ORIGINAL ARTICLE Adsorption mechanism of a cationic dye on a biomass-derived micro- and mesoporous carbon: structural, kinetic, and equilibrium insight Hosein Banna Motejadded Emrooz 1 & Mahdi Maleki 2 & Alimorad Rashidi 3 & Mohammadreza Shokouhimehr 4 Received: 11 September 2019 /Revised: 15 December 2019 /Accepted: 17 December 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract In this research, equilibrium, kinetics, and adsorption mechanism of methylene blue on a relatively large surface area (1437 m 2 g -1 ) Azolla-derived micro- and mesoporous carbon has been investigated. The porous activated carbon was charac- terized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman and also X-ray photoelectron spectroscopy (XPS), N 2 sorption, and high-resolution transmission electron microscopy. Remaining methylene blue solution revealed that the adsorption energy and adsorption capacity of the porous carbon are 21.76 kJ mol -1 and 1930 mg g -1 , respectively. Based on the kinetics results, pseudo-second-order kinetic model is dominant during the adsorption process. Diffusion of methylene blue in the porosities and in the space between the graphitic planes of carbons is the rate-limiting parameters. Adsorption of methylene blue into the graphitic planes and the micro-porosities leads to some compressive stresses on the graphitic planes. The relative graphitization value of the prepared carbons will decrease during adsorption process. FTIR and XPS results demonstrate the effect of surface nitrogen groups on the adsorption of methylene blue. During the adsorption process, a relative percent of pyridinic nitrogen will decrease, pyrrolic and graphitic nitrogen of graphitic layers will eliminate and N-(C) 3 and H-N-(C) 2 nitrogen appear. Keywords Biomass-derived porous carbon . Dye adsorption . Adsorption kinetics . Adsorption mechanism . Cationic dye 1 Introduction Dye contaminants are of the main pollution sources of water and their presence can result in serious problems for many forms of life. These toxic substances have been utilized in different industries such as printing, paper, textile, food, cos- metics and electroplating [1]. Considerable amounts of waste- water are generated during the utilization of dyes in the indus- trial processes [2]. Therefore, improper disposal of these con- taminants can bring about serious environmental problems [3]. Methylene blue (MB), one of these toxic dyes, is widely used in the large number of industries as a colorant agent. Although this compound is not classified as so hazardous material, it can cause permanent eye damages in human and animals. On inhalation, it can lead to short period of rapid or difficult breathing. Ingestion of methylene blue results in the burning sensation and may give rise to several problems such as nausea, vomiting, profuse sweating, mental confusion, and methemoglobinemia [1–3]. Therefore, removal of this harm- ful organic component from the wastewaters is of great neces- sity [4]. Several processes such as trickling filter [5], membrane filtration [6], activated sludge [7], chemical coagulation, and adsorption [8, 9] have been developed for removing of dye contaminants from wastewaters. Among them, adsorption has been paid more attentions due to the effectiveness, low cost, * Hosein Banna Motejadded Emrooz Motejadded@iust.ac.ir * Mohammadreza Shokouhimehr mrsh2@snu.ac.kr 1 Nanotechnology Department, School of New Technologies, Iran University of Science and Technology, Narmak, Tehran 16846, Iran 2 Center of Excellence for Ceramic Materials in Energy and Environment Applications, School of Metallurgy & Materials Engineering, Iran University of Science and Technology, Narmak, Tehran 16846, Iran 3 Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), Tehran, Iran 4 Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 08826, Republic of Korea Biomass Conversion and Biorefinery https://doi.org/10.1007/s13399-019-00584-1