How to remove tile adhesive from percelain tiles.

[SkipperGrant]

Hello,

Laid a bunch of porcelain 1200mm oak tiles and been difficult to clean off tile adhesive.  When we wash down and use the germi its difficult to see the white ghosting when everthing is wet.  Tried scrubbing brush on harder stuff and still on.  Can you use some kind of hydrloric solution

  

acid wash or something else?