Figure 4

Elimination of isocyanic acid from the carbamazepine molecule with remaining dibenzazepine (60, numbering see supplementary information). This reaction occurs during the 1^st decomposition stage of adsorbed carbamazepine and by thermal decomposition of pure carbamazepine. In the latter, both products evolve as gases. For adsorbed carbamazepine, only isocyanic acid is released while dibenzazepine remains on the activated carbon in the 1_st stage independent of its loadings or type of adsorbent.