Nombona, Nolwazi2025-01-302025-01-302025-042024-10*A2025http://hdl.handle.net/2263/100403DOI: https://doi.org/10.25403/UPresearchdata.28269458.v1Thesis (PhD (Chemistry))--University of Pretoria, 2024.This study evaluates the effectiveness of adsorbent films for the adsorptive removal of organic dyes, particularly methylene blue (MB) from aqueous solutions. The adsorbent films consist of solvothermally synthesized metal-organic framework (MOF)/crystalline nanocellulose (CNC) composites, supported on a cellulose acetate (CA) substrate. Three adsorbent films were fabricated, i.e. CA-supported MOF-5/CNC (1), CA-supported Cu-BDC/CNC (2), and CA-supported Ni-BDC/CNC (3). This composition results in water-stable adsorbent films, which are recyclable with minimized secondary contamination. The successful preparation of the adsorbent films was verified by several characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) analysis and X-ray photoelectron spectroscopy (XPS). Batch adsorption experiments were carried out for the decontamination of MB from aqueous solutions under different conditions including varying pH, contact time, initial MB concentration, and temperature. The optimum adsorption conditions were at pH 11, at 360 minutes, at an initial MB concentration of 6 mg/L, and at 25 °C. Under these conditions, the adsorbent films achieved adsorption capacities between 2.79 - 4.29 mg/g, with corresponding maximum % removals between 77 - 85 %. The adsorption isotherms and kinetic models revealed multilayer chemical adsorption on the surface of film 1 as indicated by the experimental results which were best described by the Freundlich isotherm and pseudo-second-order kinetic models. On the surfaces of films 2 and 3, the isotherms and kinetic models revealed monolayer chemical adsorption according to the Langmuir isotherm and pseudo-second-order kinetic models. Thermodynamic parameters showed the adsorption processes were exothermic in nature and feasible. The films showed good recyclability, after five adsorption cycles, film 1 maintained 76% of its original adsorption capacity, film 2 maintained 73%, and film 3 67%. The films showed pH-dependent selectivity, demonstrating preferential affinity for anionic methyl orange (MO) at acidic pH and a preference for cationic MB at alkaline pH. The practical applicability of the adsorbent films was assessed in the treatment of real textile industry effluent where the films achieved between 20 - 45 % effluent removal. The economic assessment of the adsorption processes was conducted by considering the cost of chemicals and the energy cost of the adsorption process. The adsorption costs for films were calculated to be between USD 43.60 and 53.00. These findings suggest that cellulose derivatives and MOFs have the potential to perform synergistically to result in stable, recyclable, versatile, and cost-effective adsorbents for the removal of organic dyes from polluted water.  en© 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.UCTDSustainable development goals (SDGs)Metal organic framework (MOF)NanocelluloseWater remediationAdsorptionNatural and Agricultural sciences theses SDG-06SDG-06: Clean water and sanitationThesisu17226199https://doi.org/10.25403/UPresearchdata.28269458