Retrieving data which doesn't exist in the other table

I have two tables SCHOLAR and MEMBER table. I want to display list of scholars from Scholar table which scholar_id doesn't found in Member table. But the result of my Second dd is empty which actually it has data in database. What am i doing wrong?I think my code is fine.

public function list()
{
    $scholars = Member::all();
    $scholar_ids = [];
    foreach ($scholars as $scholar) {
    array_push($scholar_ids, $scholar->scholar_id);
}

$scholar_exits = Scholar::where('scholar_id','=', $scholar_ids)->get();

<!-- First -->
dd($scholar_ids);
<!-- Second -->
dd($scholar_exits);

}

<!-- First dd result -->
array:7 [▼
  0 => 7
  1 => 8
  2 => 12
  3 => 13
  4 => 14
  5 => 15
  6 => 16
]

<!-- Second dd result -->

Collection {#275 ▼
  #items: []
}

Hope anyone can help me here.

via Chebli Mohamed