can sodium persulfate etch or damage a titanium heater? I use Sodium Persulfate to etch copper on a PCB process. I have been using glass heater on the etching tank but the glass is too fragile; it breaks too easily. 

I read that titanium heater is used commercially (in aquariums as well). I don't know much about chemistry, could anyone tell me if it is okay to use titanium with Sodium Persulfate?

Sodium Persulfate to water ratio is 1:10 and the maximum temperature is about 50 C.
If the surface of the immersed element is all titanium, the answer appears to be that it won't get corroded unless the temperature is much higher than 50$^\circ$C; see http://www.azom.com/article.aspx?ArticleID=1336

The case is changed if there are joints or parts made of something else, as in this illustration: http://www.saltwatereddies.com/content-popup_image/pID-2199/popup_image.html

I would think that would not be so safe.  

Of course, if you've been breaking glass heating elements right and left, you have little to lose by trying the titanium one...