Is it permissible to issue a divorce to a wife who has been absent for two years, and is it a condition for her to be pure when divorced?

A permissible divorce occurs during a period of purity (Tuhr) in which intercourse has not taken place. If you wish to divorce your wife, divorce her with a single pronouncement during a period of purity in which you have not had intercourse with her. The divorce takes effect the moment it is uttered, even if the wife is not present or unaware of the divorce. If you divorce her while she is at her family's house, she must return to your house and remain there until her waiting period (Iddah) expires. You are not permitted to expel her from it. Allah Almighty says: "O Prophet, when you [Muslims] divorce women, divorce them for [the commencement of] their waiting period and keep count of the waiting period, and fear Allah, your Lord. Do not expel them from their houses, nor should they leave, unless they commit a clear immorality." The woman in her waiting period must remain in the marital home, and her husband is not permitted to expel her from it. Divorce is not a trivial matter and should only be resorted to when all means of reconciliation have been exhausted.