Study On The Modification Of Polyurethane Foam And Its Adsorption Performance For Gold Ion

Polyurethane foam is widely used in the separation and enrichment of gold in geological samples,but the biggest problem facing the direct use of polyurethane foam adsorption gold is the poor selectivity and the low adsorption rate(about 80%).The factors of significantly lower results of the gold in the enrichment of tungsten ore,antimony ore and lead ore by polyurethane foam were systematically analyzed.Then the effeciive solution was proposed for the most important interfering elements Sb and W in adsorption of gold.Diphenyl thiourea-loaded polyurethane foam was prepared by loading diphenyl thiourea,which greatly improved the selectivity of adsorption.Then the method of rapid determination of gold in tungsten ore,antimony ore and lead ore by polyurethane foam adsorption was established.On the other hand,a lot of research has been done on improving the adsorption rate of gold by polyurethane foam.A method for the determination of gold in geological sample by Inductively Coupled Plasma Optical Emission Spectrometry(ICP-OES)with polyurethane foam was first established.Although the adsorption rate of pretreated polyurethane foam to gold was greatly increased,but the linear range is still narrow,the adsorption effect of high content samples was still not satisfactory.Therefore,increasing the adsorption capacity by modifying polyurethane foam loaded extraction agenthas become the research direction in this paper.Compared with unloaded polyurethane foam,carbon-loaded polyurethane foam can effectively increase the adsorption capacity of gold,but the efficiency of existing preparation method of carbon-loaded polyurethane foam is not high,this paper established the preparation method of carbon-loaded polyurethane foam made from activated carbon ethanol solution.By optimized conditions including the type of load medium,concentration of reagent,soaking time,the time of the preparation of carbon-loaded polyurethane foam was greatly shortened and the preparation efficiency was greatly improved.At present,the time of prepared 100 carbon-loaded polyurethane foams can be controlled within 30 min.A method for determination of gold in geological samples by ICP-OES combined with carbon-loaded polyurethane foam made by using this method was proposed.At the same time,the adsorption behavior of gold on carbon-loaded polyurethane foam was investigated in static adsorption experiments.The effects of initial mass concentration of gold(0.1,0.5,2.0,10.0 mg/L)and temperature(5,25,50,7?)on the adsorption of gold on carbon-loaded polyurethane foam were evaluated.The thermodynamic parameters,adsorption isothermal and kinetic models for the adsorption of gold on carbon-loaded polyurethane foam were calculated.The results show that the adsorption of gold on carbon-loaded polyurethane foam was a spontaneous in low temperature and exothermic process,the adsorption equilibrium was basically reached after 20 min,the equilibrium adsorption decreases with the increase of temperature,the adsorption rate was jointly controlled by intra-particle diffusion and membrane diffusion.The adsorption data has been described by the Langmuir isotherm models.Kinetics fit pseudo second-order models,hence adsorption kinetic parameters were calculated,and the correlation coefficient R2>0.9990.The adsorption dominated by a monolayer chemical adsorption.The research has guiding significance in the application and renovation of carbon-loaded polyurethane foam to gold enrichment.