To understand the water purification mechanism of potassium permanganate as a coagulation-aid during the preoxidation process,the microtopography of its reductive products,the newly formed hydrous manganese dioxide an...To understand the water purification mechanism of potassium permanganate as a coagulation-aid during the preoxidation process,the microtopography of its reductive products,the newly formed hydrous manganese dioxide and the aged hydrous manganese dioxide,was investigated.The morphology of natural organic matter(NOM)adsorbed by the newly formed hydrous manganese dioxide was also com-pared with that of NOM alone.By using the tapping mode atomic force microscopy(AFM),the observation results show that the newly formed hydrous manganese dioxide possess a perforated sheet(with a thickness of 0-1.75 nm)as well as some spherical particle structures compared with the hydrous manganese dioxide with 2 h aging time,which demonstrated that the newly formed hydrous manganese dioxide had a large surface area and adsorption capacity.When 1 mmol/L newly formed hydrous manganese dioxide was added,the micro-topography of NOM molecules shifted from a loosely dis-persed pancake shape(with adsorption height of 5-8.5 nm)to a densely dispersed and uniform spherical structure.These results provide a valid proof that it is the perfect adsorption capability of the newly formed hydrous manganese dioxide that might result in the coagulation aid effect of potassium permanganate preoxidation.展开更多
基金This work was supported by the National Key Basic Research and Development(973)Program of China(Grant No.2004CB418505)。
文摘To understand the water purification mechanism of potassium permanganate as a coagulation-aid during the preoxidation process,the microtopography of its reductive products,the newly formed hydrous manganese dioxide and the aged hydrous manganese dioxide,was investigated.The morphology of natural organic matter(NOM)adsorbed by the newly formed hydrous manganese dioxide was also com-pared with that of NOM alone.By using the tapping mode atomic force microscopy(AFM),the observation results show that the newly formed hydrous manganese dioxide possess a perforated sheet(with a thickness of 0-1.75 nm)as well as some spherical particle structures compared with the hydrous manganese dioxide with 2 h aging time,which demonstrated that the newly formed hydrous manganese dioxide had a large surface area and adsorption capacity.When 1 mmol/L newly formed hydrous manganese dioxide was added,the micro-topography of NOM molecules shifted from a loosely dis-persed pancake shape(with adsorption height of 5-8.5 nm)to a densely dispersed and uniform spherical structure.These results provide a valid proof that it is the perfect adsorption capability of the newly formed hydrous manganese dioxide that might result in the coagulation aid effect of potassium permanganate preoxidation.
