The Assembly, Regulation And Application Of Cu-EDTA Complex In Aqueous Solution

According to the development status of current techniques for the treatment of electroplating wastewaters containing Cu-EDTA, Cu2+ is removed out of wastewater in the form of chelated heavy metal Cu-EDTA because of its convenience and no secondary pollution, where adsorption is one of the widely used methods to remove Cu-EDTA. However, there still exist some problems in the adsorption process. For example, the synthesis or modification of adsorbent needs to be taken place though a complex process; there is only an interaction in the adsorption process, leading to poor efficiency. Hence, some corresponding solutions for above problems are proposed and the specific research work and achievements are as follows:(1) With the assistance of dodecylamine(DA), the chelating metal pollutant Cu-EDTA can be separated from wastewater and made into lamellar Cu-EDTA@2DA supramoelcualr material by self-assembly. DA was employed to bind with Cu-EDTA to form the Cu-EDTA@2DA building block through electrostatic attraction between Cu-EDTA and DA, and further self-assemble into giant lamellar structure by hydrophobic interaction. This kind of Cu-EDTA@2DA supramoelcualr material is used skillfully as adsorbent and it is striking that it shows excellent efficiency in adsorbing anion dyes and oil-soluble dyes due to electrostatic attraction and hydrophobic interaction, respectively. Meanwhile, this kind of Cu-EDTA@2DA supramoelcualr material can be recycled upon desorption of dyes in N, NDimethylformamide(DMF). As far as we know, this is the first case by using industrial wastes to build well-defined useful supramolecular materials through self-assembly, which realizes the strategy of ?fight poison with poison‘. Maybe this work can open a new vista for the practical application of molecular self-assembly technique.(2) Polymer/surfactant mixed system was used for the first time to remove the Cu-EDTA from wastewater, where PEI not only binds SDS through strong electrostatic attraction and hydrophobic interaction but also coordinates with Cu2+ in the present of EDTA. PEI is a ―bridge‖ to connect Cu-EDTA and SDS and then to form insoluble aggregates and precipitate out of water through cooperative interaction among polymer, surfactant and Cu-EDTA. This cooperative effect in the removal of Cu-EDTA is significantly related to pH because of the existence of PEI, which not only influence the electrostatic attraction between PEI and SDS but also influence the coordination between PEI and Cu2+. And the window of optimal pH is in a broad range of 9~10. Although the addition of electrolyte(NaCl) can screen strong electrostatic attraction between PEI and SDS, hydrophobic interaction between the hydrocarbon tail of SDS and the hydrophobic segments( the ethylene groups) of PEI is the main drive force to form insoluble aggregates, leading to Cu-EDTA out of water. Such a cooperative flocculation process is of great potential interest in the removal of heavy metal ions from industrial water containing surfactants.