The ornamental design for an airpurifier, as shown and described.
1. Air purifier
1.1 : Perspective
1.2 : Front
1.3 : Back
1.4 : Left
1.5 : Right
1.6 : Top
1.7 : Bottom
Material is a metal, synthetic resin, or a combination thereof; The subject design relates to an air purifier, which is a device purifying indoor air by a filtering process; The subject design is entirely formed in a low hexahedron shape, and used by being engaged with a holder or installed in a wall-hanging form; Fig. 1.1 illustrates a perspective view of subject design; Fig. 1.2 illustrates a front view of the subject design; Fig. 1.3 illustrates a rear view of the subject design; Fig. 1.4 illustrates a left side view of the subject design; Fig. 1.5 illustrates a right side view of the subject design; Fig. 1.6 illustrates a top view of the subject design; Fig. 1.7 illustrates the bottom view of the subject design.