Lowson et al.(2005)によるThe kinetics of the dissolution of chlorite as a function of pH and at 25℃〕(1687p)から〕

『25℃およびpHの関数としての緑泥石の溶解のカイネティックス』


Abstract
 Far from equilibrium, quasi-steady state dissolution rates of an iron rich chlorite (Mg2.76Fe2+1.90Fe3+0.07Al0.97)[Si2.48Al1.52O10](OH)8, have been measured as a function of H+ concentration for the pH range 3 to 10.5 and at 25℃. The rates ware determined using a single pass flow through cell and with a time frame for observing the steady state condition of between 10 to 50 days. Rates are independent of the buffers used to control the pH, sample preparation, experimental methodology and chlorite composition. The results were collated with literature values allowing the rate to be expressed as a function as a function of H+ as;
   log R = - [ 9.79 aH0.49 + 13.00 + 16.79/aH0.43]
where R stands for the dissolution rate in mol m-2 s-1 and ai refers to the activity of the subscripted aqueous species. When the data for the Al3+ concentration at the outlet was incorporated into the analysis it was found that the rate could also be described by the relationship
   R = 10-10.46(aH +3/aAl 3+)0.27
which suggests the rate controlling complex is formed via a proton attack of the lattice aluminium.』

要旨
 鉄に富む緑泥石(Mg2.76Fe2+1.90Fe3+0.07Al0.97)[Si2.48Al1.52O10](OH)8)の平衡から離れた準定常状態溶解速度が、pH 3〜10.5および25℃でH+濃度の関数として測定された。1台のフロースルー反応器を用いて10〜50日間の定常状態条件を観察するための時間枠で、速度は決定された。速度は、pHコントロールに用いた緩衝剤・試料処理・実験方法・緑泥石組成には依存しない。結果は、以下のように速度をH+関数のような関数として表現できるように文献値と対照させた;
   log R = - [ 9.79 aH0.49 + 13.00 + 16.79/aH0.43]
ここで、R はモル/m2/秒単位の溶解速度で、ai は下付き文字の溶存種の活動度を表わす。出口でのAl3+濃度のデータが組み込まれる場合は、速度は以下の関係でも記述できることがわかり、
   R = 10-10.46(aH +3/aAl 3+)0.27
これは速度をコントロールする錯体が、格子アルミニウムへのプロトンの作用を経て形成されることを示している。』

1. Introduction
2. Experimental
 2.1. Method
 2.2. Material
 2.3. Buffer reagents
 2.4. Assigned uncertainties
3. Results and interpretation
 3.1. Experimental method
 3.2. Data
 3.3. Congruency of dissolution
 3.4. The role of buffers
 3.5. Comparison with previous dissolution data
 3.6. Rate constants, reaction orders and reaction mechanism
4. Conclusions
Acknowledgments
References



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