基于高级氧化技术的污酸废水除氯性能与机制研究

Study on the performance and mechanism of the removal of Cl from acidic wastewater based on advanced oxidation process

氯离子(Cl-)的高效脱除是有色冶金污酸废水资源化领域的一项瓶颈难题。近年来,高级氧化技术在废水除氯方面表现出极大的应用潜力,本文围绕二氧化铅(PbO_(2))、铋酸钠(NaBiO_(3))和过硫酸氢钾(PMS)三种强氧化剂的除氯效率、机制、成本和运营管理展开了对比分析,指出PbO_(2)、NaBiO_(3)和PMS的投加量分别为理论值的4、1.5及1.5倍,反应温度分别为50、20和60℃时,剩余Cl-浓度低于200 mg/L,达到污酸回用的要求。将除氯固体产物与氯气吸收液混合反应,实现了PbO_(2)和NaBiO_(3)的再生,再生药剂5次循环试验的除氯效率高于90%。PbO_(2)、NaBiO_(3)和PMS除氯过程涉及羟基自由基(·OH)、硫酸根自由基(·SO_(4)^(-))、氯自由基(·Cl)等高活性中间物种的参与,其中直接氧化、·OH间接氧化和·SO_(4)^(-)间接氧化对PMS脱氯的贡献分别约为84%、9%和7%。综合评价实际应用价值,NaBiO_(3)因其可再生、副产物回收价值高且反应温度低,在成本和能耗方面更具优势,PMS因未引入杂质,在操作管理方面更为简单。

The efficient removal of chloride ion(Cl-)is a bottleneck problem in the field of the recycling of waste acid generated from the nonferrous metallurgy.In recent years,advanced oxidation process has shown great application potential in removal of Cl-.In this paper,the dechlorination efficiency,mechanism,cost and operation management of lead dioxide(PbO_(2)),sodium bismuthate(NaBiO_(3))and potassium peroxymonosulfate(PMS)were compared and analyzed.In order to achieve the residual Cl-concentration of less than 200 mg/L for the requirements of waste acid reuse,the dosage of PbO_(2),NaBiO_(3)and PMS were 4,1.5 and 1.5 times of the theoretical value,while the required reaction temperature were 50,20 and 60℃,respectively.The regeneration of PbO_(2)and NaBiO_(3)were realized by mixing the dechlorination solid products with chlorine gas absorption solution,and the dechlorination efficiency of the regenerated reagents were higher than 90%in five cycles.Highly active intermediate species such as hydroxyl radical(·OH),sulfate radical(·SO 4)and chlorine radical(·Cl)were involved in the dechlorination processes of PbO_(2),NaBiO_(3)and PMS.The contribution of direct oxidation,indirect oxidation of·OH and indirect oxidation of·SO_(4)for dechlorination process of PMS were about 84%,9%and 7%,respectively.In terms of practical application value,NaBiO_(3)has more advantages in cost and energy consumption due to its renewability,high by⁃product recovery value and low reaction temperature,while PMS is simpler in terms of operation and management because it does not introduce impurities.