Preparation and characterization of MWCNT–COOH–cellulose–MgO NP nanocomposite as adsorbent for removal of methylene blue from aqueous solutions: isotherm, thermodynamic and kinetic studies

Abstract: In this work, MWCNT–COOH–cellulose nanocomposite was prepared with MWCNT–COOH, SOCl2 as leaving group and cellulose as an adsorbent (A1); MgO nanoparticles have been successfully coated on the surface of nanocomposite by directly adding to A1 (MWCNT–COOH–cellulose–MgO; A2), magnesium nitrate was added to A1 and MgO nanoparticles were achieved by coating indirectly on the surfaces (MWCNT–COOH–cellulose–MgO; A3). These nanocomposites (A1, A2, and A3) were used for the removal of methylene blue (MB) dye from aqueous solution. For characterization of adsorbent surfaces, the FT-IR, TEM, SEM, and XRD analysis were used. The effects of initial concentration of MB dye, contact time, and temperature on the adsorption were studied. According to the results, 55 min was selected as the optimum contact time for the removal process. The equilibrium data of adsorption were well fitted and the Langmuir (type III) model had the best agreement because it possesses high value of linear regression, high value R², and least value of average relative error, ARE (%). Parameters of thermodynamics including enthalpy (∆H^°), entropy (∆S^°), and Gibbs energy (∆G^°) were calculated. Kinetic data had best agreement with pseudo-second-order model. Graphical abstract: Schematic synthesis of MWCNT–COOH–cellulose–MgO NP nanocomposite as adsorbent[Figure not available: see fulltext.]