Delete duplicates in each column

I want to remove duplicates in every column.
here is the macro code which removes duplicate entries on declared columns.

Sub abc()
'
' abc Macro
'

'
    Columns("AB:AB").Select
    Range("AB117").Activate
    ActiveSheet.Range("$AB$1:$AB$339").RemoveDuplicates Columns:=1, Header:= _
        xlYes
    Columns("AC:AC").Select
    ActiveSheet.Range("$AC$1:$AC$339").RemoveDuplicates Columns:=1, Header:= _
        xlYes
    Columns("AD:AD").Select
    ActiveSheet.Range("$AD$1:$AD$339").RemoveDuplicates Columns:=1, Header:= _
        xlYes
    Columns("AE:AE").Select
    ActiveSheet.Range("$AE$1:$AE$339").RemoveDuplicates Columns:=1, Header:= _
        xlYes
End Sub

What I am trying to get is to remove duplicate in every column in entire sheet through a macro. Please help