Code to remove duplicates in datatable

Public Function RemoveDuplicateRows(ByVal _dTable As DataTable, ByVal _colName As String) As DataTable
Dim _hTable As New Hashtable()
Dim _duplicateList As New ArrayList()

For Each drow__1 As DataRow In _dTable.Rows
If _hTable.Contains(drow__1(_colName)) Then
_duplicateList.Add(drow__1)
Else
_hTable.Add(drow__1(_colName), String.Empty)
End If
Next

For Each dRow__2 As DataRow In _duplicateList
_dTable.Rows.Remove(dRow__2)
Next

Return _dTable
End Function