Screening of Microorganisms for Biodegradation of Simazine Pollution (Obsolete Pesticide Azotop 50 WP)

The capability of environmental microorganisms to biodegrade simazine—an active substance of 2-chloro-s-triazine herbicides (pesticide waste since 2007)—was assessed. An enormous metabolic potential of microorganisms impels to explore the possibilities of using them as an alternative way for thermal and chemical methods of utilization. First, the biotope rich in microorganisms resistant to simazine was examined. Only the higher dose of simazine (100 mg/l) had an actual influence on quantity of bacteria and environmental fungi incubated on substrate with simazine. Most simazine-resistant bacteria populated activated sludge and biohumus (vermicompost); the biggest strain of resistant fungi was found in floral soil and risosphere soil of maize. Compost and biohumus were the sources of microorganisms which biodegraded simazine, though either of them was the dominant considering the quantity of simazine-resistant microorganisms. In both cases of periodic culture (microorganisms from biohumus and compost), nearly 100% of simazine (50 mg/l) was degraded (within 8 days). After the repeated enrichment culture with simazine, the rate of its degradation highly accelerated, and just after 24 h, the significant decrease of simazine (20% in compost and 80% in biohumus) was noted. Although a dozen attempts of isolating various strains responsible for biodegradation of simazine from compost and biohumus were performed, only the strain identified as Arthrobacter urefaciens (NC) was obtained, and it biodegraded simazine with almost 100% efficiency (within 4 days)

Current-Voltage Characteristics of the Composites Based on Epoxy Resin and Carbon Nanotubes

Polymer composites based on epoxy resin were prepared. Multiwalled carbon nanotubes synthesized on iron-cobalt catalyst were applied as a filler in a polymer matrix. Chlorine or hydroxyl groups were incorporated on the carbon nanotubes surface via chlorination or chlorination followed by hydroxylation. The effect of functionalized carbon nanotubes on the epoxy resin matrix is discussed in terms of the state of CNTs dispersion in composites as well as electrical properties. For the obtained materials current-voltage characteristics were determined. They had a nonlinear character and were well described by an exponential-type equation. For all the obtained materials the percolation threshold occurred at a concentration of about 1 wt%. At a higher filler concentration >2 wt%, better conductivity was demonstrated by polymer composites with raw carbon nanotubes. At a lower filler concentration <2 wt%, higher values of electrical conductivity were obtained for polymer composites with modified carbon nanotubes

Equilibrium of Trichloroethylene Adsorption from Aqueous Solution onto Activated Carbons

The adsorption of trichloroethylene from aqueous solutions onto three activated carbons (DTO, AG5, WD-ekstra) was studied. Adsorption isotherms within the temperature range 298–343 K could be described by the Freundlich and Dubinin–Astakhov equations. The characteristic curves for the adsorption processes were determined. It was found out that the temperature dependence of the adsorption equilibrium was well described by the Dubinin–Astakhov model. The isosteric enthalpy of the adsorption was determined. The Do model and combinations of the van't Hoff and Dubinin–Astakhov equations in the form of a logarithmic equation were used to describe the dependence of the adsorption isosteric enthalpy on the degree of filling

Different Approaches to Oxygen Functionalization of Multi-Walled Carbon Nanotubes and Their Effect on Mechanical and Thermal Properties of Polyamide 12 Based Composites

In this work the preparation of polyamide 12 (PA12) based composites reinforced with pristine and surface-modified carbon nanotubes is reported. A qualitative and quantitative evaluation of multi-walled carbon nanotube functionalization with oxygen containing reactive groups achieved by different procedures of chemical treatment is presented. Simple strong oxidative acid treatment as well as chlorination with subsequent chloroacetic acid treatment were applied. Carbon nanotubes (CNTs) were also subjected to chlorine and ammonia in gaseous atmosphere with small differences in after-ammonia treatment. Commercial COOH-functionalized carbon nanotubes were compared with nanotubes that were laboratory modified. The effect of CNT functionalization was evaluated basing on the improvement of mechanical and thermal properties of polyamide 12 composites prepared by in situ polymerization. It was found that high concentration of oxygen-containing functional groups on nanotube surface is not sufficient to improve the composite performance if the structure of carbon nanotubes is defective. Indeed, the best effects were achieved for composites containing nanotubes modified under mild conditions, seemingly due to a compromise between morphology and surface chemical structure

Adsorption of 1,2-Dichlorobenzene from the Aqueous Phase onto Activated Carbons and Modified Carbon Nanotubes

This study aimed to describe the adsorption process of ortho-dichlorobenzene (o-DCB) onto activated carbons (ACs) and modified carbon nanotubes (CNTs) from the aqueous phase. The starting material NC_7000 carbon nanotubes were modified by chlorination (NC_C) and then by the introduction of hydroxyl groups (NC_C_B). The concentration of o-DCB in solutions was performed by UV-VIS spectrophotometry. After adsorption, the activated carbons were regenerated by extraction with organic solvents such as acetone, methanol, ethanol, and 1-propanol; the carbon nanotubes were regenerated by methanol. The degree of adsorbate recovery was determined by gas chromatography (GC) with flame ionization detection, using ethylbenzene as an internal standard. The equilibrium isotherm data of adsorption were satisfactorily fitted by the Langmuir equations. The results indicate that carbon adsorbents are effective porous materials for removing o-DCB from the aqueous phase. Additionally, activated carbons are more regenerative adsorbents than carbon nanotubes. The recoveries of o-DCB from ACs were in the range of 76–85%, whereas the recoveries from CNTs were in the range of 23–46%. Modifications of CNTs affect the improvement of their adsorption properties towards o-DCB compared to unmodified CNTs. However, the introduction of new functional groups on carbon nanotube surfaces makes the regeneration process less effective

Chlorination of Carbon Nanotubes Obtained on the Different Metal Catalysts

In this paper, a chlorination method is proposed for simultaneous purification and functionalization of carbon nanotubes, thus increasing their ability to use. Carbon nanotubes were obtained by CVD method through ethylene decomposition on the nanocrystalline iron or cobalt or bimetallic iron-cobalt catalysts. The effects of temperature (50, 250, and 450°C) in the case of carbon nanotubes obtained on the Fe-Co catalyst and type of catalyst (Fe, Co, Fe/Co) on the effectiveness of the treatment and functionalization were tested. The phase composition of the samples was determined using the X-ray diffraction method. The quantitative analysis of metal impurity content was validated by means of the thermogravimetric analysis. Using X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive Spectroscopy (EDS) analysis, and also Mohr titration method, the presence of chlorine species on the surface of chlorinated samples was confirmed

Synergistic and antagonistic effects between biosurfactants from the group of soforolipids and alkylopolyglikosides of various alkyl chain lenghts and their use in the design of cleaning agents for the food industry

The paper presents the results of testing the performance parameters of mixtures of biosurfactants from the group of sophorolipids and alkylpolyglycosides with different alkyl chain lengths. In order to determine the synergistic and antagonistic effects in two-component surfactant systems, research was carried out to determine the performance parameters determining their use in washing preparations, such as foam height (FH) and foam stability (FS) and wetting angle analysis (CA). The results are presented in tables 3, 4 and 5. Determination of the content of the active substance in the raw material samples was carried out using the method of refractometric determination of the refractive index. Both synergistic and antagonistic effects were found. On the basis of the obtained test results, the highest synergistic effect of performance parameters was obtained for the mixture of biosurfactants from the group of sophorolipids and the alkylpolyglycoside D-glucopyranose, oligomer, C10-16-alkylglycosides. In this case, the synergy occurred for all performance parameters FH (14%), FS (28%) and CA (46%). The synergistic effects were used to design a concentrated formulation of a cleaning agent in the food industry. The planned experiment method was used in order to obtain an optimal solution in terms of ensuring the appropriate level of cleaning efficiency. A twenty-two-point experiment plan was developed based on the Scheff model in order to optimize the composition in terms of obtaining the operational parameters of the mixture constituting the formulation's framework assumed in the optimization criteria. Optimization criteria were determined on the basis of studies of commercially available analogues. Thanks to the use of formulations of raw materials exhibiting synergistic effects in the design of the frame, the foam height and stability higher than those specified in the optimization criteria were obtained