Removing Duplicates Entries from each column with a for loop.

All, I am trying to use a For loop to parse a spreadsheet where each column is a computer and remove duplicate software entries in the column. This individual macro code works.

 Sub Remove_Dups()
    
    Columns("A:A").EntireColumn.Select
    Range("A1:A20").RemoveDuplicates Columns:=1, Header:=xlYes
   
    Columns("B:B").EntireColumn.Select
    Range("B1:B20").RemoveDuplicates Columns:=1, Header:=xlYes
   
    Columns("C:C").EntireColumn.Select
    Range("C1:C20").RemoveDuplicates Columns:=1, Header:=xlYes
   
    Columns("D:D").EntireColumn.Select
    Range("D1:D20").RemoveDuplicates Columns:=1, Header:=xlYes
   
    Columns("E:E").EntireColumn.Select
    Range("E1:E20").RemoveDuplicates Columns:=1, Header:=xlYes
   
    Columns("F:F").EntireColumn.Select
    Range("F1:F20").RemoveDuplicates Columns:=1, Header:=xlYes
    
    Columns("G:G").EntireColumn.Select
    Range("G1:G20").RemoveDuplicates Columns:=1, Header:=xlYes
    
    Columns("H:H").EntireColumn.Select
    Range("H1:H20").RemoveDuplicates Columns:=1, Header:=xlYes
    
    
End Sub

When I try to use a for loop it does nothing.

Sub Remove_Dups()

Dim col As Integer

 For col = 1 To 8
   Columns("A:A").EntireColumn.Select
   Range(Cells(col, 1), Cells(col, 20)).RemoveDuplicates Columns:=1, Header:=xlYes
 Next col

End Sub

Thanks for the help.
TonyM