Filter properties of seam material from paved urban soils

International audienceDepositions of all kinds of urban dirt and dust including anthropogenic organic substances like soot change the filter properties of the seam filling material of pervious pavements and lead to the formation of a new soil substrate called seam material. In this study, the impact of the particular urban form of organic matter (OM) on the seam materials CECpot, the specific surface area (As), the surface charge density (SCD), the adsorption energies (Ea) and the adsorption of Cd and Pb were assessed. The Cd and Pb displacement through the pavement system has been simulated in order to assess the risk of soil and groundwater contamination from infiltration of rainwater in paved urban soils. As, Ea and SCD derived from water vapor adsorption isotherms, CECpot, Pb and Cd adsorption isotherms where analyzed from adsorption experiments. The seam material is characterized by a darker munsell-color and a higher Corg (12 to 48g kg-1) compared to the original seam filling. Although, the increased Corg leads to higher As (16m2g-1) and higher CECpot (0.7 to 4.8cmolckg-1), with 78cmolckg-1C its specific CECpot is low compared to OM of non-urban soils. This can be explained by a low SCD of 1.2×10-6molc m-2 and a low fraction of high adsorption energy sites which is likely caused by the non-polar character of the accumulated urban OM in the seam material. The seam material shows stronger sorption of Pb and Cd compared to the original construction sand. The retardation capacity of seam material for Pb is similar, for Cd it is much smaller compared to natural sandy soils with similar Corg concentrations. The simulated long term displacement scenarios for a street in Berlin do not indicate an acute contamination risk for Pb . For Cd the infiltration from puddles can lead to a breakthrough of Cd through the pavement system during only one decade. Although they contain contaminations itself, the accumulated forms of urban OM lead to improved filter properties of the seam material and may retard contaminations more effectively than the originally used construction sand

Conventional Study on Novel Dicationic Ionic Liquid Inclusion with β-Cyclodextrin

This study focuses on the synthesis and characterization of the inclusion complex of β-Cyclodextrin (β-CD) with dicationic ionic liquid, 3,3′-(1,4-Phenylenebis [methylene]) bis(1-methyl-1H-imidazol-3-ium) di(bromide) (PhenmimBr). The inclusion complex was prepared at room temperature utilizing conventional kneading technique. Proton (1H) NMR and 2D (1H–1H) COSY NMR were the primary characterization tools employed to verify the formation of the inclusion complex. COSY spectra showed strong correlations between protons of imidazolium and protons of β-CD which indicates that the imidazolium ring of PhenmimBr has entered the cavity of β-CD. UV absorption indicated that β-CD reacts with PhenmimBr to form a 2:1 β-CD-PhenmimBr complex with an apparent formation constant of 2.61 × 105 mol&−2 L2. Other characterization studies such as UV, FT-IR, XRD, TGA, DSC and SEM studies were also used to further support the formation of the β-CD-PhenmimBr inclusion complex

Zaleznosc poszczegolnych form kwasowosci glebowej od pH

The pH influence on the particular forms of soil acidity and the relations between soil neutralization and charge were investigated. Clay fractions of six acidic soils of different origin were examined after conversion into homoionic sodium and aluminium forms. Results indicate that soil exchange acidity should be defined not on the basis of neutral salt extraction but on the basis of surface charge available to acidic ions adsorption. The amount of pH dependent acidity neutralized with pH increase can be quantitatively described by the increase of negative surface charge and the decrease of positive surface charge.Badano wpływ pH na poszczególne formy kwasowości glebowej oraz związek neutralizacji gleby z jej ładunkiem powierzchniowym. Do badań użyto sodowych i glinowych form frakcji ilastych wydzielonych z kilku gleb kwaśnych. Stwierdzono, iż do opisu kwasowości wymiennej bardziej nadaje się definicja oparta na wielkości ładunku powierzchniowego dostępnego dla jonów kwaśnych, aniżeli oparta na rugowaniu tychże jonów za pomocą soli obojętnej. Ilość kwasowości zależnej od pH neutralizowana podczas wzrostu pH badanych próbek dawała się ilościowo opisać poprzez zmiany ładunku powierzchniowego

Dystrybucja ujemnego ladunku powierzchniowego we frakcji koloidalnej gleb na tle zmian pH

An examination of negative charge distribution among solid soil phase components and its relations to pH of the equilibrium solution was conducted by model experiments on clays separated from selected acidic soils. It was noted that negative charge blocking by iron and aluminium oxides occurs, with the most pronounced effect in brown and podzol clays. On the basis of measured values of sample charges before and after removal of organic matter the organic matter charges were calculated to have a more linear pH dependence than that seen for natural clays. This effect is attributed to the presence of positive charges in the clays investigated.Badano zależność od pH oraz rozkład ładunku ujemnego pomiędzy poszczególne komponenty fazy stałej dla frakcji koloidalnych wydzielonych z wybranych gleb kwaśnych Polski. Stwierdzono, że w badanych próbkach tlenki i wodorotlenki żelaza i glinu blokują powierzchniowy ładunek ujemny, co jest najbardziej wyraźne w glebie brunatnej i płowej. Na podstawie uzyskanych wielkości ładunku powierzchniowego przed i po usunięciu z próbek materii organicznej obliczono wielkości ładunków powierzchniowych dla samej materii organicznej. Zależność ładunku samej materii organicznej od pH miała bardziej liniowy charakter niż w obecności składników mineralnych, co wskazuje na rolę ładunku dodatniego składników mineralnych