples became vulnerable to fungal attack. Movingui, padouk, and tali became less resistant to fungi attack (class 3). The SEM of wood revealed that the extractives were removed from the fibres. The effect of extractives on fungal growth showed that extracts weakly inhibited fungal growth up to concentrations of 250 μg/mL but extracts of tali and movingui totally inhibited fungal growth at a concentration of 500 μg/mL.

Quantitative Analysis of Poly(ethylene terephthalate) Microplastics in Soil via Thermogravimetry–Mass Spectrometry

The use of plastic materials in daily life, industry, and agriculture can cause soil pollution with plastic fragments down to the micrometer scale, i.e., microplastics. Quantitative assessment of microplastics in soil has been limited so far. Until now, microplastic analyses in soil require laborious sample cleanup and are mostly restricted to qualitative assessments. In this study, we applied thermogravimetry-mass spectrometry (TGA-MS) to develop a method for the direct quantitative analysis of poly(ethylene terephthalate) (PET) without further sample pretreatment. For this, soil samples containing 1.61 ± 0.15 wt % organic matter were spiked with 0.23-4.59 wt % PET bottle recyclate microplastics. dl-Cysteine was used as the internal standard (IS). Sample mixtures were pyrolyzed with a 5 K min-1 ramp (40-1000 °C), while sample mass loss and MS signal intensity of typical PET pyrolysis products were recorded. We found MS signal intensities linearly responding to microplastic concentrations. The most-promising results were obtained with the IS-corrected PET pyrolysis product vinylbenzene/benzoic acid ( m/ z = 105, adj. R2 = 0.987). The limits of detection and quantification were 0.07 and 1.72 wt % PET, respectively. Our results suggest that TGA-MS can be an easy and viable complement to existing methods such as pyrolysis or thermogravimetry-thermal desorption assays followed by gas chromatography/mass spectrometry detection or to spectral microscopy techniques.

Experimental Study on Wear Behaviors of TBM Disc Cutter Ring in Hard Rock Conditions

ABSTRACTTo improve the wear resistance of disc cutters for tunnel boring machines (TBMs), this study is devoted to investigating the effects of rocks and cutter ring properties on the wear behaviors of disc cutters and the matching characteristics between the cutter ring properties and hard rocks. Cutter–rock wear tests were performed and the results show that the cutter ring properties and rock types significantly affect the cutter ring wear. The mass losses of cutter ring samples sliding against different types of hard rock are different and vary with the cutter ring properties because of the discrepancies in loads, vibrations, rock properties, and transition of the wear mechanisms. Finally, matching characteristics between the cutter ring properties and hard rocks are revealed.

Termiticidal activity of chitosan against the subterranean termites Reticulitermes flavipes and Reticulitermes virginicus.

Chitosan is a derivative form of chitin, which is the major component of exoskeletons of arthropods and the cell walls of fungi. The antimicrobial activity of chitosan against lepidopterans, aphids, fungi and bacteria has been extensively investigated, but only one report on the termiticidal effect of chitosan on termites has been published. In this study, we examined the termiticidal activity of chitosan by exposing single colonies of Reticulitermes flavipes (Kollar) and Reticulitermes virginicus Banks to wood treated with six different concentrations of chitosan solutions. Termite mortality and percent mass loss of wood samples after exposure to termites for 4 weeks were calculated. High termite mortality (≥ 94%) occurred during exposure of R. flavipes termites to chitosan-treated wood with ≥38 mg g-1 treatment concentrations (≥ 2% chitosan), while <50% termite mortality was observed at lower treatment concentrations (11-15 mg g-1 ; 0.5% and 1% chitosan). For R. virginicus, 100% mortality was observed at all levels of treatment concentrations. A decrease in the percent mass loss of the wood sample was apparent in samples treated with solutions with an increasing chitosan concentration, with a significant difference (P < 0.05) between lower and higher treatment concentrations. Treatment retention in wood samples upon leaching was also determined and showed retention levels of between 0 and 30 mg g-1 chitosan retention. This study investigated the exposure of subterranean termites to chitosan as a wood preservative. The results show that chitosan treatments at sufficiently high loadings could protect wood against termites, preferably under non-leaching conditions. © 2018 Society of Chemical Industry.