Synthesis and characterization of activated carbon from red pumpkin skin for the removal of ionic dyes

Abstract

The aim of this study was to valorize agricultural waste in the form of red pumpkin skin to prepare activated carbon chemically activated by ZnCl2, used as a biosorbent for the removal of two types of dyes, namely methylene blue (MB) and Congo red (CR), present in industrial effluents. Physico-chemical tests were used to characterize the new biosorbent such as Fourier transform infrared spectrophotometry, scanning electron microscopy, pH at zero charge potential, X-ray diffraction and Brunauer Emmett Teller. The results obtained showed that the biosorbent owns an amorphous structure and a specific surface area of 36.51 m2/g. The adsorption of CR and MB onto the prepared activated carbon was performed in batch mode. The effect of several parameters such as contact time, initial concentration, dose of activated carbon, pH and temperature on dye removal was investigated. The adsorption of MB and CR on activated carbon is described by the Langmuir model and is governed by a pseudo-second-order kinetics model with a correlation coefficient of 0.999 for both dyes.