铁锰胶体对地下水中无机磷的吸附-脱附特性

Adsorption and desorption properties of iron and manganese colloids to inorganic phosphorus in groundwater

地下水中磷富集已成为水体富营养化的重要污染来源之一,但对于地下水中磷的污染过程认识不清。本研究对比了地下水中常见4种铁锰胶体(水铁矿胶体、针铁矿胶体、二氧化锰胶体和水钠锰矿胶体)对无机磷的吸附和脱附性能的差异。结果表明:铁锰胶体对磷的吸附主要是单分子层的化学吸附,锰胶体吸附量与吸附速率均大于铁胶体,中性pH和较高离子强度有利于铁锰胶体对磷的吸附,但有机质的存在会大大降低对磷的吸附量,尤其是针铁矿胶体受有机质的影响程度最大,其中腐殖酸影响比富里酸更大。同时,钙离子对磷从铁锰胶体上的脱附影响高于钠离子,且铁胶体的脱附效率高于锰胶体。以上研究结果为理解地下水中磷污染过程提供数据支撑。

Recent studies have shown that phosphorus enrichment in groundwater has become one of the important pollution sources of water eutrophication.However,the process of phosphorus pollution in groundwater is not clear.The differences of adsorption-desorption characteristics among four common iron and manganese colloids(ferrihydrite colloids,goethite colloids,manganese dioxide colloids and birnessite colloids)toward inorganic phosphoruswere compared.The results showed that phosphorus adsorption onto iron and manganese colloids was dominated by a monolayer and chemical process.The adsorption capacities and rates of manganese colloids were greater than those of iron colloids.The conditions of neutral pH and high ionic strength were favorable for the adsorption of phosphorus by iron and manganese colloids,while the presence of organic matter greatly decreased phosphorus adsorption capacity,especially the highest suppression effect occurred onto goethite colloids,and humic acid presented a stronger suppression than fulvic acid.Moreover,the phosphorus desorption were effected more seriously by Ca~(2+) ions than that by Na~+ ones,and the desorption rate by iron colloids was higher than that by manganese ones.Therefore,above results can provide the data support for phosphorus pollution process in groundwater.