Study on removing mo from tungstate solution by activated carbon loaded with copper

It is difficult to separate Mo from tungstate solution due to their extreme similar chemical properties. At present the most effective method for separating Mo from tungstate solution is based on the sulfur affinity of Mo. Through sulfidation, MoO42- can be transformed into MoS42-, while W still exists as WO42-, and then MoS42- can be selectively separated.We notice that copper also shows strong affinity towards sulfur, and copper or copper compounds can adsorb sulfur-containing species through Cu–S bonding. Then, if copper or its compounds can be loaded on the surface of an appropriate carrier with high specific surface area, a new effectively adsorbent for removing Mo should be prepared.In this research, activated carbon is chosen as the carrier to load copper to prepare a new adsorbent, and the preparation technology is investigated. The results indicate that the optimal preparation conditions of copper-loaded activated carbon comprise electroplating voltage 4 V, electroplating time 20 min, calcination time 2 h and sulfidation with Na2S solution. Under the conditions of adsorption time 30 min and 5.0 g copper-loaded activated carbon, 98.85% Mo can be removed from 100 mL feed solution with 50 g L−1 WO3 and 0.351 g L−1 Mo. There are only 0.001–0.008 g WO3/g Mo lost and all the separation coefficients (after separation, separation coefficient = (WO3(in solution)/WO3(in residue))/(Mo(in solution)/Mo(in residue))) are higher than 6000. Freundlich isothermal adsorption model is employed to study the adsorption mechanism and it can well describe the relationship between adsorption capacity and equilibrium concentration.