Study On The Methods Of Recovering Palladium From Waste Liquid From The Process Of Producing Tetraphenylphenylphosphine Palladium

Palladium and palladium catalysts are widely used in modern industry and ordinary day's lives,and the demand for palladium is substantially increasing every year.However,as a natural resource,the reality of palladium resource is not optimistic.As a kind of non-renewable resources,the global palladium resources are relatively scarce.In order to reduce the excessive consumption of energy,but also reduce the burden on the environment,the recovery and utilization of secondary palladium is particularly important.On the base of reviewing the recovery methods of palladium and the research status all over the world,the waste liquid from the factory producing of tetrakispalladium was chosen.After analyzing its composition and physicochemical properties,several methods to recovery palladium from low palladium-containing organic waste liquid were investigated,and the main results are listed as following:(1)By zinc reduction method,the effects of feed ratio,reaction temperature and time on recovery were investigated.When the feed ratio of waste liquid and zinc powder is 10: 1,the temperature is 45 ?,the reaction time is 6 hours,the recovery rate of palladium is 87.10%.(2)Chemical precipitation combined with electrodeposition method has been developed for purifying palladium after chemical enrichment.The effects of cathode material,palladium concentration,temperature and time on electrodeposition were studied.The separation rate of the chemical precipitation method was 93.66% when the ratio between raw waste liquid and deionized water was 1:2 in netural condition.The recovery rate got 66.10% under the following conditions,in which palladium was deposited at-0.85 V and-0.75 V for 6h at an initial concentration of 95.14mg/L,and the temperature was 25? when copper was used as the working electrode and the graphite electrode as the auxiliary electrode.Combined,the final recovery rate was 61.91%.(3)The adsorption and direct electrodeposition method were abandonedbecause of their low efficiency below 5% and 30% under the best technical parameters.(4)Economic analysis was carried out on the zinc reduction method and chemical precipitation combined with electrodeposition method.From the aspect of higher economic and environmental benefits,the chemical precipitation combined with electrodeposition method was more suitable for industrialization.