响应面法优化石灰处理高氟废水的研究

Study on optimizing lime treatment of high fluoride concentration wastewater by response surface methodology

为强化石灰法处理高氟废水的效率,采用响应面Box-Behnken设计,考察了投量、温度、pH值等因素对除氟效率的影响.结果表明,投量为理论值(14.73 g)的118%、温度62.25℃、pH值8.0的最优工况时,F-可从初始10000 mg·L^(-1)降至107.026 mg·L^(-1).投加石灰后,F-除了与溶解的Ca^(2+)生成结晶,还可被未溶解的石灰吸附.据此建立了石灰法结晶-吸附除氟模型,发现常温时(20℃)吸附是主要除氟途径.因OH-与被吸附F-离子之间有交换作用,当pH值大于10.0时F-的最大吸附量随pH值增加而降低.

In order to enhance the removal efficiency of lime process in the treatment of high fluoride concentration wastewater,the effects of dosage,temperature and pH value on fluoride removal efficiency were investigated by the Box-Behnken design of Response Surface Methodology.The results show that F-could be reduced from 10000 mg·L^(-1) to 107.026 mg·L^(-1) when the dosage was 118%of the theoretical value(14.73 g),the temperature was 62.25℃and the pH value was 8.0.After adding lime,F-could not only been crystallized by dissolved Ca^(2+),but also been adsorbed by undissolved lime.Based on this phenomenon,a fluoride removal model of crystallization-adsorption by lime was established,and it was found that adsorption at room temperature(20℃)was the main way to remove fluoride.Because of the exchange between OH-and adsorbed F-ions,the maximum adsorption capacity of F-decreased with the increase of pH when pH value was greater than 10.0.