How to rid black ants in my apartment ?

half a teaspoon of BAKING SODA

half a teaspoon of ICING SUGAR

you can mix the dry powders in a tablespoon using a matchstick as a stirstick.    Now grab a pinch of the dry powder between your thumb and finger and sprinkle it where you see the ants walking  .  They are following the ant in front of them looking for food.  You are supplying the food.  Sprinkle it near the baseboard where the ants are and leave it.  The ants will pick it up and take it back to their Queen (she is the only ant that eats and lays baby ants.) They become the workers .  She can live for 3 years.  So when she eats the baking soda, she explodes. DEAD  the ants themselves expire within 2 weeks.  Done unless there is more than 1 queen so you may have to do it again.  You do not need a lot of powder to kill them off so that tablespoon could be used for 3 dozen queens.  My mom uses it in the garden too.  Safe for pets and baby. Non poisonous to stretchy bellies.

if they are the very small odoriferous (sugar) ants then terro gel will work but it takes awhile, just keep feeding them 

"black ants" are carpenter ants and none of the liquids and baits you find at most stores will work because they are only interested in eating wood not sugar.

You have to buy bait that works on carpenter ants.

With the right bait, they will carry it back and feed it to the queen killing the entire colony

Report it to the apartment management. If enough people are having problems they could spray outside the building.  See if you can spot any ant nests in the ground. 

Buy gel form of ant killer. Put it were you see their trail coming in, by the floor radiator. 

Do NOT spray. Give them time to take the the gel poison back to the nest. Put a few dots in the kitchen

We get ants every year early summer. We have the house sprayed in the outside and use gel in the inside,

https://www.homedepot.com/p/COMBAT-0-95-oz-Source-...

Terro does work great but another method (and it depends on the type of ant, I have found this to work with the small ones) is to combine even amounts of confectioners sugar and baking soda then sprinkle it around the area where you see the ants.  The ones running around will collect it to bring back to the queen who will then eat it and explode.  The baking soda makes this happen, the sugar is the lure.  Once the queen is dead the other ants, the drones will either die off or leave as they no longer have a queen.  Unfortunately this method can take up to 2 weeks for results but the up side is most kitchens have confectioners sugar and baking powder.  Good luck!

Type of ant comes into play. My go to is combat gel, comes in a tube. You just put a little in the paths the ants take and wait. If it is the right stuff for those ants, you'll see them start to gather around it in a few hours. Let them enjoy, they take it back and it kills the entire colony of them. Takes about three/four days.  Little black ants are often looking for sugar based things. Big black ants like carpenter ants, will love that gel.

Find where they enter and spray that with ant spray, or with a smell they don't like such as mint or wintergreen.  If they find another way in, do that entry too.  

Go outside on the ground floor and look around the house for any sign of ants on or near the house.  Spray there or buy ant traps.  

Terro liquid bait traps are the best.  They will attract more ants, but that is good.  Keep putting out traps until there are not more coming.  The ants are taking them back to their nest and killing the queen.  You can try to seal off entry places, but they'll find more.  Just kill the scouts going forward and use the baits again in 6 months if they come back.

--edit--

Don't use sprays. They generally just kill on the spot meaning the nest still lives.

I second the motion of "?" Terro liquid ant bait stations.

The natural remedies' mostly work .....but the bait stations are designed for the food to be taken to the colony which will eliminate the source. 

Terro liquid ant bait stations