Electron Donor Interactions Research Articles

Efficient Rhodamine B dye uptake onto MgZrO3@g-C3N4 nanostructures: Fabrication and adsorption mechanism

Pristine graphitic carbon nitride (g-C3N4) was synthesized by calcination of urea under elevated temperature. A blend of g-C3N4 nanosheets and nanosized ZrO2 and MgO precursors were used to prepare MgZrO3@g-C3N4 hybrid nanocomposite (MZCN) then it was assessed for the adsorption of Rhodamine B (RhB) dye from aqueous solution. The X-ray diffraction analysis revealed the development of the monoclinic ZrO2, cubic MgO, and hexagonal graphitic carbon nitride phases. The energy diffraction X-rays (EDX), photoelectron electron, and Fourier transformed infrared (FT-IR) spectroscopy analyses collectively validated the formation of the presumed composite. An improved porosity with a surface area 35.86 m2.g−1 and pore volume 0.087 cm3.g−1 were determined by N2 adsorption setup. The adsorption kinetics fitted well with the pseudo-first-order model (R2 > 0.99), which designated an adsorption process influenced by physisorption. The kinetics models investigations revealed a film diffusion control of the adsorption process. The adsorption equilibrium matched perfectly with the Langmuir isotherm model (R2 > 0.99) marking a maximum adsorption capacity of 370.8 mg g−1, demonstrating outstanding monolayer adsorption process. In addition, the Freundlich constant (n = 1.76) value is falling in the range 1–10 suggested a favorable adsorption of RhB onto the composite surface. The mechanistic enquiry suggested van der Waal, hydrogen bonds and π–π electron–donor interactions between the electron-rich RhB and the functional groups in the adsorbent’s molecule. This work stipulates that MgZrO3@g-C3N4 holds promise as efficient adsorbent for organic dyes from contaminated wastewater.

PCDD/F adsorption enhancement over nitrogen-doped biochar: A DFT-D study

Polychlorinated dibenzo-p-dioxin/furans (PCDD/F) have a great threat to the environment and human health, resulting in controlling PCDD/F emissions to regulation far important for emission source. Considering 2,3,4,7,8-pentachlorodibenzo-p-furan (PeCDF) identified as the most contributor to international toxic equivalent, 2,3,4,7,8-PeCDF can be considered as the target molecule for the adsorption of PCDD/F emission from industries. With the aim to in-depth elucidate how different types of nitrogen (N) species enhance 2,3,4,7,8-PeCDF on the biochar and guide the specific carbon materials design for industries, systematic computational investigations by density functional theory calculations were conducted. The results indicate pristine biochar intrinsically interacts with 2,3,4,7,8-PeCDF by π-π electron donor and acceptor (EDA) interaction, six-membered carbon rings of PeCDF parallel to the biochar surface as the strongest adsorption configuration. Moreover, by comparison of adsorption energy (−150.16 kJ mol−1) and interaction distance (3.593 Å) of pristine biochar, environment friendly N doping can enhance the adsorption of 2,3,4,7,8-PeCDF on biochar. Compared with graphitic N doping and pyridinic N doping, pyrrolic N doping biochar presents the strongest interaction toward 2,3,4,7,8-PeCDF molecule due to the highest adsorption energy (−155.56 kJ mol−1) and shortest interaction distance (3.532 Å). Specially, the enhancing adsorption of PeCDF over N doped biochar attributes to the enhancing π-π electron EDA interaction and electrostatic interaction. In addition, the effect of N doping species on PeCDF adsorbed on the biochar is more than that of N doping content. Specially, the adsorption capacity of N doping biochar for PCDD/F can be improved by adding pyrrolic N group most efficiently. Furthermore, pyrrolic N and pyridinic N doping result in the entropy increase, and electrons transform from pyrrolic N and pyridinic N doped biochar to 2,3,4,7,8-PeCDF molecule. A complete understanding of the research would supply crucial information for applying N-doped biochar to effectively remove PCDD/F for industries.

Chemically reduced graphene oxide based aerogels - Insight on the surface and textural functionalities dependent on handling the synthesis factors

Efficient adjusting of reduced graphene oxide aerogels properties requires information about experimental factor-aerogel property relationship. In this work, the reduced graphene oxide aerogels surface and textural functionalities in relation to precursor concentration, gelation time and hydrogel freezing temperature were studied in detail, with the use of dynamic adsorption method of gaseous organic probes and experimental design. The precursor concentration and the hydrogel freezing temperature have the strongest influence on textural properties - a negative correlation with apparent surface area was observed. The highest value of 229.36 m2 g−1 was obtained for samples synthesized at the lowest concentration of precursor (2 mg mL−1) and hydrogel freezing temperature (−196 °C). Low precursor concentration promote formation of more hydrophobic aerogels. All aerogels display tendencies for dispersive, dipole-type and electron donor interactions. Moreover, a repulsion of electron lone pairs was observed, as well as shape-based selectivity (originating from porosity and surface roughness) in gas-solid adsorption process. Analysis of the free surface energy revealed that the maximum value (193.21 mJ m−2) is obtained at 7.2 mg mL−1 precursor concentration, − 104 °C hydrogel freezing temperature and 23 h gelation time. Presented findings can translate directly into reduced graphene oxide aerogels tailored for specific applications such as adsorption or catalysis.

Band structure of a nonparabolic two-dimensional electron gas system

Using angle-resolved photoelectron spectroscopy (ARPES), we study the band structures of two-dimensional electron gases (2DEGs) formed at Te-doped surfaces of InAs(110), as a result of band bending. The selected surface system is very clean and stable; therefore, ARPES spectra may be registered in short times, with minimal adsorption of residual gases and no photon beam-induced damage. We record a set of data that allows for a detailed analysis of the 2DEG band shapes, their thermal dependencies, and for an assessment of the many-body interactions. We find the electron-phonon interaction extremally weak and the electron-electron interactions hidden in dominant electron-donor interactions. While 2DEG band shapes are observed to be variable in correlation with the 2DEG density, this is tracked down to the variability of the band-bending potential and nonparabolicity of the system, and not to the many-body interactions. Thus, many-body renormalization of the 2DEG bands is not required, and the bands are described well by using the one-electron theoretical frame.

Facile route for synthesis of Fe0/Fe3C/γ-Fe2O3 carbon composite using hydrothermal carbonization of sugarcane bagasse and its use as effective adsorbent for sulfamethoxazole removal

Non-toxic mesoporous magnetic carbon composite was synthesised from hydrothermal carbonization of sugarcane bagasse with Iron (III) nitrate nonahydrate in two steps along with thermo-chemical oxidation process using sodium hydroxide. IR spectrum exposed the presence of oxygenated functional groups and FeO whereas XRD analysis revealed the availability of Fe0/Fe3C/γ-Fe2O3 at varying intensities. SEM analysis showed the spherical shaped carbon is well encapsulated with iron particles. Textural studies showed that after thermo-chemical activation intensified the surface area on composites to about 491.474 m2 g−1 thereby, promoting improved porosity on the carbon matrix. The fabricated composite showed magnetization of 32.84 emu g−1 and SMX adsorption capacity as 169.49 mg g−1. Kinetics and isotherm studies revealed that removal of SMX fitted well in Pseudo-second order and Langmuir models. The mode of interaction of SMX on magnetic carbon composites with respect to different pH was studied showing that π-π electron donor interaction (EDA), hydrophobic interaction, charge assisted hydrogen bond formation were responsible for SMX removal. The selectivity nature of magnetic composite with respect to SMX was studied in the presence of multiple pollutant. Use of magnetic carbon helps in industrialising the material to high level due to their unique property in separation and recycling. Application of hydrothermal carbonization is found to be applicable for wet solid substance thereby evolving structural carbon compound.

COMPARISON OF STINGING NETTLE ADSORPTION PERFORMANCE TOWARDS ANIONIC AND CATIONIC DYES

Stinging nettle was used as lignocellulosic adsorbent for the removal of cationic dye – malachite green (MG), and anionic dye – Congo red (CR), from aqueous solution, without any chemical pretreatment. The adsorption equilibrium data fitted well with the Langmuir model for the adsorption of both dyes, with the calculated maximum adsorption capacity of 270.27 mgg-1 and 172.14 mgg-1 for MG and CR, respectively. The adsorption process was controlled by the pseudo-second-order model in the adsorption of MG and by the pseudo-first-order model in the adsorption of CR. The thermodynamics modelling displayed that the process was spontaneous and endothermic. The π–π electron–donor interaction, hydrogen bonds and pore diffusion may also be effective, besides electrostatic interaction between the adsorbate and the adsorbent in the mechanism of MG and CR uptake.

Corrosion Inhibition of Mild Steel and 304 Stainless Steel in 1 M Hydrochloric Acid Solution by Tea Tree Extract and Its Main Constituents.

Tea tree extract, containing antioxidant constituents α-terpineol, terpinen-4-ol, and α-terpinene, has a wide range of applications in the cosmetic, food, and pharmaceutical industries. In this study, tea tree extract showed an anticorrosive effect under 1 M HCl solution on mild steel (MS) and 304 stainless steel (STS). Uniform corrosion for MS and pitting corrosion for STS at 298 K were retarded, with inhibition efficiencies of 77% and 86%, respectively. The inhibition of uniform and pitting corrosion was confirmed by scanning electron microscopy and laser scanning confocal microscopy in terms of surface roughness and pitting morphologies. The most effective constituent contributing to the inhibitory performance of tea tree extract was revealed to be α-terpineol, with an inhibition efficiency of 83%. The adsorption of tea tree extract was confirmed by surface characterization analysis using Fourier transform infrared spectroscopy, Raman spectroscopy, and Electrochemical impedance spectroscopy. Interestingly, G- and D-peaks of Raman spectra were detected from the inhibited steels, and this finding is the first example in the corrosion inhibition field. The anticorrosion mechanism can be explained by the formation of organic-Fe complexes on the corroded steel surface via electron donor and acceptor interactions in the presence of an oxygen atom of the hydroxyl group or ether of organic inhibitors.

Measuring Surface Energies of GaAs (100) and Si (100) by Three Liquid Contact Angle Analysis (3LCAA) for Heterogeneous Nano-BondingTM

ABSTRACTAnalysis of the total surface energy γTand its three components as established by the van Oss-Chaudhury-Good Theory (vOCG) is conducted via Three Liquid Contact Angle Analysis (3LCAA). γTis correlated with the composition of the top monolayers (ML) obtained from High-Resolution Ion Beam Analysis (HR-IBA). Control of γTenables surface engineering for wafer bonding (Nano-BondingTM) and/or epitaxial growth. Native oxides on boron-doped p-Si(100) are found to average γTof 53 ± 1.4 mJ/m2) and are always hydrophilic. An HF in methanol or aqueous HF etch for 60 s always renders Si(100) hydrophobic. Its γTdecreases by 20% to 44 ± 3 mJ/m2in HF in methanol etch and by 10% to 48 ± 3 mJ/m2in aqueous HF. On the contrary, GaAs(100) native oxides are found to always be hydrophobic. Tellurium n+-doped GaAs(100) yields an average of γTof 37 ± 2 mJ/m2, 96% of which is due to the Lifshitz-Van der Waals molecular interactions (γLW= 36 ± 1 mJ/m2). However, hydrophobic GaAs(100) can be made highly hydrophilic. After etching, γTincreases by almost 50% to 66 ± 1.4 mJ/m2. 3LCAA shows that the γTincrease is due to electron acceptor and donor interactions, while the Lifshitz-van der Waals energy γLWremains constant. IBA combining the 3.039 ± 0.01 MeV oxygen nuclear resonance with <111> channeling, shows that oxygen on Si(100) decreases by 10% after aqueous HF etching, from 13.3 ± 0.3 monolayers (ML) to 11.8 ± 0.4 ML 1 hour after etch.Te-doped GaAs(100) exhibits consistent oxygen coverage of 7.2 ± 1.4 ML, decreasing by 50% after etching to a highly hydrophilic surface with 3.6 ± 0.2 oxygen ML. IBA shows that etching does not modify the GaAs surface stoichiometry to within 1% . Combining 3LCAA with HR-IBA provides a quantitative metrology to measure how GaAs and Si surfaces can be altered to a different hydroaffinity and surface termination.

RuCl3 anchored onto post-synthetic modification MIL-101(Cr)-NH2 as heterogeneous catalyst for hydrogenation of CO2 to formic acid

A series of efficient ruthenium chloride (RuCl3)-anchored MOF catalysts, such as RuCl3@MIL-101(Cr)-Sal, and RuCl3@MIL-101(Cr)-DPPB, have been successfully synthesized by post-synthetic modification (PSM) of the terminal amino of MIL-101(Cr)-NH2 with salicylaldehyde, 2-diphenylphosphinobenzaldehyde (DPPBde) and anchoring of Ru(III) ions. The stronger coordination electron donor interaction between Ru(III) ions and chelating groups in the RuCl3@MIL-101(Cr)-DPPB enhances its catalytic performance for CO2 hydrogenation to formic acid. The turnover number (TON) of formic acid was up to 831 in reaction time of 2h with dimethyl sulfoxide (DMSO) and water (H2O) as mixed solvent, trimethylamine (Et3N) as organic base, and PPh3 as electronic additive.

Determination of surface free energy components of organic liquids by the thin layer wicking method

<p><span lang="EN-US">Using the layer wicking method (TLW method) the electron-donor interactions of surface free energy of the organic liquids: benzene (C<sub>6</sub>H<sub>6</sub>), toluene C<sub>6</sub>H<sub>5</sub>CH<sub>3</sub>), and tetrahydrofuran ((CH<sub>2</sub>)<sub>4</sub>O) was determined. <span lang="EN-US">For this purpose the penetration rate measurements of these liquids in the porous layers of silica gel and alumina were performed. </span></span>The obtained values of the electron-donor parameter of surface free energy of the studied organic liquids were compared with the literature data obtained by the direct measurement of the interface tensions of water/organic liquids.</p>

Effects of inter-subband couplings on bound and extended states of terahertz cascade structures

We theoretically analyze the effect of inter-subband couplings on the eigenstates of a terahertz heterostructure in the presence of coulombic donors. We find that the inter-subband electron-donor interaction causes a drastic reorganization of the eigenenergies and a strong admixture between the subbands that decisively influences the optical absorption spectrum of the structure. These results illustrate the importance of the inter-subband couplings in the formulation of the eigenstates of imperfect terahertz heterostructures.

The influence of surface roughness and surface dynamics on the attachment of Methicillin-Resistant Staphylococcus aureus onto orthodontic retainer materials.

Staphylococci species have been isolated from removable orthodontic retainers. The aims of this study were to determine the most suitable device to analyze surface roughness of autopolymerized acrylic and thermoplastic materials and whether the surface dynamics of these materials influences the attachment of Methicillin-Resistant Staphylococcus aureus (MRSA). Clinically simulated samples of autopolymerized acrylic and thermoplastic material were first evaluated using laser non-contact, stylus mechanical profilometries and atomic force microscopy (AFM) followed by contact angle measurement to characterize their surface dynamics. Finally, an in vitro biofilm assay was carried out using a constant depth film fermentor to assess biofilm attachment. The results showed a significant difference between the roughness values obtained from the tested profilometers with the AFM exhibiting the most consistent roughness values. MRSA tended to accumulate initially within the microscopic irregularities of autopolymerized acrylic samples whereas acid-base and electron donor interactions influenced the bacterial attachment onto the thermoplastic samples.

Physicochemical properties of phospholipid model membranes hydrolyzed by phospholipase A2 (PLA2) in the presence of cholesterol at different temperatures

The physicochemical studies of the model biological membranes were undertaken to seek for correlations between the bilayer composition, the temperature 20°C and 37°C, the time of the enzymatic catalysis process, the surface free energy, as well the electron–donor interactions (the hydrogen bonding). The phospholipase A2 (PLA2) action on supported lipid bilayer and lipid vesicles was compared. The investigated liposomes and supported bilayers were composed of two phospholipids (1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine – DPPC and 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine – DOPC), which differ in hydrocarbon chains saturation, and mixed phospholipid/cholesterol systems. The results show that the changes of electron–donor parameter of the films during their hydrolysis process may be an indicator of the presence of polar products of catalysis in the membrane. Furthermore, the presence of cholesterol in phospholipid membranes and the temperature increase regulate the enzyme action what is reflected in the changes of thermodynamic parameters of the supported lipid bilayers, as well as in the size and polydispersity of the corresponding liposomes.

Changes in wetting properties of alumina surface treated with DPPC in the presence of phospholipase A2 enzyme

Wetting properties of commercial Al(2)O(3) plates contacted with dipalmitoylphosphatidylcholine (DPPC) or DPPC+enzyme (phospholipase PLA(2)) in NaCl solution were determined by thin layer wicking and with the help of Washburn equation. Van Oss et al.'s approach to interfacial free energy interactions was applied to determining the solid surface free energy components. Wicking experiments were performed both for bare and alumina plates precontacted overnight with the probe liquid saturated vapours, as well as the untreated and DPPC (or DPPC+PLA(2)) treated alumina plates. For this purpose the penetration rates of n-octane, water and formamide were measured. From these experiments it resulted that original alumina surface is strongly polar with electron-donor interactions originating from the surface hydroxyl groups. Adsorption of DPPC on Al(2)O(3) plates slightly increased the hydrophobic character of the alumina surface (considerable decrease of the electron-donor, γ(s)(-) parameter and γ(s)(AB) component was visible) in such a way that the hydrocarbon chains were directed outwards and the polar part towards the alumina surface. However, after the enzyme action the products of DPPC hydrolysis by PLA(2) (palmitic acid and lysophosphatidylcholine) increased again the hydrophilic character of Al(2)O(3) surface (a minor increase in γ(s)(AB) component and drastic increase of the electron-donor γ(s)(-) parameter was noticeable). After treatment with DPPC or DPPC+enzyme PLA(2) solution the changes of the total surface free energy of alumina and its Lifshits-van der Waals (γ(s)(LW)) component were in the range 7-10 mJ/m(2), but the most considerable and delivering more interesting information were the changes of the electron-donor (γ(s)(-)) parameter ranging from 27 to 35 mJ/m(2). Moreover, the changes of the alumina surface wettability were dependent on the time of the enzyme contacting with DPPC in NaCl solution. On the basis of the obtained results it seems that the thin layer wicking method can be an additional useful tool in investigations of the effect of phospholipid and PLA(2) action on the hydrophilic-hydrophobic character of alumina surface.

Synthesis and applications of main-chain Ru(ii) metallo-polymers containing bis-terpyridyl ligands with various benzodiazole cores for solar cells

A series of π-conjugated bis-terpyridyl ligands (M1–M3) bearing various benzodiazole cores and their corresponding main-chain Ru(II) metallo-polymers were designed and synthesized. The formation of metallo-polymers were confirmed by NMR, relative viscosity, and UV-visible titration measurements. The effects of electron donor and acceptor interactions on their thermal, optical, electrochemical, and photovoltaic properties were investigated. Due to the strong intramolecular charge transfer (ICT) interaction and metal to ligand charge transfer (MLCT) in Ru(II)-containing polymers, the absorption spectra covered a broad range of 260–750 nm with the optical band gaps of 1.77–1.63 eV. In addition, due to the broad sensitization areas of the metallo-polymers, their bulk heterojunction (BHJ) solar cell devices containing [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as an electron acceptor exhibited a high short-circuit current (Jsc). An optimum PVC device based on the blended polymer P1:PCBM = 1:1 (w/w) achieved the maximum power conversion efficiency (PCE) value up to 0.45%, with Voc = 0.61 V, Jsc = 2.18 mA cm−2, and FF = 34.1% (under AM 1.5 G 100 mW cm−2), which demonstrated a novel family of conjugated polyelectrolytes with the highest PCE value comparable with BHJ solar cells fabricated from ionic polythiophene and C60.

Surface modification of glass plates and silica particles by phospholipid adsorption

The effect of phospholipid adsorption on the hydrophobicity of glass plates and on the surface charge of silica particles using contact angle and electrophoretic mobility measurements, respectively, was investigated. Deposition of successive statistical monolayers of dipalmitoylphosphatidylcholine (DPPC) on the glass surface showed zig-zag changes of water contact angle, especially on the first few monolayers. This behavior is qualitatively coherent with the oscillations observed in zeta potential values for increasing DPPC concentration. The results indicate that the phospholipid is adsorbed vertically on the plates, exposing alternately its polar head and non-polar hydrocarbon chains in successive layers. On the other hand, experiments conducted on glass plates prior hydrophobized by contact with n-tetradecane suggest that DPPC molecules may to some extent dissolve in the relatively thick n-alkane film and then expose their polar heads over the film surface thus producing polar electron-donor interactions. The effect of both DPPC and dioleoylphosphatidylcholine (DOPC) on the electrokinetic potential of silica spheres confirms adsorption of the phospholipids, leading to a decrease in the (originally negative) zeta potential of silica and even reversal of its sign to positive at acidic pH. Hydrophobic interactions between phospholipid molecules in the medium and those already adsorbed may explain the overcharging. The adsorption of neutral phospholipids may reduce the zeta potential as a consequence of the shift of the electrokinetic or slip plane. The effect is more evident in the case of DOPC, suggesting a less efficient packing of this phospholipid because of the presence of double bonds in its molecule, which in fact is well known.

Surface and mechanical properties of some new biopolyurethane composites

Surface tension parameters and morphology of biopolyurethane composite surfaces based on natural polymers, before and after applying high frequency cold plasma treatment, have been evaluated. These surface tension parameters were calculated having on their basis the geometrical mean approach [Owens and Wendt, J Appl Polym Sci,13, 1741 (1969); Rabel Physicalische Blatter, 33, 151 (1977); and Kalble J. Adhesion, 1, 102 (1969)], acid/base method [Lifshitz-van der Waals, van Oss et al., Langmuir,4, 884 (1988)], and on the theoretical methods involving quantitative structure–properties relationships (Bicerano). For all the investigated films, the polar terms contribute significantly to the total surface tension as due to the large electron donor interactions. High frequency cold plasma alters the surface energy of composites by changing their surface polarity and hydrophilicity. Hydrophile/hydrophobe balance was studied by means of the free energy of hydration and interfacial tension between biomaterials and water. Mechanical properties of the polyurethane biocomposites were investigated in comparison with those of the porcine carotid arteries. POLYM. COMPOS., 31:1956–1964, 2010. © 2010 Society of Plastics Engineers.

Surface free energy of polypropylene and polycarbonate solidifying at different solid surfaces

Advancing and receding contact angles of water, formamide, glycerol and diiodomethane were measured on polypropylene (PP) and polycarbonate (PC) sample surfaces which solidified at Teflon, glass or stainless steel as matrix surfaces. Then from the contact angle hystereses (CAH) the apparent free energies γ s tot of the surfaces were evaluated. The original PP surface is practically nonpolar, possessing small electron donor interaction ( γ s − = 1.91 mJ/ m 2 ), as determined from the advancing contact angles of these liquids. It may result from impurities of the polymerization process. However, it increases up to 8–10 mJ/m 2 for PP surfaces contacted with the solids. The PC surfaces both original and modified show practically the same γ s − = 6.5 6.7 mJ/ m 2 . No electron acceptor interaction is found on the surfaces. The γ s tot of modified PP and PC surfaces depend on the kind of probe liquid and contacted solid surface. The modified PP γ s tot values determined from CAH of polar liquids are greater than that of original surface and they increase in the sequence: Teflon, glass, stainless steel surface, at which they solidified. No clear dependence is observed between γ s tot and dielectric constant or dipole moment of the polar probe liquids. The changes in γ s tot of the polymer surfaces are due to the polymer nature and changes in its surface structure caused by the structure and force field of the contacting solid. It has been confirmed by AFM images.

Sorption of Phenyl Urea Herbicides to Black Carbon

In this work, we developed a dialysis technique to determine black carbon (BC; diesel soot)-water distribution coefficients (K(BC)) of nine phenyl urea herbicides (PUHs). The K(BC) at 1 microg/L ranged over 2 orders of magnitude, with diuron displaying the highest log K(BC) of 4.5. The K(BC) were 20-170 times higher than corresponding estimated partitioning coefficients to organic carbon (K(OC)). This is consistent with earlier findings for more hydrophobic compounds. There was a linear increase in log K(BC) with decreasing thermodynamic difference between the geometrically optimized and planar molecule conformation (DeltaE(planar)). Hence, previous observations of enhanced BC adsorption of planar compounds (e.g., non-ortho-polychlorinated biphenyls) were confirmed also for the polar PUHs. Further, the data suggested indirectly that for molecules with several different functional groups (such as the PUHs), specific electron donor and acceptor interactions may be of more relevance for the adsorption to BC than the ability of the molecule to undergo dispersive van der Waals interactions. Sorption coefficients estimated from poly parameter linear solvation energy relationships (pp-LSER) based on data for activated carbon were 1-1.5 log units higher than the experimental data for diesel soot. This illustrates the complexity in applying models developed for one BC form to another, and calls for more data on soot-water distribution descriptors.

Surface characterization of biopolyurethanes based on cellulose derivatives

Surface tension parameters and surface morphology of biopolyurethanes based on cellulose derivatives thin films, before and after HF cold plasma treatment has been investigated. Calculations are based on the geometric mean approach of Owens and Wendt, Rabel and Kälble, on the Lifshitz-van der Waals acid/base approach of van Oss and co-workers and on the theoretical methods involving quantitative structure-property relationship. For all the investigated samples the polar component contributes significantly to the total surface tensions, as due to the large electron donor interactions. HF cold plasma treatment modifies the surface energy of biopolyurethanes by changing their surface polarity and hydrophilicity. The hydrophilic/hydrophobic balance was studied by means of the free energy of hydration between the biomaterial film and water. The protein adsorption tests of fibrinogen were effected to evaluate the applicability of these biopolyurethanes as biomedical thromboresistant devices.