Publications by authors named "Tippu S Sheriff"

Article Synopsis
  • Bisphenol AF (BPAF) can be effectively degraded using ultrasound-assisted methods that generate hydrogen peroxide in situ, utilizing a copper(II) catalyst with dioxygen and hydroxylamine.
  • The in situ generated hydrogen peroxide significantly enhances BPAF degradation rates from 46.7% to 94.8% in about 15 minutes, following a pseudo-first-order kinetic model.
  • The research also explores factors affecting BPAF degradation, such as pH levels, the presence of anions, humic acid, and concentrations of reactants, while identifying degradation products through mass spectrometry and proposing a degradation pathway.
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Manganese (II) ions (Mn(II)) catalyse the oxidative degradation of Calmagite (CAL, 2-hydroxy-1-(2-hydroxy-5methylphenylazo)-4-naphthalenesulfonic acid) at room temperature using added and in situ generated hydrogen peroxide (HO), using 1,2-dihydroxybenzene-3,5-disulfonate, disodium salt and monohydrate (Tiron) as the co-catalyst for the in situ generation of HO. The percentage of CAL degradation with the in situ generated HO was 91.1 % after 30 min which is lower than that in the added HO/Mn(II) system (96.

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The asymmetric unit of the title complex, [NiBr(NO){P(C6H5)3}2], comprises two independent mol-ecules each with a similar configuration. The Ni(II) cation is coordinated by one bromide anion, one nitrosyl anion and two tri-phenyl-phosphane mol-ecules in a distorted BrNP2 tetra-hedral coordination geometry. The coordination of the nitrosyl group is non-linear, the Ni-N-O angles being 150.

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The kinetics and mechanism for the bleaching of Calmagite (H3CAL, 3-hydroxy-4-(2-hydroxy-5-methylphenylazo)naphthalene-1-sulfonic acid) in aqueous solution at pH 8.00 and 23 ± 1 °C using in situ generated H2O2 is described. Complete mineralisation of H3CAL results with turnover frequencies (TOF = moles of H3CAL bleached per mole of manganese per hour) of 40 h(-1).

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Nucleophilic aromatic substitution of tetrachloro-o-benzoquinone by pyridine and reduction of the o-quinone to the catechol by hydroxylamine forms 1,2-dihydroxy-3,5,6-trichlorobenzene-4-pyridinium chloride. This compound reacts with manganese(II) acetate in air to form chlorobis(3,5,6-trichlorobenzene 4-pyridinium catecholate)manganese(III), which represents the first complex of this ligand class to be structurally characterized by X-ray diffraction; this complex is active in the catalytic reduction of dioxygen to hydrogen peroxide under ambient conditions and turnover frequencies (TOFs) >10,000 h(-1) can be obtained.

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Hydrogen peroxide (H(2)O(2)) generated from the manganese(II) catalysed reduction of dioxygen has been shown to efficiently oxidize Calmagite (3-hydroxy-4-(2-hydroxy-5-methylphenylazo)naphthalene-1-sulfonic acid) in aqueous solution at pH 8.0 and 20 +/- 1 degrees C with de-protonated Tiron (1,2-dihydroxybenzene-3,5-disulfonate, disodium salt) acting as an essential co-ligand.

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