This study was carried out to study the effectiveness of green functionalization on three carbonaceous adsorbents which are CNF, MWCNT and GAC. There are two methods of green functionalization used; DI water functionalization and thermal treatment. From FTIR images of H2O-functionalization, CNF and MWCNT shows some improvement where low concentration OH band's intensity is increase. However, MWCNT is the only adsorbent that obtained additional functional group after functionalized in water bath sonicator at 55oC for 24 hours which are 2 peaks of O-H at 3849.4 and 3743.2 cm-1, and alkynyl C=C stretch at 2343.1 cm-1. However, there is no significant change in functional group attached to GAC after the sonication. After thermal treatment, the FTIR images show that low concentration OH band of all three adsorbents have reduced or completely removed. While, from FESEM images, all carbonaceous adsorbents were exposed to microwave radiation (heat no 3) for 10 minutes. Before the thermal treatment, there are a lot of bright spots can be seen indicating there are surface functional groups present on the surface of the adsorbent. Unfortunately, after being treated by microwave radiation, only a few functional groups attached to the surface can be seen. Adsorbent surface becomes smoother. All these changes will reduce the adsorption capacity of the dye. The diameter range is remained the same after the thermal treatment The diameter range for CNF and MWCNT prior to heat treatment is 52.05 - 105.2 and 12.33 - 22.16 nm respectively. After treatment, range of diameters for CNF is 54.51 - 100.1 nm, while, for MWCNT diameter is range from 13.49 - 20.37 nm. © 2016 The Authors.