Synthesis Of Pdtu Series Resin, Its Gold, Silver Ions Adsorption Properties Of Study

In this paper, research on thiourea resin and its adsorption to noble metal ions were reviewed, and the preparation of a series of polymeric ester thiourea resins (PDTU) as well as its adsorption performance was studied by the numbers.PDTU resins were produced from triphosgene, diethylleneglycol, potassium thiocyanate and polyamines by three steps. The yields based on diethylleneglycol for the four resins were 90.2%, 91.3%, 92.1% and 92.5% respectively. IR proved that the functional groups of resins were accorded with expectant. TG and DTA indicated that PDTU- I and PDTU-IV had favorable thermal stability below 187°C and 135°C respectively.Adsorption performance was studied by batch and dynamic methods. The batch experiment showed that the adsorption performance of PDTU-IV and for Au(III) and Ag( I) were favorable, the maximum adsorption capacity for Au(III) and Ag( I) were 4.65 and 5.30 mmol·g^-1. Adsorption mechanism was also studied. The results showed that the adsorption data fit the Boyd's diffusion equation of liquid film and Langmuir adsorption isotherm well, and the adsorption was an endothermal process. The results of the dynamic experiment showed that the capacity of PDTU-IV for Au(III) was 2.94 mmol·g^-1. The ratios of adsorption and desorption were 78.62% and 72.24%. Meanwhile the capacity of PDTU- I for Ag( I ) was 2.50 mmol·g^-1. The ratios of adsorption and desorption were 25.85% and 63.96% respectively. Based on the above research, the adsorption performance for binary systems (noble-base metal ions) was also studied. In Au(III)-base metal ions systems, the seperated coefficients achieved 800 upwards. Meanwhile in Ag( I )-base metal ions systems, the seperated coefficients achieved 10 upwards. The large seperated coefficient showed that PDTU resins had good selectivity performace for the noble metal ions in the binary systems. And resins had favorable repetitive property.The resins fore-and-after adsorptions were characterized by SEM, IR, XRD and XPS. SEM showed that the appearance of resins had a lot of changes after adsorption. IR proved that the peaks of the functional groups of resins had changes in displacement or intensity. The XRD showed that there was no Au(0) or Ag(0) on resins. The XPS of resins revealed that the Au(III),Ag( I) ions were chelating with the resins to form a compound while adsorbing.