Chemistry March 2005 Vol 54/1 []

CONTENTS & ABSTRACTS

InEnglish. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.

Chemistry



Volume 54 No. 1March 2005



Solvatochromicprobes within ionic liquids; 3–11

Mihkel Koel

Abstract. Spectroscopic studies on a set of ionic liquids were performedusing different solvato­chromic probe molecules. Different probes were found tocharacterize ionic liquids as solvents differently. Mixtures of ionic liquidswith organic solvents exhibit nonlinear behaviour of polarity with compositionas measured by Reichardt’s dyes.

Key words: ionic liquids, binary mixtures, solvatochromic shift,Reichardt’s dyes, Nile Red.

Arylationof substituted hydrazines with arylboronic acids; 12–15

Liina Raus, Olga Tšubrik, and UnoMäeorg

Abstract. Copper-mediatedarylation of di- and trisubstituted hydrazines with aryl- and hetero­arylboronicacids is described. Boronic acids were chosen because of their commercial andsynthetic availability and mild reaction conditions of the corresponding C–Ncross-coupling reactions.

Key words: N-arylation,C–N cross-coupling, arylboronic acid, hydrazine.

Oxidativedecomposition of benzoic acid in the presence of metal ionic catalysts;16–23

Rein Munter, Marina Trapido, and Yelena Veressinina

Abstract. Catalytic ozonation as one of the advanced oxidation processesgives a wide range of opportunities for the enhancement of the degradation ofresistant compounds. The efficiency of catalytic ozonation with homogeneous(containing dissolved ions of Fe2+, Mn2+, Cu2+,Ni2+, Mo6+) and heterogeneous (Fe2O3,MnO2, Ni2O3, CuO, Al2O3,MoO3, TiO2) catalysts and non-accompanied ozonation wascompared for the degradation of benzoic acid (BA). A combination of ozonationand the Fenton reagent was found to be quite effective for BA. Although aslight acceleration was followed in the catalytic ozonation of BA, asignificant improvement in the COD removal was observed. The current studyproved that catalytic ozonation may be efficient for the degradation ofresistant compounds but the performance of catalysts in ozonation is quitesensitive towards treatment conditions and the compound.

Key words: catalytic ozonation, benzoic acid (BA), Fenton treatment,homogeneous catalysts, heterogeneous catalysts.

Interactionof metal cations with different humic substances from sea and lake sediments;24–34

Monika Übner, Maili Treumann, AnuViitak, and Margus Lopp

Abstract. Specific precipitation of metals (Zn2+, Mg2+,Mn2+, Pb2+, Cu2+) with different humicsubstances (humic, fulvic, and hymatomelanic acids) was studied. Zn2+was selected as a model cation. From the humic substances sea humic acid wasthe best precipitating fraction in the whole pH range with Zn2+. AtpH 7 both sea and lake humic acid gave the same metal/acid precipitationorder: Pb2+ > Cu2+ > Zn2+ >Mn2+ > Mg2+. Humic acid (as a gel) from bothsediments showed the best adsorption for heavy metals.

Key words: fulvic acid, heavy metals, humic acid, humic substances,hymatomelanic acid, lake sediment, sea sediment, stability constant.

Characteristics and natural attenuation of the Pääskülalandfill leachate; 35–44

Aare Selberg, Malle Viik, Kai Peet, andToomas Tenno

Abstract. Theleachate composition can vary throughout a landfill, and leachate productiondecreases with placement of the final cover. Anaerobic decomposition, which canproduce a leachate with high concentrations of biogenous pollutants, occurs inthe covered landfill. Pääsküla landfill (Tallinn, Estonia) was built as atemporal landfill on peat deposits in
1974. In June 2003 the landfill wasclosed and covered but the leachate will filter over many years. In March 2004the leachate contained 62.6 mg/L total nitrogen (Ntot),6.9 mg/L total phosphorus (Ptot), 668 mg O2/LCOD, and 160 mg O2/L BOD7. In the leachate 91% of the nitrogen wasdetermined as ammonia. In March 2004 the content of pollutants was higher thanthe corresponding values analysed in 1971 and
1993. It is connected withmethane production in the closed landfill. The effluent enters the Vääna Riverthrough the Pääsküla River and in the sampling place of the Vääna River thevalues of pollutants were 2.4 mg/L Ntot, 0.05 mg/L Ptot,26 mg O2/L COD, and 1.7 mg O2/L BOD7.The concentrations of pollutants had decreased as a result of dilution in therivers but it is an insufficient antipollution measure.

Key words: landfill, leachate, natural attenuation,dilution, anaerobic decomposition.

Thermochemicalliquefaction of reed; 45–56

Rein Veski, Vilja Palu, Hans Luik, and Kristjan Kruusement

Abstract. The current paper gives a survey about the use of reed biomassand reed peat for the production of liquid fuels and experimental data on thethermochemical liquefaction (semicoking at up to 520 °C,water conversion, and catalytic hydrogenation at 380 °C)of reed (Phragmites australis or P. communis). Reed is a new sourceof energy, for the burning of which experience is already evolving in Estonia.Liquefaction conditions have a great influence on the yield of products. In ourstudy the highest yields of oil and oil plus coke (oil 25.7%, coke 28.5%) wereobtained by using the Fischer retort. The yield of oil fractions washedsuccessively out from pyrolytic water (in some cases also coke and catalyst)containing the reaction mixture with water (further divided to ether solublesand insolubles of water soluble oil), and benzene and acetone (water insolubleoil) as well as total oil decreases in the order: semicoking ® water conversion ® catalytic hydrogenation (except acetone solubles). The sharpestdecrease was observed in the water soluble oil: from 15.1% to 0.7%. At the sametime the proportion of the most desirable benzene solubles in total oilincreased from 28.4% in the case of semicoking to 50.1% in the case ofhydrogenation, which was accompanied with an increase in the carbon content inbenzene solubles from 71.5% to 83.0%.

Key words: reed, Phragmites australis,thermochemical liquefaction, liquid fuels.

Abbreviations: A = acetone solubles of water insoluble oil,B = benzene solubles of water insoluble oil, E = ethersolubles of water soluble oil, W = ether insolubles of water solubleoil, OM = organic matter.