Not that I know of, there are some research loosely talking about it here and there.
this question is mostly regarding how to use technology to prevent
part of the warranties it brings us, in a jugdement that often is totally subjective, and even sometimes doesn't have social consensus.
This is a very interesting question, even though you could argue that for some contents, social consensus could be reached with overwhelming majority. The problem is that a truly public blockchain is built in a way that forbids explicit regulation by a third party... (as long as it doesn't hold a majority of resources, but if it were the case I doubt that owners of illegal content would choose that system)
There is no proper regulation because blockchains are (supposed to be) anonymous, decentralized and append-only. In such a system, you must also ask yourself, who does the regulation ? (decentralization) How ? (append-only) Under which authority ? (decentralization) And who is to blame ? (anonymity)
Answering those questions is far from being trivial, and having those answers accepted by the participants might prove even harder... I'm pretty sure that any solution would go against one or several of the core principles I mentioned above…
However, I think that there is (at least) 2 distinct cases.
Illegal data stored on the blockchain :
Given how blockchain systems are currently designed, there is no way to modify data while safekeeping the integrity of the chain (hash coherency along blocks). The only solution would be a consensual hard fork, "removing" the data from the chain, similar to what was done following the DAO hack. But this is against the core principles... and I really don't see it being done every time an illegal content is identified, even less without financial incentive to do so.
But still, anyone refusing the hard fork could still provide the illegal content.
Links to illegal data are stored on the blockchain :
If only IPFS, TOR or URL links are stored on chain (which is much less costly), then there is a way to regulate those through off chain classical jurisdiction. Taking down a server / node or file would invalidate the link but wouldn't have any impact on the blockchain state. But given that TOR is still running and partially used for such activities, this would just let the problem outside the blockchain instead of solving it for real.
It's also interesting to think about blockchains such as Filecoin which puts financial incentives over IPFS storage... are they responsible ? How could they be since it is data agnostic, but how could they not be, at least partially, since they are rewarding the availability of the content ? There is a limited discussion about this here.
Overall I think it's a very important question, but economic blockchain regulations are barely there, so content regulation will surely have to wait for a while, assuming it becomes feasible AND that participants agree to it.
So, no, there is no real effort to do so because there is no room for regulation / deletion in current public blockchain systems. That's how it's built, for better or worse.
I hope that partially answers your question.