The best way to secure utility sink legs to concrete floor
Get good light to the area.  Make sure floor is very clean and dry.  Buy one tube of 100% clear silicone caulk with gun. Lift each leg individually, stick the tip of the calk tube under the foot and dispense a liberal dose of the calk product directly between the foot and the floor. Let foot rest in puddle.  Repeat for all four legs.  Do not disturb for 24-hours.