If you open IC2's jar file with WinRar, 7-zip, or whatever, you'll find it as assets/ic2/config/general.ini. When you run Minecraft with ic2 installed and no ic2.ini in the config folder, it essentially extracts this file and makes it config/IC2.ini. (I'm not certain of the exact mechanism it uses for getting this file, or at least the contents thereof, to use as IC2.ini)
However, if config/IC2.ini already exists, it tries to use that instead. If you have a leftover one from 1.7.10, this will cause problems, as the recycler blacklist will include "IC2:blockScaffold", but at some point the internal names were changed so that it now needs to be "IC2:scaffold" instead. If you edited this file heavily while playing 1.7.10, you might find it easier to change that one item. If not, it might be easier to delete IC2.ini and let it make a new one.
Just in case I'm misinterpreting your last line: If you're claiming that you don't have an ic2.ini in your config folder (as opposed to not finding it in the jar file, which was my initial interpretation), I can only guess that you're looking in the wrong place, because I can't think of a way you could get that error message without it.