Raw and surfactant-modified pineapple leaf as adsorbent for removal of methylene blue and methyl orange from aqueous solution

Abstract

Adsorption capacity of pineapple leaf powder (PLP) and surfactant-modified pineapple leaf powder (SMPLP) in removing cationic dye, methylene blue (MB) and anionic dye, methyl orange (MO) from aqueous solution was investigated. SMPLP was prepared by reacting PLP with different concentrations of cationic surfactant, hexadecyltrimethylammonium bromide (HDTMA-Br). Batch mode experiments were conducted at room temperature to study the effects of initial dye and surfactant concentrations on the adsorption capacity of PLP and SMPLP towards cationic (MB) and anionic (MO) dye. The experimental adsorption isotherm data for both MB and MO fitted well with Langmuir in comparison to the Freundlich model. The maximum monolayer adsorption capacity for MB and MO were 52.6 and 47.6 mg/g, respectively. The highest adsorption for MB and MO were achieved by PLP and PLP treated with 4.0 mM HDTMA-Br, respectively. It was found that PLP and SMPLP showed different adsorption behaviour towards cationic and anionic dye. The MO adsorption was dramatically increased with PLP treated with 4.0 mM HDTMA-Br in comparison to PLP treated with 1.0 and 2.5 mM HDTMA-Br. Thus, the concentration of HDTMA-Br affects the adsorption capacity of SMPLP towards MO. The overall result implied that PLP can be applied as an effective adsorbent material to remove different types and classes of dyes from aqueous solution.