Is it permissible for us to benefit from capital that was deposited in a usurious bank, and its forbidden interest has been disbursed previously, knowing that we now want to place it in an Islamic bank or invest it in buying an apartment?

Money mixed with usurious interest does not cease to be fundamentally lawful, and the zakat your father paid on it is valid. The usurious interest must be disposed of by spending it on Muslim welfare. The remaining money is lawful. The poor are permitted to benefit from unlawful money (usurious interest) to the extent of their essential needs.