Research on the characteristics and absorption capacity of Direct red 79 of pyrolysis biochar from lemongrass residue

Abstract

In this study, distillation waste of lemongrass was carbonized via pyrolysis under limited oxygen conditions, and they were investigated at different temperatures: 300-400-500-600°C for an hour. Lemongrass biochar is characterized using Scanning electron microscopy (SEM), infrared spectroscopy (IR) and Brunauer-Emmett-Teller (BET). The results showed that besides the main components of carbon (C) and oxygen (O), thermochemically produced biochar also contained small amounts of Mg, Ca, Si, and P. The structure still contained organic functional groups such as C=O, O-H, C-O-C, etc., with a specific surface area of 79.7231 ± 1.5243 m²/g. The lemongrass biochar samples were evaluated for its ability to adsorb dye (DR79) at different pH levels, concentrations of adsorbate and adsorbent, temperatures, and times. The highest experimental efficiency was achieved at 600°C with pH=2, adsorbing DR79 at 10 ppm with 2 g/l of material, reaching approximately 98.07%. The adsorption mechanism may be physical adsorption. These results show that, lemongrass biochar is a potential adsorbent in treating dye pollution.