Adsorptive capacity of activated carbon derived from rice husks for azo dye removal from solution
摘要
This study aimed at developing low-cost adsorbents from waste rice husk which is a nuisance to farmers through sulfuric (H2SO4) and phosphoric (H3PO4) acid treatment. The raw rice husk (RRH) was treated with 85% H3PO4 and H2SO4 and calcined at 500 °C in a muffle furnace. The effects of initial methyl orange (MO) concentrations, adsorbent dosage and contact time on the dye removal process was studies. The adsorbents were characterized by Fourier transform infrared spectroscopy (FITR), Energy Dispersive X-ray (EDX) and scanning electron microscopy (SEM). The infrared spectral data revealed the emergence of a new peak at 1097.27 cm−1 in the phosphoric acid modified RH (MH3PO4RH) along with shifts and reductions in the intensities of functional groups. The adsorption peaks at 3377.12, 3336.73 and 3449.99 cm−1 for the RH indicates the existence of hydrogen-bonded OH stretching. In RH, the C–H Stretching vibration at 2923.00, 2844.20 and 2925.57 cm−1 respectively revealed the alkane functional group being present. The peaks around 2143.06 – 2378.09 cm−1 indicate the presence of C≡C stretching while the peaks around 1671.63 – 1741.96 cm−1 correspond to C = O stretching that may be attributed to the hemicelluloses. The surface morphology changed, as seen in SEM and EDX photos, with rougher cavities and a higher proportion of carbon content, which may have an impact on the adsorptive qualities. The surface area of RRH, 0.32 m2/g increased by 14.5 fold in M