Tombácz Etelka, Nesztor Dániel, Szekeres Márta, Lewandowski Hans, Klumpp Erwin, Gerencsér-Berta Renáta
Soós Ernő Research and Development Center, University of Pannonia, Zrínyi u. 18., H-8800 Nagykanizsa, Hungary.
Department of Physical Chemistry and Materials Science, University of Szeged, Rerrich Béla tér 1, H-6720 Szeged, Hungary.
Molecules. 2025 Feb 5;30(3):696. doi: 10.3390/molecules30030696.
Protolytic reactions on the surface of a titania photocatalyst (TiO P25 containing chlorine impurities) were studied using potentiometric and calorimetric acid-base titration. The impurity was removed by either washing or heat treatment. The efficiency of purification was tested by chlorine (TOX) analysis and acid-base titration. Common intersection points of -0.023 and -0.021 mmol/g were obtained for the original and 400 °C heat-treated samples, which are in good agreement with the measured TOX value of 28 mmol/kg. The point of zero charge of the purified sample was determined to be 6.50. Titration data were fitted to simulate protolytic reactions during isothermal calorimetric titrations of purified titania. The evolved heat was measured, and data points were corrected with the heat of mixing and neutralization. The quantity of charged surface species formed in each step of titration was calculated using the parameters from the constant capacitance model fit. The partial molar enthalpy values of the exothermic and endothermic processes of surface protonation (ΔH, -17.47 to -16.10 kJ/mol) and deprotonation (ΔH, 32.53 to 27.08 kJ/mol) depend slightly on the ionic strength of suspensions. The average standard enthalpy of one proton transfer reaction is -23.54 ± 1.75 kJ/mol, which is consistent with the literature.
采用电位滴定法和量热酸碱滴定法研究了二氧化钛光催化剂（含氯杂质的TiO P25）表面的质子化反应。通过洗涤或热处理去除杂质。通过氯（TOX）分析和酸碱滴定测试纯化效率。原始样品和400℃热处理样品的共同交点为-0.023和-0.021 mmol/g，这与测得的28 mmol/kg的TOX值高度吻合。纯化样品的零电荷点确定为6.50。对滴定数据进行拟合，以模拟纯化二氧化钛等温量热滴定过程中的质子化反应。测量放出的热量，并用混合热和中和热对数据点进行校正。利用恒电容模型拟合的参数计算滴定各步骤中形成的带电表面物种的数量。表面质子化（ΔH，-17.47至-16.10 kJ/mol）和去质子化（ΔH，32.53至27.08 kJ/mol）的放热和吸热过程的偏摩尔焓值略微依赖于悬浮液的离子强度。一次质子转移反应的平均标准焓为-23.54±1.75 kJ/mol，这与文献一致。
