15And he killed it, and Moses took the blood, and with his finger put it on the horns of the altar around it and purified the altar and poured out the blood at the base of the altar and consecrated it to make atonement for it.
The verb purified comes from the word that normally means to sin (ḥṭ’). In this instance the word is in the Piel form which means to take away sin.
15 And he killed it, and Moses took the blood, and with his finger put it on the horns of the altar around it and purified the altar and poured out the blood at the base of the altar and consecrated it to make atonement for it.