如何用String.Empty替换字符串中的隐藏（奇怪）字符

please look at these codes :

请看这些代码:

Health = HttpUtility.HtmlDecode(Health).Replace("%", string.Empty).Replace("\"", string.Empty).Replace("‭‎",string.Empty).Trim();
File.WriteAllText(@"d:\a.txt", Health);
char[] ar = Health.ToCharArray();
File.WriteAllText(@"d:\a.txt", string.Empty);
foreach (char a in ar)
{
    File.AppendAllText(@"d:\a.txt", a.ToString() + Environment.NewLine);
}

int a = int.Parse(Health); //-> I Always Have Error In This Line
Healt