Exemption 2 times in one trip

I will be buying a rountrip ticket from Atlanta (US) to Shanghai and then another rountrip ticket from Shanghai to Hong Kong. My flights will be Atl -> Shanghai -> stay 4 days -> Hong Kong -> stay 5 days -> Shanghai -> 12 hour layover -> Atl. Will this work? I know I can use the 144 exemption on the way there but can I use 24 hr exemption on the way back?