Table 2 Total organic nitrogen determined for the solid catalysts.

From: Magnetic silica particles functionalized with guanidine derivatives for microwave-assisted transesterification of waste oil

Sample name

Nitrogen conc. in the catalyst (wt%)

Nitrogen conc. in the catalyst (mg/g)

Fe3O4-SiO2-EDG

2.72

27.2

Fe3O4-SiO2-DCG

0.38

3.8

Fe3O4-SiO2-DIG

1.23

12.3