Biobased carbon for effective removal of rhodamine B and Cr(VI) from aqueous solution: kinetic, isotherm and thermodynamic study

We synthesized waste biomass-based partly graphitized activated carbon from Samanea saman waste pods (SSWPAC) and used it to remove hazardous dye rhodamine B (Rh B) and metal Cr(VI) from aqueous solution. The prepared adsorbent showed a remarkable surface area of 546.016 m 2 g −1 . The adsorbent was characterized by applying Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive x-ray analysis, Raman spectroscopy, and X-ray diffraction. Within 50 min, 99.2% elimination of Rh B dye was observed at pH 2 using 1.0 g L −1 of the adsorbent, while Cr(VI) removal was 98.3% at pH 2 using 2.5 g L −1 of the adsorbent within 120 min at room temperature. The correlation coefficient R 2 favored pseudo-second-order kinetics in kinetic analyses of both adsorption processes. The isotherm experimental values of Rh B and Cr(VI) fits to Freundlich adsorption systems with correlation coefficient R 2 = 0.998 and 0.999 respectively. The results showed maximum adsorption capacity of SSWPAC for Rh B (101.01 mg g −1 ) and Cr(VI) (64.52 mg g −1 ). The phytotoxicity study exhibited successful removal of these pollutants from the solutions under study.