Remove All Html - Javascript Entities

Hi

I want your opinion about removing all no human-text (in addition html,php,javascript tags) sympols from a textarea for max security

I used CHtmlPurifier() to purify the field but not work with encoded characters like (maybe needs some settings)

<script src=http://www.example.com/malicious-code.js></script>

I could use preg_replace but I want a way based on Yii
How to achieve that with the minimum code?

Thanks