A kinetic study of the reduction of colloidal manganese dioxide by oxalic acid

被引:154
作者
PerezBenito, JF [1 ]
Arias, C [1 ]
Amat, E [1 ]
机构
[1] UNIV BARCELONA,FAC FARM,UNIDAD FISICOQUIM,E-08028 BARCELONA,SPAIN
关键词
autocatalysis; colloidal solution; kinetics; manganese dioxide; oxalic acid;
D O I
10.1006/jcis.1996.0034
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
A kinetic study of the reaction between colloidal manganese dioxide and oxalic acid in aqueous acetate media (pH 4.3-5.1) is reported. The reaction is autocatalytic and, in order to determine the rate constants k(1) and k(2) corresponding, respectively, to the noncatalytic and autocatalytic reaction pathways, the Mn(III) formed as an intermediate was stabilized by addition of sodium pyrophosphate. Joint iodimetric and spectrophotometric studies indicated that the reduction of colloidal manganese dioxide follows the sequence Mn(IV) --> R Mn(II) --> Mn(IV) Mn(III) --> R (II), where R stands for the reductant. Both reaction pathways exhibit acid catalysis, and the activation energies associated to k(1) and k(2) are 74.7 +/- 0.9 and 44.6 +/- 0.6 kJ mol(-1), respectively. The reaction is accelerated by addition of manganese(II) sulfate, and k(2) increases with rising oxalate concentration, suggesting that MnC2O4 is the active autocatalyst. The possibility that Mn(III) might collaborate in the autocatalysis through a free-radical chain mechanism is also pointed out. (C) 1996 Academic Press, Inc.
引用
收藏
页码:288 / 297
页数:10
相关论文
共 54 条
[1]  
ABDELSALAAM KM, 1975, Z PHYS CHEM NEUE FOL, V95, P139
[2]   KINETICS OF THE MANGANESE(III) - OXALATE REACTION IN ACIDIC SULFATE MEDIA [J].
ADAMCIKOVA, L ;
KRIZOVA, A ;
VALENT, I .
TRANSITION METAL CHEMISTRY, 1993, 18 (02) :218-220
[3]   THE MECHANISM OF THE PERMANGANATE-OXALATE REACTION [J].
ADLER, SJ ;
NOYES, RM .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1955, 77 (08) :2036-2042
[4]   CHARACTERIZATION OF MANGANESE DIOXIDES .4. OXIDATION OF CHROMIUM(III) IONS BY MANGANESE DIOXIDES [J].
BASAK, B ;
MALATI, MA .
JOURNAL OF INORGANIC & NUCLEAR CHEMISTRY, 1977, 39 (06) :1081-1084
[5]   The reaction between potassium permanganate and oxalic acid, and the decomposition of potassium manganioxalate. [J].
Bradley, J ;
Van Praagh, G .
JOURNAL OF THE CHEMICAL SOCIETY, 1938, :1624-1636
[6]   OXIDATION OF ARGININE BY MANGANESE(III) IN PYROPHOSPHATE AND ACETATE MEDIA - A KINETIC-STUDY [J].
CHANDRAJU, S ;
SHERIGARA, BS ;
GOWDA, NMM .
INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, 1994, 26 (11) :1105-1119
[8]   AN INORGANIC BROMATE OSCILLATOR INCORPORATING PERMANGANATE AS A REAGENT [J].
DALLISON, AM ;
MACER, DRJ ;
RODLEY, GA .
INORGANICA CHIMICA ACTA-LETTERS, 1983, 76 (04) :L219-L221
[9]   KINETICS AND MECHANISMS OF THE OXIDATION BY PERMANGANATE OF L-ALANINE [J].
DEANDRES, J ;
BRILLAS, E ;
GARRIDO, JA ;
PEREZBENITO, JF .
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2, 1988, (02) :107-112