Biochar cation exchange capacity (CEC) is a key property that is central to biochar environmental applications including the retention of soil nutrients in soil amendment and removal of certain pollutants in water-filtration applications. This presentation reports an innovative biochar ozonization process that dramatically increases the CEC value of biochars by a factor of 2. The ozonized biochars also show much better adsorption of methylene blue. Biochar samples either untreated or treated with ozone were analyzed with pH and CEC assays, water field capacity measurement, elemental analysis, methylene blue adsorption, FTIR-ATR spectroscopy, and Raman spectroscopy. Gaseous products analyses were carried out with an online universal gas analyzer over the duration of ozone treatments and temperature changes were monitored with a thermal imaging camera. The results demonstrate a doubling of CEC with a concomitantly large drop in pH of the ozonized biochar compared to the untreated sample, brought about by the creation of acidic oxygen functional groups on biochar surface, which may represent a significant progress in the viability of using surface-oxygenated biochar as a soil amendment.

Biochar surface oxygenation through ozonization for enhanced cation exchange capacity

255th National Meeting (2018)

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