Utilization of the biomass with simple preparation method is one of the keys to prepare cost-eff ective photocatalysts. Photocatalysts

such as oxidized activated carbon (OAC), Ni-, Co- doped OAC (MOAC) were prepared from bio-waste Calophyllum

inophyllum (punnai) shells via physico-chemical activation. The characterization of photo-catalysts using SEM-EDAX,

XRD and FT-IR analysis. The band-gap energy of photo-catalysts and their photo-catalytic activity were determined by DRS

and PL analysis, and the surface morphology of the catalysts was confi rmed using SEM-EDAX analysis. The insertion of

metals on the surface of the OAC and the eff ective functional groups of the catalysts were confi rmed by the FT-IR analysis.

The photo-catalytic degradation of Rhodamine-B (Rh-B) was performed using prepared photo-catalysts under 16-W lowpressure

mercury lamp-UV-light exposure. To attain maximum effi ciency, experimental parameters were optimized, such

as solution pH (8), exposure time (100 min), photo-catalyst dosage (150 mg), and initial dye conc. (30 mg/L). Ni- and Codoped

OAC have achieved higher degradation effi ciency (91.99% for NOAC and 97.28% for COAC) than OAC (35.55%)

because of metal dopants acted as semiconductors, which play a vital role in dye-degradation process. Kinetics and isotherm

parameters were evaluated using the eff ects of exposure time and initial dye conc. experimental data, respectively. Based on

the experimental result, a degradation mechanism has been predicted. Metal-doped OAC is an effi cient material for degradation

of dye-molecules from polluted-water due to its active adsorption sites. The formation of super oxide anion radicle

to produce reactive hydroxyl radicles on metal surface, which enhanced the catalytic activity on the surface of the catalysts

in the process of dye-degradation.