Methodology for the characterisation of heterogeneous fractions in wastewater.

A better knowledge of colloidal and particulate matter of urban wastewater is necessary for the optimisation of the wastewater treatment. This paper presents a methodology based on the study of each granular fraction (settleable, supracolloidal, colloidal and soluble matter) separated by different techniques of liquid-solid separation and analysed by non specific parameters (chemical oxygen demand, total suspended solids, UV spectra). The application of this methodology to a storm event allows to explain the quality variation observed during this period.

Hidden isosbestic point(s) in ultraviolet spectra.

The existence of isosbestic point(s) in a set of UV-visible spectra is rarely exploited for quantitative or qualitative information despite its interest. Indeed, the presence of isosbestic points means a quality and quantity conservation in the global composition of samples with a given relation between the concentration of absorbing compounds or mixtures of compounds. However, in some cases, for example, when a dilution occurs, no isosbestic point appears.

Polyphosphate ions encapsulated in oxothiomolybdate rings: synthesis, structure, and behavior in solution.

Cyclic oxothiomolybdates containing polyphosphate ions were prepared by simple reactions in aqueous medium of the corresponding polyphosphate ions and the cyclic precursor K(2)I(2)Mo(10)S(10)O(10)(OH)(10)(OH(2))(5).15H(2)O. K(5)[Cl(P(2)O(7)]Mo(12)S(12)O(12)(OH)(12)(H(2)O)(4)].

Study of the impact of mechanical treatments on wastewater solids by UV spectrophotometry.

The aim of this paper is, from the perspective of improvement of Total Suspended Solids (TSS) measurement by UV spectrophotometry, to study the influence of two pretreatments on the UV responses of urban wastewater (sonication and mechanical grinding). The study of optical properties evolution the different phenomena involved and show mechanical grinding as a potential pre-treatment is prosed. Mechanical grinding is applied to samples characterised by different TSS concentration and particle size distributions in order to test its feasability.

In situ UV monitoring of wastewater: a response to sample aging.

The phenomenon of wastewater sample aging is supposed to be treated with a low temperature autosampler. This work presents two examples of treated wastewater, the quality of which varies with the time of conservation. This evolution may pose some problems with respect to regulation compliance or process control.

A New Cycloaddition Process Involving Nitro Group Participation in Polynitroaromatic Chemistry.

The reaction of ethyl vinyl ether (2 equiv) with 4,6-dinitrobenzofuroxan (DNBF, 1 equiv) in dichloromethane affords a mixture of two diastereomeric dihydrooxazine N-oxide adducts, 5a and 5b, in a 4:1 ratio. Further addition of the enol reagent to this mixture results in a second cycloaddition process with formation of a bis(dihydrooxazine N-oxide) product 6, which can also be obtained directly upon treatment of DNBF with excess ethyl vinyl ether. The observed condensations are accounted for in terms of inverse electron demand Diels-Alder cycloaddition processes between the enol ether dienophile and the heterodienyl moieties of DNBF, constituted first, by the 6-NO(2) group conjugated to the 6,7-double bond and then by the 4-NO(2) group and the 4,5-double bond of the carbocyclic ring.