Adsorbent materials can be used for the removal of organic acids from air in storage rooms with heritage collections. The organic acid removal eﬃciency of two commercially available activated carbon air-ﬁlters were tested in situ in two unoccupied stores with densely packed collections. One ﬁlter was designed for outdoor type pollutants (Filter A), while the other was designed for organic acids in indoor air (Filter B). Furthermore, the acetic acid removal eﬃciency of a desiccant silica gel rotor used for dehumidiﬁcation was measured in a laboratory at diﬀerent relative humidity levels. Finally, passive removal of acetic acid by silica gel and unﬁred clay brick were tested in a chamber, and for clay brick at room level as well. Filter B had the highest removal eﬃciency. The removal eﬃciency of both ﬁlter types depended on the airﬂow and the ﬁlter performance varied considerably in situ from the values reported from standard laboratory tests. Increasing the ﬁlter airﬂow reduced the removal eﬃciency from 77% and down to 7% for Filter A, and from 92% to 24% for Filter B. There was almost no eﬀect of active air ﬁltration on the concentration of organic acids when this was measured in the middle and in the corner of the storage rooms away from the ventilation inlets. The desiccant dehumidiﬁer removed 98–100% of the acetic acid from the air, independently of the relative humidity. The desiccant rotor will, however, only be running when there is a need for dehumidiﬁcation and as a result will only periodically remove pollutants. The high acid removal eﬃciency by dry silica gel was furthermore demonstrated in a chamber test. A clay brick wall in a test room established a concentration gradient across the room and reduced the concentration of organic acids by 56% compared to close to the emission source.
Bibliografisk noteFunding Information:
This work was supported by the Independent Research Fund Denmark grant number: DFF-6121-00003.
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