Q:

How can I remove junk characters with regex? 

I have a web application that reads the contents of a web page and parses the sentences using an NLP algorithm.  I have been using regex to split the contents into single sentences and then parsing them. 
I would like to remove characters like Â from my sentences.  These characters, I imagine, are because of the HTML encoding. 
I obviously cannot use a regex like [^\w\d]+ or its variations because I need the punctuations intact.  Of course I could add individual exceptions for each of the punctuation like [^\w\d\.,:]+ and so on, but I would like it if there is an easier way to do this, like probably a character class that knows it is a... funny character? 
Any help will be much appreciated.  Thanks. 
EDIT: The app is built with PHP and I am using a simple file_get_contents() to fetch the HTML data from the site and reading the contents inside <p> tags. 

A:

This was mentioned in the comments by @TheGreatCO but you are able to create a character class of "special" characters.  You can use the hex code values to create a range in a character class.  So for any special character over ASCII 127 would be this. 
[\x80-\xFE]

That would match anything but your most basic characters.  For reference sake, here's a list of the ASCII character table with their hex codes. 
This page discusses the different ways you can reference special characters in regex.