Adsorption Behavior of Congo Red on Carbon Materials Based of Humic Acid

Abstract

In this study, a carbon composite based on humic acid (CAH) was synthesized by partially carbonizing humic acid by using aluminum sulfate with a mass ratio of 2:3 and a leavening agent oxalic acid with a fixed mass. The morphology and microstructure of the sample are measured by scanning electron microscope (SEM), x-ray diffractometer (XRD), thermal analysis (TG-DSC), Raman spectroscopy (Raman), X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FT-IR) is used to analyze the composition and structure of materials. The BET surface area of CAH is determined to be 149 m²/g. Congo red was used as a model adsorbent for adsorption research. When the dye concentration is 400 mg/L and 10mg of adsorbent powder is used. CAH has the highest dye removal rate of adsorption capacity. The pseudo-first-order and pseudo-second-order kinetic models were used to describe the kinetic data and the Langmuir and Freundlich models were applied to describe the adsorption isotherms. The results showed that the equilibrium adsorption data were found to fit better to the Langmuir adsorption model and the kinetic process of adsorption could be described by the pseudo-second-order model. Compared with humic acid, CAH composite materials can effectively improve the adsorption rate and adsorption capacity of Congo red, and the adsorption capacity is as high as 3986mg/g within 30 minutes. In addition, considering the cost issue, this study selected low-cost humic acid as a carbon source to prepare composite materials, emphasizing the importance of cost.