Comparative Adsorption of Methylene Blue Dye on Hexane-Washed and Xanthated Spent Grated Coconut (<i>Cocos nucifera</i> L.): Isotherms, Thermodynamics and Mechanisms

Abstract

A batch system investigated the application of two types of chemically modified biosorbents derived from spent grated coconut (Cocos nucifera) powder to adsorb methylene blue (MB) from aqueous solutions. The biosorbents were characterised by spectroscopic and quantitative analyses. The assessment of MB adsorption onto the investigated biosorbents was studied at different experimental conditions with different pHs (2-9) and different initial concentrations of MB (10-400 mg/L) at three different temperatures (298, 308, and 318 K). The maximum adsorption capacity (q max ) of xanthated spent grated coconut (XSGC) was higher than that of hexane-washed spent grated coconut (HSGC). The thermodynamic study indicated that the MB adsorption process was spontaneous for both biosorbents. Desorption of MB-loaded biosorbents was carried out using HCl, NaOH, and Na 2 EDTA solutions. A desorption ratio of more than 90% was obtained over three adsorption/desorption cycles for HSGC. However, XSGC demonstrated poor MB desorption, implying a stronger MB interaction with XSGC, which could be attributed to H-bonding, Yoshida H-bonding, n-π, and π-π bonding. The study showed that HSGC and XSGC could be applied as biosorbents to remove low MB concentrations from aqueous solutions.

Thermal Fabrication of Magnetic Fe3O4 (Nanoparticle)@Carbon Sheets from Waste Resources for the Adsorption of Dyes: Kinetic, Equilibrium, and UV–Visible Spectroscopy Investigations

“…The presence of carbon sheets decorated with carbonyl groups in the entire structure of the Fe 3 O 4 (np)@CSs enabled the required matrix to carry and protect magnetic iron oxide nanoparticles, as well as the carbonyl active sites attracting dye molecules during adsorption [ 46 , 47 , 48 ]. The driving forces during the adsorption of methylene blue, neutral red, and methyl orange onto magnetic Fe 3 O 4 (np)@CSs may involve Van der Waals forces, electrostatic interaction and dipole–dipole interaction between lone pairs of electrons in the dyes molecules and iron oxide structures which cause the positively charged Fe 3 O 4 (np)@CSs surfaces, as well as between the carbonyl groups and S centers in methylene blue dye [ 49 ].…”

Hydrogen Peroxide Treated Desiccated Coconut Waste as a Biosorbent in Malachite Green Removal from Aqueous Solutions

“…The spectra of DCW, HPDCW, and MG-laden HPDCW did not exhibit any notable differences, except for the existence of a new peak at 1518 cm -1 in the spectrum of MG-laden HPDCW. The spectra exhibit a broad peak at about 3356 cm -1 , suggesting the existence of hydroxyl, carboxylic, and amine functional sets in cellulose and lignin (Azaman et al, 2018;Khalid et al, 2022). Furthermore, the C-H groups derived from cellulose groups are found within the range of 2854 to 2923 cm -1 .…”