I was doing a research for ways to remove VOCs from the atmosphere without using electronic devices like air purifiers but through passive material. As a result I found about Zeolite Rocks which are claimed that can absorb formaldehyde, ammonia and other VOCs from the air or water passively.
As you may expect I purchased 500gr of small Zeolite Rocks to conduct an experiment. I want to mention here that is hard to find these rocks because they aren’t commercialized, it’s easier to find them as filters for aquarium because in general are used to remove ammonia from the water.
They also claim that the rocks are “rechargeable” by heating them in the oven in 200°C/400°F for 30min they can be used again and again.
I took daily measurements for 6 days without having the rocks anywhere near the sensor and the average result for the VOCs was 524ppb. After a week I placed under the AQI monitor 400gr of Zeolite Rocks and again I logged the measurements for a week. The average result for a week of VOCs with the rocks is 461ppd. A difference of 63ppb less VOCs.
After that I repeated the experiment, 6 days without rocks and 6 days with rocks but this time I isolated the room and I kept it without ventilation. The values were higher in this case and the rocks seemed like they couldn’t absorb VOCs any more.
In conclusion the rocks may absorb gases but you need a great quantity of rocks to achieve a good result, for example 100ppd less VOCs something which make it hard. Remember by opening the windows for a few minutes you can refresh the air quality immediately in case the outdoor air is in better conditions than the indoor.