3.2. Characterization of OTAB and CMTAB
The efficiency of grafting EDTA to the biomass was evaluated by comparing the carboxyl group and total nitrogen contents
before and after chemical modification, and the results are shown in Table 1. Compared to the OTAB, CMTAB exhibits a sharp increase of almost 3 times in carboxyl group content (from 0.297 to 0.833 mmol g−1). The total nitrogen content of CMTAB (65.7 mg g−1) is also much higher than that of OTAB (29.6 mg g−1). Considering that no other carboxyl or nitrogen source except EDTA is introduced during the whole preparation process, it could be concluded that the EDTA is well grafted to the biomass.