The Autoxidation of Co(II)/2-Aamino- 2-Hydroxymethyl-1,3-Propanediol in the Presence of Mn(II) and S(IV)

Abstract

The oxidation of Co(II)/2-amino-2-hydroxymethyl-1,3-propanediol (TRIS) by dissolved oxygen is accelerated by S(IV) oxides (SO 3 2and HSO 3 -). The effectiveness of this autocatalytic process is controlled by S(IV), manganese(II) and oxygen concentrations. The synergistic effect of Mn(II) is clearly evaluated and depends on the medium acidity and TRIS concentration, it must be related to the speciation of Co(II)/Co(III) and Mn(II)/Mn(III) complexes and the S(IV) species that participate in the rate determining step. The metal ions in the trivalent oxidation state react with S(IV) to initiate a radical chain reaction in which S(IV) is oxidized to sulfate and the metal ion is reduced to the divalent state.

Enhanced oxidation of aniline using Fe(III)-S(IV) system: Role of different oxysulfur radicals

“…An increase in the S(IV) dosage was not always able to enhance the oxidation of the organic contaminants. On the contrary, an excessively high S(IV) concentration retards the subsequent reaction, as observed inFigure 3Aand in the literature[17,31].This result is in agreement with the previously reported studies on high [M(n)]/[S(IV)] and low [S(IV)]/[O 2 ] ratios (M(n): heavy-metal ion)[32,33]. Otherwise, the system tends to be less oxidative due to the competition between target pollutants and oxysulfur free radicals and the anoxic conditions.…”

DNA damage and 2′-deoxyguanosine oxidation induced by S(IV) autoxidation catalyzed by copper(II) tetraglycine complexes: Synergistic effect of a second metal ion

“…To elucidate S(IV) autoxidation mechanisms, several studies have been performed with a variety of transition metal ions such as Fe(III)/phen (phen = 1,10-phenantroline) [5], Cu(II)/Cu(III)/G 4 [6][7][8][9][10], Co(II)/ Co(III)/NH 3 [11], Fe(II)/Fe(III)/EDTA [12], Fe(II), Mn(II), Co(II), Ni(II), Cu(II) and V(IV) with phthalocyanines [13], Mn(II)/CDTA (CDTA = trans-1,2-cyclohexyletilenedinitrilotetracetic acid) [14], CoðIIÞ=CoðIIIÞ=N À 3 [15], Co(II)/ Co(III)/TRIS [16], MnðIIÞ=MnðIIIÞ=N À 3 [17], Mn(II)/ Mn(III)/Acetate [18], Ni(II)/Ni(III) with peptides [19][20][21], cyclam [22], hydroxide [23] and Fe(II)/(III)/H 2 O [24].…”

Further studies on the synergistic effect of Ni(II) and Co(II) ions on the sulfite induced autoxidation of Cu(II) penta and hexaglycine complexes

“…However great advances were achieved in some cases, in the presence of complexing medium, where it was possible to follow the formation of one of the metal ion, at trivalent state in large excess (10 -4 -10 -3 mol L -1 ), and the effect of the presence of the second metal ion at very low concentrations (10 -8 -10 -5 mol L -1 ). [2][3][4][5][6][7][8][9] Previous work reported in the literature [1][2][3][4][5][6][7][8][9][10] carried out in complexing medium, using very low concentrations of S(IV) (10 -5 mol L -1 ) and the second metal ion (10 -8 -10 -5 mol L -1 ) showed the complexity of the systems.…”

“…In these systems: Mn(II)/Fe(III)/acetate, 2 Fe(II)/ Mn(II)/H 2 O, 11,12 Co(II)/Mn(II)/N 3 -, 3,6 Ni(II)/Co(III)/cyclam or Ni(II)/Mn(III)/cyclam, 7 Cu(II)/Ni(II)(or Fe(II)/(III), Mn(II), Cr(III))/tetraglycine, 1,8 and Co(II)/Mn(II)/Tris, 9,10 it was possible to follow the concentration of the metal ion (in large excess) at the 3+ state, by measuring the absorbance at a characteristic wavelength.…”