Chitosan-Modified Biochar and Unmodified Biochar for Methyl Orange: Adsorption Characteristics and Mechanism Exploration

Abstract

In this study, shrimp shell-derived chitosan (CS) and rice husk-derived biochar (RHB) were produced; CS and RHB were then used to synthesize chitosan-modified biochar (CSBC) hydrogel beads. N2 adsorption (77K), SEM-EDX and FT-IR techniques were used to evaluate the physicochemical properties of the adsorbents. A batch experiment was conducted to test the methyl orange (MO) adsorption performance of RHB and CSBC. The results showed that the MO adsorption process was strongly pH-dependent. The kinetics were well described by the pseudo-second-order and intra-particle diffusion models, assuming the chemisorption and intraparticle diffusion mechanisms govern the adsorption process. Homogeneous adsorption for MO on the surface of RHB and CSBC was also assumed since the isotherm data showed the best-fit to the Langmuir model. Under the experimental conditions of initial pH 3, dosage 0.2 g, contact time 240 min and temperature 298K, the maximum adsorption capacity of CSBC and RHB for MO dye adsorption was 38.75 mg.g−1 and 31.63 mg.g−1, respectively. This result demonstrated that biochar had better performance after modification with chitosan, which provided more functional groups (i.e., −NH2 and −OH groups) for enhanced electrostatic interactions and complexation between MO and CSBC. Overall, CSBC is an effective adsorbent for the removal of MO from aqueous solution.

Study on the adsorption performance of amoxicillin by hydrothermally modified coconut shell activated carbon

“…The Zeta potential point of unmodified C is 2.21, whereas the Zeta potential point of the coconut shell C after hydrothermal alkali treatment dropped to 1.03. This change indicates that the surface charge status of the modified C had changed, which may be due to some changes in the OH groups on the C surface during the hydrothermal alkali treatment, resulting in more positive charges on its surface 41 . This change helps the modified C bind to the carboxyl group on the amoxicillin molecules, thereby improving its adsorption performance.…”

Preparation of layer‐assembled W/O/W‐type microencapsulated beads and application in solid‐state fermentation

“…The positions of these absorption peaks are not shifted, indicating that the main functional groups of M‐0–3 have not changed. M‐0 has absorption peaks caused by COO– and –NH stretching vibrations at 1631 cm −1 (Loc et al., 2022), and the absorption peaks at this location almost disappeared in M‐1–3, probably because sodium alginate and chitosan chemically bonded with the hydrophilic groups on the surface of M‐0 during the coating process, which also led to the appearance of several new absorption peaks in the low band of M‐1–3 from 1500 to 500 cm −1 peaks…”

Composite Cryogels for Drug Delivery Applications: A Preliminary Study with Dye as a Model Drug

“…The amine -NH2 group in chitosan was able to accept a proton from a hydronium ion. As a result, electrostatic interaction easily occurred between NH3 + and MO -; therefore, the cryogel showed good entrapment efficiency against MO (Loc et al, 2022). Based on the results, it can be said that Gel:Cs cryogels are suitable drug release systems for loading water-soluble, anionic, and weakly acid drug molecules such as MO.…”