Improvement of methylene blue adsorption properties of lemon peel by surface modification

Abstract

In this study, methylene blue adsorption properties of lemon peel (LP), as agricultural waste, was improved by surface modification. Surface modification of the LPs was achieved by applying sulfuric acid (H2SO4) in the ratio of 1:1, 1:2, and 1:3 w/w. Adsorption success of surface modification was determined by the measurement of methylene blue solution with UV-VIS. Adsorption results were obtained at various concentration to apply for kinetic and isotherms equations. Also, surface functional groups and surface morphological properties of raw and modified LP were examined by FT-IR spectrometer and scanning electron microscope (SEM) before and after adsorption. Methylene blue adsorption capacity of LP after modification (200 mg/g) increased roughly 2.5 times compare to those in raw peel. The most suitable isotherm (R2=0.998) and kinetic models (R2=0.999) were determined as Langmuir Type I and Pseudo-second-order, respectively. Limited changes in FT-IR spectra was observed (-OH, -CH3, -C=O, -COOH).