氯耦合粉末活性炭去除水中锰的效能及机理

Efficiency and Mechanism of Manganese Removal from Water Using Chlorine Coupled with Powdered Activated Carbon

采用氯/粉末活性炭耦合技术(Cl_(2)/PAC)去除水中的锰,研究其除锰效能与机理,并考察地下水中常见无机离子和天然有机物(NOM)对除锰效率的影响。在溶液pH为7的条件下,1 mg/L氯耦合10 mg/L木质PAC,在30 min内即可将1 mg/L Mn(Ⅱ)降低至国家标准限值0.1 mg/L以下。在Cl2/PAC体系中,PAC表面首先会生成MnO_(2),然后进一步催化氧化Mn(Ⅱ)形成新的锰氧化物,从而实现了Mn(Ⅱ)的高效去除。水中Ca^(2+)、Mg^(2+)、SO_(4)^(2-)、SiO_(3)^(2-)、PO_(4)^(3-)等无机离子对Cl_(2)/PAC去除Mn(Ⅱ)影响较小,但Fe^(2+)、NH_(4)^(+)和NOM会显著抑制Mn(Ⅱ)的去除,其对自由氯的竞争是导致除Mn(Ⅱ)效率下降的主要原因。在此基础上,提出将有效氯浓度提升至1 mg/L+补偿原水中离子或NOM耗氯量的方法来消除本底物质的影响,该方法能够在30 min内将不同地下水样品中的Mn(Ⅱ)浓度降至0.1 mg/L以下。

Chlorine coupled with powdered activated carbon(Cl_(2)/PAC)was employed to remove manganese from water.This study investigated the efficiency and mechanism of manganese removal,as well as the impact of common inorganic ions and natural organic matter(NOM)found in groundwater on manganese removal efficiency.Experimental results showed that under a solution pH of 7,1 mg/L chlorine coupled with 10 mg/L wood-based PAC could reduce 1 mg/L Mn(Ⅱ)to below the standard limit of 0.1 mg/L within 30 minutes.In the Cl_(2)/PAC system,MnO_(2) was initially generated on the PAC surface,which further catalyzed the oxidation of Mn(Ⅱ)to form new manganese oxide,thereby achieving efficient removal of Mn(Ⅱ).Inorganic ions such as Ca^(2+)、Mg^(2+)、SO_(4)^(2-)、SiO_(3)^(2-) and PO_(4)^(3-)had little impact on the Mn(Ⅱ)removal efficiency of Cl_(2)/PAC,but Fe^(2+),NH4+and NOM significantly inhibited the Mn(Ⅱ)removal.Competition with free chlorine was identified as the main reason for the reduced Mn(Ⅱ)removal efficiency.Based on these findings,a method was proposed to increase the effective chlorine concentration to 1 mg/L and compensate for the chlorine demand from ions or NOM in raw water to eliminate matrix effects.This method successfully reduced Mn(Ⅱ)concentration to below 0.1 mg/L in groundwater samples with different matrices within 30 minutes.