Degradation and Mineralization of Pesticide Isoprocarb by Electro Fenton Process

Electro Fenton with volumic cathode consisting of granules of carbon graphite was applied to degrade the insecticide Isoprocarb in aqueous solutions. The effects of various factors including current intensity and pesticide initial concentration were investigated in order to obtain the best experimental conditions for its degradation and mineralization. Kinetic studies determined that the insecticide removal followed a pseudo first order. The absolute rate constant for the oxidation of Isoprocarb by hydroxyl radicals were determined as 3.32 × 109 L mol−1 s−1 by competitive kinetics method taking benzoic acid as reference compound. In this work, we have also studied the mineralization of aqueous solutions of this insecticide in term of total organic carbon (TOC). After 3 hours of electrolysis, and at I = 800 mA, more than 40 % of the organic carbon presented in the solution is mineralized. Various aromatic by-products, principally formed by oxidation of the pesticide, accompanied by hydroxylation of the aromatic cycle, have been identified. Thus, the oxidative opening of the aromatic ring leads to the formation of carboxylic acids and nitrate ions. The biodegradability of Isoprocarb is estimated by the measurement of its Biochemical Oxygen Demand (BOD5

REARRANGEMENT OF SUBSTITUTED 1,3-BENZOXAZINES INTO XANTHENE-TYPE COMPOUNDS

The rearrangement patterns of new 1,3-benzoxazines derivatives obtained by condensation of substituted salicylamides with cyclic ketones under the influence of Vilsmeier-Haack reagent has been studied. The influence of angel strain in a 4-membered spirocycle prevents the rearrangement of spiro [1,3-benzoxazine-2,1'-cyclobutan]-4(3H)-one under the action of a formylating agent. 1,3-Benzoxazines derivatives with ring sizes from 5- to 8-membered under the action of a formylating agent have formed formylxanthene derivative. Their formation reaction rate depends on the presence of electronegativity substituents at positions C-6 and C-8 of the aromatic cycle, as well as in the spiroring. In this work, we presented an effective method for the synthesis of formyl derivatives of xanthenes based on readily available salicylamide. It was found that (spiro[1,3-benzoxazine-2,1'-cyclobutan]-4(3H)-one) does not rearrange even under prolonged heating due to the spirocycle strain. The presence of bromine or iodine atoms at positions C-6 and C-8 of the aromatic cycle of 1,3-benzoxazines makes the reaction more difficult, which requires more harsh synthesis conditions.

Purification, partial characterization, and reactivity with aromatic compounds of two laccases fromMarasmius quercophilusstrain 17

Two isozymes of laccase were obtained from an induced liquid culture of Marasmius quercophilus with p-hydroxybenzoic acid as the inducer. Both the constitutive and the induced isozyme have a molecular mass of 60 kDa as determined by polyacrylamide gel electrophoresis. Using isoelectric focusing, we found three isozymes with the constitutive enzyme (pI 4, 4.2, 4.4) and four of the induced form (pI 4.75, 4.85, 4.95, 5.1). We observed certain differences between these two isozymes; the specific activity of the induced isozyme was twice as high, and two optimum pH levels (5 and 6) were observed with the induced isozyme (only one, pH 5, for the constitutive isozyme). However, both of these enzymes have the same thermal stability and the same temperature for their highest activity (80°C). Furthermore, the reactivity of both these enzymes with aromatic compounds was similar. The use of mediators extended the oxidized substrate range of the laccases studied. Various products of degradation were observed, depending on the mediator used. When laccase was used alone, the decrease of the signal corresponding to the aromatic cycle, without any formations of other peaks at different wavelengths, suggested polymerisation of aromatic compounds.Key words: laccase, Marasmius quercophilus, mediator, phenol degradation.