Method for the treatment of work pieces with a palladium colloid solution

Abstract

The invention relates to a method for the treatment of work pieces with a palladium colloid solution by bringing the work pieces into contact with the colloid solution, palladium being recovered after the use of the colloid solution. This is achieved by separating palladium colloid particles from the colloid liquid by means of a molecular filter. With this method it is easy to continuously and largely completely separate palladium from the spent processing solutions without investing large amounts of chemicals, energy and time. The spent processing solution may especially be worked up after separation of the part of the solution containing palladium such that palladium can be recovered completely and be reused for further processing.

1 . Method for the treatment of work pieces with a palladium colloid solution, comprising the method step of bringing the work pieces into contact with the colloid solution, wherein after treatment of the work pieces with the palladium colloid solution palladium is recovered from said solution by a method comprising the following method steps: 
 bringing the palladium colloid solution into contact with a molecular filter and    separating palladium colloid particles contained in the palladium colloid solution from said solution by means of the molecular filter.    
     
     
         2 . Method according to  claim 1 , wherein the molecular filter has an exclusion pore size of from 200 Dalton to 10.000 Dalton.  
     
     
         3 . Method according to  claim 2 , wherein the molecular filter has an exclusion pore size of at least 500 Dalton.  
     
     
         4 . Method according to  claim 3 , wherein the molecular filter has an exclusion size of at least 2.000 Dalton.  
     
     
         5 . Method according to any of the preceding claims, wherein the molecular filter is made of a material, selected from the group comprising polysulfones, perfluorinated polymers and ceramics.  
     
     
         6 . Method according to any of the preceding claims, further comprising the following method steps: 
 a. bringing the work pieces into contact with the colloid solution for activating the work pieces;    b. after the activating treatment has been carried out removing the colloid solution adhering to the surfaces of the work pieces from the surfaces with a rinsing liquid;    c. pressing the rinsing liquid through the molecular filter, the liquid having passed through the molecular filter being a permeate liquid and the liquid not having passed through the molecular filter being a concentrate liquid;    d. producing a palladium colloid solution by using the concentrate liquid and adding suitable replenishment agents to the concentrate liquid in appropriate amounts.    
     
     
         7 . Method according to  claim 6 , wherein the colloid solution is removed from the surfaces of the work pieces by spraying the surfaces with a rinsing liquid after the activating treatment has been carried out.  
     
     
         8 . Method according to any of the preceding claims, wherein palladium is recovered from a hydrochloric palladium colloid solution stabilized with tin.  
     
     
         9 . Method according to  claim 8 , wherein the palladium colloid solution is mixed with a hydrochloric acid solution prior to separating the colloid particles from the palladium colloid solution with the molecular filter.