Liquid-liquid phase reaction between crystal violet and sodium hydroxide: kinetic study and precipitate analysis

To investigate reaction order and kinetic parameters of the reaction
between crystal violet (CV) and sodium hydroxide (NaOH), various
concentrations of the reactants were applied. The present work also
verifies the unknown solid product produced under highly concentrated
conditions. The reaction orders of CV and NaOH were determined to be 1 and
1.17 by pseudo-rate method, respectively, with a rate constant, k, of
0.084 [(M-1.17) s-1]. In addition to pseudo-rate method, the half-life
approach is use to calculated the overall reaction order to verify the
accuracy of pseudo-rate method. The overall reaction order is determined
to be 1.9 by half-life method. Compare reaction order gained from both
methods, the overall reaction order is determined as ~2. The precipitate
formation was observed when high concentrations of CV (0.01~0.1 M) and
NaOH (1.0 M) were applied. Fourier transform infrared (FTIR) spectroscopy
was used to compare the spectra of the precipitate generated and a
commercial solvent violet 9 (SV9). Based on the FTIR spectra, it was
confirmed that the molecular structure of the precipitate matched that of
solvent violet 9.

为探究结晶紫（Crystal Violet, CV）与氢氧化钠（Sodium Hydroxide, NaOH）的反应级数及动力学参数，本研究采用不同浓度的反应物开展实验。此外，本研究还对高浓度反应条件下生成的未知固态产物进行了验证。通过拟速率法，测得结晶紫与氢氧化钠的反应级数分别为1和1.17，对应的速率常数$k$为0.084 [(M⁻¹·¹⁷)·s⁻¹]。除拟速率法外，本研究还采用半衰期法计算总反应级数，以验证拟速率法结果的准确性，最终通过半衰期法测得总反应级数为1.9。对比两种方法得到的反应级数，确定总反应级数约为2。当使用高浓度的结晶紫（0.01~0.1 M）与氢氧化钠（1.0 M）进行反应时，可观察到沉淀生成。本研究采用傅里叶变换红外（Fourier Transform Infrared, FTIR）光谱法，对比了生成的沉淀物与商用溶剂紫9（Solvent Violet 9, SV9）的光谱图谱。基于FTIR光谱结果，证实该沉淀物的分子结构与溶剂紫9完全一致。