Abstract:

Disinfection is an essential part of drinking water treatment. The sodium hypochlorite disinfection gains a bright development prospect because of its effectiveness and safety. Preparation of sodium hypochlorite in an undivided cell offers several advantages as high current efficiency, low power consumption, simple operation and easy accessibility of raw electrolytic material, but its reaction mechanism still needs to be discussed and its poor stability is the main limitation for its broader application. The effect of temperature, PH, electrolyte type, electrolyte concentration, etc. on the current efficiency in an undivided cell was studied and an optimized electrolysis condition was acquired. Also, the electrolysis reaction order of n=4.38 was determined by differential method, the reaction rate constant of electrolysis was calculated and the kinetic equation was established to further determine the electrolysis mechanism. According to the concentration change of the available chlorine in sodium hypochlorite solution through time, the kinetic features of available chlorine attenuation was modeled by pseudo first-order and pseudo second-order equations to further adjust and control its stability.

Key words: undivided cell, electrolysis, sodium hypochlorite, stability, kinetic modeling, available chlorine

摘要：

消毒是饮用水处理工艺中必不可少的一个环节，而化学消毒法中的次氯酸钠消毒法因具有很好的消毒效果及安全性而拥有较好的发展前景。无隔膜法电解制备次氯酸钠具有反应装置简单经济、电解原料简单易得、能耗低等优点，但其机理仍需探讨，其较差的稳定性也限制更广泛的应用。探究了温度、pH、电解质类型、电解质浓度等多种因素对无隔膜电解制备次氯酸钠的电解效率的影响，得到了优化的电解条件。用微分法确定电解反应级数n=4.38，计算电解的反应速率常数，建立动力学方程，对电解机理和步骤进行了深入的探讨。同时探究了次氯酸钠溶液中有效氯浓度随时间的变化，并建立了有效氯衰减一级、二级动力学模型，以便对其稳定性进行调控。

关键词: 无隔膜法, 电解, 次氯酸钠, 稳定性, 动力学模型, 有效氯