I use a Philippine produced coco peat substrate, COCOGREEN, with charcoal added to it. It does absorb odor and does not harm my inverts. It is basically carbon which is commonly found in most habitats. Activated carbon is also widely used as a filtering medium in aquariums. I don't see any problems.
i use various types and mixtures of substrate, depending on the order and species in mind. All said i usually use finely sifted organic potting soil as a base medium. I put about a 1/4"-1/2" of horticulture charcoal (available at lowes, home depot, or most green houses/nurserys) on top of a layer of gravel. Now organic potting soil and a layer of water filled gravel create ideal conditions for fungis, mold, spores, bacteria, mites, etc etc etc. So you can imagine problems that may arise if not properly upkept. I also mix in sparse amounts of charcoal into the entire substrate mix itself. I have seen no signs of the charcoal affecting scorpions, theraphosids, or solifugae. Even when they burrow to the bottom layer and become in directly extended to the charcoal for extended periods of time. The charcoal helps and mostly stops and bacterial or fungal outbreaks, and one can only assume it helps to deter mites and other pests. Including symbiotic mites that may find their way into your enclosure.
So i would condone the use of horticulture charcoal in appropriate amounts.
Although odor in an enclosure to me are signs of unhealthy conditions.. or a prey item or large bolus left. Not to offend.