Relative Basicity of Trioctylamine to Carboxylic Acid in Selected Organic Diluents

The relative basicity of trioctylamine （TOA）, pKa,BS, in protic polar diluent （1-octanol）, non-protic polar diluent [methyl iso-butyl ketone （MIBK）] and inert diluent （CCl4） were determined for 11 mono-carboxylic acids, and the dependence of PKa,BS on the nature of solute and diluent type was discussed. The results show that pKa,BS determined by half neutralization with the solute carboxylic acid is in the order of 1-octanol〉MIBK〉CCl4 for a fixed TOA concentration, and it increases with increasing acidity and hydrophobicity of the carboxylic acid. Compared with two parameters of the solute extracted （acidity and hydrophobicity）, pKa,BS is more sensitive to hydrophobicity of the acid. A mathematic equation representing relationship between the apparent extraction equilibrium （K11） and the system properties （PKa,BS and pKa） was proposed： 1g K11 = 2pKa,BS=pKa. It is proved that the extraction equilibrium of mono-carboxylic acids can be predicted by the above equation with reasonable accuracy.

疏通岩溶隧道排水系统堵塞的清洗溶剂对结构的无损性测评

岩溶地区隧道工程普遍存在岩溶结晶阻塞排水系统的问题,严重威胁隧道工程的结构安全及其长期运营。文章在疏通岩溶排水堵塞的清洗溶剂制备与效能研究基础上,确定了清洗溶剂为浓度2000 ppm、重铬酸盐指数为17.71%的单分子羧酸类有机酸溶剂,并开展选定清洗溶剂对隧道衬砌结构混凝土与排水系统PVC塑料纤维材料的无损性测评。首先开展有机酸溶剂浸泡混凝土试件的试验,评估溶剂对混凝土侵蚀的强度损伤状况。其次开展有机酸试剂溶液浸泡PVC排水板与塑料盲沟管的试验,从宏观角度和微观角度评估溶剂对隧道排水系统侵蚀的质量损失状况和腐蚀损伤状况。试验结果表明:单分子羧酸类有机酸溶剂的侵蚀降低了混凝土材料强度指标约7%~9%左右,单分子羧酸类有机酸溶剂对排水系统塑料材料几乎没有腐蚀损伤影响。