A study on oxygen-plasma treatment of ink-jet paper is presented. Paper was exposed to a weakly ionized, highly dissociated oxygen plasma with an electron temperature of 5 eV, a positive-ion density of 8 × 1015 m−3 and a density of neutral oxygen atoms of 5 × 1021 m−3. Optical emission spectroscopy (OES) was applied as a method for detection of the reaction products during the plasma treatment of the paper. OES spectra between 250 and 1000 nm were measured continuously during the plasma treatment. The wettability of the samples before and after the plasma treatment was determined by measuring the contact angle of a water drop. The appearance of the surface-functional groups was determined by using high-resolution x-ray photoelectron spectroscopy (XPS), while changes in the surface morphology were monitored with scanning electron microscopy (SEM). Already after 1 s of the plasma treatment the surface, which was originally hydrophobic, changed to hydrophilic, as indicated by a high absorption rate of a water drop into the paper. The OES showed a rapid increase of the CO and OH bands for the first few seconds of the plasma treatment, followed by a slow decrease during the next 40 s. The intensity of the O atom line showed reversed behaviour. The XPS analyses showed a gradual increase of oxygen-rich functional groups on the surface, while SEM analyses did not show significant modification of the morphology during the first 10 s of the plasma treatment. The results were explained by degradation of the alkyl ketene dimer sizing agent during the first few seconds of the oxygen-plasma treatment.

GC analysis of extractive compounds in beech woodVarious highly hydrophobic beech wood lipids were characterized and their quantities measured in hexane extracts by GC, using short and long capillary columns. More polar compounds were also identified in acetone extracts. Triglycerides, steryl esters, sterols, unsaturated fatty acids, as well as various monosaccharide units were determined as possible pollutants of papermaking systems.

• The heartwood of two European larch trees was examined for the content of lipophilic extractives. Hexane was used as a solvent for extractions, while gas chromatography with fl ame ionisation detection

• The heartwood of two European larch trees was examined for the content of hydrophilic extractives. Ethanol was used as a solvent for extractions of adequately pretreated samples, while gas chromatography with fl ame ionisation detection (GC-FID), gas chromatography coupled to mass spectrometry (GC-MS SAŽETAK • U radu su prikazani rezultati istraživanja hidrofi lnih ekstraktivnih tvari u srži dvaju stabala europskog ariša. Kao otapalo za ekstrakciju prethodno adekvatno obrađenih uzoraka upotrijebljen je etanol, a za kemijske analize primijenjene su plinska kromatografi ja s plameno-ionizacijskim detektorom (GC-FID), plinska kromatografi ja povezana s masenom spektrometrijom (GC-MS) i tekućinska kromatografi ja visoke djelotvornosti (HPLC-SEC). U uzorcima su identifi cirani i kvantitativno procijenjeni različiti fenolni spojevi kao što su fl avonoidi i lignani. Taksifolin i dihidrokamferol najzastupljeniji su

Due to its chemical composition, waste sludge generated in the paper industry may be used as a raw material for brick production. Brick manufacture is limited to the warmer months of the year whereas sludge is produced continuously by different effluent treatment devices. Therefore, it has to be stored until further processing. For this reason, it is essential that it is not subject to significant chemical and microbiological decomposition during storage. In the experiment, sludge from a tissue paper mill was tested for its stability. It was stored for several weeks during winter and summer periods in a pile, 2 m in height, in an open but covered store. Different leachable organic and inorganic compounds indicating possible ongoing deterioration processes, as well as pH value, redox potential, temperature, humidity and dry matter content were evaluated weekly in water extracts of homogenized sludge samples. According to the test results, the material may be considered to be chemically and microbiologically stable as there was practically no emission of odorous and toxic compounds such as H2S, NH3 and butyric acid despite prolonged storage times and elevated environmental temperatures. All the microbial species identified in the sludge during storage belong to the typical microflora of the environment.