Is it possible to divorce an absent wife whose whereabouts are unknown, and what are the necessary procedures for that? And is she entitled to maintenance, given that she left the home without her husband's knowledge?

If the wife is disobedient (nashiz), she is not entitled to maintenance. Divorce occurs merely by uttering the words, and it does not require the wife's presence or knowledge. As for legal procedures, one should refer to specialists. It is advisable to present the matter to Islamic centers, as they function as a Sharia (definition) court. Civil divorce alone does not terminate the marriage according to Sharia. It is also important to note that residing in non-Muslim countries entails risks to one's religion and morals.