This function strips incompatible iso characters from ms office documents. If no ascii conversion is found the character is ignored.

msword_to_ascii.php

/**
 * This function strips incompatible iso characters
 * from ms office documents. If no ascii conversion is found
 * the character is ignored.
 *
 * @author hannuraina
 * @param  array|string   $replace  value(s) to replace
 * @return array|string   $items
 */
function msword_to_ascii($replace) {
  if (empty($replace)) {
    return $replace;
  }

  // convert single values to array
  $items = !is_array($replace) ? [$replace] : $replace;
  array_walk($items, function(&$item, $key) {
    if (is_string($item)) {
      $value = @iconv('UTF-8', 'ASCII//TRANSLIT', trim($item));

      // word/excel generated characters will fail with
      // default iconv implentation on linux. target
      // windows input charset.
      $item = $value ? $value : @iconv('Windows-1252', 'ASCII//TRANSLIT//IGNORE', trim($item));
    }
  });

  // determine return type from original input
  return is_array($replace) ? $items : reset($items);
}