RARE-EARTH ELEMENT COMPLEXATION BY CARBONATE AND OXALATE IONS
RARE-EARTH ELEMENT COMPLEXATION BY CARBONATE AND OXALATE IONS
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DOI：
10.1016/0016-7037(87)90072-x
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发表时间：
1987-03-01
影响因子：
5
通讯作者：
BYRNE, RH
中科院分区：
文献类型：
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作者：
CANTRELL, KJ;BYRNE, RH
通过测定磷酸三丁酯与高氯酸水溶液相的分配平衡，测定了稀土碳酸盐和草酸盐的络合常数。碳酸盐络合常数与海水中的稀土元素（25° C，35%，1 atm）可以用原子序数Z来描述。nlog sw β 1= 4.853+ 0.1135（Z− 57）− 0.003643（Z− 57）2 log sw β 2= 80.197+ 0.1730（Z− 57）− 0.002714（Z− 57）2其中sw β 1=[MCO+ 3][M 3+][CO 2− 3] T，sw β 2=[M（CO 3）− 3][M 3+][CO 2− 3] 2 'T [M 3+]是海水中未络合稀土的浓度，[MCO+ 3]和[M（CO− 3）2]是碳酸盐络合物的浓度，[CO 2− 3] T是海水中总的（游离+离子配对）碳酸盐离子浓度（摩尔标度）。我们的分析表明，在总碳酸根离子浓度为1.39× 10− 4 mol/Kg H2 O的海水中，最轻稀土La的碳酸根络合物占总金属的86%，7%为游离La 3+，其余7%以氢氧化物、硫酸盐、氯化物和氟化物络合物的形式存在。对于Lu，最重的稀土，碳酸盐络合物占总金属的98%，0.3%是未络合的，1.5%与氢氧化物、硫酸盐、氯化物和氟化物络合。草酸盐和碳酸盐常数线性相关。这种相关性似乎是相当有用的估计三价金属的草酸盐稳定常数从各自的草酸盐稳定常数。
Rare earth carbonate and oxalate complexation constants have been determined through ex-amination of distribution equilibria between tributyl phosphate and an aqueous perchlorate phase. Carbonate complexation constants appropriate to the REE in seawater (25° C, 35%., 1 atm) can be described in terms of atomic number, Z. nlog sw β 1= 4.853+ 0.1135 (Z− 57)− 0.003643 (Z− 57) 2 log sw β 2= 80.197+ 0.1730 (Z− 57)− 0.002714 (Z− 57) 2 where sw β 1=[MCO+ 3][M 3+][CO 2− 3] T, sw β 2=[M (CO 3)− 3][M 3+][CO 2− 3] 2'T [M 3+] is an uncomplexed rare earth concentration in seawater,[MCO+ 3] and [M (CO− 3) 2] are carbonate complex concentrations, and [CO 2− 3] T is the total (free plus ion paired) carbonate ion concentration in seawater (molal scale). Our analyses indicate that in seawater with a total carbonate ion concentration of 1.39× 10− 4 moles/Kg H 2 O, carbonate complexes for the lightest rare earth, La, constitute 86% of the total metal, 7% is free La 3+ and the remaining 7% exists as hydroxide, sulfate, chloride and fluoride complexes. For Lu, the heaviest rare earth, carbonate complexes are 98% of the total metal, 0.3% is uncomplexed and 1.5% is complexed with hydroxide, sulfate, chloride and fluoride. Oxalate and carbonate constants are linearly correlated. This correlation appears to be quite useful for estimating trivalent metal-arbonate stability constants from their respective oxalate stability constants.