荧光示踪分析法测定酸化液中酸浓度

Tracer Fluorophotometric Determination of Acid Concentration in Acidizing Fluids

实验测得，当盐酸浓度在0．1--0．7mol／L时，异硫氰酸荧光素（FITC）盐酸溶液的相对荧光强度Fr与氢离子浓度C（H^＋）之间有良好的线性关系。据此，以已知浓度的现场土酸样为标准溶液，直接或加入AlCa3使氢氟酸解离后测Fr，建立了Fr～盐酸浓度和Fr～总酸浓度工作曲线。随机取8份现场土酸样，分别稀释20倍和10倍，测定Fr，利用工作曲线求得总酸浓度和其中的盐酸浓度，与滴定法测定值的相对误差最大为8．72％。采用溶胶-凝胶法，即通过高化学活性组分正硅酸四乙酯的水解、综合反应制备含FITC的溶胶，加入适量表面活性剂Triton X-100后陈化适当时间（～7d），使之转变为凝胶，再干燥固化，得到了固定在玻璃探头表面的固态光化学传感膜。该膜外观均匀光滑无裂纹，SEM照片显示膜表面有含FITC的裂纹，AFM照片显示膜表面起伏不平。将该传感器放入盐酸中，测得Fr与盐酸浓度（0．1--0．4mol／L）之间有良好的线性关系。该传感膜可用于快速测定酸化液的C（H^＋）。图13表2参6。

A good linear relationship is obtained between relative fluorescence intensity, Fr, and hydrogen ion concentration, C （H^＋ ）, for fluorescein isothiocyanate （FITC） in hydrochloric acid solution at acid concentration in range 0.1-0.7 mol/L. On this basis, Fr-HCl acid and Fr-total acid concentration working curves are constructed for mud acid of known concentration, taken from well acidizing sites, and used as standard solution by determining Fr of FITC in this solution, which is treated by AlCl3 to dissociate HF in cases of total acid determination. 8 mud acid samples taken random from acidizing sites are diluted 20 and 10 times to determine Fr and to obtain total acid and HCl acid concentrations with relative error ≤ 8.72 % in comparison with titration values. A solid photochemical sensor film on glass measuring head is prepared by a sol-gel process through hydrolysis and condensation of tetraethyl orthcsilicate to give an FITC containing sol solution, conversion of the sol to a gel in the presence of appropriate amount of surfactant Triton X- 100 in a proper ageing time, about 7 days, and drying of the gel. The solid film is homogeneous, smooth and fracture-free; pores with FITC included on its surfaces are shown on SEM photos; undulation of film surfaces is shown on AFM photos. With this sensor put into HCl acid, Fr values are fast determined and a goocl linear relationship between Fr and acid concentration is obtained at HCl acid concentration in range 0.1--0.4 mol/L. This sensor can be used for fast determination of hydrogen ion concentration in acidizing fluids.