DOLOMITE DISSOLUTION KINETICS AT LOW PH - A CHANNEL-FLOW STUDY

被引:46
作者
ORTON, R [1 ]
UNWIN, PR [1 ]
机构
[1] UNIV WARWICK,DEPT CHEM,COVENTRY CV4 7AL,W MIDLANDS,ENGLAND
来源
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS | 1993年 / 89卷 / 21期
关键词
D O I
10.1039/ft9938903947
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
The dissolution kinetics of the (100) face of dolomite [CaMg(CO3)2] single crystals have been determined at low pH (3-4) in aqueous solution using channel-electrode shielding measurements. An improved channel-flow cell, designed to allow channel depths (and hence transport rates) to be readily varied over a wide range, has permitted the conditions under which mass transfer influences the dissolution process to be determined for the first time. In contrast to calcite (CaCO3), the dissolution of dolomite displays a half-order, rather than first-order, dependence on the crystal/solution interfacial H+ concentration. Complementary microscopy studies of reacted dolomite surfaces indicate that the dissolution process occurs via the formation of etch pits, the geometries of which are very sensitive to the magnitude of local mass transfer, and hence H+ concentration at the crystal/solution interface. Under most mass-transfer conditions the dissolution rate, inferred from etch-pit morphologies, is observed to be highly anisotropic at the microscopic level. The general consequences of such effects in macroscopic dissolution studies, which generally assume uniform surface reactivity, are discussed.
引用
收藏
页码:3947 / 3954
页数:8
相关论文
共 28 条
[1]   THE INFLUENCE OF SURFACE-STATE AND SATURATION STATE ON THE DISSOLUTION KINETICS OF BIOGENIC ARAGONITE IN SEAWATER [J].
ACKER, JG ;
BYRNE, RH .
AMERICAN JOURNAL OF SCIENCE, 1989, 289 (09) :1098-1116
[2]  
Adams R.N, 1969, ELECTROCHEMISTRY SOL, P220
[3]   THE EFFECT OF CARBOXYLIC-ACIDS ON THE DISSOLUTION OF CALCITE IN AQUEOUS-SOLUTION .2. D-TARTARIC,I-TARTARIC AND MESO-TARTARIC ACIDS [J].
BARWISE, AJ ;
COMPTON, RG ;
UNWIN, PR .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, 1990, 86 (01) :137-144
[4]   CALCITE DISSOLUTION KINETICS IN THE SYSTEM H2O-CO2-CACO3 WITH PARTICIPATION OF FOREIGN IONS [J].
BUHMANN, D ;
DREYBRODT, W .
CHEMICAL GEOLOGY, 1987, 64 (1-2) :89-102
[5]   THE KINETICS OF DISSOLUTION OF DOLOMITE IN CO2-H2O SYSTEMS AT 1.5-DEGREES-C TO 65-DEGREES-C AND O-ATM TO 1-ATM PCO2 [J].
BUSENBERG, E ;
PLUMMER, LN .
AMERICAN JOURNAL OF SCIENCE, 1982, 282 (01) :45-78
[6]   COMPARATIVE-STUDY OF THE KINETICS AND MECHANISMS OF DISSOLUTION OF CARBONATE MINERALS [J].
CHOU, L ;
GARRELS, RM ;
WOLLAST, R .
CHEMICAL GEOLOGY, 1989, 78 (3-4) :269-282
[7]   THE DISSOLUTION OF CALCITE IN AQUEOUS-SOLUTION AT PH LESS-THAN-4 - KINETICS AND MECHANISM [J].
COMPTON, RG ;
UNWIN, PR .
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, 1990, 330 (1609) :1-+
[8]   THE EFFECT OF CARBOXYLIC-ACIDS ON THE DISSOLUTION OF CALCITE IN AQUEOUS-SOLUTION .1. MALEIC AND FUMARIC ACIDS [J].
COMPTON, RG ;
PRITCHARD, KL ;
UNWIN, PR ;
GRIGG, G ;
SILVESTER, P ;
LEES, M ;
HOUSE, WA .
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I, 1989, 85 :4335-&
[9]   THE DIRECT MEASUREMENT OF DISSOLUTION KINETICS AT THE CALCITE WATER INTERFACE [J].
COMPTON, RG ;
PRITCHARD, KL ;
UNWIN, PR .
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1989, (04) :249-251
[10]   STEP DYNAMICS AND SPIRAL GROWTH ON CALCITE [J].
GRATZ, AJ ;
HILLNER, PE ;
HANSMA, PK .
GEOCHIMICA ET COSMOCHIMICA ACTA, 1993, 57 (02) :491-495