Iodine and methylene blue adsorption properties of the high surface area nanoporous carbon materials derived from agro-waste and rice husk is reported. Rice husk was pre-carbonized at 300 °C in air followed by leaching out the silica nanoparticles by extraction with sodium hydroxide solution. The silica-free rice husk char was mixed with chemical activating agents sodium hydroxide (NaOH), zinc chloride (ZnCl2), and potassium hydroxide (KOH) separately at a mixing ratio of 1:1 (wt%) and carbonized at 900 °C under a constant flow of nitrogen. The prepared carbon materials were characterized by scanning electron microscopy (SEM), Fourier transformed-infrared spectroscopy (FT-IR), powder X-ray diffraction (pXRD), and Raman scattering. Due to the presence of bimodal micro- and mesopore structures, KOH activated samples showed high specific surface area ca. 2342 m2/g and large pore volume ca. 2.94 cm3/g. Oxygenated surface functional groups (hydroxyl, carbonyl, and carboxyl) were commonly observed in all of the samples and were essentially non-crystalline porous particle size of different sizes (<200 μm). Adsorption study revealed that KOH activated samples could be excellent material for the iodine and methylene blue adsorption from aqueous phase. Iodine and methylene blue number were ca. 1726 mg/g and 608 mg/g, respectively. The observed excellent iodine and methylene blue adsorption properties can be attributed to the well-developed micro- and mesopore structure in the carbon material. This study demonstrates that the agricultural waste, rice husk, and derived nanoporous carbon materials would be excellent adsorbent materials in water purifications.
Simultaneous Methylene Blue Adsorption and pH Neutralization of Contaminated Water by Rice Husk Ash
