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A solid source of 'active' oxygen (acetylperoxyborate, APB), when dissolved in aqueous solution in the presence of a single-site microporous catalyst containing redox centres (Fe(III)AlPO-31, Mn(III)AlPO-5, Fe(III)AlPO-5), converts cyclohexane with high efficiency (ca. 88%) and exceptionally high selectivity (ca. 81%) to adipic acid at 383 K; this procedure is also effective in converting styrene to styrene oxide and -pinene and (+)-limonene to their corresponding epoxides.

The kinetics of the oxidation of substituted phenyl methyl sulfides by hydrogen peroxide in borate/boric acid buffers were investigated as a function of pH, total peroxide concentration, and total boron concentration. Second-order rate constants at 25 degrees C for the reaction of methyl 4-nitrophenyl sulfide and H(2)O(2), monoperoxoborate, HOOB(OH)(3) (-), or diperoxoborate, (HOO)(2)B(OH)(2) (-), are 8.29 x 10(-5), 1.51 x 10(-2) and 1.06 x 10(-2) M(-1) s(-1), respectively. Peroxoboric acid, HOOB(OH)(2), is unreactive. The Hammett rho values for the reactions of a range of substituted phenyl methyl sulfides and hydrogen peroxide, monoperoxoborate or diperoxoborate are -1.50 +/- 0.1, -0.65 +/- 0.07 and -0.48 (two points only), respectively. The rho values for the peroxoborates are of significantly lower magnitude than expected from their reactivity compared to other peroxides. Nevertheless the negative rho values indicate positive charge development on the sulfur atom in the transition state consistent with nucleophilic attack by the organic sulfides on the peroxoborates as with the other peroxides. The kinetic parameters, including the lack of reactivity of peroxoboric acid, are discussed in terms of the differences in the transition state of reactions involving peroxoboron species with respect to those of other peroxides.

This paper is concerned with the preparation and use of Mg/Al double-layered hydroxides for boron removal from waste liquor. The structure of the DLHs synthesized is proposed to be Mg 2 AlNa 1.4 (OH) 7.57 Cl 0.03 (NO 3 ) 0.8 ‚ x(H 2 O) which does not contain any carbonate anions. For treating model waters with various starting boron concentrations (5-500 mg/L), the maximum boron percentage removal was >80% for DLH-60 and >90% for DLH-450. The boron removal capacity is 5.4-17.3 mg of B/g for DLH-450 and 1.2-13 mg of B/g for DLH-60, respectively. The raw water's pH does not affect the boron removal performance. After six cumulative regenerations, boron percentage removal with regenerated DLHs decreased to about 40%. Overall, DLH-450 has a greater boron removal capacity than DLH-60 for both freshly prepared and regenerated materials. For the treatment of industrial effluent ([B] 0 ) 17 mg/L), 86.6% boron removal was achieved at the dose of 36 g/L for DLH-60 and 93.5% at the dose of 16 g/L for DLH-450. Arsenic can be completely removed by both DLHs. The main mechanism of boron removal with DLH-60 is proposed to be anion exchange while that with DLH-450 is adsorption. For DLH-450, both Langmuir and Freundlich isotherm models fit well for the experimental results.

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