The initial settings for the Scan to USB function of your Brother machine is set to Duplex(two-sided) Scanning. Because of this, even numbered pages will be blank when you scan single-sided documents and save them into mobile device.

The Brother Image Viewer app on your mobile device has a function for deleting even numbered pages.
Follow the steps below to delete the blank even number pages.

1. Open the Launcher on your Android™ mobile device.
    
2. Tap the Brother Image Viewer icon. The list of documents will be displayed.
    
3. Choose the scanned data that has the blank even numbered pages and the thumbnail display will appear.
    
4. Tap Menu and then tap Edit Image or Select page(s) to delete.
    
5. On the upper side of the display, tap   to choose even numbered pages.
    
6. Tap Delete and then tap OK to confirm.