Synthesis of chitosan/MCM-48 and β-cyclodextrin/MCM-48 composites as bio-adsorbents for environmental removal of Cd2+ ions; kinetic and equilibrium studies

• Published in: Reactive & functional polymers Vol. 154; p. 104675
• Main Authors: Jiang, Yuliang, Abukhadra, Mostafa R., Refay, Nermen M., Sharaf, Mohamed F., El-Meligy, Mohammed A., Awwad, Emad Mahrous
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2020; Elsevier BV
• Subjects: Adsorbents; Adsorption; Cadmium; Chemical synthesis; Chitosan; Composite materials; Correlation coefficients; Cyclodextrins; Endothermic reactions; Equilibrium modeling; Functional groups; MCM-48; Multilayers; β-Cyclodextrin; β-Cyclodextrin; Cadmium; Equilibrium modeling; MCM-48; Chitosan; Adsorption
• ISSN: 1381-5148; 1873-166X
• DOI: 10.1016/j.reactfunctpolym.2020.104675

Chitosan/MCM-48 (CH/MCM) and β-cyclodextrin/MCM-48 (CD/MCM) composites were synthesized as promising and eco-friendly bio-adsorbents for Cd2+ ions from water. The composites showed novel porous structures and complex functional groups making them of high adsorption capacities. The adsorption behaviors of CH/MCM and CD/MCM are highly controlled by the tested pH values realizing their best capacities at pH 7. The kinetic evaluation indicated the excellent agreement between the uptake of Cd2+ by CH/MCM and CD/MCM with the pseudo-first-order model achieving equilibrium intervals of 480 min and 600 min, respectively. Based on the values of Chi-squared (X2) and the correlation coefficient, the composites displayed adsorption properties related to the Freundlich hypothesis with a multilayer form. Additionally, the Gaussian energies of them are 2.23 KJ/mol (CH/MCM) and 2.46 KJ/mol (CD/MCM) reflecting physical uptake of Cd2+ by the studied composites. The thermodynamic investigation implied spontaneous uptake of Cd2+ by the composites with endothermic reactions. The prepared CH/MCM and CD/MCM are of 122.4 mg/g and 152.2 mg/g theoretical qmax, respectively which are higher values than the reported results for several studied adsorbents. Moreover, the synthetic CH/MCM and CD/MCM showed high reusability as adsorbents for Cd2+ to be applied effectively six times. [Display omitted] •Chitosan/MCM and β-cyclodextrin/MCM composites were used as bio-adsorbents for Cd2+ ions.•Chitosan/MCM and β-cyclodextrin/MCM achieved uptake capacities of 122.4 and 152.2 mg/g, respectively.•The adsorption reactions of Cd2+ by the composites are physical, spontaneous, and endothermic reactions.•They are recyclable materials and have higher uptake capacities than several studied absorbents.