Try this,

unicode_string = unicode_string.encode('ascii','ignore')

Here I update my answer, you cant encode the list object, you need to encode the list elements, i.e. list[0], list[1] or in whatever index that your target value is sitting.

list_element = list_element[0].encode('ascii','ignore')

yeah .. i forgot to tell i already tried that but with utf8. I doesn't work.

QWebException: 'list' object has no attribute 'encode'