How i make to convert 8 -> 08 in sqlite?

I have on several dates database:

07:00
8:00
09:00
10:00

when I used the command in sqlite:

DELETE FROM notification WHERE hour < '11:00'

when inserting to the database in a given 8:00 insert it converts to 08:00!

Insert:

INSERT INTO notificacao VALUES(null, '8:00', 'test', 'test', 1)