Carbonization of rubber (Hevea brasiliensis) seed shell by one-step liquid phase activation with H2SO4 for methylene blue adsorption

The rubber (Hevea brasiliensis) seed shell, which is an agricultural waste, was carbonized by one-step liquid phase activation with H2SO4 to be a potential bio-char adsorbent for methylene blue (MB) adsorption from aqueous solution. Carbonized rubber seed shell (CRSS) was characterized by a CHNS-O, Brunauer-Emmett-Teller (BET), X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope with an energy dispersive X-ray spectrometer (SEM-EDX), point-of-zero charge (pH(pzc)), and proximate analyses. Batch mode adsorption studies were conducted by varying operational parameters such as adsorbent dosage (0.02-0.30 g), solution pH (3-11), initial MB concentrations (50-300 mg/L) and contact time (0-1,440 min). The equilibrium data were well correlated by Langmuir isotherm compared with Freundlich and Temkin models. The maximum adsorption capacity, q(max), of CRSS for MB adsorption was 208.3 mg/g at optimum pH 8 and temperature 303 K. The kinetic uptake profiles are well described by the pseudo-second-order model. All results mentioned above revealed that the CRSS can be feasibly utilized for the removal of MB from aqueous solution.