含氯预氧化剂与碳材料联用去除饮用水中高浓度锰

Combination of Chlorine-containing Pre-oxidants and Carbon Materials to Remove High Concentration of Manganese from Drinking Water Source:Synergistic Effect and Mechanism

将三种含氯预氧化剂——氯(Cl_(2))、氯胺(NH_(2)Cl)和二氧化氯(ClO_(2))与粉末活性炭(PAC)、碳纳米管(CNT)两种碳材料联合,考察去除饮用水中高浓度锰的效果与机理,并探究有效氧化体系在不同初始锰离子浓度及实际水条件下的除锰效果。结果表明:只有氯与碳材料的联用体系表现出了催化氧化能力,PAC比CNT具有更好的催化效果,4 mg/L Cl_(2)联合10 mg/L PAC或CNT分别反应10 min和50 min时,Mn(Ⅱ)浓度可达到饮用水标准;氯胺、二氧化氯与碳材料组合均没有表现出催化氧化作用。碳材料通过吸附络合及导电作用加速了电子转移,且其表面形成的具有自催化作用的MnO_(2)涂层进一步加速了Mn(Ⅱ)的氧化。实际水条件下,有效氧化体系中氯与PAC联用体系由于其他阳离子以及有机物竞争吸附位点和氧化剂从而减慢了氧化速率;而单独二氧化氯在实际水与去离子水中的氧化效果差异不大。实际应用中,通过在水厂进水中同时投加氯和PAC可以长效去除原水中高浓度的锰,而单独投加适宜剂量的二氧化氯也是一种快速控制高浓度锰的策略,两种有效氧化体系可为含锰原水的处理提供技术方法。

Three kinds of chlorine-containing pre-oxidants,chlorine(Cl_(2)),chloramine(NH_(2)Cl)and chlorine dioxide(ClO_(2))and two kinds of carbon materials,namely powdered activated carbon(PAC)and carbon nanotubes(CNT),were combined to study the effect and mechanism of removing high concentration of manganese from drinking water,and explore the manganese removal effect of effective oxidation system under different initial concentrations of manganese ions and actual water conditions.The results showed that only the combined system of chlorine and carbon materials had catalytic oxidation ability and PAC showed better catalytic effect than CNT.The removal efficiency of Mn(Ⅱ)could meet drinking water standards with 4 mg/L Cl_(2) combined 10 mg/L PAC or CNT reaction respectively for 10 minutes and 50 minutes.Various combinations of chloramine,chlorine dioxide and carbon materials did not show catalytic oxidation effect.Carbon materials accelerated electron transfer through adsorption,complexation and conduction,and the autocatalytic MnO_(2) coating formed on the surface further accelerated the oxidation of Mn(Ⅱ).Under actual water conditions,the oxidation rate of Mn(Ⅱ)by chlorine combined with PAC in the effective oxidation system was slowed down due to other cations and organics’competing for adsorption sites and oxidants.However,the removal efficiency of Mn(Ⅱ)by chlorine dioxide alone showed no difference in oxidation efficiency between actual water and deionized water.In practical,the high concentration of manganese in the raw water could be effectively removed for a relative long reaction time by adding chlorine and PAC to the inlet water of the water treatment plant,while the appropriate dose of chlorine dioxide alone was an effective control strategy for the high concentration of manganese.The two effective oxidation systems provide a technical method for the treatment of manganese-containing raw water.