电解法制备低浓度次氯酸钠消毒水的参数优化及表观动力学探究

Parameter optimization and investigation of the apparent kinetics of low concentrations of aqueous sodium hypochlorite disinfectant prepared by electrolysis

高浓度次氯酸钠(NaClO)溶液在储存及使用过程中易产生有效氯浓度降低、氯气中毒等问题,因此在环境卫生消毒过程中为保证消毒水的稳定与使用安全,应尽量降低NaClO浓度。以低浓度食盐水为原料,利用无隔膜电解法制备了低浓度NaClO消毒水,采用单因素实验法研究了盐水流量、盐的质量浓度、电流密度与进水温度4个工艺参数对电解效果的影响,并以有效氯浓度、电流效率和运行费用为评价指标对电解参数进行了优化。结果表明,当盐水流量为75 mL/min、盐的质量浓度为7 g/L、电流密度为1 A/dm^(2)、进水温度为30℃时,有效氯浓度和电流效率较高,运行费用最低。对电解制备消毒水反应进行了表观动力学探究,确定了该反应为一级反应,并归纳出盐的初始质量浓度a和电流密度J与反应速率常数k的关系分别为:k=0.007a^-0.459,k=0.003J^0.423。

High concentrations of sodium hypochlorite(NaClO)solution can lead to a decrease in the effective chlorine concentration,chlorine poisoning and other problems during storage and usage.Therefore,in order to ensure the stability and safe use of the disinfectant during environmental sanitation disinfection,the concentration of NaClO should be reduced as far as possible.Using low concentrations of salt water as the raw material,low concentrations of aqueous NaClO disinfectant have been prepared by a non-diaphragm electrolysis method.The effects of four process parameters—brine flow rate,salt concentration,current density and inlet temperature-on the electrolysis were studied by single factor experiments.The electrolytic parameters were optimized using the concentration of available chlorine,current efficiency and running cost as the evaluation indices.The results showed that when the brine flow is 75 mL/min,the mass concentration of brine is 7 g/L,the current density is 1 A/dm^(2),and the inlet temperature is 30℃,the effective chlorine concentration and current efficiency are higher,and the operating cost is minimized.The apparent reaction kinetics of the preparation of aqueous disinfectant by electrolysis was investigated,and it was determined that the reaction was a first order reaction.The relationships between the initial mass concentration a of salt water,the current density J and the reaction rate constant k were investigated,and the following kinetic equations were obtained:k=0.007a^-0.459,k=0.003J^0.423.