Adsorption of Mn+7 ions on chitosan/cellulose composite: experimentally and theoretically approaches

Water pollution is threatening the environment, humans and all living organisms. Therefore, it is crucial to apply efficient, safe and cheap ways to keep water clean. In this regard, natural wastes (algae, fruits, etc) can be used as energy sources to compensate the shortage of resources and energy. In our study, well washed and grinded Fucus spiralis (FS) and Sargassum muticum (SM) were impregnated with chitosan (CH) to obtain new composites (FS-CH and SM-CH). The new campsites were then used as adsorbents for Mn+7 metal ion from wastewater. To characterize these composites, we apply IR and SEM tests. This characterization was done on various factors, temperature, composite weight, pH, metal ion adsorption isotherms, kinetics, thermodynamics, time and the initial concentration of Mn+7. The results showed that the metal ion removal percentage was inversely proportional to temperature. The metal ion removal percentage was consistent when the weight of composite changes from 0.05 g to 0.3 g for (FS-CH), whereas it was consistent till 0.2 g then decreased when the weight of composite changes from 0.2 g to 0.3 g for (SM-CH). The metal ion removal percentage was also consistent under pH 0-6 then decreased. The metal ion removal percentage was directly proportional to time. The reusability was 100% in the second time then decreased at 3(rd) and 4(th) times. The thermodynamic results showed that the adsorption of the metal ion Mn+7 onto (FS-CH and SM-CH) was spontaneous and exothermic process. Langmuir, Freundlich, Temkin isotherm and first second order model, order, Intraparticle diffusion kinetic model, Elovich kinetic models were applied on the adsorption isotherm of Mn+7 onto (FS-CH and SM-CH). Quantum mechanics calculations were carried out using DFT methods to compute ESP, Frontier molecular orbitals and global properties. Also, QMAIM was performed to analysis and calculate the types of interactions between chitosan/cellulose composite and Mn+7 ions in gas and water phases. The binding energy between Mn+7 and chitosan/cellulose composite was calculated in gas and water.

Automated summary

In this study, new composites of FS and SM impregnated with chitosan were used as adsorbents for Mn+7 metal ion in wastewater. The percentage of metal ion removal was found to be dependent on factors such as temperature, pH, composite weight, and time. The adsorption process was shown to be spontaneous and exothermic.