Hola, en mi caso para crear una URL para SEO, suelo usar esta función, espero te sirva.
Código PHP:
Ver originalfunction sanear_string($toClean) {
'Š' => 'S', 'š' => 's', 'Ð' => 'Dj','Ž' => 'Z', 'ž' => 'z', 'À' => 'A', 'Á' => 'A', 'Â' => 'A', 'Ã' => 'A', 'Ä' => 'A',
'Å' => 'A', 'Æ' => 'A', 'Ç' => 'C', 'È' => 'E', 'É' => 'E', 'Ê' => 'E', 'Ë' => 'E', 'Ì' => 'I', 'Í' => 'I', 'Î' => 'I',
'Ï' => 'I', 'Ñ' => 'N', 'Ò' => 'O', 'Ó' => 'O', 'Ô' => 'O', 'Õ' => 'O', 'Ö' => 'O', 'Ø' => 'O', 'Ù' => 'U', 'Ú' => 'U',
'Û' => 'U', 'Ü' => 'U', 'Ý' => 'Y', 'Þ' => 'B', 'ß' => 'Ss','à' => 'a', 'á' => 'a', 'â' => 'a', 'ã' => 'a', 'ä' => 'a',
'å' => 'a', 'æ' => 'a', 'ç' => 'c', 'è' => 'e', 'é' => 'e', 'ê' => 'e', 'ë' => 'e', 'ì' => 'i', 'í' => 'i', 'î' => 'i',
'ï' => 'i', 'ð' => 'o', 'ñ' => 'n', 'ò' => 'o', 'ó' => 'o', 'ô' => 'o', 'õ' => 'o', 'ö' => 'o', 'ø' => 'o', 'ù' => 'u',
'ú' => 'u', 'û' => 'u', 'ý' => 'y', 'ý' => 'y', 'þ' => 'b', 'ÿ' => 'y', 'ƒ' => 'f', ',' => '', '.' => '', ':' => '',
';' => '', '_' => '', '<' => '', '>' => '', '\\'=> '', 'ª' => '', 'º' => '', '!' => '', '|' => '', '"' => '',
'@' => '', '·' => '', '#' => '', '$' => '', '~' => '', '%' => '', '€' => '', '&' => '', '¬' => '', '/' => '',
'(' => '', ')' => '', '=' => '', '?' => '', '\''=> '', '¿' => '', '¡' => '', '`' => '', '+' => '', '´' => '',
'ç' => '', '^' => '', '*' => '', '¨' => '', 'Ç' => '', '[' => '', ']' => '', '{' => '', '}' => '', ' '=> '-',
);
}