The first step should be to ask a question so that you can get an answer which gives you data that you can analyze and discuss. Research generally tries to ask a question that results in some improvement for the world. How to better electrowin copper would be a good question. It seems that you are not just looking to move copper from one electrode to the other, but to understand what might be going on within the solution, because, after all, impure copper in one place is not that different from pure copper in another place.
What is the question that changing anode materials will answer? Different anode materials may dissolve (or not) and change the composition of the solution, which could be desirable, or it might be considered a contamination. Different anode materials will give different voltage vs current curves, because active metals will assist the electrolysis.
In a commercial environment, purifying copper should be routine until the solution becomes so loaded with active metal contaminants that voltage adjustments have to be made to continue plating purest copper, and now a decision has to be made about disposing of the solution. More noble contaminants, like silver and gold would precipitate.
So what could you do with a solution of copper sulfate and ferrous sulfate? Zinc has been mentioned as a frequent impurity, but in large operations, nickel is the soluble impurity of considerable value https://metalrecyclingmachines.com/metal-recycling/metal-recovery-systems/copper-electrolytic-refining-plant.html Lower pH keeps some metal hydroxides in solution rather than precipitating, but will increase the electricity needed to transport a given amount of copper. Nickel sulfate may not be available for you, so I suppose ferrous sulfate could be used.
Perhaps you could pick one anode material and vary the solution to mimic the end of life solution loaded with impurities (in your case, ferrous sulfate). In this case, an iron anode would seem best. Then with variable ratios of copper to iron (and perhaps at a couple of pHs, since this could be changed to assist the process), what voltages, or probably better, what current densities (amps/cm^2) are optimal for squeezing the last bit of copper out of the solution? So the anode could remain the same composition, but vary in area. (You will also have to try just dumping in a wad of steel wool - skip the electrolysis. This is an out-of-the-box shot to just see what will happen. No guarantees.) I suspect that too low a current takes too long but will give pure copper output (as seen on a stainless wire cathode), while a high current density will get the copper out of the solution faster, but it might be contaminated (how? air, iron, solution - I don't know).
Good luck. Be safe.