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Combined effects of temperature, mineral type, and surface roughness on chlorite dissolution kinetics in the acidic pH
Applied Clay Science ( IF 5.3 ) Pub Date : 2021-02-01 , DOI: 10.1016/j.clay.2020.105931
Ruxue Liao , Wenwu Chen , Nan Wang , Jingke Zhang

Abstract Many studies reported the chlorite dissolution kinetics in acidic pH—resulting in the development of chlorite dissolution rate law covering the pH and temperature dependence—but they rarely discussed how various intrinsic factors, including chlorite types, structural complexity, and surface roughness (refers specifically to the ratio between Brunauer–Emmett–Teller surface area, BET SA, and geometric surface area, GSA, in this paper), influenced the chlorite dissolution rate or the mechanism for dissolution congruency. In this study, results obtained from mixed-flow reactor experiments performed on a Mg-rich chlorite, over a pH range of 2–6 at 25 °C and 95 °C, indicated that pH and temperature control not only the chlorite dissolution rate but also the congruency of element release. Low pH facilitated the dissolution of Fe from chlorite interlayers and caused incongruent element release rates at 25 °C, while higher temperature experiments at the same pH overcame the differences in surface reactivity between the interlayer and the tetrahedral-octahedral-tetrahedral (TOT) layer, and finally evolved into congruent dissolution. The lower pH also made chlorite dissolution more resistant to varying flow rates. A dissolution rate constant of 10–10.51 mol/m2/s, a reaction order of 0.32, and activation energy of 42.03 kJ/mol were determined for the Mg-rich chlorite dissolution kinetics at 25 °C, in an acid-enhanced mechanism. Longer-term reactive transport modeling (RTM) on the chlorite dissolution demonstrated that low pH and large specific surface area (SSA) decreased the chlorite percentage, bulk surface area, and saturation index quicker, and in a non-linear fashion. Chlorite with higher SSA lost more bulk surface area (BSA) than that with lower SSA, when the same mass of chlorite was dissolved. Through tabulating and recalculating a series of data from the literature, the combined effects of intrinsic and extrinsic factors—including chlorite type, BET SA/GSA ratio, and temperature—were explored. Fe-rich chlorite dissolves faster than Mg-rich chlorite in acid and neutral pH, due to the oxidative dissolution mechanism. The chlorite dissolution rate constant is linearly and positively correlated to BET SA/GSA for the same type of chlorite (Fe-rich and Mg-rich). Higher temperatures help reduce the effects of extrinsic and intrinsic factors on chlorite dissolution rates.

中文翻译:

温度、矿物类型和表面粗糙度对酸性 pH 条件下亚氯酸盐溶解动力学的综合影响

摘要 许多研究报道了酸性 pH 下的亚氯酸盐溶解动力学——导致发展了涵盖 pH 和温度依赖性的亚氯酸盐溶解速率定律——但他们很少讨论各种内在因素,包括亚氯酸盐类型、结构复杂性和表面粗糙度(具体指Brunauer-Emmett-Teller 表面积 BET SA 和几何表面积 GSA 之间的比率(在本文中)影响亚氯酸盐溶解速率或溶解一致性的机制。在本研究中,在 25 °C 和 95 °C、2-6 的 pH 值范围内对富镁亚氯酸盐进行的混合流反应器实验获得的结果表明,pH 值和温度不仅控制亚氯酸盐的溶解速率,而且还有元素释放的一致性。低 pH 值促进了亚氯酸盐夹层中 Fe 的溶解,并导致 25 °C 下元素释放速率不一致,而在相同 pH 值下进行的高温实验克服了夹层和四面体-八面体-四面体 (TOT) 层之间表面反应性的差异,并最终演变成全等溶解。较低的 pH 值也使亚氯酸盐的溶解更能抵抗变化的流速。在酸增强机制中,25 °C 下富镁亚氯酸盐溶解动力学的溶解速率常数为 10-10.51 mol/m2/s,反应级数为 0.32,活化能为 42.03 kJ/mol。亚氯酸盐溶解的长期反应迁移模型 (RTM) 表明,低 pH 值和大比表面积 (SSA) 降低了亚氯酸盐百分比、体积表面积、和饱和指数更快,并以非线性方式。当溶解相同质量的亚氯酸盐时,具有较高 SSA 的绿泥石比具有较低 SSA 的绿泥石损失更多的体表面积 (BSA)。通过对文献中的一系列数据进行制表和重新计算,探索了内在和外在因素(包括亚氯酸盐类型、BET SA/GSA 比率和温度)的综合影响。由于氧化溶解机制,富铁亚氯酸盐在酸性和中性 pH 值下比富镁亚氯酸盐溶解得更快。对于相同类型的亚氯酸盐(富铁和富镁),亚氯酸盐溶解速率常数与 BET SA/GSA 呈线性正相关。较高的温度有助于减少外在和内在因素对亚氯酸盐溶解速率的影响。当溶解相同质量的亚氯酸盐时,具有较高 SSA 的绿泥石比具有较低 SSA 的绿泥石损失更多的体表面积 (BSA)。通过对文献中的一系列数据进行制表和重新计算,探索了内在和外在因素(包括亚氯酸盐类型、BET SA/GSA 比率和温度)的综合影响。由于氧化溶解机制,富铁亚氯酸盐在酸性和中性 pH 值下比富镁亚氯酸盐溶解得更快。对于相同类型的亚氯酸盐(富铁和富镁),亚氯酸盐溶解速率常数与 BET SA/GSA 呈线性正相关。较高的温度有助于减少外在和内在因素对亚氯酸盐溶解速率的影响。当溶解相同质量的亚氯酸盐时,具有较高 SSA 的绿泥石比具有较低 SSA 的绿泥石损失更多的体表面积 (BSA)。通过对文献中的一系列数据进行制表和重新计算,探索了内在和外在因素(包括亚氯酸盐类型、BET SA/GSA 比率和温度)的综合影响。由于氧化溶解机制,富铁亚氯酸盐在酸性和中性 pH 值下比富镁亚氯酸盐溶解得更快。对于相同类型的亚氯酸盐(富铁和富镁),亚氯酸盐溶解速率常数与 BET SA/GSA 呈线性正相关。较高的温度有助于减少外在和内在因素对亚氯酸盐溶解速率的影响。通过对文献中的一系列数据进行制表和重新计算,探索了内在和外在因素(包括亚氯酸盐类型、BET SA/GSA 比率和温度)的综合影响。由于氧化溶解机制,富铁亚氯酸盐在酸性和中性 pH 值下比富镁亚氯酸盐溶解得更快。对于相同类型的亚氯酸盐(富铁和富镁),亚氯酸盐溶解速率常数与 BET SA/GSA 呈线性正相关。较高的温度有助于减少外在和内在因素对亚氯酸盐溶解速率的影响。通过对文献中的一系列数据进行制表和重新计算,探索了内在和外在因素(包括亚氯酸盐类型、BET SA/GSA 比率和温度)的综合影响。由于氧化溶解机制,富铁亚氯酸盐在酸性和中性 pH 值下比富镁亚氯酸盐溶解得更快。对于相同类型的亚氯酸盐(富铁和富镁),亚氯酸盐溶解速率常数与 BET SA/GSA 呈线性正相关。较高的温度有助于减少外在和内在因素对亚氯酸盐溶解速率的影响。对于相同类型的亚氯酸盐(富铁和富镁),亚氯酸盐溶解速率常数与 BET SA/GSA 呈线性正相关。较高的温度有助于减少外在和内在因素对亚氯酸盐溶解速率的影响。对于相同类型的亚氯酸盐(富铁和富镁),亚氯酸盐溶解速率常数与 BET SA/GSA 呈线性正相关。较高的温度有助于减少外在和内在因素对亚氯酸盐溶解速率的影响。
更新日期:2021-02-01
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