Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method（SFM） was applied for the complex decomposition and simultaneous removal...Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method（SFM） was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia.The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion.Ammonia was separated from solution as crystalline struvite,and the copper mainly co-precipitated as copper hydroxide together with struvite.Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide.Hydrogen bonding was concluded to be the key factor leading to the co-precipitation.In addition,incorporation of copper ions into the struvite crystal also occurred during the treatment process.展开更多
The effect of the amount of precipitant ammonia on the Cu0/Cu＋ratio of Cu/Si O2 prepared by the deposition–precipitation method is investigated. Species at different preparation stages, resulted from the amount of a...The effect of the amount of precipitant ammonia on the Cu0/Cu＋ratio of Cu/Si O2 prepared by the deposition–precipitation method is investigated. Species at different preparation stages, resulted from the amount of ammonia used, are identified by the XRD and FTIR techniques. Chrysocolla together with either copper nitrate hydroxide or copper hydroxide coexist in the uncalcined catalysts. Upon calcination, the latter two species are converted to Cu O particles while chrysocolla remains. Following reduction, Cu O is transformed to metallic Cu and chrysocolla is converted to Cu2 O. The value of Cu0/Cu＋ratio can be evaluated using the peak areas in their TPR profiles. Hydrogenation of dimethyl oxalate（DMO） to ethylene glycol（EG） shows that the selectivity of EG depends on the Cu0/Cu＋ratio. Catalyst prepared with the addition of ammonia solution at n（NH3）/n（Cu2＋） = 0.9 for precipitation–deposition gains a more suitable Cu0/Cu＋ratio upon reduction and thus has a higher selectivity for EG.展开更多
基金supported by the National Natural Science Foundation of China(No.51204213)the Key Project of Science and Technology of Hunan Province(No.2013WK2007)the Innovation Stimulating Program of Central South University(No.2015CX001)
文摘Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method（SFM） was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia.The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion.Ammonia was separated from solution as crystalline struvite,and the copper mainly co-precipitated as copper hydroxide together with struvite.Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide.Hydrogen bonding was concluded to be the key factor leading to the co-precipitation.In addition,incorporation of copper ions into the struvite crystal also occurred during the treatment process.
基金Funding for the present study from the National Basic Research Program of China(973 Program,No.2011CB710800)the Opening Foundation(2014)of Zhejiang Zanyu Technology Co.,Ltd
文摘The effect of the amount of precipitant ammonia on the Cu0/Cu＋ratio of Cu/Si O2 prepared by the deposition–precipitation method is investigated. Species at different preparation stages, resulted from the amount of ammonia used, are identified by the XRD and FTIR techniques. Chrysocolla together with either copper nitrate hydroxide or copper hydroxide coexist in the uncalcined catalysts. Upon calcination, the latter two species are converted to Cu O particles while chrysocolla remains. Following reduction, Cu O is transformed to metallic Cu and chrysocolla is converted to Cu2 O. The value of Cu0/Cu＋ratio can be evaluated using the peak areas in their TPR profiles. Hydrogenation of dimethyl oxalate（DMO） to ethylene glycol（EG） shows that the selectivity of EG depends on the Cu0/Cu＋ratio. Catalyst prepared with the addition of ammonia solution at n（NH3）/n（Cu2＋） = 0.9 for precipitation–deposition gains a more suitable Cu0/Cu＋ratio upon reduction and thus has a higher selectivity for EG.
