Adsorption of Methylene Blue and Methyl Orange from Aqueous Solution using Orange Peel and CTAB-Modified Orange Peel

Cationic and anionic dyes are frequently used in industrial sectors and cause many environmental and health problems. Orange peel has the potential to absorb dye as an adsorbent. This study aimed to explore the adsorption of methylene blue (MB) as a cationic dye and methyl orange (MO) as an anionic dye using orange peel (OP) and its modification using cetyltrimethylammonium bromide (CTAB). OP and OP-CTAB biomass materials were characterized using FT-IR (Fourier transform infrared), surface area analysis using BET (Brunauer-Emmett-Teller) and SEM EDX (Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy). Based on the study results, OP has a microporous skin structure and OP-CTAB mesopores. Based on the effect of contact time, it is known that the best adsorption process on MB was to use OP adsorbent with the optimum amount of dye adsorbed produced at 50th minute that was 5.881 ppm, while the best adsorption process on MO was using OP-CTAB adsorbent with the optimum amount of dye was at 50th that was equal to 13.34 ppm. Based on the adsorption kinetics data, the adsorption of MO and MB dyes by OP and OP-CTAB followed the pseudo second order reaction kinetics model. The adsorption of MO and MB by both OP and OP-CTAB followed Langmuir's adsorption isotherm, meaning that the adsorption process in both MO and MB using OP and OP-CTAB appeared on homogeneous surface sites, while there was no interaction between adsorbate molecules and adjacent locations that means the adsorption process only occurred physically.