I had the same problem. It took me a lot of research to get it fixed.
I use the "utf8_general_ci" collation for my database (and for the tables inside it).
In the head section of my views, I have: <meta charset="UTF-8" />
In CodeIgniter's config.php file, I have: $config['charset'] = 'UTF-8';
In CodeIgniter's database.php file, I have:
'char_set' => 'utf8',
'dbcollat' => 'utf8_general_ci',
And all my CodeIgniter controllers, libraries, models and views are saved as Utf-8 files (not plain ASCII). My text editor has an option for that.
Hope this will help you.