AC is not suitable for electrolysis because
In electrolysis the ionization of the electrolyte takes place where the positive and negative charges move towards opposite electrodes. For this the electrodes are required to be maintained at opposite polarity as long as the process continuous which is possible while supplying a dc current. But if we pass an ac current the polarity of the electrodes will be continuously changing and the ions will not be attracted towards any particular electrode resulting in no ionization. Hence electrolysis cannot take place with ac current.