Adsorption of Basic Dyes Using Walnut Shell-based Biochar Produced by Hydrothermal Carbonization

• DOI: 10.1007/s40242-018-8018-0
• Publication Date: 2018-07-11T05:33:12Z
• Authors: Chunli Kang; Ling Zhu; Yixue Wang; Yuhan Wang; Kunkun Xiao; Tao Tian
• Keywords: Hydrothermal Carbonization; Nitric acid; Specific surface area; Methylene blue; Potassium hydroxide; Malachite green; Carbon fibers

Hydrothermal carbon(HC) was prepared from walnut shells, which are abundant in Northeastern China. The prepared HC was used as a precursor to produce nitric acid modified carbon(MC). The hydrothermal carbonization included dehydration and decarboxylation processes wherein the hemicellulose was completely decomposed and the cellulose was partly decomposed, with some oxygen-containing functional groups being produced. The aromaticity, specific surface area and pore content of the HC increased, but its polarity decreased. With 6 mol/L nitric acid and a modification time of 15 min, the specific surface area and pore content decreased, but the proportion of oxygen-containing functional groups on the surface increased significantly, thereby improving the dye adsorption performance. The adsorption of methylene blue and malachite green was best described by the pseudo-second-order kinetic and Langmuir isotherm models. The adsorption capacity of MC was determined to be much larger than that of HC.