Adsorption of dyes using hexadecyltrimethylammonium modified pineapple leaf powder

The feasibility of pineapple leaf powder (PLP) and surfactant modified pineapple leaf powder (SMPLP) in removing diverse types of dyes was evaluated. SMPLP was prepared by reacting PLP with different concentrations (1.0 mM, 2.5 mM and 4.0 mM) of cationic surfactant, hexadecyltrimethylammonium bromide (HDTMA-bromide). The PLP and SMPLP were characterized using Fourier Transform Infrared (FTIR) Spectroscopy. Screening test on the adsorption of PLP and SMPLP on different types of dyes was performed. The PLP and SMPLP exhibited higher adsorption affinity towards cationic and anionic dyes, respectively. The research was further emphasized on the adsorption capacity of PLP and SMPLP towards methylene blue (MB) and methyl orange (MO). The adsorption process was carried out in batch mode at room temperature with different initial concentrations of MB and MO aqueous solutions ranging from 5.0 to 1000.0 mg/L. The suitability of adsorbent was tested by fitting the adsorption data into Langmuir and Freundlich isotherm equilibrium models. The experimental data fitted well with the Langmuir isotherm model for both MB and MO with monolayer adsorption capacity of 52.632 and 47.619 mg/g, respectively. The highest removal of MB was achieved using PLP while SMPLP treated with 4.0 mM HDTMA-bromide showed the highest adsorption capacity towards MO. The decrease of the MB removal capacity by PLP modified with higher concentration of HDTMA-bromide indicated that the adsorbed cationic surfactant blocked the adsorption sites of MB. The removal of MO was the highest with SMPLP treated with 4.0 mM HDTMA-bromide due to the increase in positive potential of SMPLP that can adsorbed anionic charge of MO. Therefore, the utilization of surfactant modified pineapple leaves could enhance the adsorption of anionic contaminants from aqueous solution